A mayonnaise-like product and a process for its manufacture

Abstract: The invention concerns a mayonnaise-like product with a pH from 2 to 5, comprising from 55 to 85% fat, at least 0.1% milk proteins or vegetable proteins, denatured at a degree between 70 and 80%, at least 1% sugar and 0.5% salt and from 0.1 to 20% vinegar.

Description: The invention concerns a mayonnaise-like product with a high fat content, with an emulsifier other than egg yolk and with a low pH and a process for its manufacture. The preparation of acid oil-in-water emulsions with high fat content and with emulsifiers other than egg yolk, is known in the art. Usually, emulsions prepared with low molecular weight (LMW) emulsifiers have low viscosity. Examples are emulsions prepared with ethoxylated monoglycerides, diacetyl tartaric acid ester of mono- and diglycerides and hydrolised lecithins. High viscosity emulsions are possible with polyoxyethylene-(20)-sorbitan monostearate at concentrations higher than 1%, but the taste is unacceptably bitter. Generally, viscosity is increased in oil-in-water emulsions by using thickening or gelling agents like polysaccharides, gums or cold swelling starches. But when it is used in high fat emulsions prepared with LMW emulsifiers, the result is poor texture or destabilisation of the emulsion occurs. On the other hand, high molecular weight (HMW) emulsifiers (proteins) are known for their emulsifying function and ability to lend viscosity to emulsions. Generally, milk proteins combined with thickeners are used for this purpose in low to medium fat emulsions (1-55 % fat). Emulsions with higher fat content are difficult to prepare because the complex structural properties of proteins directly influence their emulsifying functions. In the food industry, acidified protein solutions are advantageous for industrial processing due to microbiological safety. Regarding the effects of acid, proteins can be divided in two general categories : 1. Those with a generally flexible, random coiled structure like casein and skim milk powder, which precipitate upon direct acidification and thereby lose their emulsifying properties. This makes the emulsification with oil and the production of high fat emulsions with directly acidified solutions impossible. 2. The proteins with generally compact, inflexible structures, like whey, soya and pea proteins, which are all mixtures of different types of serum albumins and globulins. Although these proteins generally do not precipitate upon acidification, they still undergo structural changes at the iso-electric pH, yet in most cases, emulsification with oil is still possible. High fat emulsions prepared in this way have high viscosity, but they become gelatinised during storage and result in rough texture. In the case of US Patent No. 3 892 873 supplementary emulsifying agents, like ethoxylated monoglycerides, polyoxyethylene sorbitans, mono- and diesters of higher fatty acids and glycerin, may be used. WO 93/25086 describes partly denaturized whey proteins and their use as emulsifiers for foodstuff emulsions. Denaturized whey proteins to be used as emulsifiers are first mixed, in the presence of some oil, with a solution of salt and some carbohydrates in water. Then oil (50 % by weight) is added, and the aqueous phase and the oily phase are homogenized. After completion of the homogenization, a further aqueous phase containing vinegar is added. The product is said to have the consistency of a highly viscous mayonnaise. It is known that emulsifying properties of proteins are improved when they are first emulsified with oil before heating and/or acidification. The drawback of this solution is first that it is not possible to operate continuously but batchwise and secondly that there is a greater chance of contamination. The object of the present invention is to provide a process for the manufacture of a mayonnaise-like product with a high molecular weight emulsifier, with a high fat content and wherein it is possible to operate the heating and/or the acidification of the basic solution before the emulsification with the oil, while retaining the emulsifying properties of the used proteins. According to the present inventions a mayonnaise-like product having a pH from 2 to 5 and comprising from 55 to 85% by weight oil, at least 0,1% by weight milk proteins or vegetable proteins denatured at a degree between 70 and 80%, at least 1% by weight sugar and 0,5% by weight salt, and from 0.1 to 20% by weight vinegar, the water content being normally comprised between 10 and 20% by weight, is manufactured by a process comprising the steps of preparing an aqueous phase containing 5 to 40% by weight milk proteins or vegetable proteins, 10 to 40% by weight sugar and 5 to 10% by weight salt, heating said aqueous phase, cooling said aqueous phase, acidifying the obtained product with 0.1 to 20% by weight vinegar, and