Patent Publication Number: US-11653688-B2

Title: Allulose syrups

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a national phase of International Application No. PCT/GB2016/050422, filed Feb. 19, 2016, which claims priority from U.S. Provisional Application No. 62/168,337, filed May 29, 2015, and U.S. Provisional Application No. 62/120,165, filed Feb. 24, 2015, the entire disclosures of each of which are incorporated herein by reference for all purposes. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to allulose syrups, use of allulose syrups in the manufacture of food or beverage products, and food and beverage products made using the allulose syrups. 
     BACKGROUND OF THE INVENTION 
     Many food and beverage products contain nutritive sweeteners such as sucrose (generally referred to as ‘sugar’ or ‘table sugar’), glucose, fructose, corn syrup, high fructose corn syrup and the like. Although desirable in terms of taste and functional properties, excess intake of nutritive sweeteners, such as sucrose, has long been associated with an increase in diet-related health issues, such as obesity, heart disease, metabolic disorders and dental problems. This worrying trend has caused consumers to become increasingly aware of the importance of adopting a healthier lifestyle and reducing the level of nutritive sweeteners in their diet. 
     In recent years, there has been a movement towards the development of replacements for nutritive sweeteners, with a particular focus on the development of low or zero-calorie sweeteners. One proposed alternative to nutritive sweeteners is allulose (also known as D-psicose). Allulose is known as a “rare sugar”, since it occurs in nature in only very small amounts. It provides around 70% of the sweetness of sucrose, but only around 5% of the calories (approximately 0.2 kcal/g). It may therefore essentially be considered to be a ‘zero calorie’ sweetener. 
     In view of its scarcity in nature, production of allulose relies on the epimerization of readily available fructose. Ketose-3-epimerases can interconvert fructose and allulose, and various ketose-3-epimerases are known for carrying out this conversion. 
     U.S. Pat. No. 8,030,035 and PCT publication no. WO2011/040708 disclose that D-psicose can be produced by reacting D-fructose with a protein derived from  Agrobacterium tumefaciens , and having psicose 3-epimerase activity. 
     US patent publication no. 2011/0275138 discloses a ketose 3-epimerase derived from a microorganism of the  Rhizobium  genus. This protein shows a high specificity to D- or L-ketopentose and D- or L-ketohexose, and especially to D-fructose and D-psicose. This document also discloses a process for producing ketoses by using the protein. 
     Korean patent no. 100832339 discloses a  Sinorhizobium  YB-58 strain which is capable of converting fructose into psicose (i.e. allulose), and a method of producing psicose using a fungus body of the  Sinorhizobium  YB-58 strain. 
     Korean patent application no. 1020090098938 discloses a method of producing psicose using  E. coli  wherein the  E. coli  expresses a polynucleotide encoding a psicose 3-epimerase. 
     Allulose is present in processed cane and beet molasses, steam treated coffee, wheat plant products and high fructose corn syrup. D-allulose is the C-3 epimer of D-fructose and the structural differences between allulose and fructose result in allulose not being metabolized by the human body to any significant extent, and thus having “zero” calories. Thus, allulose is thought to be a promising candidate as a replacement for nutritive sweeteners and as a sweet bulking agent, as it has essentially no calories and is reported to be sweet while maintaining similar properties to sucrose. 
     A convenient product form for allulose is an allulose syrup, i.e. a syrup comprising allulose and water. It has been found that allulose syrups may be susceptible to degradation over time (i.e. gradual reduction in allulose content), to color formation, to the formation of impurities (such as hydroxymethylfurfural—HMF), to crystallization, and to inadequate microbial stability. 
     An object of the present invention is to provide an allulose syrup that addresses the above problems. 
     SUMMARY OF THE INVENTION 
     According to a first aspect, the present invention provides an allulose syrup having a total dry solids content of from 50% to 80% by weight, and comprising allulose in an amount of at least 80% by weight on a dry solids basis, wherein the pH of the syrup is from 2.5 to 6.0. 
     In an embodiment, the allulose syrup has a total dry solids content of from 50% to 70% by weight, and comprises allulose in an amount of at least 80% by weight on a dry solids basis, wherein the pH of the syrup is from 2.5 to 6.0. 
     In an embodiment, the allulose syrup has a total dry solids content of from 70% to 80% by weight, and comprises allulose in an amount of at least 90% by weight on a dry solids basis, wherein the pH of the syrup is from 3.0 to 5.0. 
     In an embodiment, the total dry solids content of the allulose syrup is from 71% to 78% by weight. In another embodiment, the total dry solids content of the allulose syrup is from 71% to 73% by weight. In another embodiment, the total dry solids content of the allulose syrup is from 76% to 78% by weight. In another embodiment, the total dry solids content of the allulose syrup is from 50% to 71% by weight. 
     In an embodiment, the pH of the allulose syrup is from 3.5 to 4.5. In an embodiment, the pH of the allulose syrup is from 3.8 to 4.2. 
     In an embodiment, the allulose syrup comprises allulose in an amount of at least 95% by weight on a dry solids basis. 
     In an embodiment, the allulose syrup comprises less than 1000 ppm of HMF. 
     In an embodiment, the allulose syrup comprises sulfur dioxide in an amount of from 0.1 to 20 ppm. 
     In an embodiment, the allulose syrup comprises sulfur dioxide in an amount of from 1 to 20 ppm. 
     In an embodiment, the allulose syrup comprises less than 10 parts per billion of isovaleraldehyde. 
     In an embodiment, the allulose syrup comprises less than 2 parts per billion of 2-aminoacetophenone. 
     In an embodiment, the allulose syrup further comprises one or more additives. In an embodiment, the one or more additives may include a stability-enhancing additive. In an embodiment, the one or more additives may include an anti-oxidant. In an embodiment, the one or more additives may include a buffer. In an embodiment, the one or more additive may be selected from the group consisting of ascorbic acid or salts thereof; isoascorbic acid (erythorbate) or salts thereof; citric acid or salts thereof; acetic acid or salts thereof; salts of bisulfite or metabisulfite; and tocopherol acetate. 
     In an embodiment, the shelf-life of the allulose syrup as defined by maintaining an allulose content of greater than 80% by weight on a dry solids basis is at least 3, 6, 9, 12 months, or more than 12 months. In other words, an allulose content of greater than 80% by weight on a dry solids basis is maintained when the allulose syrup is stored for at least 3, 6, 9, 12 months, or more than 12 months. 
     In an embodiment, the shelf-life of the allulose syrup as defined by maintaining an allulose content of greater than 90% by weight on a dry solids basis is at least 3, 6, 9, 12 months, or more than 12 months. 
     In an embodiment, the shelf-life of the allulose syrup as defined by maintaining an allulose content of greater than 95% by weight on a dry solids basis is at least 3, 6, 9, 12 months, or more than 12 months. 
     According to a further aspect, the present invention provides a process for preparing an allulose syrup according to the first aspect. The process for preparing the allulose syrup includes:
         providing an allulose syrup;   adjusting the dry solids content of the allulose syrup such that it is from 50% to 80% by weight;   adjusting the allulose content of the allulose syrup such that allulose is present in an amount of at least 80% by weight on a dry solids basis; and   controlling the pH of the allulose syrup so that it is from 2.5 to 6.0.       

     In an embodiment, the process includes:
         providing an allulose syrup;   adjusting the dry solids content of the allulose syrup such that it is from 60% to 80% by weight;   adjusting the allulose content of the allulose syrup such that allulose is present in an amount of at least 80% by weight on a dry solids basis; and   controlling the pH of the allulose syrup so that it is from 2.5 to 6.0.       

     In an embodiment, the process includes:
         providing an allulose syrup;   adjusting the dry solids content of the allulose syrup such that it is from 70% to 80% by weight;   adjusting the allulose content of the allulose syrup such that allulose is present in an amount of at least 90% by weight on a dry solids basis; and   controlling the pH of the allulose syrup so that it is from 3.0 to 5.0.       

