A plant-based yogurt and its preparation method

Abstract

This invention relates to the field of food processing technology, and more particularly to a plant-based yogurt and its preparation method. The preparation method includes pressing oil-containing plant seeds to obtain semi-defatted raw materials and raw oil; mixing the semi-defatted raw materials with stabilizers, sweeteners, and water, and then grinding to obtain a slurry; the mass ratio of the semi-defatted raw materials to the aqueous solution is 1:(10-16); mixing the raw oil with the slurry to obtain an emulsion; sterilizing the emulsion at a high temperature of 135℃-145℃ for 4-7 seconds to obtain a sterilized emulsion; and mixing the sterilized emulsion with a starter culture for fermentation. This invention, by employing a high-temperature instantaneous sterilization process, significantly reduces the raw material cost of plant-based yogurt and improves its texture, taste, and flavor. Simultaneously, this sterilization process effectively kills various microorganisms and their spores in the raw materials, has a short sterilization time, and provides good sterilization effect, which is beneficial for obtaining better fermented flavor in subsequent fermentation processes.

Description

Technical Field

[0001] This invention relates to the field of food processing technology, and in particular to a plant-based yogurt and its preparation method. Background Technology

[0002] Plant-based yogurt is a lactic acid bacteria fermented beverage made primarily from grains, nuts, and water, with or without added flavorings or other additives, through high-pressure homogenization. Its notable characteristics include high protein, zero cholesterol, and rich micronutrients, making it ideal for health-conscious individuals, those with milk allergies, and those with lactose intolerance. However, plant-based yogurt has a high fat content, poor stability after dairy processing, a shorter shelf life, and difficulty in controlling the number of spores due to the raw materials themselves, leading to issues such as an unsmooth texture and unpleasant flavor after fermentation.

[0003] In the prior art, CN115444034A provides a low-fat, low-sugar walnut milk double-protein flavored fermented milk and its preparation method, which uses walnut protein and pure milk to prepare fermented walnut milk through compound fermentation. Essentially, it is not pure walnut fermentation. Similarly, CN113712082A provides a process for making walnut pollen juice yogurt, which adds milk powder to walnut pollen for fermentation to obtain yogurt similar to cow's milk yogurt, but it is not plant-based yogurt in essence. CN114711298A provides a method for preparing walnut fermented milk; however, the fermented milk produced has relatively few types and amounts of nutrients.

[0004] The inventor previously disclosed a method for preparing plant-based yogurt using a dominant fermentation strain isolated from their own culture in patent CN114940956A. However, in all embodiments of this patent, the mass ratio of semi-skimmed raw material to water was 1:8, resulting in a high material-to-water ratio. This leads to a greater requirement for oil-containing plant seed raw materials, thus increasing the cost of preparing plant-based yogurt. When the material-to-water ratio is adjusted to be lower than 1:8, the texture of the resulting plant-based yogurt changes significantly, and its taste and flavor deteriorate noticeably. Summary of the Invention

[0005] In order to further reduce the raw material cost of the plant-based yogurt preparation process (CN114940956A), this invention is proposed.

[0006] First, this invention provides a method for preparing plant-based yogurt, comprising:

[0007] (1) Press the seeds of oil-containing plants to obtain semi-degreased raw materials and raw oil;

[0008] (2) The semi-degreased raw material is mixed with stabilizer, sweetener and water and then ground into a slurry to obtain a slurry; the mass ratio of the semi-degreased raw material to the aqueous solution is 1:(10-16);

[0009] (3) The raw material oil is mixed with the slurry to obtain an emulsion;

[0010] (4) The emulsion is sterilized at 135℃~145℃ for 4~7s to obtain the sterilized emulsion;

[0011] (5) The sterilized emulsion is mixed with a starter culture and fermented to produce the plant-based yogurt.

[0012] Through extensive experimentation with various combinations of conditions in the preparation method, this invention unexpectedly discovered that high-temperature instantaneous sterilization can effectively reduce the material-to-water ratio and significantly decrease the amount of oil-containing plant seeds used, thereby lowering production costs, while maintaining the texture of plant-based yogurt. Simultaneously, high-temperature instantaneous sterilization can kill multiple microorganisms from oil-containing plant seeds within a short time, greatly improving the microbial safety of plant-based yogurt. Furthermore, by killing the spores of various microorganisms, the fermented yogurt also has a smoother texture and better flavor.