homogenizing the product with the oil to obtain a fine emulsion. The mayonnaise-like product to be manufactured according to the invention , has a high fat content, a low pH, contains emulsifiers other than egg yolk, has a high viscosity, smooth texture, good stability and taste. An advantage of such emulsion is the supply of high fat spreadable products in third world countries made with locally available raw materials. The product could also be consumed for health reasons since it has a reduced cholesterol content. Due to the absence of the chemically complex raw material egg yolk, the shelf-life of these products are also improved. In the present description, all the percentages are given in weight. The milk proteins are taken from the group consisting of skim milk, particularly skim milk powder, buttermilk, casein and whey proteins. The vegetable proteins are taken from the group consisting of soya proteins, pea proteins and any combination of these proteins. The whey proteins used consist of undenatured whey protein concentrate (WPC) obtained by any separation process of milk. The casein consists of soluble proteins also obtained by any separation process. The skim milk powder used consists of undenatured spray dried skim milk. The milk powder obtained through spray drying has a protein content between 40 and 95%. The pea or soya proteins used consist of undenatured, purified extracts, with the highest possible solubility index. The denaturation of the proteins, together with the simultaneous presence of salt and sugar is necessary for the mayonnaise-like product manufactured according to the invention. The denaturation will be explained more deeply hereunder in relation with the process for the manufacture. The product contains at least 0.1% milk proteins or vegetable proteins, more particularly between 0.1 and 5% of these proteins. The type of oil used in the product is not critical and the oil can be any edible oil, more particularly processed and refined oils like soya oil, sunflower oil, palm oil and coconut oil. In a preferred embodiment of the mayonnaise-like product, it contains from 70 to 80% soya oil, from 1 to 5% of proteins taken in the group consisting of whey proteins, skim milk powder, pea proteins and soya proteins, from 1 to 2% salt, from 1 to 5% sugar and from 3 to 10% vinegar. In the case of higher fat contents and with some of the proteins mentioned above a further improvement of emulsion stability and texture is necessary. This improvement is possible by using a low molecular weiqht emulsifier which is taken from the group consisting of monoglycerides, ethoxylated monoglyceride, polyoxy-ethylene sorbitans, mono- and diesters of higher fatty acids and glycerin. Using these emulsifiers, the texture of the emulsion becomes more smooth and creamy. Furthermore, in case of emulsions based on skim milk powder, the emulsion stability is clearly improved. The preferred low molecular weight emulsifier is polyoxyethylene-(20)-sorbitan monostearate. Generally, this low molecular weight emulsifier is present in an amount comprised between 0.01 and 2%. Preferably, this emulsifier is present in an amount of 0.1 to 0.2%. The product to be manufactured may furthermore comprise any aroma, spices, vegetable and fruit pieces and thereby the viscosity normally used for this type of foodstuff. Depending on the oil content, the mayonnaise-like product can be a spread or a salad-dressing. It was found, according to the invention, that for the first and the second type of high molecular weight emulsifier, it is possible to avoid precipitation caused by direct acidification and gelatinisation during storage, by heating the emulsifier in the presence of salt and sugar. The process according to the invention comprises the heat denaturation of the emulsifier (proteins), in the presence of salt and sugar, which prevents gel formation and enables direct acidification procedures. According to the process of the invention, following process steps are carried out : Preparing an aqueous solution containing 5 to 40% milk proteins or vegetable proteins, 5 to 40% sugar and 3 to 10 % salt, heating said mixture, cooling the mixture, acidifying the obtained product with 0.1 to 20% vinegar, homogenising the product with the oil to obtain a fine emulsion. The proteins and the oil used are the same as already mentioned in relation with the product. Concerning the preparation of the basic water solution, it is preferable to have a protein content between 5 and 30%, a sugar content between 5 and 20% and a salt content between 5 and 10%. The preferred concentration of low molecular weight emulsifier is between 0.1 and 1%. In particular, polyoxyethylene-(20)-sorbitan monostearate and ethoxylated monoglycerides are used. The heating step occurs at a temperature comprised between 50 and 140°C during between 5 seconds and 30 minutes. Preferably, the