Probiotic and antioxidant kefir drink

Abstract

The kefir drink (40) comprises a fermented liquid obtained by using natural, unpasteurised red berry juice (26) as a fermentation substrate. Preferably, the kefir drink (40) is fermented by the addition of at least 40 grams of kefir granules (16) and at least 5 grams of sugar (31a) per litre of natural, unpasteurised red berry juice (26), undiluted or diluted up to 50% by volume, for 12 to 48 hours at a temperature between 18 and 28°C, wherein the kefir granules (16) have been removed from the fermented liquid obtained.

Description

[0001] PROBIOTIC AND ANTIOXIDANT KEFIR DRINK DESCRIPTION TECHNICAL SECTOR OF THE INVENTION

[0002] The present invention falls within the field of food biotechnology, with a focus on fermented and probiotic beverages.

[0003] OBJECT OF THE INVENTION

[0004] The present invention presents a probiotic and antioxidant kefir beverage.

[0005] BACKGROUND OF THE INVENTION AND TECHNICAL PROBLEM TO BE SOLVED

[0006] Kefir, or kefir, is a fermented beverage traditionally made from milk, water, or tea, using kefir grains as a starter culture. These kefir grains contain lactic acid bacteria and yeasts that interact to ferment the substrates, resulting in a beverage with probiotic properties.

[0007] Milk kefir has been widely consumed due to its benefits for gut health, thanks to the presence of live bacteria and yeasts. However, using milk as a substrate means it lacks some bioactive compounds that can be found in other natural products, such as fruits.

[0008] On the other hand, water or tea kefir is a dairy-free option, but it has a limited nutritional composition compared to fruit kefir, as it does not provide the same amount of vitamins, antioxidants, and other beneficial compounds.

[0009] In the state of the art, kefir drinks obtained from fruit juices are known.

[0010] Documents W02009008144A1 and W02009008143A1 use the solid byproduct obtained during the sake brewing process, or starch, as the fermentation substrate. Document US4671962A uses chicory as the substrate, while document W02011005128A2 uses whey as a byproduct.

[0011] WO1992003533 describes a process for producing stable kefir-type fermented beverages by fermenting reconstituted wort with various strains of microorganisms. The wort used is solidified and heat-treated. Separately, JPS61135540A adds a small amount of fruit juice to milk to adjust the citric acid content, and then inoculates specific quantities of kefir cultures and Streptococcus diacetylactis to carry out fermentation at a specific temperature for a set number of hours, resulting in a fresh and pleasant-tasting fruit kefir beverage.

[0012] Document CN117084340A describes the production of an antioxidant fruit and vegetable water kefir beverage by activating kefir grains with brown sugar, which are then fermented in a substrate of mixed fruit and vegetable juice, including grape juice, watermelon juice, and tomato juice. In the first step, kefir grains are cultured in water at a concentration of 4 to 6% by mass, in water with brown sugar, at 25 to 30°C for 1 to 3 days. Subsequently, in the second step, the water kefir grains are fermented in a mixture of fruit and vegetable juice at a concentration of 3 to 7% by volume. In this second step, the fermentation temperature is 33 to 39°C and the fermentation time is 24 to 48 hours.

[0013] Document CN101720967A refers to a milk kefir beverage with fruit and vegetable juice fermented by a kefir starter. The concentrated fruit and vegetable juice is diluted to a solids content of 10 to 12%, the juice acidity is adjusted, and it is subsequently pasteurized at 85°C for 5 minutes before fermentation. The aforementioned concentrated fruit juice includes: apple juice, orange juice, carrot juice, pineapple juice, tomato juice, mango juice, lychee juice, and blends of two or more fruit and vegetable juices.

[0014] The technical problem to be solved is obtaining a kefir beverage rich in nutrients and bioactive compounds that also allows for low production costs.

[0015] EXPLANATION OF THE INVENTION

[0016] The present invention presents a probiotic and antioxidant kefir beverage.

[0017] The differentiating characteristics of the kefir beverage of the present invention are described.

[0018] The kefir beverage (food product) of the present invention comprises a fermented product obtained by using unpasteurized natural red fruit juice as a fermentation substrate. In other words, the kefir beverage of the present invention is a fermented beverage obtained through a fermentation process in which unpasteurized natural red fruit juice acts as the fermentation substrate.