[0013] In this invention, the high-temperature instantaneous sterilization is a UHT sterilization process.

[0014] Preferably, in step (2), the mass ratio of the semi-degreased raw material to water is 1:(10-14).

[0015] Preferably, in step (2), the mass ratio of the semi-degreased raw material to water is 1:(11-13).

[0016] At the above-mentioned material-to-water ratio, the plant-based yogurt prepared using the UHT sterilization process has the best texture and excellent taste and flavor; compared with the plant-based yogurt obtained by the 1:8 material-to-water ratio in the CN114940956A preparation process, it has better texture and taste and flavor.

[0017] Preferably, in step (4), the emulsion is instantaneously sterilized at a high temperature of 139℃~145℃ for 5~7s.

[0018] Preferably, the fermentation agent contains Lactobacillus plantarum WL-100.

[0019] Lactobacillus plantarum WL-100 is an industrially applicable microbial strain with health benefits. This strain was deposited on March 9, 2022, at the China General Microbiological Culture Collection Center (CGMCC). The address of the depository is: Institute of Microbiology, Chinese Academy of Sciences, No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing; Postcode: 100101; Classification name: WL-100; Accession number: CGMCC No. 24490.

[0020] Preferably, the ratio of the amount of starter culture added to the volume of the sterilized emulsion is 2 to 5 × 10⁻⁶. 6 CFU: 1 mL.

[0021] Preferably, fermentation is stopped when the acidity reaches 60–90°T.

[0022] Preferably, the fermentation temperature is 37℃~46℃.

[0023] Preferably, in step (1), the raw oil is used after being heated at 180-220°C for 15-30 minutes.

[0024] Preferably, the fat content of the semi-degreased raw material is 30-65%.

[0025] Preferably, in step (3), 1-5% of the raw material oil is mixed with the slurry based on the mass of the slurry.

[0026] Preferably, the oil-bearing plant seeds are any one or more of the following: walnuts, peanuts, almonds, and sunflower seeds.

[0027] Preferably, the sweetener is at least one selected from sucrose, glucose, fructose, and sugar alcohol.

[0028] Preferably, the sugar alcohol is at least one selected from sorbitol, maltitol, xylitol, isomaltitol, mannitol, lactitol, and erythritol.

[0029] Preferably, the amount of sucrose added is 1-9 wt% of the mass of the semi-defatted raw material.

[0030] Preferably, the emulsion obtained in step (3) is homogenized before step (4).

[0031] Preferably, the pressure of the homogenizer is 40-50 MPa.

[0032] Preferably, the pressing method is hydraulic pressing, the pressing pressure is 15-40 MPa, and the pressing time is 20-60 minutes.

[0033] Preferably, the stabilizer in step (2) is at least one of diacetyl tartaric acid mono- and diglycerides, hydroxypropyl distarch phosphate, agar, pectin, and gellan gum.

[0034] Preferably, the percentage of the stabilizer added to the semi-degreased raw material is as follows: 0.4-0.7 wt% of diacetyl tartaric acid mono- and diglycerides, or 2-5 wt% of hydroxypropyl distarch phosphate, or 0.5-0.8 wt% of agar, or 0.5-0.7 wt% of pectin, or 0.4-0.7 wt% of gellan gum.

[0035] Preferably, in step (2), the grinding speed is 20,000 to 45,000 r / min and the grinding temperature is 50 to 90°C.

[0036] Preferably, in step (3), 1-5% of the raw material oil is mixed with the slurry and then stirred at high speed of 20,000-25,000 r / min for 10-25 min to obtain an emulsion.

[0037] Preferably, the fermented emulsion is cooled to below 4°C and stored at 4-6°C for more than 9 hours to obtain the plant-based yogurt.

[0038] Furthermore, the present invention provides plant-based yogurt prepared according to any of the above embodiments.

