Patent Description:
Fruit products are now widely recognized as valuable components in a healthy diet. The most important product derived from fruits is juice. The manufacture of fruits for the production of juices generates great amounts of by-products. One of the most significant in terms of overall bulk is the peel of the fruit.

Regarding citrus fruits, the production of juice implies mainly the use of the endocarp, that is, the partitions of the fruit where most of the juice is found. The pericarp, which is composed of the albedo (mesocarp, the fruit wall) and the flavedo (exocarp, the outer peel of the fruit) are generally not used for the production of juice. Historically, the peel by-products coming from the extraction of fruit juice were neglected in terms of human consumption. At first, the by-products were simply discarded. Later, they were processed and exploited as low-value products for animal consumption such as fodder. However, the current trend is for the industry to maximize the value of the by-products generated as waste after juice extraction, i.e. to turn them as much as possible into products suitable for human consumption.

There are several interesting components present in the peel by-products of citrus fruits that, if extracted efficiently and processed properly, can become part of the human diet or can be apt for human cosmetic use. The albedo is rich in carbohydrates, pectin and dietary fiber, and the flavedo contains, apart from wax and essential oils, a series of vesicles with a high content of bitter juice. This juice, currently known in the technical field as cloudy, is of lower quality than the juice obtained from the endocarp, but can still be considered for human consumption as it contains high-value ingredients such as vitamins and natural antioxidants. Likewise, the peel of other fruits such as pomegranate, watermelon and others also contain desirable components such as vitamins, minerals and fiber.

Peel-derived juice is increasingly being used in the production of fruit juice drinks and beverages, and it is added to soft drinks and other foods to improve their nutritional content. Moreover, many of the ingredients found in the peel of a variety of fruits such as citrus fruits and pomegranate are also being directed to human use as cosmetic additives and ingredients with desirable biological properties. This demands quicker, cheaper and more efficient ways to produce peel-derived juice.

The industrial production of peel-derived juice is complicated by several factors: i) the raw juice extracted from the peel of the fruit is difficult to separate from the rest of the peel components; ii) it usually has a high content in pectins which make it very viscous, hindering its extraction and processing; iii) the stability of this juice must be ensured along its industrial processing, so that no undesirable changes in colour due to oxidation and other chemical reactions take place; iv) its bitterness must be eliminated in order to make it suitable for human consumption; v) an extra complicating issue is the fact that the viscosity, bitterness and other properties of the raw material vary not only among different types of fruits, but also among different varieties of the same fruit and even between different harvests of the same variety (ripening stage, quality, humidity),which challenge the design of a universal process for its manufacture. Thus, a single flexible process that could handle different fruits, varieties and harvests and could still deliver a final peel-derived juice within strict quality standards in terms of shelf-life, stability, viscosity and other parameters would clearly represent a step forward.

Some approaches have been disclosed in order to maximize the value of the peel components. US patent application <CIT> discloses processes for the conversion of citrus by-products for human consumption. The processes involve pressing peels to release juice from vesicles and then grinding peels in water to create a slurry. The oils are removed by a flotation technique, and the peel particles are debittered with water in steps of boiling and washing. <CIT> discloses a process for the production of refined citrus peel juice comprising a step where the raw peel juice is subjected to microfiltration to form a rentate of peel solids and a permeate of clarified peel juice, the latter being subsequently debittered.

In spite of what has been described in the art, new methods for the production of peel-derived juice that can address the mentioned issues are still being sought.

Inventors have surprisingly found a universal procedure for the production of peel-derived juice that can be applied to a variety of fruits. Advantageously this method does not involve lengthy chemical treatments, and only entails one step of biochemical (enzymatic) treatment. The method combines a series of steps that allow it to be flexible enough to be used for a wide variety of fruits such as citric fruits, pomegranate or watermelon, but at the same time reliable enough to always give a final product meeting the highest standards.

In particular, the method is endowed with a step where a particular shredding grid is used for the initial grinding of the raw material. This shredder type has been found to give optimal results when combined with the rest of the critical steps. Further, the raw extracted juice can be initially treated with a quantity of degrading enzymes that is proportional to its initial viscosity, which results in a more controlled set of properties of the processed juice and to a more rational use of the enzymes. Moreover, the method is characterized by the addition of ascorbic and cirtic acids before the pasteurization step, which surprisingly allows having a peel derived juice that does not oxidize overly and therefore does not change in color, which is one of the problems often seen in industrial methods for obtaining juice from the fruit peel. The method can be fine-tuned so that the processed peel-derived juice can have the right values for such important properties as color (<FIG>), centrifugable pulp (<FIG>), turbidity (<FIG>) viscosity (<FIG>) and shelf life (<FIG>), as will be seen in the experimental data presented below.