[0019] Kefir drink is obtained by activating a fermentation by adding at least 40 grams of kefir grains, and at least 5 grams of sugar, per liter of natural red fruit juice, either undiluted or diluted up to 50% by volume.

[0020] In other words, the unpasteurized natural red fruit juice used as a fermentation substrate is not diluted with any liquid, such as water or milk, and each liter is 100% unpasteurized natural red fruit juice enriched with kefir grains and sweetened. Alternatively, the natural red fruit juice used as a fermentation substrate is diluted with a liquid, such as water or milk, and each liter contains at least 50% unpasteurized natural red fruit juice.

[0021] The term “sugar” used throughout this description should be understood in a broad and non-restrictive sense, and includes sugar, sugar substitutes, sweeteners, or a combination thereof. Examples of sweeteners include sucralose, stevia, honey, etc.

[0022] Throughout this document, the term “granule” should be understood as synonymous with the term “grain”.

[0023] Kefir drink is obtained by fermentation for 12 to 48 hours at a temperature between 18 and 28 °C of the above proportions of kefir grains, sugar and unpasteurized natural red fruit juice.

[0024] Throughout this document, each indicated temperature includes deviations of ± 1 °C, and these deviations are therefore within the scope of the present invention.

[0025] In kefir drink, the kefir grains have been removed from the previously obtained fermented product.

[0026] The fermented liquid obtained from the removed kefir grains has been filtered, packaged, carbonated, and refrigerated to stop fermentation and for preservation. Preferably, in the case of kefir beverages, the fermented liquid obtained from the removed kefir grains has been filtered and then packaged.

[0027] Optionally, in the kefir drink, the fermented product obtained, with the kefir grains removed, filtered and packaged, has subsequently been carbonated, either naturally or exogenously.

[0028] Optionally, in the kefir drink, the fermented product obtained from the removed kefir grains, subsequently filtered and carbonated, has been refrigerated for preservation.

[0029] The advantages of the kefir beverage of the present invention are described below in relation to its differentiating characteristics.

[0030] The present invention provides a technological solution in which the kefir beverage comprises a fermented product obtained by using natural, unpasteurized juice from red fruits as a fermentation substrate. Being a natural juice, it contains a microbiological load that interacts with the lactic acid bacteria and yeasts present in the kefir grains.

[0031] By using natural red fruit juice, i.e., juice from fresh, unpasteurized fruit, as a fermentation substrate, its inherent bioactive composition is utilized, resulting in a fermented kefir beverage with high added value.

[0032] This invention focuses on the use of unpasteurized red fruits as a fermented substrate in the kefir beverage, quite unlike state-of-the-art solutions where fruit juices or mixed fruit and vegetable juices are incorporated pasteurized with the consequent degradation of vitamins and bioactives.

[0033] The present invention focuses specifically on the substrates used to obtain the kefir beverage, comprising these red fruits, from which we obtain the natural, unpasteurized juice, for example, optionally by pressing, or alternatively by crushing or blending.

[0034] In our case, we do not use heat-treated concentrates, which allows us to preserve the vitamins, minerals, and bioactive compounds present in the fruit. Optionally, the kefir beverage is obtained through a process that does not require the addition of milk. Alternatively, milk may be added during the kefir beverage production process, depending on the target market.

[0035] Optionally, the kefir drink may be obtained exclusively from fruit juice as a fermentation substrate, sweetened and enriched with kefir grains to start fermentation.

[0036] Kefir drink is obtained from natural red fruit juice: strawberries, cherries, blueberries, raspberries, blackberries, currants, among others, either as an individual product or a mixture of the aforementioned fruits, acting as a fermentation substrate.

[0037] Unlike milk or water kefir, red berry kefir offers a probiotic fermented beverage with a superior nutritional profile, thanks to the presence of vitamins, minerals, and bioactive compounds naturally found in fruits. Specifically, red berries are known for their high anthocyanin content, a type of flavonoid. These anthocyanins include subclasses such as cyanidins, pelargonidins, peonidins, and delphinidins, which differ in their chemical structure and the colors they produce (red, blue, and purple). These substances possess antioxidant and anti-inflammatory properties and have been shown to help reduce the risk of cardiovascular disease and certain types of cancer. They may also improve cognitive function and eye health.

[0038] In the case of red fruits, such as strawberries, cherries, blueberries, raspberries, blackberries and currants, they stand out for their high content of vitamin C, polyphenols and antioxidants, reaching very high volumes in the waste.