     In an embodiment of the process, the dry solids content is from 70 to 78% by weight, the allulose content of the syrup is at least 90% by weight on a dry solids basis, and the pH is controlled to between 3.5 to 4.5. 
     According to a further aspect, the present invention provides the use of the allulose syrup according to the first aspect in the preparation of a food or beverage product. 
     According to a further aspect, the present invention provides a food or beverage product comprising an allulose syrup according to the first aspect and at least one additional food or beverage ingredient. 
     In an embodiment, the at least one additional food or beverage ingredient includes at least one ingredient selected from the group consisting of flavorants, colorants, sweeteners other than allulose, dietary fibers, acidulants, water, and combinations thereof. 
     In an embodiment, the allulose syrup comprises 50 to 80% dry solids by weight, and greater than 80% allulose on a dry solids basis, a measured pH between 2.5 and 6.0 and a shelf life of at least 3 months. 
     In an embodiment, the allulose syrup comprises 60 to 80% dry solids by weight, and greater than 90% allulose on a dry solids basis, a measured pH between 3.0 and 5.0 and a shelf life of at least 3 months. 
     In an embodiment, the allulose syrup comprises 70 to 80% dry solids by weight, and greater than 90% allulose on a dry solids basis, a measured pH between 3.0 and 5.0 and a shelf life of at least 3 months. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    shows how the purity of an allulose syrup composition (initial pH 3.4) changes over time at 25° C., 30° C. and 35° C. 
         FIG.  2    shows how the color of an allulose syrup composition (initial pH 3.4) changes over time at 25° C., 30° C. and 35° C. 
         FIG.  3    shows how the amount of HMF in an allulose syrup composition (initial pH 3.4) changes over time at 25° C., 30° C. and 35° C. 
         FIG.  4    shows how the pH of an allulose syrup composition (initial pH 3.4) changes over time at 25° C., 30° C. and 35° C. It should be noted that the data points for storage at 25° C. are the same as for storage at 30° C. 
         FIG.  5    shows how the pH of an allulose syrup composition (initial pH 4.0) changes over time at 4° C., 25° C., 35° C. and 50° C. 
         FIG.  6    shows how the color of an allulose syrup composition (initial pH 4.0) changes over time at 4° C., 25° C., 35° C. and 50° C. 
         FIG.  7    shows how the amount of HMF in an allulose syrup composition (initial pH 4.0) changes over time at 4° C., 25° C., 35° C. and 50° C. 
         FIG.  8    shows how the purity of an allulose syrup composition (initial pH 4.0) changes over time at 4° C., 25° C. and 35° C. 
         FIG.  9    shows how the pH of the allulose syrup product samples of Example 2 changes over time at 40° C. 
         FIG.  10    shows how the pH of the allulose syrup product samples of Example 2 changes over time at 50° C. 
         FIG.  11    compares change in the pH of the allulose syrup product samples of Example 2 (starting pH 4.0) at 50° C. with an allulose syrup composition with an initial pH of 3.9. 
         FIG.  12    shows how the allulose purity of the allulose syrup product samples of Example 2 changes over time at 40° C. 
         FIG.  13    shows how the allulose purity of the allulose syrup product samples of Example 2 changes over time at 50° C. 
         FIG.  14    shows how the color of the allulose syrup product samples of Example 2 changes over time at 40° C. 
         FIG.  15    shows how the color of the allulose syrup product samples of Example 2 changes over time at 50° C. 
         FIG.  16    shows how the HMF content of the allulose syrup product samples of Example 2 changes over time at 40° C. 
         FIG.  17    shows how the HMF content of the allulose syrup product samples of Example 2 changes over time at 50° C. 
         FIG.  18    shows how the allulose content of the allulose syrup product samples of Example 5 changes over time at different temperature, pH and DS content. 
         FIG.  19    shows how the allulose content of the allulose syrup product samples of Example 5 changes over time at 25° C. 
         FIG.  20    shows how the allulose content of the allulose syrup product samples of Example 5 changes over time at 35° C. 
         FIG.  21    shows how the HMF content of the allulose syrup product samples of Example 5 changes over time at 25° C. 
         FIG.  22    shows how the HMF content of the allulose syrup product samples of Example 5 changes over time at 35° C. 
         FIG.  23    shows how the color of the allulose syrup product samples of Example 5 changes over time at 25° C. 
         FIG.  24    shows how the color of the allulose syrup product samples of Example 5 changes over time at 35° C. 
         FIG.  25    shows how the pH of the allulose syrup product samples of Example 6 over time is affected by additives. 
         FIG.  26    shows how the allulose purity of the allulose syrup product samples of Example 6 over time is affected by additives. 
         FIG.  27    shows how the allulose purity of the allulose syrup product samples of Example 6 over time is affected by the addition of ascorbate and isoascorbate. 
         FIG.  28    shows how the allulose purity of the allulose syrup product samples of Example 6 over time is affected by the addition of citrate and acetate. 
         FIG.  29    shows how the HMF content of the allulose syrup product samples of Example 6 over time is affected by the addition of ascorbate and isoascorbate. 
         FIG.  30    shows the change in allulose content at 6 months at 77% DS as modelled using DOE software according to Example 7 (each contour line represents a 2% decrease in change in allulose content from time 0). 
         FIG.  31    shows the change in allulose content at 6 months at 25° C. as modelled using DOE software according to Example 7. 
         FIG.  32    shows color change at 6 months at 77% DS as modelled using DOE software according to Example 7. 
         FIG.  33    shows color change at 6 months at 25° C. as modelled using DOE software according to Example 7. 
         FIG.  34    shows HMF formation at 6 months and 77% DS as modelled using DOE software according to Example 7. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention is based on the finding that allulose syrups with improved storage stability can be prepared by careful control of certain parameters. 
     The term “allulose” as used herein refers to a monosaccharide sugar of the structure shown as a Fischer projection in below Formula I. It is also known as “D-psicose”: 
     
       
         
         
             
             
         
       
     