heating occurs under continuous agitation at a temperature of 85°C , whereafter the product is maintained at this temperature for 1 to 5 minutes. The heating should effect a denaturation degree of the protein between 70 and 80%. The denaturation degree is determined by measuring the nitrogen solubility at pH 4.5 of a 5% solution of the heat treated mixture ( Heat gelation of oil-in-water emulsions stabilised by whey protein, R. Jost and al., J. Food Sci.51(2), pages 440-444). The cooling step is carried out at a temperature comprised between 1 to 40°C. The acidification occurs to a pH value between 2 and 5. Any food grade acid can be used, particularly acetic acid or vinegar. According to an embodiment of the process, a pre-emulsification with oil is made before the homogenising step to form a coarse emulsion. The pre-emulsification and homogenising step can be carried out with any suitable equipment existing on the market. According to a further embodiment of the invention, vinegar and oil combined are emulsified and homogenised with the preheated water phase. The process according to the invention has the advantage that the quantity of water is small relative to the oil phase, thereby allowing for convenient heating and acidification procedures, which facilitates industrial manufacturing of such products. The process according to the invention has the additional advantage that no thickeners like starches or gums are needed to obtain high viscosity. The invention will now be further explained by the following examples. Example 1 An aqueous phase, containing 22.2% skim milk powder, 7.2% salt, 16.6% sugar and 1.1% polyoxyethylene-(20)- sorbitan monostearate, was prepared.All the ingredients were mixed together in a Stephan batch mixer. The mixture was heated indirectly with steam to 85°C and held at this temperature for 5 minutes, after which it was cooled down to 25°C, while scraping the surface continuously at an average speed. Then, vinegar was added to the mixture while stirring. The emulsion was prepared by gradually adding the oil to the waterphase. A fine emulsion was obtained by passing through a colloid mill. The emulsion has following composition: Soya oil 75% Skim milk powder 4% Vinegar (11% acetic acid) 7% Salt 1.3% Sugar 3% Polyoxyethylene-(20)-sorbitan monostearate 0.2% Water 9.5% Total 100% The emulsion viscosity, stability and texture were compared to a reference sample as for the preceding example. The following results were obtained : Emulsion Viscosity (Pa.s) Stability Texture Heated waterphase 8.1 stable smooth Unheated waterphase 5.5 oil separation sandy Example 2 An aqueous phase, containing 6.3% whey protein concentrate (WPC)(60% protein), 6.3% salt and 14.6% sugar, was prepared. All the ingredients were mixed together in a Stephan batch mixer. The mixture was heated indirectly with steam to 85°C and held at this temperature for 5 minutes, after which it was cooled down to 25°C, while scraping the surface continuously at an average speed. Then, vinegar was added to the mixture while stirring. The emulsion was prepared by gradually adding the oil to the waterphase. A fine emulsion was obtained by passing it through a colloid mill. The emulsion had following composition : Soya oil 75% WPC 1.3% Acetic acid (11%) 4.5% salt 1.3% sugar 3% water 14.9% Total 100% The emulsion viscosity, stability and texture were compared to an emulsion of which the waterphase was not heated. The viscosity was determined at 20°C using a Bohlin CS 50 rheometer at a shear rate of 10 m/sec. The samples were checked for texture and oil separation after 3 months at 32°C. Emulsion Viscosity (Pa.s) Stability Texture Heated waterphase 15.23 stable smooth Unheated waterphase 17.54 oil separation gelatinised Example 3 An aqueous phase, containing 8.7% pea protein (95% protein), 5.6% salt, 13% sugar and 0.4% ethoxylated monoglyceride, was prepared. The same procedure as for example 1 was carried out, except for the indirect heating ,which was done at 60°C. The viscosity of the product was 4.9 Pa.s and the stability and texture were unchanged after 3 months storage at 32°C. The preparation of a 70% oil-in-water emulsion was not possible with the unheated reference. Similar results were obtained when ethoxylated monoglyceride is replaced by polyoxyethylene-(20)-sorbitan monostearate. Example 4 An aqueous phase, containing 8.7% soya protein (95% protein), 5.6% salt, 13 % sugar and 0.8% polyoxyethylene-(20)-sorbitan monostearate, was prepared. The preparation of the emulsion was carried out as in example 1. The viscosity of the product was 4 Pa.s and the stability and texture were unchanged after 3 months storage at 32 °C. The preparation of a 70 % oil-in-water emulsion was not possible with the unheated reference. Similar results were obtained when polyoxyethylene-(20)-sorbitan monostearate is replaced by ethoxylated monoglyceride in the recipe.