[0039] The present invention covers both the case of using as a fermentation substrate natural juice, either made from red fruits that meet supermarket standards, or made from red fruits that do not meet these standards and are classified as rejects, or a combination of these.

[0040] As an optional advantage, we can utilize red fruits that do not meet the aesthetic standards required by supermarkets, due to insufficient size, shape, or color, and which are otherwise discarded. In this way, we add value to a byproduct that would initially be thrown away, resulting in savings in emissions, water, and land use. The present invention relates to a kefir beverage obtained through a fermentation process using natural, unpasteurized red fruit juice, expanding the range of probiotic products available on the market. This invention not only offers an alternative to traditional kefir made with milk, water, and tea, but also harnesses the nutrients, vitamins, minerals, and bioactive compounds of red fruits, resulting in a highly nutritious beverage and providing an accessible kefir option for consumers with lactose intolerance and / or vegans.Preferably, the use of fruits that would be discarded for aesthetic reasons is encouraged, aligning the invention with sustainability goals while reducing production costs.

[0041] Advantages of other optional features of the present invention are set out in the preferred embodiments section.

[0042] Optionally, in the kefir beverage, the fermented product obtained, filtered, and packaged has been naturally carbonated for 12 to 48 hours at a temperature between 18 and 28 °C. Alternatively, in the kefir beverage, the fermented product obtained, filtered, and packaged has been exogenously carbonated by the addition of pressurized carbon dioxide.

[0043] Optionally, in the kefir drink, the kefir grains added for fermentation are either fresh or freeze-dried kefir grains.

[0044] Preferably, in the kefir drink, the fermented product obtained has, on a logarithmic scale, more than 8 CFU / mL of lactic acid bacteria to guarantee its probiotic potential.

[0045] Throughout this document, the term “ufe” or “UFO” should be understood as “colony forming unit” which is an indicator of the amount of live microorganisms in a liquid, in this case said liquid corresponds to the fermented product obtained from kefir granules, sugar and / or substitute, and unpasteurized natural red fruit juice.

[0046] Throughout this document, the term “L” should be understood as “liter”, and the term “mL” should be understood as “milliliter” or thousandth of a liter.

[0047] Preferably, in the kefir beverage, the fermented product obtained has a concentration of phenolic compounds greater than or equal to 100 mg GAE / 100 mL and has an antioxidant activity greater than or equal to 0.3 mmol Fe 2+ / 100 mL, to guarantee its functional and antioxidant potential. Throughout this document, the term “g” should be understood as “gram” and “mg” should be understood as “milligram”.

[0048] Throughout this document, the expression “mg GAE” should be understood as milligrams of gallic acid equivalent.

[0049] Throughout this document, the term “mmol” refers to one thousandth of a mole. Optionally, in the kefir beverage, the fermented product has been subjected to high hydrostatic pressure to extend its shelf life at room temperature.

[0050] Optionally, in the kefir beverage, the fermented product has been subjected to pasteurization treatments to extend its shelf life at room temperature.

[0051] Preferably, in kefir beverage, the unpasteurized natural red fruit juice used as a fermentation substrate is obtained from red fruits discarded for aesthetic reasons.

[0052] Preferably, in kefir, the unpasteurized natural red fruit juice used as a fermentation substrate comprises strawberry, cherry, blueberry, raspberry, blackberry, and / or currant juice, or a combination of these juices. Advantageously, the juice of these red fruits can be easily extracted from them, as they do not contain rinds or peels covering the edible portions.

[0053] Optionally, in kefir, the fermentation substrate is free of milk, lactose, or dairy products, making it suitable for consumers with lactose intolerance and / or vegans, which significantly expands the potential market. Red fruit kefir represents a non-dairy alternative, richer in nutrients and bioactive compounds, such as the polyphenols, flavonoids, carotenoids, and vitamins found in fruit juices.

[0054] Optionally, in the kefir drink, the unpasteurized natural red fruit juice used as a fermentation substrate has been previously extracted from the red fruits by pressing.