     According to a first aspect, the present invention provides an allulose syrup having a total dry solids content of from 50% to 80% by weight, and comprising allulose in an amount of at least 80% by weight on a dry solids basis, wherein the pH of the syrup is from 2.5 to 6.0. 
     According to an embodiment, the allulose syrup has a total dry solids content of from 70% to 80% by weight, and comprises allulose in an amount of at least 90% by weight on a dry solids basis, wherein the pH of the syrup is from 3.0 to 5.0. 
     The total dry solids content of the allulose syrup is from 50% to 80% by weight. For example, the total dry solids content may be 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79% or 80% by weight, as well as all intermediate values. 
     In an embodiment, the total dry solids content of the allulose syrup is from 70% to 80% by weight. For example, the total dry solids content may be 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79% or 80% by weight, as well as all intermediate values. In an embodiment, the total dry solids content of the allulose syrup is from 71% to 78% by weight. In another embodiment, the total dry solids content of the allulose syrup is from 71% to 73% by weight. In another embodiment, the total dry solids content of the allulose syrup is from 76% to 78% by weight. 
     In another embodiment, the total dry solids content of the allulose syrup is from 50% to 70% by weight. 
     It has been found that, although the compositional stability of the allulose syrup is generally highest towards the lower end of the total dry solids content range of the invention, microbial stability is generally highest towards the higher end of the total dry solids content range of the invention. Accordingly, the selection of a suitable total dry solids content within the range of the invention can be made depending on the key attribute for the particular application. 
     The pH of the allulose syrup is from 2.5 to 6.0. For example, the pH of the syrup may be 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9 or 6.0, as well as all intermediate values. 
     In an embodiment, the pH of the allulose syrup is from 3.0 to 5.0. For example, the pH of the syrup may be 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9 or 5.0 as well as all intermediate values. 
     In an embodiment, the pH of the allulose syrup is from 3.5 to 4.5. For example, the pH of the syrup may be 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4 or 4.5 as well as all intermediate values. In an embodiment, the pH of the allulose syrup is from 3.8 to 4.2. In an embodiment, the pH of the allulose syrup is about 4.0. 
     It has been found that allulose degradation and HMF formation can be minimized by increasing the pH, but that undesirable color formation is also promoted by increasing the pH. It has been found that the pH according to the present invention is optimal both in terms of minimizing allulose degradation and HMF formation, and minimizing undesirable color formation. 
     It is surprising that allulose syrups have been found to be most stable in the above range of pH, since monosaccharide syrups have previously been found to be most stable at lower pH, e.g. between 2.2 and 3.0 (Smirnov V, Geispits K; Stability of Monosaccharides in Solutions of Different pH; BioChem. Moscow, 1957, 22:849-854). 
     The allulose syrup comprises allulose in an amount of at least 80% by weight on a dry solids basis (i.e., of the total dry solids present in the allulose syrup, at least 80% by weight is allulose). For example, the allulose syrup may comprise allulose in an amount of 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% by weight on a dry solids basis, as well as all intermediate values. 
     In an embodiment, the allulose syrup comprises allulose in an amount of at least 90% by weight on a dry solids basis (i.e., of the total dry solids present in the allulose syrup, at least 90% by weight is allulose). For example, the allulose syrup may comprise allulose in an amount of 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% by weight on a dry solids basis, as well as all intermediate values. In an embodiment, the allulose syrup comprises allulose in an amount of at least 95% by weight on a dry solids basis. 
     In an embodiment, the allulose syrup comprises less than 1000 ppm of HMF (hydroxymethylfurfural). For example, the allulose syrup may comprise less than 900 ppm, less than 800 ppm, less than 700 ppm, less than 600 ppm, less than 500 ppm, less than 400 ppm, less than 300 ppm, less than 200 ppm or less than 100 ppm of HMF. In certain embodiments, the allulose syrup comprises more than 0.1 ppm and less than 1000 ppm of HMF (hydroxymethylfurfural), for example more than 0.1 ppm and less than 900 ppm, more than 0.1 ppm and less than 800 ppm, more than 0.1 ppm and less than 700 ppm, more than 0.1 ppm and less than 600 ppm, more than 0.1 ppm and less than 500 ppm, more than 0.1 ppm and less than 400 ppm, more than 0.1 ppm and less than 300 ppm, more than 0.1 ppm and less than 200 ppm, or more than 0.1 ppm and less than 100 ppm. 
     In an embodiment, the allulose syrup comprises sulfur dioxide in an amount of from 0.1 to 20 ppm. 
     In an embodiment, the allulose syrup comprises sulfur dioxide in an amount of from 1 to 20 ppm. 
     In an embodiment, the allulose syrup comprises less than 10 parts per billion of isovaleraldehyde. 
     In an embodiment, the allulose syrup comprises less than 2 parts per billion of 2-aminoacetophenone. 
     In an embodiment, the allulose syrup further comprises one or more additives. In an embodiment, the one or more additives may include a stability-enhancing additive. In an embodiment, the one or more additives may include an anti-oxidant. In an embodiment, the one or more additives may include a buffer. The incorporation of a buffer in the allulose syrup maintains the pH of the allulose within the desired range for a longer period of time, such that storage stability is further enhanced. In an embodiment, the stability enhancing additives are included at around 0.01-2.0% by weight based on the total weight of the allulose syrup. 
     In an embodiment, the stability-enhancing additive may be selected from the group consisting of ascorbic acid and salts thereof; isoascorbic acid (erythorbate) and salts thereof; citric acid and salts thereof; acetic acid and salts thereof; and salts of bisulfite and metabisulfite; and tocopherol acetate. In the case of salts, suitable salts include alkali metal salts, particularly sodium and potassium salts, and especially sodium salts. Specific examples of stability-enhancing additives useful in the present invention include ascorbate, isoascorbate, sodium citrate, sodium acetate, tocopherol acetate and metabisulfite. In an embodiment, the stability enhancing additives are included at around 0.2% by weight based on the total weight of the allulose syrup in the case of ascorbic acid or salts thereof; isoascorbic acid (erythorbate) or salts thereof; citric acid or salts thereof; acetic acid or salts thereof; and tocopherol acetate. In an embodiment, the stability enhancing additives are included at around 0.02% by weight based on the total weight of the allulose syrup in the case of salts of bisulfite or metabisulfite. 
     The concentration of buffer included in the allulose syrup may be around 0.01-2.0% by weight based on the total weight of the allulose syrup. The concentration of buffer included in the allulose syrup may be around 0.2% by weight based on the total weight of the allulose syrup in the case of ascorbic acid or salts thereof; isoascorbic acid (erythorbate) or salts thereof; citric acid or salts thereof; acetic acid or salts thereof; and tocopherol acetate. The concentration of buffer included in the allulose syrup may be around 0.02% by weight based on the total weight of the allulose syrup in the case of salts of bisulfite or metabisulfite. 
     The allulose syrup of the present invention has a shelf-life of at least 3 months. In particular, the allulose syrup of the present invention maintains an allulose content of at least 80% on a dry solids basis for at least 3 months, preferably at least 6 months, at least 9 months, at least 12 months or more than 12 months. 
     The allulose syrup of the present invention has a shelf-life of at least 3 months. In particular, the allulose syrup of the present invention maintains an allulose content of at least 90% on a dry solids basis for at least 3 months, preferably at least 6 months, at least 9 months, at least 12 months or more than 12 months. 
     The allulose syrup of the present invention preferably has a shelf-life of at least 6 months. In particular, the allulose syrup of the present invention preferably maintains an allulose content of at least 95% on a dry solids basis for at least 6 months, preferably at least 9 months, at least 12 months or more than 12 months. Allulose content is measured by standard HPLC methods such as the Sacch.03 method set forth by the corn refiners association (http://com.org/wp-content/uploads/2009/12/SACCH.03.pdf). 
     Preferred ranges for the dry solids include 60-80%, 70-80%, 71-78%, 71-73% or 76-78%. Preferred pH ranges are between 3.5 and 4.5 or between 3.8 and 4.2. Preferred allulose content is greater than 95% allulose on a dry solids basis. Preferably, the syrup has a limited amount of the following compounds: less than 1000 ppm hydroxymethylfurfural (HMF); sulphur dioxide at a concentration of less than 20 parts per million; isovaleraldehyde at a measured concentration of less than 10 parts per billion; and 2-aminoacetophenone at a concentration of less than 2 parts per billion. Optionally, the syrup can have any of the following compounds alone or in combination thereof: a stability enhancing ingredient including one or more of: 1) ascorbic acid or salts thereof, 2) isoascorbic acid (erythorbate) or salts thereof, 3) citric acid or salts thereof, 4) acetic acid or salts thereof, 5) salts of bisulfite or metabisulfite, and/or 6) tocopherol acetate. The allulose syrup may have a concentration of greater than 90% (e.g. greater than 95%) with a shelf-life of at least 3, 6, 9, 12 months, or more than 12 months. 
     According to a further aspect, the present invention provides a process for preparing an allulose syrup. The process comprises: providing an allulose syrup; adjusting the dry solids content of the allulose syrup such that it is from 50% to 80% by weight; adjusting the allulose content of the allulose syrup such that allulose is present in an amount of at least 80% by weight on a dry solids basis; and controlling the pH of the allulose syrup so that it is from 2.5 to 6.0. 
     According to an embodiment, the process for preparing an allulose syrup comprises: providing an allulose syrup; adjusting the dry solids content of the allulose syrup such that it is from 60% to 80% by weight; adjusting the allulose content of the allulose syrup such that allulose is present in an amount of at least 80% by weight on a dry solids basis; and controlling the pH of the allulose syrup so that it is from 2.5 to 6.0. 
     According to an embodiment, the process for preparing an allulose syrup comprises: providing an allulose syrup; adjusting the dry solids content of the allulose syrup such that it is from 70% to 80% by weight; adjusting the allulose content of the allulose syrup such that allulose is present in an amount of at least 90% by weight on a dry solids basis; and controlling the pH of the allulose syrup so that it is from 3.0 to 5.0. 
     According to an embodiment, the process for preparing an allulose syrup comprises: providing an allulose syrup; adjusting the dry solids content of the allulose syrup such that it is from 70% to 78% by weight; adjusting the allulose content of the allulose syrup such that allulose is present in an amount of at least 90% by weight on a dry solids basis; and controlling the pH of the allulose syrup so that it is from 3.5 to 4.5. 
     The process optionally comprises removing or avoiding the production of HMF to limit the content to less than 1000 ppm, or more preferably less than 100 ppm. The process optionally comprises removing or avoiding the production of isovaleraldehyde to limit the content to less than 10 parts per billion. The process optionally comprises removing or avoiding the production of aminoacetophenone to limit the content to less than 2 parts per billion. The process optionally comprises adding one or more additives to the syrup. These procedures need not be carried out in the same order recited above (for example, the pH adjustment may be performed before adjustment of the dry solids content). 
     The description of the embodiments of the allulose syrup herein applies mutatis mutandis to the process for preparing an allulose syrup. 
     According to a further aspect, the present invention provides the use of the allulose syrup according to the first aspect in the preparation of a food or beverage product, as well as food or beverage products made using the sweetener syrup. 
     Food or beverage products which may be contemplated in the context of the present invention include baked goods; sweet bakery products (including, but not limited to, rolls, cakes, pies, pastries, and cookies); pre-made sweet bakery mixes for preparing sweet bakery products; pie fillings and other sweet fillings (including, but not limited to, fruit pie fillings and nut pie fillings such as pecan pie filling, as well as fillings for cookies, cakes, pastries, confectionary products and the like, such as fat-based cream fillings); desserts, gelatins and puddings; frozen desserts (including, but not limited to, frozen dairy desserts such as ice cream—including regular ice cream, soft serve ice cream and all other types of ice cream—and frozen non-dairy desserts such as non-dairy ice cream, sorbet and the like); carbonated beverages (including, but not limited to, soft carbonated beverages); non-carbonated beverages (including, but not limited to, soft non-carbonated beverages such as flavored waters and sweet tea or coffee based beverages); beverage concentrates (including, but not limited to, liquid concentrates and syrups as well as non-liquid ‘concentrates’, such as freeze-dried and/or powder preparations); yogurts (including, but not limited to, full fat, reduced fat and fat-free dairy yogurts, as well non-dairy and lactose-free yogurts and frozen equivalents of all of these); snack bars (including, but not limited to, cereal, nut, seed and/or fruit bars); bread products (including, but not limited to, leavened and unleavened breads, yeasted and unyeasted breads such as soda breads, breads comprising any type of wheat flour, breads comprising any type of non-wheat flour (such as potato, rice and rye flours), gluten-free breads); pre-made bread mixes for preparing bread products; sauces, syrups and dressings; sweet spreads (including, but not limited to, jellies, jams, butters, nut spreads and other spreadable preserves, conserves and the like); confectionary products (including, but not limited to, jelly candies, soft candies, hard candies, chocolates and gums); sweetened breakfast cereals (including, but not limited to, extruded (kix type) breakfast cereals, flaked breakfast cereals and puffed breakfast cereals); and cereal coating compositions for use in preparing sweetened breakfast cereals. Other types of food and beverage product not mentioned here but which conventionally include one or more nutritive sweetener may also be contemplated in the context of the present invention. 
     An allulose syrup in accordance with the present invention may be used in combination with one or more other food or beverage ingredients, including any of the food and beverage ingredients known in the art. Such additional food and beverage ingredients include, but are not limited to, flavorants, colorants, sweeteners other than allulose (including other sugars such as sucrose, fructose, allose, tagatose and other rare sugars, synthetic high intensity sweeteners such as sucralose, acesulfame K, saccharin, aspartame and the like, natural high intensity sweeteners such as  Stevia  and Monk Fruit Extract sweeteners and the terpene glycosides present therein, and the like), dietary fibers (including soluble dietary fibers such as soluble corn fiber and polydextrose), acidulants, water, and the like. 
     Specific illustrative examples of food and beverage products which may be prepared using an allulose syrup in accordance with the invention include, but are not limited to: 
     a beverage, such as a carbonated or non-carbonated beverage or a juice drink comprising allulose syrup and one or more synthetic high intensity sweeteners such as sucralose; 
     a beverage, including a beverage concentrate, comprising an allulose syrup, a natural high intensity sweetener (such as a  Stevia  sweetener), and a dietary fiber (e.g., a soluble dietary fiber, such as a soluble corn fiber), and an acidulant (e.g., citric acid); 
     a yogurt, such as a Greek yogurt, comprising allulose syrup (which may be free of any artificial sweeteners); 
     a frozen dessert, comprising allulose syrup, a dietary fiber (e.g., a soluble dietary fiber, such as a soluble corn fiber), a natural high intensity sweetener (such as a  Stevia  sweetener and/or a Monk Fruit Extract sweetener), and a food system stabilizer; 
     a cookie, such as a chocolate chip cookie, comprising an allulose syrup and a corn starch; 
     a confectionary, such as a gummy candy, comprising an allulose syrup and a natural high intensity sweetener (e.g., a  Stevia  sweetener); and 
     a flavored syrup, such as a maple-flavored syrup, comprising an allulose syrup, fructose, and an acidulant (e.g., citric acid). 
     EXAMPLES 
     The invention will now be further described and illustrated by means of the following examples, it being understood that these are intended to explain the invention, and in no way to limit its scope. 
     SUMMARY 
     It was determined from stability experiments that allulose syrup produced at one set of conditions has a more rapid purity degradation than allulose syrup produced at another set of conditions (Example 1). The main difference between these syrups was initial pH. An accelerated stability study (Example 2) was carried out with pH values around the narrow range of predicted stability and also with additives and at different % dry solids. It was determined that 71-77% dry solids and a pH of around 3.8 to 4.2 provided optimum storage stability. Microbial stability was also investigated (Example 2). The allulose syrup was very stable at 77% and less stable at 72%. The results could be used to predict a low limit on microstability of 60% DS. Another stability study was carried out at ambient storage temperatures with pH values and dry solids content around the ranges of predicted stability (Example 3). Finally, a more detailed study of additives with respect to stability at two different dry solids levels and optimal pH was carried out (Example 4). Some of the additives reduced the change in color, composition and HMF. 
     Example 1 
     Each sample consisted of 3500 mL of allulose syrup in a 4 quart (4.54 liter) square plastic container. The sampling was carried out at 0 and 2 months. 
     Analytical 
     Samples were analyzed using methods known to those skilled in the art. The allulose composition was determined by standard HPLC methods, such as the Sacch.03 method set forth by the corn refiners association (http://com.org/wp-content/uploads/2009/12/SACCH.03.pdf). DS was measured by refractive index, pH was measured at a dilution resulting in less than 40% solids, color was analyzed by measuring the absorbance of the syrup at 450 nm and subtracting the background at 600 nm and dividing the result by the path length of the cuvette. HMF, isovaleraldehyde, aminoacetophenone, were analyzed using reverse phase HPLC with UV detection. 
     The purity of the allulose composition dropped significantly in the course of 2 months, as shown in  FIG.  1   . There was a clear trend that higher temperature resulted in a greater change in composition. 
     Changes in color were minor ( FIG.  2   ). At 35° C. the syrup did increase in color more rapidly. However, at 25 and 30° C., the color change was minimal and did not exceed 2. 
     The HMF content increased in each sample over 2 months ( FIG.  3   ). The content of HMF in the sample at 35° C. increased to 180 ppm HMF after 2 months. The content of HMF in the 25° C. and 30° C. samples was lower. 
     The pH value decreased similarly over 2 months for each sample. It is noteworthy that the pH started lower in this prepared material than previously studied material which started at a pH of 4.0 and which had improved stability, as discussed below. 
     The main difference in composition between the two products is an initial pH difference of approximately 0.6 pH units. Additionally, pH in the first study remained above pH 3.5 for the first 5 months at 4° C., 25° C. and 35° C. ( FIG.  5   ), whereas, in the second study, pH was always below 3.5 ( FIG.  4   ). Color development ( FIG.  2   ) was lower in the second study at 25° C. for two months (0.67) compared to the first study ( FIG.  6   ) at the same time and temp (1.32). 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Carbohydrate profiles for allulose syrup stored 
               