In essence, inventors have come across a procedure made up of a series of steps that, when executed together, ensure a high quality for the final product as well as a high stability and long shelf-life.

Thus, a first aspect of the invention is a process for obtaining fruit peel juice comprising the steps of: a) Grinding of the fruit peel in an aqueous solution at <NUM>-<NUM> degrees Celsius with a mill comprising a shredding grid that is characterized by having an opening with circular shape from <NUM> to <NUM> of diameter and a surface area from <NUM> to <NUM><NUM>. ; b) Submitting the product of step a) to an enzymatic treatment selected from the group consisting of pectinase, pectinlyase, beta-glucanase and combinations thereof; c) Separating the liquid phase from the solid phase obtained in step b); d) Sieving the liquid phase obtained in step c); and e) Adding citric acid and ascorbic acid to the liquid phase of step d); f) Pasteurizing the product obtained in step e) by thermal treatment; g) Centrifuging the product obtained in step f); provided that when the fruit is pomegranate, in step e) only citric acid is added and provided that when the fruit is lemon, in step e) no acid is added.

The juice can be successfully incorporated as an additive in a variety of final products for human consumption such as foods, mixtures with dairy products, cookies and others. It can also be incorporated as an antioxidant rich ingredient in a variety of cosmetic products.

The obtainable juice can be incorporated in a variety of drinks to increase their nutritional content.

For the sake of understanding, the following definitions are included.

The term "grinder", as used herein refers to a grinding machine for producing particle size reduction through shearing and shredding based on the use of a rotating piece armed with cutting devices that operates at very high speeds. In the case at hand, the "shredding grid" has a series of holes which effectively act as blades, cutting the fruit peel. The holes in the shredding grid can have various sizes and shapes. In the case of the present invention, the holes are circular holes of a size from <NUM> to <NUM> of radius (<NUM> to <NUM> of diameter) and an area of around ("opening") <NUM>-<NUM><NUM>, more preferably of <NUM><NUM>.

The term "decanting" as used herein refers to a process for the separation of a mixture of two or more components by removing a layer of liquid, generally one from which a precipitate has settled. In the present application, decantation refers to separating a liquid phase containing a juice from a more solid phase containing a precipitate with solid particles.

The term "pasteurizing" as used herein refers to a process of killing bacteria in a juice or a concentrate of juice, by heating. This process is intended to kill most of the bacteria that cause spoilage, preventing the juice from losing its quality and extending its shelf-life.

The term "color" as used herein (as applied to a juice) refers to the use of the USDA scale color standard, which is applied for mandarin and orange. Currently this system is taken as a standard, and is based on <NUM> different colors approximately, each one identified by a combination of a letter and a number. The result is qualitative and the observer selects the closer color of the guide which corresponds with the product [www.

The term "ascorbic acid" as used herein (as applied to a juice) refers to the compound whose IUPAC name is (<NUM>R)-[(<NUM>S)-<NUM>,<NUM>-Dihydroxyethyl]-<NUM>,<NUM>-dihydroxyfuran-<NUM>(<NUM>H)-one. The method used for the determination of total ascorbic acid in the fruit juice was as specified in the standard AOAC methods, <NUM> and <NUM>. This method was chosen due to its advantages compared to other methods. It is sensitive, economic, practical and less time-consuming [JBT FoodTech Citrus Systems, 2011a; AOAC, <NUM>; <NPL>].

The term "centrifugable pulp" as used herein (as applied to a juice) refers to the percentage of pulp sedimented after centrifugation at <NUM> during <NUM> minutes. The method used for the determination centrifugable pulp is described in UNE-EN <NUM>:<NUM>. (AENOR, <NUM>, IFUMA60, <NUM>). The results were determined at the end of the production process and during the time of cloudy storage.