[0055] Additionally, in kefir, the fermentation substrate consists exclusively of unpasteurized natural red fruit juice. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] To complement the description of the object of the invention and to aid in a better understanding of its distinguishing characteristics, this descriptive document includes, as an integral part thereof, a set of figures which, for illustrative and non-limiting purposes, depict the following:

[0057] Figure 1 represents each of the stages of the method by which the kefir beverage (food product) that is the subject of the present invention is obtained; and

[0058] Fig. 2 represents, on the vertical axis, the concentration in phenolic compounds, that is, the total content of phenolic compounds (in milligrams of gallic acid equivalent, mg GAE) per 100 milliliters, of different kefir drinks represented from left to right on the horizontal axis: water, strawberry, blueberry and blackberry, for three times each: “Initial” means just before fermentation, “Final” means after fermentation for 48h with kefir grains, and “7 days” means after seven days of refrigeration at 5 ± 1 °C, and where for each column of the figure three samples have been taken and the mean value and standard deviation are shown (n = 3 ± SE);

[0059] Figure 3 represents, on the vertical axis, the equivalent ferric antioxidant potential, in millimoles of Fe 2+for every 100 milliliters, of different kefir drinks represented from left to right on the horizontal axis: water, strawberry, blueberry and blackberry, for three moments each: “Initial” means just before fermentation, “Final” means after fermentation for 48h with kefir grains, and “7 days” means after seven days of refrigeration at 5 ± 1 °C, and where for each column of the figure three samples have been taken and the mean value and standard deviation are shown (n = 3 ± SE);

[0060] Figure 4 represents, on the vertical axis, the lactic acid bacteria (probiotics) present, in colony-forming units (CFU) per milliliter on a logarithmic scale (“log CFU / ml”), of different kefir beverages represented from left to right on the horizontal axis: water, strawberry, blueberry, and blackberry, for three time points each: “Initial” means just before fermentation; “Final” means after fermentation for 48 hours with kefir grains; and “7 days” means after seven days of refrigeration at 5 ± 1 °C. Three samples were taken for each column in the figure, and the mean and standard deviation are shown (n = 3 ± SE). DETAILED EXPOSURE OF IMPLEMENTATION MODES / EXAMPLES

[0061] Reference 40 in Fig. 1 refers to the kefir beverage (40) of the present invention obtained by the process shown in Fig. 1 itself, which shows the key process steps, listed as 31, 32, 33, 35, 36 and 37.

[0062] To obtain the kefir beverage (40), which is a fermented beverage, the process in Fig. 1 comprises the step of adding (31) to a container kefir grains (16) previously cultured in a step that will be described later, sugar (31a), and unpasteurized natural red fruit juice (26). The proportions for the addition step (31) are 5 grams of sugar (31a) and 40 grams of previously cultured kefir grains (16) per liter of unpasteurized natural red fruit juice (26) to activate the fermentation process.

[0063] Preferably, the adding step (31) includes the step of covering the container with a gauze that allows the passage of oxygen.

[0064] In Fig. 1, after the addition stage (31), the process comprises a fermentation stage (32), which is a primary fermentation carried out over a period of 12 to 48 hours between 18 and 28 °C.

[0065] During primary fermentation, lactic acid bacteria and yeasts ferment the sugars (fructose and glucose) in the unpasteurized natural red fruit juice (26), generating compounds such as lactic acid, small amounts of alcohol, and carbon dioxide, which gives the kefir beverage (40) a slight natural carbonation. In other words, in the fermentation stage (32), the sugars (fructose and glucose) in the unpasteurized natural red fruit juice (26) are metabolized by the bacteria and yeasts in the kefir grains (16). The unpasteurized natural red fruit juice (26), sweetened with sugar (31a) and / or a sugar substitute, and enriched with the kefir grains (16), is transformed into a primary fermented product obtained in the fermentation stage (32).

[0066] The values ​​shown in Figs. 2 to 4, for the kefir drink (40) obtained in the process of Fig. 1, said natural unpasteurized red fruit juice (26) used as a fermentation substrate in the fermentation stage (32) is not diluted with a liquid, for example, with water and / or milk, juices of other fruits, each liter being 100% natural unpasteurized red fruit juice (26).

[0067] Alternatively, the natural red fruit juice used as a fermentation substrate in the fermentation stage (32) is diluted with a liquid: with water, milk, and / or juices of other fruits, including in each liter at least 50% unpasteurized natural red fruit juice (26).

[0068] Continuing with Fig. 1, after the fermentation stage (32), the process includes a stage of removing (33) or separating the kefir grains (16) from the fermented product obtained in the fermentation stage (32). The kefir grains (16) are removed by filtration, for example, using a strainer or mesh, among other options.