               
                 in Railcars at an initial pH of 3.4 
               
            
           
           
               
               
               
            
               
                   
                   
                 Allulose 
               
               
                   
                 Date 
                 Content 
               
               
                   
                   
               
            
           
           
               
               
               
               
            
               
                   
                 Original load out 
                 Oct. 26, 2014 
                 95.42 
               
               
                   
                 After railcar storage 
                 Jan. 21, 2015 
                 93.42 
               
               
                   
                 Difference 
                   
                 −2.00 
               
               
                   
                   
               
            
           
         
       
     
     The allulose content change seen during the lower pH stability storage study was additionally confirmed in the bulk product in railcars (Table 1). The compositional changes were slightly less at 3 months in railcars, than two months at 25° C. in the storage study (i.e. 2% in 3 months vs. 3% in 2 months). The effect of container volume was demonstrated in another example as well, when 300 gallon totes were less susceptible to allulose content changes than 1 quart containers. A likely explanation may be that pH is more stable in larger containers as the surface area to volume ratio is smaller. An alternative explanation could be that the average temperature was lower in the larger containers, but this was not directly observed. 
     In summary, the allulose content of the syrup prepared having an initial pH of 3.4 changed within 2 months. The allulose content of the syrup prepared having an initial pH of 4.0 also changed over time, but at a slower rate ( FIGS.  5 - 8   ). The primary physical difference in those two syrups appears to be pH. Additional examples below demonstrate that pH has a large effect on compositional stability. 
     Example 2—Storage Stability 
     Final allulose syrup product samples were subjected to a range of pH and different DS and temperatures. Another series of samples had sodium metabisulfite and sodium citrate added. Separate sub samples were taken at pre-determined intervals and their carbohydrate composition, color, HMF, DS and pH analyzed. 
     