Claims: A process for the manufacture of a mayonnaise-like product having a pH from 2 to 5 and comprising from 55 to 85% by weight oil, at least 0,1% by weight milk proteins or vegetable proteins denatured at a degree between 70 and 80%, at least 1% by weight sugar and 0,5% by weight salt, and from 0.1 to 20% by weight vinegar, wherein the following steps are carried out: preparing an aqueous phase containing 5 to 40% by weight milk proteins or vegetable proteins, 10 to 40% by weight sugar and 5 to 10% by weight salt, heating the aqueous phase, cooling the aqueous phase, acidifying the obtained product with 0.1 to 20% by weight vinegar, and homogenizing the product with oil to obtain a fine emulsion. The process of claim 1, wherein the manufactured mayonnaise-like product contains from 0,1 to 5% milk proteins or vegetable proteins. The method of claims 1 or 2, wherein the milk proteins are selected from the group consisting of skim milk, buttermilk, casein and whey proteins and the vegetable proteins are selected from the group consisting of soya proteins and pea proteins and any combinations of said proteins. The process of claim 1 to 3, wherein the heating is carried out at a temperature between 50 and 140°C for a time between 5 s and 30 min. The process of any of claims 1 to 4, wherein the cooling is carried out at a temperature between 1 and 40°C. The process of any of claims 1 to 5, wherein before the homogenization step a pre-emulsification with the oil is carried out to form a coarse emulsion. The process of any of claims 1 to 6, wherein a combination of vinegar and oil is emulsified and homogenised with the previously heated aqueous phase. The process of any of claims 1 to 7, wherein the oil is selected from the group consisting of refined and processed vegetable oils like soya oil, sunflower oil, palm oil and coconut oil. The method of any of claims 1 to 8, wherein the manufactured mayonnaise-like product contains from 70 to 80% by weight soya oil, from 1 to 5% by weight proteins selected from the group consisting of whey protein, casein, skim milk powder, pea protein and soya protein, from 1 to 2% by weight salt, from 1 to 5% by weight sugar, and from 3 to 10% by weight vinegar. The method of any of claims 1 to 9, wherein the aqueous phase further contains a low molecular weight emulsifier selected from the group consisting of monoglycerides, ethoxylated monoglyceride, polyoxy-ethylene sorbitans, and mono- and diesters of higher fatty acids and glycerin. The method of claim 10, wherein the manufactured mayonnaise-like product contains a protein selected from the group consisting of skim milk powder, casein, pea protein and soya protein, and a low molecular weight emulsifier according to claim 10. The method of claim 11, wherein the low molecular weight emulsifier is polyoxyethylene-(20)-sorbitan monostearat being present in the manufactured mayonnaise-like product in an amount between 0,02 and 2% by weight.

Inventors: CAMPBELL LYDIA, TRUECK HANS UWE, CAMPBELL, LYDIA, TRUECK, HANS UWE
Applicants: NESTLE SA, SOCIETE DES PRODUITS NESTLE S.A.
Application year: 1996
Main classification: A23L1
IPC codes: A23L1, A23J1