[0069] Optionally, after the removal step (33), the kefir grains (16) may be reused for future batches of kefir drinks (40), or the kefir grains (16) may be discarded.

[0070] Optionally, after the removal step (33), the process includes a sweetening step (34). The sweetening step (34) is optional and will depend on the market. Sugar or sweeteners such as sucralose, stevia, honey, etc., can be used.

[0071] After the removal stage (33), the process comprises the filtering and packaging stage (35) of the fermented product obtained and filtered into a container, for example, the filtering and packaging stage (35) includes a bottling stage in a bottle after filtering the fermented product with a filter mesh.

[0072] After the filtering and packaging stage (35), the process includes the stage of gasifying (36) naturally or exogenously, so that the fermented product obtained, filtered and packaged, carbonates, since the microorganisms are present in the fermented product, and it continues to ferment.

[0073] Optionally, the carbonation stage (36) includes naturally carbonating the fermented product for 24 to 48 hours between 18 and 28 °C to carbonate it.

[0074] As an alternative to natural gasification, the gasification stage (36) includes exogenously gasifying (carbonating) the fermented product by injecting pressurized carbon dioxide (CO2), ensuring more precise control of the gasification level and avoiding spillage of the fermented product that may occur when doing natural gasification.

[0075] Following the carbonation step (36), the resulting fermented product is cooled in a refrigeration step (37) of the process to halt fermentation and preserve the organoleptic, probiotic, and functional properties of the fruit kefir (40). For example, the fermented product obtained after the carbonation step (36) is stored at 5 °C for 48 hours, although other combinations of temperature and refrigeration time are acceptable. This ensures the stability of the kefir beverage (40).

[0076] In Fig. 1, after the cooling stage (37), the kefir drink (40) is obtained, which is a fermented drink by the process described above.

[0077] Optionally, the kefir beverage (40) is obtained by a process comprising the pasteurization stage or application of high hydrostatic pressures (38).

[0078] In any case, this pasteurization stage or application of high hydrostatic pressures (38) is after the gasification stage (36), always using the kefir drink (40) as a fermentation substrate in the previous fermentation stage (32) unpasteurized natural red fruit juice (26).

[0079] Preferably, this pasteurization stage or application of high hydrostatic pressures (38) is after the refrigeration stage (37).

[0080] If a longer shelf life and room temperature are desired, the fruit kefir drink (40) can be pasteurized, for example, at 70 to 85 °C for 10 to 20 seconds, with the consequent reduction in probiotic properties, vitamins and bioactive compounds and antioxidant capacity.

[0081] In the option of using high hydrostatic pressure (HHP), a non-thermal treatment used as an alternative to traditional pasteurization, bioactives and probiotics are preserved without significantly affecting their flavor, texture, and nutritional content. In the case of kefir beverages (40), HHP offers an effective way to control pathogenic microorganisms and extend shelf life while maintaining the probiotic benefits and sensory properties of the product. For example, an appropriate dose of such high hydrostatic pressure would be 200 MPa for 5 to 10 minutes.

[0082] The kefir beverage (40) of the present invention is obtained by the process described above, which uses natural red fruit juice from strawberries, blueberries, blackberries, currants, etc., due to its high anthocyanin content and antioxidant activity. Advantageously, the unpasteurized natural red fruit juice (26), used as a fermentation substrate in the fermentation stage (32), provides an optimal balance of acidity and natural sugars (fructose and glucose), which facilitates fermentation and gives the kefir beverage (40) an attractive organoleptic profile, rich in vitamins, minerals, and anthocyanins such as cyanidins, pelargonidins, peonidins, and delphinidins. These compounds possess antioxidant and anti-inflammatory properties and have been shown to help reduce the risk of cardiovascular disease and certain types of cancer. Furthermore, they may improve cognitive function and visual health.

[0083] Kefir grains (16), rich in lactic acid bacteria and yeasts, ferment the unpasteurized natural red fruit juice (26) in the fermentation stage (32), with some microbiological competition occurring since the unpasteurized natural red fruit juice (26) also contains microorganisms that can alter the fermentation stage (32).

[0084] However, as shown in Fig. 4, the red fruit kefir beverage (40) obtained using the process described above, after 7 days of refrigeration, has a concentration of lactic acid bacteria (probiotics) greater than 8 log CFU / mL, which guarantees the probiotic effects of the kefir beverage (40). These values ​​are obtained when using strawberry, blueberry, and blackberry individually as fermentation substrates.