       
         
           
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 Sample carbohydrate profile 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 Dex- 
                 Fruc- 
                 Allu- 
                   
                   
                 Nominal 
               
               
                   
                 trose % 
                 tose % 
                 lose % 
                 Others % 
                 pH 
                 DS % 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Campaign 1 
                 0.5 
                 2.2 
                 93.0 
                 4.3 
                 3.4 
                 77.0 
               
               
                 Product 
               
               
                   
               
            
           
         
       
     
                     TABLE 3                  Nominal screening experiments to be run.                             pH   Temp ° C.   DS %   Additive                                     3.4   40   77   —       3.4   50   77   —       3.4   40   71   —       3.4   50   71   —       3.5   40   77   —       3.5   50   77   —       4.0   40   77   —       4.0   50   77   —       4.0   40   77   Sodium citrate       4.0   50   77   Sodium citrate       4.0   40   77   Sodium                   metabisulfite       4.0   50   77   Sodium                   metabisulfite       4.5   40   77   —       4.5   50   77   —                    
Methods
 
     Samples of starting material were taken. The pH and DS were measured and recorded. One sub sample of each was taken as is, the next adjusted to pH 3.6, another to pH 4.0 and the final one to pH 4.7 using dilute HCl or sodium carbonate. One subset of starting material was diluted to 71% DS. Another subset of the pH 4.0 batch had sodium citrate or sodium metabisulfite added. Sealed sample containers were placed into different temperature ovens at 40° C. and 50° C. Extracts from each of the samples were removed from each oven periodically. Samples were chilled quickly in an ice bath and analyzed for carbohydrate composition, HMF, color and pH. 
     Analytical 
     Samples were analyzed to determine their DS, pH, carbohydrate composition, HMF content and color. For pH and color the samples were analyzed at a standard DS. 
     In general, pH dropped over the course of the experiments, see  FIG.  9    and  FIG.  10   . The decrease in pH is more pronounced in samples starting at higher pH, and the pH drops faster at higher temperature. It appears that the pH of each sample becomes more stable around a value near 3.0 to 3.3. 
     Two of the samples that were adjusted to start at pH 4.0 had additives added. The first was with 75 ppm sodium metabisulfite (MBS) and the second was 60 ppm sodium citrate (NaCit). 
     The pH drift data ( FIGS.  9  and  10   ) at pH 4.0 matches the stability study of an allulose syrup product which the product pH started at 3.9 and samples were stored at 50° C. (comparison in  FIG.  11   ). 
     Allulose content dropped in all samples following the trend of higher temperature, lower pH and longer time resulting in faster allulose losses ( FIGS.  12  and  13   ). The pH 4.0 samples with additives show a similar rate of allulose loss as the pH 4.0 sample with no additive. This may be explained by the similar pH changes observed above and due to very low levels of the additives. 
     Surprisingly, the sample with only a slightly lower DS, (71% vs. 77%) starting at pH 3.37 showed much less allulose loss than its equivalent pH sample at 77% DS. The rate of allulose loss at 71% DS was approximately half that at 77% DS, demonstrating that a narrow range of DS has a dramatic and unexpected effect on allulose syrup stability. Similar effects are not observed for similar monosaccharide syrups such as glucose or high fructose corn syrups within such a narrow range of DS. 
     Color was measured and plotted against time ( FIGS.  14  and  15   ). High pH, longer time and high temperature increased the color formation. By increasing the pH it is possible to mitigate the allulose content loss, however there is an upper limit bound by increasing color in the final product. This results in a surprisingly narrow pH range being acceptable for long term storage of allulose syrup. This range appears to be between pH 3.5 and 4.5 when both color and composition stability are considered. Similar effects are not observed for similar monosaccharide syrups such as glucose or high fructose corn syrups within such a narrow range of pH. 
     The change in HMF over time for these samples is shown in  FIGS.  16  and  17   . Low pH, high temperature and longer time contributed to increased HMF formation. 
     Example 3—Crystallization Stability 
     Allulose syrups were prepared at 50, 60, 71, 77, and 85% DS and were equilibrated at 25° C., 15° C. and 4° C. These samples were seeded with ˜0.1% crystalline allulose and crystallization was monitored visually and by change in dry solids of the syrup fraction after 1 month of storage. 
     Results: 
     Change in DS is shown in Table 4. A change in DS greater than 0 indicates crystallization, and a larger number indicates a larger amount of crystallization. At 25° C., 77% DS and below did not crystallize substantially, although seed crystals also did not dissolve at 77% DS, suggesting 77% is near the limit of solubility at 25° C. The 85% DS sample did crystallize. At 15° C., 71% DS and below samples did not crystallize, while 77% and 85% did have crystal formation. At 4° C., 60% DS and below samples did not crystallize, while the 71% DS sample had very minor crystallization that did not appreciably affect the bulk syrup DS. Therefore, for storage of a crystallization stable syrup at ambient and reduced temperatures, 77% solids or less is desirable. For cool (&lt;25° C.) temperatures, 71% solids or less is more desirable. 
     
       
         
           
               
             
               
                 TABLE 4 
               
             
            
               
                   
               
               
                 Crystallization Stability: 
               
               
                 Change in DS 
               
            
           
           
               
               
               
            
               
                   
                 2 weeks 
                 4 weeks 
               
               
                   
                   
               
            
           
           
               
               
               
               
            
               
                   
                 4° C. 
                   
                   
               
               
                   
                 50% ds 
                 0 
                 0 
               
               
                   
                 60% ds 
                 0 
                 0 
               
               
                   
                 71% ds 
                 0 
                 0 
               
               
                   
                 77% ds 
                 5 
                 5 
               
               
                   
                 85% ds 
                 9 
                 9 
               
               
                   
                 15° C. 
               
               
                   
                 50% ds 
                 0 
                 0 
               
               
                   
                 60% ds 
                 0 
                 0 
               
               
                   
                 71% ds 
                 0 
                 0 
               
               
                   
                 77% ds 
                 2 
                 2 
               
               
                   
                 85% ds 
                 7 
                 8 
               
               
                   
                 25° C. 
               
               
                   
                 50% ds 
                 0 
                 0 
               
               
                   
                 60% ds 
                 0 
                 0 
               
               
                   
                 71% ds 
                 0 
                 0 
               
               
                   
                 77% ds 
                 0 
                 0 
               
               
                   
                 85% ds 
                 5 
                 6 
               
               
                   
                   
               
            
           
         
       
     
     Example 4—Microbial Stability 
     Microbial stability was assessed at 72% and 77% dry solids content by a challenge study with osmophilic yeasts and molds. 
     An aliquot of 250 grams of each DS level control sample was placed into two sterile glass jars (250 grams×2 for each moisture level, total 4 containers). An aliquot of 1,000 grams of each DS level sample was placed into two sterile Nalgene containers (1,000 grams×2 for each DS level, total 4 containers). Each 1,000 gram sample (8 containers total) was inoculated with osmophilic mold and yeast separately (less than 1% of total volume). The containers were mixed and incubated at room temperature for 2-3 hours to equilibrate the inoculum. Then, 250 grams of the mixture was placed into a 250 mL sterile glass jar to make triplicates for each testing condition (24×250 mL glass jars). An initial sample for plating (T=0) was taken and incubation started at 25 and 35° C. Samples were then taken at intervals as planned for plating. 
     At 77% DS osmophilic yeasts and molds were rapidly made non-viable. However at 72% DS, allulose syrup took 4 weeks to completely kill all viable yeasts and molds at 25° C. 
     Microbial stability was also assessed at 50% and 60% dry solids content by a challenge study with osmophilic yeasts and molds using the same method. At 60% DS, it took allulose syrup 2 months to completely remove viability of osmophilic yeasts and molds, and at 50% DS, viability of yeasts and molds was not removed completely even after 4 months. This suggests that 60% solids is the minimum solids concentration for allulose syrup that can reasonably be considered resistant to spoilage by microbial contamination and more ideally the concentration is 70-77% solids. 
     Based on the findings in Tables 5a-e below and those in the crystallization and reactivity examples above, final product stability has an optimum DS that is fairly narrow for allulose syrup. Lower DS reduces the rate of degradation in all parameters, however a final product DS that is below 60% DS does not maintain good microbial stability. Higher DS results in more rapid degradation and also crystallization. Therefore an optimal DS of 60-80% is required and more preferably a DS of 71-78% is required for long term stability of allulose syrup and more preferably a DS of 71-73% should have the highest combined allulose content stability, microbial stability and crystalline stability. In cases where microbial stability is the key attribute necessary, 76-78% DS would have the best microbial stability. Additionally, final product stability is optimized in a narrow range of pH, from 3.5 to 4.5 and more preferably in a pH range from 3.8 to 4.2 in order to optimize the trade-off between carbohydrate stability and color/HMF formation. Lower pH was shown to increase the rate of allulose content loss and HMF formation, while higher pH was shown to result in more rapid formation of color. 
     