The term "viscosity" as used herein (as applied to a juice) refers to the measure of the resistance the juice opposes to deformation. It corresponds to the informal concept of "thickness". Of note, the methodology used in the present application to determine the viscosity is performed using a Brookfield® viscometer and following the method described in the Laboratory manual of JBT FoodTech Citrus Systems (JBT FoodTech Citrus Systems, 2011b)
The term "turbidity" as used herein refers to the cloudiness or haziness of the juice caused by large numbers of individual particles that are typically invisible to the naked eye. Of note, the methodology used in the present application to determine the turbidity is performed by the previous dilution of samples of cloudy (at <NUM>%) and a second step of centrifugation (<NUM> rpm, <NUM>). After that, determination of solution turbidity is performed following the spectrophotometrical method of attenuation based on Beer's law, which explains the relationship between transmitted and Incident lights. For the analysis distilled water as blank, optical glass cuvettes of <NUM> thickness and a wavelength of <NUM> were used. (IFUREC07, <NUM>; EPA, <NUM>, Anderson, <NUM>).

The term "stability" as used herein refers to the time (days) which the cloudy remains without phase separation or without clarification and is determined by visual observations along the storage time.

The term "Brix index" as used herein refers to the sugar content in an aqueous solution. One degree Brix is <NUM> gram of sucrose in <NUM> grams of solution.

The term "debittering step" as used herein refers to a step where the product is treated so that the compounds that give it a bitter taste are eliminated. For instance, it is common practice to use the enzyme naringinase. It is a debittering enzyme that is used in the commercial production of citrus beverages and juices. It breaks down the compound naringin that gives citrus juices its bitter taste.

The term "stone fruit" as used herein refers to a fruit in which an outer fleshy part (exocarp, or skin; and mesocarp, or flesh) surrounds a shell (the pit, stone, or pyrene) of hardened endocarp with a seed (kernel) inside. The crucial characteristic of a drupe is that the hard, "lignified" stone (or pit) is derived from the ovary wall of the flower. Typical stone fruits include apricot, cherry, nectarine, peach or plum.

As mentioned above, a first aspect of the invention is a process for obtaining fruit peel juice comprising the steps of: a) Grinding of the fruit peel in an aqueous solution at <NUM>-<NUM> degrees Celsius with a mill comprising a shredding grid that is characterized by having an opening with circular shape from <NUM> to <NUM> of diameter and a surface area from <NUM> to <NUM><NUM>; b) Submitting the product of step a) to an enzymatic treatment selected from the group consisting of pectinase, pectinlyase, beta-glucanase, cellulase and combinations thereof; c) Separating the liquid phase from the solid phase obtained in step b); d) Sieving the liquid phase obtained in step c); and e) Adding citric acid and ascorbic acid to the liquid phase of step d); f) Pasteurizing the product obtained in step e) by thermal treatment; g) Centrifuging the product obtained in step f); provided that when the fruit is pomegranate, in step e) only citric acid is added and provided that when the fruit is lemon, in step e) no acid is added.

In an embodiment of the first aspect of the invention, in step c) the separation of the liquid phase from the solid phase is carried out by decanting.

In an embodiment of the first aspect of the invention, the grinding of the fruit peel in an aqueous solution is carried out at <NUM> to <NUM> degrees Celsius.

In another embodiment of the first aspect of the invention, in step a) the mill comprises a shredding grid that is characterized by having an opening with circular shape.

In another embodiment of the first aspect of the invention, in step a) the mill comprises a shredding grid that is characterized by having an opening with circular shape and a surface area (opening) of <NUM><NUM>.

In another embodiment of the first aspect of the invention, the process further comprises a step h) characterized by concentrating the liquid phase obtained in step g) and wherein the Brix index of the processed peel juice is from <NUM> to <NUM>.

In another embodiment of the first aspect of the invention, the process has an efficiency such that from <NUM> to <NUM> metric tons of preconcentrated cloudy, <NUM> metric ton of final cloudy is obtained.

In another embodiment of the first aspect of the invention, in step b) the amount of pectinase added is from <NUM> to <NUM> ppm, the amount of pectinlyase added is from <NUM> to <NUM> ppm, the amount of beta-glucanase added is from <NUM> to <NUM> ppm, and the amount of cellulase added is from <NUM> to <NUM> ppm.

In another embodiment of the first aspect of the invention, in step b) the amount of enzyme added is directly proportional to the viscosity of the product obtained in step a).

In another embodiment of the first aspect of the invention, in step b) the amount of enzyme added is directly proportional to the viscosity of the product obtained in step a), and said viscosity is controlled by a viscosimeter deployed in-line which allows monitoring the viscosity continuously. In other words, the viscosity of the product resulting from step a) dictates the amount of enzyme added in step b), such that when the viscosity is higher, a higher amount of enzyme is added.