[0085] As previously mentioned, any combination of unpasteurized natural red fruit juice (26), acting as a substrate in the fermentation stage (32), falls within the scope of the present invention, and the proportions of strawberry, blueberry, blackberry, and / or other red fruit juice can be selected to achieve a lactic acid bacteria (probiotic) concentration greater than 8 log CFU / mL. Comparatively, Fig. 4 shows a lactic acid bacteria (probiotic) concentration of around 5.5 log CFU / mL for a traditional kefir beverage, using water as the fermentation substrate, after 7 days of refrigeration.

[0086] Likewise, in Fig. 2, the total polyphenol (phenolic compound) content of the kefir drink (40) after 7 days of refrigeration is 100 to 200 mg GAE / 100 mL using strawberry juice or blackberry juice in the process, supporting a kefir drink (40) with a high richness in bioactive compounds.

[0087] As discussed above, any combination of unpasteurized natural red fruit juice (26), acting as a substrate in the fermentation stage (32), is within the scope of the present invention, and the proportions of strawberry, blueberry, blackberry, and / or other red fruit juice can be selected to achieve a desired total polyphenol content of the kefir beverage (40) within the range of values ​​of 100 to 200 mg GAE / 100 mL.

[0088] Throughout this document, “mg GAE” refers to milligrams of gallic acid equivalent. Comparatively, Figure 2 shows a total polyphenol (phenolic compound) content of approximately 10 mg GAE / 100 mL for a traditional kefir beverage, using water as the fermentation substrate, after 7 days of refrigeration.

[0089] Similarly, in Fig. 3, the antioxidant activity of the kefir beverage (40) after 7 days of refrigeration is 0.3 to 0.8 mmol Fe 2+ / 100 mL, for example, for cranberry juice (greater than 0.4 mmol Fe) 2+ / 100 mL) and the blackberry one (greater than 0.6 mmol Fe 2+ / 100 mL), supporting a kefir beverage (40) with a high richness in bioactive compounds. Comparatively, Fig. 3 shows an antioxidant activity of the kefir beverage (40) after 7 days of refrigeration below 0.05 mmol Fe 2+ / 100 mL for a traditional kefir drink, using water as the fermentation substrate, after 7 days of refrigeration.

[0090] As previously mentioned, any combination of unpasteurized natural red fruit juice (26), acting as a substrate in the fermentation stage (32), falls within the scope of the present invention, and the proportions of strawberry, blueberry, and blackberry juice and / or other red fruit can be selected to achieve a desired antioxidant activity value within the range of 0.3 to 0.8 mmol Fe 2+ / 100 mL.

[0091] Furthermore, the resulting kefir beverage (40) is preferably distinguished by its lactose-free nature, making it suitable for people with lactose intolerance or those following a vegan diet, unlike a milk kefir beverage. As for tea or water kefir beverages, although they do not contain lactose, they lack the nutritional richness present in the red fruit kefir beverage (40) of the present invention.

[0092] The kefir beverage (40) obtained by the process described in Fig. 1 above guarantees a final food product with a high content of vitamins, antioxidants, and bioactive compounds present in the fruits, making it a healthier and more functional kefir beverage (40) compared to traditional kefir beverages. According to this invention, the red fruit kefir beverage (40) obtained from unpasteurized natural red fruit juice (26) as a fermentation substrate in the fermentation stage (32) exhibits the characteristics described above.

[0093] The results in Figs. 2 to 4 demonstrate that, unlike milk or water kefir drinks, red fruit kefir (40) offers a probiotic fermented beverage with a superior nutritional profile, due to the presence of bioactive compounds with high antioxidant potential.

[0094] The kefir drink (40), obtained by the process described above, may have other optional steps, such as a step of preparing (10) the kefir granules (16) and a step of obtaining (20) unpasteurized natural red fruit juice (26), also shown in Fig. 1 and described below.

[0095] Optionally, before the adding step (31) the process includes the step of preparing (10) the kefir granules (16).

[0096] This step of preparing (10) the kefir grains (16) includes the step of obtaining (11) kefir grains, preferably fresh. Fresh kefir grains can be obtained from various sources, but they are commonly cultured from other existing fresh kefir grain mother cultures. These fresh kefir grains are obtained from individuals who already have them in cultivation, from specialized suppliers, or from microbiology laboratories. It is preferable to use specialized suppliers.