       
         
           
               
               
             
               
                 TABLE 5a 
               
             
            
               
                   
               
               
                 Control samples: One large container 
                   
               
            
           
           
               
               
               
               
               
            
               
                 (250 mL sterile glass jar) 
                 T = 0 
                 T = 1 w 
                 T = 2 w 
                 T = 4 w 
               
            
           
           
               
               
               
               
               
               
               
            
               
                 DS level 
                 Temp 
                   
                 May 8, 2014 
                 May 15, 2014 
                 May 21, 2014 
                 Jun. 6, 2014 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
            
               
                 (%) 
                 (° C.) 
                 LIMS 
                 Osmo M 
                 Osmo Y 
                 Osmo M 
                 Osmo Y 
                 Osmo M 
                 Osmo Y 
                 Osmo M 
                 Osmo Y 
               
               
                   
               
               
                 72 
                 25 
                 372602 
                 &lt;10 
                 &lt;10 
                 &lt;10 
                 &lt;10 
                 &lt;10 
                 &lt;10 
                 &lt;10 
                 &lt;10 
               
               
                 72 
                 35 
                 372603 
                 &lt;10 
                 &lt;10 
                 &lt;10 
                 &lt;10 
                 &lt;10 
                 &lt;10 
                 &lt;10 
                 &lt;10 
               
               
                 77 
                 25 
                 372604 
                 &lt;10 
                 &lt;10 
                 &lt;10 
                 &lt;10 
                 &lt;10 
                 &lt;10 
                 &lt;10 
                 &lt;10 
               
               
                 77 
                 35 
                 372605 
                 &lt;10 
                 &lt;10 
                 &lt;10 
                 &lt;10 
                 &lt;10 
                 &lt;10 
                 &lt;10 
                 &lt;10 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
               
               
               
               
               
             
               
                   
                 TABLE 5b 
               
             
            
               
                   
                   
               
               
                   
                   
                   
                   
                 T = 0 
                 T = 1 w 
                 T = 2 w 
                 T = 4 w 
               
               
                   
                 DS level 
                 Temp 
                   
                 May 8, 2014 
                 May 15, 2014 
                 May 21, 2014 
                 Jun. 6, 2014 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
               
            
               
                 Experimental Samples: 
                 (%) 
                 (° C.) 
                 LIMS 
                 Osmo M 
                 Osmo Y 
                 Osmo M 
                 Osmo Y 
                 Osmo M 
                 Osmo Y 
                 Osmo M 
                 Osmo Y 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
               
            
               
                 Inoculum:  Z. rouxii   
                 72 
                 25 
                 372606 
                 — 
                 335,000 
                 — 
                 425 
                 — 
                 55 
                 — 
                 &lt;10 
               
               
                 Replicates: 3 
                 72 
                 25 
                 372607 
                 — 
                 312,000 
                 — 
                 265 
                 — 
                 40 
                 — 
                 &lt;10 
               
               
                 Plating: 12/point 
                 72 
                 25 
                 372608 
                 — 
                 309,000 
                 — 
                 440 
                 — 
                 55 
                 — 
                 &lt;10 
               
               
                 Container: 12 
                 72 
                 35 
                 372609 
                 — 
                 311,000 
                 — 
                 &lt;10 
                 — 
                 &lt;10 
                 — 
                 &lt;10 
               
               
                 Min total vol: 
                 72 
                 35 
                 372610 
                 — 
                 260,500 
                 — 
                 &lt;10 
                 — 
                 &lt;10 
                 — 
                 &lt;10 
               
               
                 1,800 grams 
                 72 
                 35 
                 372611 
                 — 
                 290,000 
                 — 
                 &lt;10 
                 — 
                 &lt;10 
                 — 
                 &lt;10 
               
               
                   
                 77 
                 25 
                 372612 
                 — 
                 317,500 
                 — 
                 &lt;10 
                 — 
                 &lt;10 
                 — 
                 &lt;10 
               
               
                   
                 77 
                 25 
                 372613 
                 — 
                 301,500 
                 — 
                 &lt;10 
                 — 
                 &lt;10 
                 — 
                 &lt;10 
               
               
                   
                 77 
                 25 
                 372614 
                 — 
                 299,000 
                 — 
                 &lt;10 
                 — 
                 &lt;10 
                 — 
                 &lt;10 
               
               
                   
                 77 
                 35 
                 372615 
                 — 
                 277,000 
                 — 
                 &lt;10 
                 — 
                 &lt;10 
                 — 
                 &lt;10 
               
               
                   
                 77 
                 35 
                 372616 
                 — 
                 279,000 
                 — 
                 &lt;10 
                 — 
                 &lt;10 
                 — 
                 &lt;10 
               
               
                   
                 77 
                 35 
                 372617 
                 — 
                 287,000 
                 — 
                 &lt;10 
                 — 
                 &lt;10 
                 — 
                 &lt;10 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
               
               
               
               
               
             
               
                   
                 TABLE 5c 
               
             
            
               
                   
                   
               
               
                   
                   
                   
                   
                 T = 0 
                 T = 1 w 
                 T = 2 w 
                 T = 4 w 
               
               
                   
                 DS level 
                 Temp 
                   
                 May 8, 2014 
                 May 15, 2014 
                 May 21, 2014 
                 Jun. 06, 2014 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
               
            
               
                 Experimental Samples: 
                 (%) 
                 (° C.) 
                 LIMS 
                 Osmo M 
                 Osmo Y 
                 Osmo M 
                 Osmo Y 
                 Osmo M 
                 Osmo Y 
                 Osmo M 
                 Osmo Y 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
               
            
               
                 Inoculum: Osmo molds 
                 72 
                 25 
                 372618 
                 2,700 
                 — 
                 585 
                 — 
                 10 
                 — 
                 &lt;10 
                 — 
               
               
                 Replicates: 3 
                 72 
                 25 
                 372619 
                 2,400 
                 — 
                 485 
                 — 
                 &lt;10 
                 — 
                 &lt;10 
                 — 
               
               
                 Plating: 12/point 
                 72 
                 25 
                 372620 
                 3,050 
                 — 
                 590 
                 — 
                 &lt;10 
                 — 
                 &lt;10 
                 — 
               
               
                 Container: 12 
                 72 
                 35 
                 372621 
                 2,250 
                 — 
                 &lt;10 
                 — 
                 &lt;10 
                 — 
                 &lt;10 
                 — 
               
               
                 Min total vol: 
                 72 
                 35 
                 372622 
                 2,300 
                 — 
                 &lt;10 
                 — 
                 &lt;10 
                 — 
                 &lt;10 
                 — 
               
               
                 1,800 grams 
                 72 
                 35 
                 372623 
                 2,700 
                 — 
                 &lt;10 
                 — 
                 &lt;10 
                 — 
                 &lt;10 
                 — 
               
               
                   
                 77 
                 25 
                 372624 
                 3,250 
                 — 
                 155 
                 — 
                 &lt;10 
                 — 
                 &lt;10 
                 — 
               
               
                   
                 77 
                 25 
                 372625 
                 2,800 
                 — 
                 150 
                 — 
                 &lt;10 
                 — 
                 &lt;10 
                 — 
               
               
                   
                 77 
                 25 
                 372626 
                 2,850 
                 — 
                 175 
                 — 
                 &lt;10 
                 — 
                 &lt;10 
                 — 
               
               
                   
                 77 
                 35 
                 372627 
                 2,500 
                 — 
                 &lt;10 
                 — 
                 &lt;10 
                 — 
                 &lt;10 
                 — 
               
               
                   
                 77 
                 35 
                 372628 
                 3,150 
                 — 
                 &lt;10 
                 — 
                 &lt;10 
                 — 
                 &lt;10 
                 — 
               
               
                   
                 77 
                 35 
                 372629 
                 2,800 
                 — 
                 &lt;10 
                 — 
                 &lt;10 
                 — 
                 &lt;10 
                 — 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
               