In another embodiment of the first aspect of the invention, in step b) the treatment is administered from <NUM> to <NUM> minutes and the temperature at which it is carried out is from <NUM> to <NUM> degrees Celsius.

In another embodiment of the first aspect of the invention, in step b) the amount of pectinase added is from <NUM> to <NUM> ppm, the amount of pectinlyase added is from <NUM> to <NUM> ppm, the amount of beta-glucanase added is from <NUM> to <NUM> ppm, and the amount of cellulase added is from <NUM> to <NUM> ppm, and wherein the treatment is administred from <NUM> to <NUM> minutes and the temperature at which it is carried out is from <NUM> to <NUM> degrees Celsius.

In another embodiment of the first aspect of the invention, the process further comprises a step i) wherein the product obtained in steps g) or h) is pasteurized by thermal treatment.

In another embodiment of the first aspect of the invention, the process for obtaining fruit peel juice further comprises a step i) comprising pasteurizing the product obtained in steps g) or h) by thermal treatment.

In another embodiment of the first aspect of the invention, step e) comprises adding citric acid together with ascorbic acid to adjust the pH to a value from <NUM> to <NUM> and a final concentration from <NUM> to <NUM>/kg.

In another embodiment of the first aspect of the invention, the process further comprises an additional debittering step between steps g) and h). In another embodiment of the first aspect of the invention, the debittering comprises a treatment characterized by the absorption of the compounds that confer bitterness in a column.

The product "obtainable by" the process of the invention is used here to define the product by the process for obtaining it. For the purposes of the invention the expressions "obtainable", "obtained" and equivalent expressions are used interchangeably, and in any case, the expression "obtainable" encompasses the expression "obtained".

Throughout the description and claims the word "comprise" and variations of the word, are not intended to exclude other technical features, additives, components, or steps. Furthermore, the word "comprise" and its variations encompasses the term "consisting of". Additional objects, advantages and features of the invention will become apparent to those skilled in the art upon examination of the description or may be learned by practice of the invention. The following examples are provided by way of illustration, and they are not intended to be limiting of the present invention. Furthermore, the present invention covers all possible combinations of particular and preferred embodiments described herein.

In order to prove that the process for obtaining fruit peel juice of the present invention is superior to very closely related methods, it was decided to run a series of comparative experiments. The fruit peel juice obtained by the invention was compared to the fruit peel juice of a very closely related method. As it can be seen from the data presented below, the method of the invention (method <NUM>) unexpectedly outperforms the closely related method (method <NUM>) in terms of turbidity, viscosity, color and stability of the final product.

This method falls within the definition of claim <NUM> as it is set out in the present application, and is characterized by:.

Method <NUM>, that is, a process for producing fruit peel juice that is very closely related, but different, to the method of the invention, gave a fruit peel juice obtained showing a dark yellow color classified in the USDA color scale as OJ1 and OJ2 (<FIG>), centrifugable pulp of <NUM> % (<FIG>), turbidity value below <NUM> (<FIG>), viscosity of <NUM> centiPoisses (cPs) (<FIG>) and a maximum shelf life of <NUM> days (<FIG>). In addition the obtained fruit peel juice according to this procedure gave a phase separation due to stability loss, with a little dark yellow tonality and the preservation of sensory properties was kept for a maximum of <NUM> days.

Claim 1:
A process for obtaining fruit peel juice comprising the steps of:
a) Grinding of the fruit peel in an aqueous solution at <NUM>-<NUM> degrees Celsius with a mill comprising a shredding grid that is characterized by having an opening with circular shape from <NUM> to <NUM> of diameter and a surface area from <NUM> to <NUM><NUM>;
b) Submitting the product of step a) to an enzymatic treatment selected from the group consisting of pectinase, pectinlyase, beta-glucanase, cellulase and combinations thereof;
c) Separating the liquid phase from the solid phase obtained in step b);
d) Sieving the liquid phase obtained in step c); and
e) Adding citric acid and ascorbic acid to the liquid phase of step d);
f) Pasteurizing the product obtained in step e) by thermal treatment;
g) Centrifuging the product obtained in step f);
provided that when the fruit is pomegranate, in step e) only citric acid is added and provided that when the fruit is lemon, in step e) no acid is added.