[0097] Thus, the preparation step (10) comprises the step of cultivating (12) kefir grains, either after the obtaining step (11) as shown in Fig. 1 or during the obtaining step (11), being partially cultivated both before and after the obtaining step (11), as described above.

[0098] In the cultivation stage (12), the kefir grains are initially placed in a liquid medium for fermentation. This liquid medium may consist of sugar water, with 4 to 6% sucrose and an approximate ratio of 1 to 5 fresh kefir grains per 100 mL of water. The liquid medium provides nutrients to the bacteria and yeasts present in the fresh kefir grains, thus initiating the cultivation stage (12). This liquid medium is maintained for 48 hours at a temperature between 18 and 24 °C, resulting in cultured kefir grains (16), which may be used in the addition stage (31) described above, as shown in Fig. 1.

[0099] Optionally, after the cultivation stage (12), the process includes the maintenance stage (13) of the kefir grains. In this maintenance stage (13), the kefir grains (16) are kept healthy between cultivations, that is, between one cultivation stage (12) and a subsequent cultivation stage (12). Once the kefir grains have been recovered and washed with softened water, they are stored refrigerated at a temperature between 5 and 8 °C with 20 g / L sugar water and 3 g / L unrefined salt, which provides minerals. Under these conditions, the kefir grains (16) can be kept for up to one month. The low temperatures slow microbial activity, prolonging the time between cultivations.

[0100] Optionally, the kefir grains that have taken part in the cultivation stage (12) can be carefully filtered and reused in a new batch of liquid medium.

[0101] Additionally, after the cultivation stage (12) and / or the maintenance stage (13), the process comprises the stage of storing (14) the kefir grains (16), which includes the stage of drying or freezing the kefir grains (16).

[0102] In this freezing stage, the kefir grains (16) are carefully washed, lightly dried, and then frozen in a freezer, for example, at temperatures of -18 °C to -20 °C, in small portions within an airtight container. This freezing stage allows the kefir grains (16) to be preserved for several months.

[0103] In this drying stage, the kefir grains (16) are dried in a dehydrator at low temperature or are freeze-dried. After drying, the kefir grains (16) are kept in an airtight container, allowing them to be rehydrated later to reactivate the culture.

[0104] Optionally, the process includes, after the storage stage (14), the stage of reactivating (15) the kefir granules (16).

[0105] In the event that the kefir grains (16) are frozen in the storage stage (14), the reactivation stage (15) comprises the stage of slowly defrosting the kefir grains (16) in the freezer, and then the stage of immersing the kefir grains (16) in the liquid medium described above.

[0106] In the case where the kefir grains (16) are dried (dehydrated) in the storage step (14), the reactivation step (15) comprises placing the kefir grains (16) in warm water and rehydrating the kefir grains for 8 hours, renewing the warm water every 2 hours, until they regain their gelatinous consistency and their ability to ferment, ready to be used in the fermentation step (32). Thus, as shown in Fig. 1, the cultured kefir grains (16) may be used in the fermentation step (32), either directly after the cultivation step (12), or after the cultivation (12), maintenance (13), storage (14), and reactivation (15) steps, or a combination of these options. Optionally, before the addition stage (31) the process includes the stage of obtaining (20) unpasteurized natural red fruit juice (26).

[0107] This stage of obtaining (20) unpasteurized natural red fruit juice (26) optionally includes the stage of disinfecting (21) equipment and materials to be used, using 15% peracetic acid, leaving it to act for 5 minutes before use, and without rinsing the equipment and materials with water afterwards.

[0108] This stage of obtaining (20) unpasteurized natural red fruit juice (26) also includes the stage of selecting (22) a raw material, that is, one or more types of red fruits, including strawberries, cherries, blueberries, raspberries, blackberries, currants, etc. These red fruits must be healthy and show no signs of rot. However, fruits that cannot be marketed fresh, either due to their small size or the presence of deformities, may be used, thus promoting the revaluation of the by-products.

[0109] This step of obtaining (20) unpasteurized natural red fruit juice (26) additionally includes the step of washing and rinsing the raw material (23). The raw material is disinfected with water and food-grade bleach at a concentration of 2 mL of sodium hypochlorite / L of water for 5 to 10 minutes. Other disinfectants such as peracetic acid, chlorine dioxide, or acetic acid may be used. After washing, the raw material is rinsed thoroughly with water to remove any remaining disinfectant.