               
               
               
               
               
             
               
                   
                 TABLE 5d 
               
             
            
               
                   
                   
               
               
                   
                 T = 0 
                 T = 1 w 
                 T = 2 w 
                 T = 4 w 
                 T = 2 m 
                 T = 3 m 
                 T = 4 m 
                 T = 6 m 
               
            
           
           
               
               
            
               
                   
                 T (week) 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
            
               
                 DS level 
                 Temperature 
                 0 
                 1 
                 2 
                 4 
                 8 
                 13 
                 17 
                 26 
               
               
                 (%) 
                 (° F.) 
                 Osmo M 
                 Osmo M 
                 Osmo M 
                 Osmo M 
                 Osmo M 
                 Osmo M 
                 Osmo M 
                 Osmo M 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
            
               
                 50 
                 77 
                 6,517 
                 1,690 
                 417 
                 45 
                 30 
                 40 
                 195 
                   
               
               
                 50 
                 95 
                 6,817 
                 4,233 
                 3,167 
                 377 
                 &lt;10 
                 &lt;10 
                 &lt;10 
               
               
                 60 
                 77 
                 6,683 
                 5,033 
                 1,117 
                 23 
                 &lt;10 
                 &lt;10 
                 &lt;10 
               
               
                 60 
                 95 
                 6,450 
                 990 
                 &lt;10 
                 &lt;10 
                 &lt;10 
                 &lt;10 
                 &lt;10 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
               
               
               
               
               
               
             
               
                   
                 TABLE 5e 
               
             
            
               
                   
                   
               
               
                   
                 T = 0 
                 T = 1 w 
                 T = 2 w 
                 T = 4 w 
                 T = 2 m 
                 T = 3 m 
                 T = 4 m 
                 T = 6 m 
               
            
           
           
               
               
            
               
                   
                 T (week) 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
            
               
                 DS level 
                 Temperature 
                 0 
                 1 
                 2 
                 4 
                 8 
                 13 
                 17 
                 26 
               
               
                 (%) 
                 (° F.) 
                 Osmo Y 
                 Osmo Y 
                 Osmo Y 
                 Osmo Y 
                 Osmo Y 
                 Osmo Y 
                 Osmo Y 
                 Osmo Y 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
            
               
                 50 
                 77 
                 319,333 
                 11,243 
                 125 
                 &lt;10 
                 &lt;10 
                 &lt;10 
                 &lt;10 
                   
               
               
                 50 
                 95 
                 335,000 
                 65 
                 &lt;10 
                 &lt;10 
                 &lt;10 
                 &lt;10 
                 &lt;10 
               
               
                 60 
                 77 
                 312,500 
                 393 
                 23 
                 &lt;10 
                 &lt;10 
                 &lt;10 
                 &lt;10 
               
               
                 60 
                 95 
                 331,167 
                 &lt;10 
                 &lt;10 
                 &lt;10 
                 &lt;10 
                 &lt;10 
                 &lt;10 
               
               
                   
               
            
           
         
       
     
     Example 5—Allulose Syrup Stability within a Narrow pH Range and Ambient Storage Temperatures 
     This series of experiments was set up to determine allulose syrup stability within a narrow range of pH and DS at ambient temperature range of 25-35° C. 
     Samples of allulose syrup of 93.8% allulose content were pH adjusted to 3.8, 4.0 and 4.2 pH units and DS adjusted to 77% and 71% and incubated at 25° C. and 35° C. Samples were analyzed periodically. 
     Results 
     There is some divergence of composition in the ranges of 71-77%, 25-35° C., starting pH 3.8-4.2 ( FIG.  18   ). Lower pH, higher DS and higher temperature all contribute to small changes in allulose content. 
     All 25° C. (77° F.) data show essentially no change in composition, over the course of two months ( FIG.  19   ). However, the 35° C. data show a moderate decrease in allulose content over the course of two months (0.5 to 1.5% decrease dependent on pH and % DS) ( FIG.  20   ). Higher pH and lower DS appear to be more stable. Even within a narrow pH range of 3.8 to 4.2, higher pH was more stable compositionally at 35° C. At 25° C. there is no difference identified. These results highlight the surprisingly narrow, temperature, pH, and DS conditions required for allulose syrup stability. 
     HMF is an undesirable dehydration product from monosaccharide syrups. Here we can see that higher temperatures result in greater HMF formation ( FIGS.  21  and  22   ). The results suggest that higher pH results in less HMF formation in the range of 3.8 to 4.2. 
     Temperature effect on color was dramatic ( FIGS.  23  and  24   ). pH effect on color was also apparent with higher pH resulting in more color. DS % had a minor effect on color, with lower DS having lower color development; this was more pronounced at higher temperatures. This again demonstrates that there is a surprisingly narrow range for color and allulose content stability, which pH, DS, and temperature all have substantial effects. 
     The results demonstrate stability under the conditions tested for 25° C. At higher temperature, DS, and pH even within the narrow range have noticeable effects, with color developing fastest at higher DS and higher pH and allulose content changing most quickly with higher DS and lower pH. If higher temperatures higher than 25° C. will be encountered, a pH of 4.0 and 71% DS will help control color changes and allulose content changes. 
     Example 6—Stability Improvement with Syrup Additives 
     Additives have an effect on stability. These additives may stabilize the syrup by buffering the pH to help control at pH 4.0 and also to minimize oxidation. 
     One temperature 30° C. (86° F.) has been used to assess the effect of additives on stability. 
     Approximate composition of campaign 1 material: 
                                                 Allulose %   pH   DS                                                            Starting Material   94   3.3   77.5                        
Method
 
     Each sample consisted of 1000 mL of syrup in a plastic container. Two gallons of this material were pH adjusted to 4.0 using 1M sodium carbonate (NaCO 3 ), by slow and careful addition and regular pH measurement at 1:1 dilution. This material was then split into two separate containers and one was diluted to 71% DS (11.5 lbs 77% DS syrup, plus 0.97 lbs water). 
     After dilution, the samples were subsampled into 500 mL plastic containers. Fresh 10% solutions (25 mL) of ascorbate, isoascorbate, sodium citrate, sodium acetate, and 1% tocopherol acetate, and metabisulfite were prepared and pH adjusted with sodium carbonate to ˜4.0 pH. 10 mL of these solutions were added and mixed in with the corresponding samples as in Table 6. 
     The following samples will be prepared as above and then placed in the 30° C. oven and sampled as Table 7 below. 
     
       
         
           
               
             
               
                 TABLE 6 
               
             
            
               
                   
               
               
                 Samples 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                   
                 Ascor- 
                 Isoascor- 
                 Sodium 
                 Sodium 
                 Tocopherol 
                 Metabi- 
               
               
                 DS 
                 pH 
                 bate 
                 bate 
                 Citrate 
                 Acetate 
                 Acetate 
                 sulfite 
               
               
                   
               
               
                 71 
                 4.0 
                 0.2% 
                   
                   
                   
                   
                   
               
               
                 71 
                 4.0 
                   
                 0.2% 
               
               
                 71 
                 4.0 
                   
                   
                 0.2% 
               
               
                 71 
                 4.0 
                   
                   
                   
                 0.2% 
               
               
                 71 
                 4.0 
                   
                   
                   
                   
                 0.2% 
               
               
                 71 
                 4.0 
                   
                   
                   
                   
                   
                 0.02% 
               
               
                 77 
                 4.0 
                 0.2% 
               
               
                 77 
                 4.0 
                   
                 0.2% 
               
               
                 77 
                 4.0 
                   
                   
                 0.2% 
               
               
                 77 
                 4.0 
                   
                   
                   
                 0.2% 
               
               
                 77 
                 4.0 
                   
                   
                   
                   
                 0.2% 
               
               
                 77 
                 4.0 
                   
                   
                   
                   
                   
                 0.02% 
               
               
                   
               
            
           
         
       
     
     The sampling and testing schedule is detailed in Table 7. 
                     TABLE 7                  Stability Robustness Samples                                             Color       Carbohydrates (%           Sample   pH   Before Heat   DS RI (% as is)   as is)   HMF               0 Months   x   x   x   x   x       1 Months   x   x       x   X       2 Months   x   X       x   x       4 Months   x   X       x   x       6 Months   x   x   x   x   x                    
Results
 