[0039] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0040] This invention significantly reduces the raw material costs of plant-based yogurt by employing a high-temperature instantaneous sterilization process, while also improving the texture, taste, and flavor of the yogurt. Simultaneously, this sterilization process effectively kills various microorganisms and their spores in the raw materials, with a short sterilization time and high sterilization effect, which is beneficial for obtaining better fermented flavor in subsequent fermentation processes. Testing showed that no microorganisms (Escherichia coli, Staphylococcus aureus, Salmonella, molds and yeasts, aerobic Bacillus, and thermoresistant Bacillus) were detected during a 21-day storage period, while maintaining good texture and flavor, thus solving the microbial problem during the storage period of purely plant-based fermented beverages. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0042] Unless otherwise specified, all methods used in the examples were conventional or performed according to techniques or conditions described in the literature in this field, or in accordance with the product instructions. Reagents and instruments used without specified manufacturers were all conventional products that could be purchased from legitimate channels.

[0043] The following examples and comparative examples were conducted using the same batch of raw materials.

[0044] Example 1

[0045] This embodiment provides a plant-based yogurt, and the preparation method is as follows:

[0046] (1) Weigh out the raw materials (peeled walnuts) and set aside;

[0047] (2) Press the raw material at 20 MPa for 30 min to obtain a semi-degreased raw material with a fat content of 32.45%; and heat the pressed raw oil at 180℃ for 20 min and cool it to room temperature for later use.

[0048] (3) The semi-degreased raw material obtained in step (2) is mixed with stabilizer, sucrose and water and then ground into a slurry to obtain a slurry;

[0049] The weight ratio of semi-degreased raw material to water is 1:10.

[0050] The amount of sucrose added is 1-9 wt% of the mass of the semi-defatted raw material;

[0051] The stabilizer is diacetyl tartaric acid mono- and diglycerides, which accounts for 0.5 wt% of the semi-degreased raw material.

[0052] (4) Add raw material oil at 1.0% of the mass of the slurry obtained in step (3), and stir at high speed of 25000r / min for 20min to obtain emulsion;

[0053] (5) The emulsion obtained in step (4) is homogenized under high pressure at 50 MPa once to obtain an emulsion.

[0054] (6) The emulsion obtained in step (5) is heated to 139°C using UHT sterilization process and sterilized for 5 seconds;

[0055] (7) The starter culture Lactobacillus plantarum WL-100 was prepared at a concentration of 2×10⁻⁶. 6 Add CFU / mL to the sterilized emulsion obtained in step (6) and ferment at 42°C until the acidity is 70°T, then stop fermentation.

[0056] (8) Quickly cool the fermented emulsion from step (7) to 4°C and store it at 4°C for 10 hours until it matures.

[0057] Example 2

[0058] This embodiment provides a plant-based yogurt, the only difference from the preparation method in Embodiment 1 is that the weight ratio of semi-skimmed raw materials to water is adjusted to 1:12.

[0059] Example 3

[0060] This embodiment provides a plant-based yogurt, the only difference from the preparation method in Embodiment 1 is that the weight ratio of semi-skimmed raw materials to water is adjusted to 1:14.

[0061] Example 4

[0062] This embodiment provides a plant-based yogurt, the only difference from the preparation method in Embodiment 1 is that the weight ratio of semi-skimmed raw materials to water is adjusted to 1:16.

[0063] Comparative Example 1

[0064] This comparative example provides a plant-based yogurt, prepared by the following method:

[0065] (1) Weigh out the raw materials (peeled walnuts) and set aside;

[0066] (2) Press the raw material at 20 MPa for 30 min to obtain a semi-degreased raw material with a fat content of 32.45%; and heat the pressed raw oil at 180℃ for 20 min and cool it to room temperature for later use.

[0067] (3) The semi-degreased raw material obtained in step (2) is mixed with stabilizer, sucrose and water and then ground into a slurry to obtain a slurry;

[0068] The weight ratio of semi-degreased raw material to water is 1:8;

[0069] The amount of sucrose added is 1-9 wt% of the mass of the semi-defatted raw material;

[0070] The stabilizer is diacetyl tartaric acid mono- and diglycerides, which accounts for 0.5 wt% of the semi-degreased raw material.

[0071] (4) Add raw material oil at 1.0% of the mass of the slurry obtained in step (3), and stir at high speed of 25000r / min for 20min to obtain emulsion;

[0072] (5) The emulsion obtained in step (4) is homogenized under high pressure at 50 MPa once to obtain an emulsion.

[0073] (6) Heat the emulsion obtained in step (5) to 95°C for 10 min;

[0074] (7) The starter culture Lactobacillus plantarum WL-100 was prepared at a concentration of 2×10⁻⁶. 6 Add CFU / mL to the sterilized emulsion obtained in step (6) and ferment at 42°C until the acidity is 70°T, then stop fermentation.