[0110] This stage of obtaining (20) unpasteurized natural red fruit juice (26) comprises the extraction stage (24) of the unpasteurized natural red fruit juice (26) from the red fruits, where the juice is extracted from the red fruits using either a hydraulic or pneumatic press, a centrifugal or screw extractor, a blender, a crusher, or other equipment. Red fruits such as strawberries, blueberries, blackberries, currants, etc., are used to take advantage of their high anthocyanin content and, therefore, their high antioxidant capacity. Alternatively, the unpasteurized natural red fruit juice (26), including its pulp (25a), may be directly added in the addition stage (31).

[0111] Alternatively, after the extraction step of the natural red fruit juice (26), the obtaining step (20) preferably comprises the filtration step (25) of the natural red fruit juice (26), obtaining, on the one hand, the filtered, unpasteurized natural red fruit juice (26) to be added in the adding step (31), and, on the other hand, the pulp (25a), as shown in Fig. 1. Advantageously, in this preferred option, the filtration step (25) facilitates the stability of the kefir beverage product (40) by removing suspended solids, pulp, skin and seed particles, or any other unwanted residue. Mesh filters, plates, or membranes may be used, in addition to centrifugation. Preferably, a fine mesh filter with a diameter of 0.5 to 2 millimeters is used.

[0112] The scope of the present invention is defined by the following claims.

Claims

CLAIMS 1.- Probiotic and antioxidant kefir drink (40) characterized in that it comprises a fermented product obtained by using unpasteurized natural red fruit juice (26) as a fermentation substrate.

2. Kefir beverage (40) according to claim 1, which is fermented by the addition of at least 40 grams of kefir grains (16) and at least 5 grams of sugar (31a), per liter of unpasteurized natural red fruit juice (26) undiluted or diluted to 50% by volume, for 12 to 48 hours at a temperature between 18 and 28 °C; and wherein the kefir grains (16) have been removed from the resulting fermented beverage.

3. Kefir beverage (40) according to claim 2, wherein the fermented beverage obtained from the removed kefir grains (16) has been filtered, packaged, carbonated, and refrigerated to stop fermentation and for preservation.

4. Kefir beverage (40) according to claim 1, 2 or 3, wherein the fermented product obtained, filtered and packaged has been subjected to natural gasification for 12 to 48 hours at a temperature between 18 and 28 °C.

5. Kefir beverage (40) according to claim 1, 2 or 3, wherein the fermented product obtained, filtered and packaged, has been subjected to exogenous gasification by the addition of pressurized carbon dioxide.

6. Kefir beverage (40) according to claim 2 or 3, wherein the kefir granules (16) added for fermentation are in fresh or freeze-dried form.

7. Kefir beverage (40) according to any one of the preceding claims, wherein the fermented product obtained has, on a logarithmic scale, more than 8 cfu / mL of lactic acid bacteria.

8. Kefir beverage (40) according to any one of the preceding claims, wherein the fermented product obtained has a concentration of phenolic compounds greater than or equal to 100 mg of gallic acid equivalent / 100 mL and has an antioxidant activity greater than or equal to 0.3 mmol Fe 2+ / 100 mL.

9. Kefir beverage (40) according to any one of claims 1 to 6, wherein the fermented product obtained has been subjected to the application of high hydrostatic pressures to extend its shelf life at room temperature.

10. Kefir beverage (40) according to any one of the preceding claims 1 to 6, wherein the fermented product obtained has been subjected to pasteurization treatments to extend its shelf life at room temperature.

11. Kefir beverage (40) according to any one of the preceding claims, wherein the unpasteurized natural red fruit juice (26) used as a fermentation substrate comprises strawberry, cherry, blueberry, raspberry, blackberry, and / or currant juice, or a combination of these juices.

12. Kefir beverage (40) according to any one of the preceding claims, wherein the fermentation substrate is free of milk, lactose or dairy products.

13. Kefir beverage (40) according to any one of the preceding claims, wherein the unpasteurized natural red fruit juice (26) used as a fermentation substrate has been previously extracted from red fruits by pressing.

14. Kefir beverage (40) according to any one of the preceding claims, wherein the fermentation substrate comprises exclusively unpasteurized natural red fruit juice (26).

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