     No dramatic changes in pH were observed at 2 months, although both controls appear to be trending downwards in pH ( FIG.  25   ). As expected, the pH does not drop for the samples containing added buffering compounds: ascorbate, isoascorbate, citrate and acetate. 
     No dramatic changes have been observed at 3 months at 30° C. in terms of composition ( FIG.  26   ), but there are minor changes. It appears that added MBS may result in more rapid allulose content loss. Tocopherol acetate performs somewhat better than the control at 71% DS and about the same as the control at 77% DS. 
     Addition of both ascorbate and isoascorbate ( FIG.  27   ) and of both sodium citrate and sodium acetate ( FIG.  28   ) controlled allulose content changes after 3 months storage at 30° C. 
     HMF increased in all samples. However, one subset of additive samples displayed a substantially smaller amount of HMF increase. The samples with reduced HMF increase were those containing either ascorbate or isoascorbate, displaying less than half the HMF increase of the control samples ( FIG.  29   ). 
     Ascorbate and isoascorbate have the ability to control HMF formation, whereas, sodium citrate and sodium acetate showed promise at controlling pH and allulose content changes. Neither MBS nor tocopherol acetate addition resulted in a significant benefit. 
     Example 7—Surface Response Study of Temperature, pH and DS 
     The purpose of this study was to determine the effects and interplay of pH, DS, and temperature on product stability over a narrow range of product conditions. 
     Allulose Syrup was used for this study. Each sample consisted of 1 quart (1.14 liter) of Allulose Syrup in a 1 quart (1.14 liter) round plastic HDPE container. This container was chosen because it is made of the same material as ISBT totes used for customer storage. For each time/temperature combination, a single quart container was packed. 
     
       
         
           
               
             
               
                 TABLE 8 
               
             
            
               
                   
               
               
                 Stability Sample Factors and Response 
               
            
           
           
               
               
               
               
               
               
            
               
                 Name 
                 Units 
                 Type 
                 Std. Dev. 
                 Low 
                 High 
               
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 Initial pH 
                 pH 
                 Factor 
                 0 
                 3.5 
                 4.5 
               
               
                 DS 
                 % 
                 Factor 
                 0 
                 50 
                 80 
               
               
                 Temperature 
                 C 
                 Factor 
                 0 
                 25 
                 35 
               
               
                 HMF 
                 ppm 
                 Response 
               
               
                 Allulose 
                 % 
                 Response 
               
               
                 Color 
                 CU 
                 Response 
               
               
                   
               
            
           
         
       
     
     Three factors and three responses were modeled using DOE software with the ranges for the variables of interest in Table 8. Additionally, resulting pH at the sample time points was measured. 
     The Box-Behnken design produced the following experiments in Table 9. 
     
       
         
           
               
               
               
               
               
             
               
                   
                 TABLE 9 
               
               
                   
                   
               
               
                   
                   
                 Factor 1 
                 Factor 2 
                 Factor 3 
               
               
                   
                   
                 A:pH 
                 B:DS 
                 C:Temp 
               
               
                   
                 Run 
                 pH 
                 % 
                 ° C. 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 1 
                 4.5 
                 50 
                 30 
               
               
                   
                 2 
                 3.5 
                 65 
                 25 
               
               
                   
                 3 
                 4 
                 65 
                 30 
               
               
                   
                 4 
                 3.5 
                 80 
                 30 
               
               
                   
                 5 
                 3.5 
                 65 
                 35 
               
               
                   
                 6 
                 4 
                 50 
                 25 
               
               
                   
                 7 
                 4 
                 65 
                 30 
               
               
                   
                 8 
                 4 
                 80 
                 25 
               
               
                   
                 9 
                 4 
                 65 
                 30 
               
               
                   
                 10 
                 4.5 
                 65 
                 25 
               
               
                   
                 11 
                 4 
                 65 
                 30 
               
               
                   
                 12 
                 3.5 
                 50 
                 30 
               
               
                   
                 13 
                 4 
                 65 
                 30 
               
               
                   
                 14 
                 4.5 
                 80 
                 30 
               
               
                   
                 15 
                 4 
                 80 
                 35 
               
               
                   
                 16 
                 4 
                 50 
                 35 
               
               
                   
                 17 
                 4.5 
                 65 
                 35 
               
               
                   
                 18 
                 4.0 
                 71 
                 25 
               
               
                   
                   
               
            
           
         
       
     
     Zero time samples were taken from each container and submitted for color, HMF, DP1-4, and pH analysis. Original containers were then placed in the appropriate stability chamber at 25° C., 30° C., or 35° C. as indicated in column factor 3 in Table 9. 
     After incubation for 3 weeks, 6 weeks, 3 months and 6 months, samples of each container were submitted for Color, HMF, DP1-4, and pH analysis. The results were analyzed using DOE software, and predictions for optimized conditions were generated. Contour plots were generated for allulose content, HMF, and color. 
     There were notable changes in allulose content over the six months of this response surface study. 
     When looking at the response surface of change in allulose in relation to temperature and pH at 77% DS at 6 months as shown in  FIG.  30   , there is substantial failure space where allulose content changes by more than 2%. It is surprising that there is only a narrow window in the far right hand corner at pH greater than 4.0 and temperature less than 27° C. where the allulose content of the syrup does not change substantially. 
     When looking at the change in allulose response surface for DS and pH at 25° C. ( FIG.  31   ) it is clear that the desirable zone of low allulose content change gets smaller and smaller as DS increases. Keeping in mind that DS is bound on the low end by microstability at approximately 60% DS and at the high end by reactivity and crystallization at 78% DS, we can see that there is a narrow acceptable space where change in allulose content is acceptable. At 65% DS and above, 25° C. and a pH about 4.25 are essential for stability at 6 months. 
     The acceptable stable storage conditions are further bounded in terms of solids, pH, and storage temperature when color is considered. For use in food, colorless food ingredients are desired. In this experiment, color of the syrup was analyzed as absorbance at 450 nm with background subtracted at 600 nm. A change in color of more than 4 is generally considered unacceptable. When changes in color for 77% DS allulose syrup were modeled as a response surface after 6 months storage for temperature and pH ( FIG.  32   ) we can see that both temperature and pH are critical factors. Temperature must be maintained near or below 25° C. and ideally at a pH between 3.7 and 4.2. Keeping in mind that crystallization at a DS of 77% begins to occur at temperatures below 25° C. and allulose content stability requires a pH greater than 4.0, this means that the ideal storage space at this DS is very narrow at a temperature of 25° C., pH 4.0-4.2. Further bounding DS between 60-78 for reactivity and microstability, it is clear from the pH and DS modeled response surface ( FIG.  33   ) that lower DS is more stable for color generation, but the ideal pH is still near 4.0. Further consideration of the economical importance of a syrup containing the minimum amount of water possible to reduce shipping costs and allow the broadest use in food applications, this means that, practically, the stable space for economic use of allulose syrup that is shelf stable is very narrow. This is substantially different from other known saccharide syrups; for example, dextrose syrup is known to be reasonably stable to a variety of conditions and temperatures without developing substantial color, or reduction in dextrose content. 
     Hydroxymethylfurfural (HMF) is an undesirable dehydration product from monosaccharide syrups.  FIG.  34    demonstrates the modeled temperature pH response surface for change in HMF at 77% DS. HMF production is highest at low pH and high temperature and is lowest at high pH and low temperature. Less than 100 ppm HMF is generally preferred for food ingredients. Thus, another pH boundary can be placed on allulose syrup: when stored at 25° C., it should be above pH 3.70. 
     Optimization: The modeled surface response data were used to minimize changes in allulose, HMF, and color. In the first case, no constraints were placed on pH, DS and temperature. Allulose content was given an importance of 3, and color and HMF an importance of 2. There were many solutions all with similar desirability scores and all of them had a recommended temperature of 25° C. and recommended DS of 50% with a pH range of 3.8-3.9. However, when DS is constrained to a microbially safe range and economically viable range of 71-78% DS, the desirable solutions all recommended a temperature of 25° C. and a pH range of 4.2-4.4. 
     SUMMARY 
     The results of the response surface study combined with crystallization and microbial stability and reactivity studies demonstrate that stability of allulose syrup over a period of 6 months is dependent on a very narrow temperature, pH and DS range, which is unconventionally and surprisingly narrow for a saccharide solution. 
     Advantages of the Invention 
     A syrup form that is more stable has benefits in that it can be stored for longer time periods and still be saleable, it has broader customer appeal, it can be shipped to geographic locations that require lengthy shipping and holding times. Additionally, improved product stability means that the product as used will retain a higher quality of composition and taste. This is beneficial from a calorie labelling position and final consumer product quality position.