[0075] (8) Quickly cool the fermented emulsion from step (7) to 4°C and store it at 4°C for 10 hours until it matures.

[0076] Comparative Example 2

[0077] This comparative example provides a plant-based yogurt, the only difference from Comparative Example 1 being that the weight ratio of semi-skimmed raw materials to water is adjusted to 1:10.

[0078] Test case

[0079] The plant-based yogurts prepared in the examples and comparative examples were tested, including sensory evaluation, texture analysis, and microbiological testing.

[0080] 1. Sensory evaluation

[0081] Ten tasters scored the samples according to the criteria in Table 1, and described and analyzed the color, aroma, taste, and stability. The scoring criteria were as follows: a 10-point scale, with 1 being the worst and 10 being the best; the five criteria were color, aroma, taste, stability, and overall acceptability, ensuring that all other conditions were consistent.

[0082] Table 1 Sensory Evaluation Criteria for Plant-Based Yogurt

[0083]

[0084]

[0085] The test results are shown in Table 2.

[0086] Table 2 Comparison of Sensory Indicators

[0087]

[0088]

[0089] 2. Texture evaluation

[0090] Test method:

[0091] The method of Yang et al. (YANG M, LI N, TONG L, et al. Comparison of physicochemical properties and volatile flavor compounds of pea protein and mung bean protein-based yogurt[J]. Lwt-Food Science and Technology, 2021, 152.) was referenced and modified. All samples were analyzed using a texture analyzer equipped with an A / BE probe under the following conditions: pre-test velocity 1 mm / s, test velocity 1 mm / s, post-test velocity 1 mm / s, test strain 30%, and trigger force 10 g. The textural properties of walnut yogurt were evaluated using hardness, consistency, and cohesiveness.

[0092] The test results are shown in Table 3.

[0093] Table 3 Comparison of texture

[0094]

[0095] 3. Microbial testing

[0096] After storing the yogurt samples from each example and comparative example at 4°C for 21 days, the microbial limits, limits, and methods were determined according to T / WSJD 12—2020 "Plant Protein Beverages - Plant-based Yogurt". The specific test items and methods are as follows: Escherichia coli, GB 4789.3 Method II; Staphylococcus aureus, GB 4789.10 Method I; Salmonella, GB 4789.4; Molds and yeasts, GB 4789.15. All microbial tests were conducted by a third-party testing organization, PONY Testing Group Co., Ltd.

[0097] In response to the common problem of spores in plant materials, aerobic Bacillus was detected in accordance with NY / T 1331-2007 (Part 2). The detection was conducted by Beijing Nutrition Source Research Institute Co., Ltd., a third-party testing institution.

[0098] The results are shown in Table 4.

[0099] Table 4 Comparison of Microbiological Indicators

[0100]

[0101]

[0102] Note: + indicates detected, - indicates not detected, unit CFU / g.

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing plant-based yogurt, characterized in that, include: (1) Press the seeds of oil-bearing plants to obtain semi-degreased raw materials and raw oil; (2) The semi-degreased raw material is mixed with stabilizer, sweetener and water and then ground into a slurry to obtain a slurry; the mass ratio of the semi-degreased raw material to the aqueous solution is 1:(11~13). (3) The raw material oil is mixed with the slurry to obtain an emulsion; (4) The emulsion is instantaneously sterilized at 135℃~145℃ for 4~7s to obtain sterilized emulsion; (5) The sterilized emulsion is mixed with a starter culture and fermented to produce the plant-based yogurt.

2. The preparation method according to claim 1, characterized in that, In step (4), the emulsion is instantaneously sterilized at a high temperature of 139℃~145℃ for 5~7 seconds.

3. The preparation method according to claim 1, characterized in that, The fermentation agent contains Lactobacillus plantarum WL-100.

4. The preparation method according to claim 1, characterized in that, In step (1), the raw oil is used after being heated at 180~220℃ for 15~30 minutes.

5. The preparation method according to claim 1, characterized in that, The fat content of the semi-degreased raw material is 30-65%.

6. The preparation method according to claim 1, characterized in that, In step (3), based on the mass of the slurry, 1-5% of the raw material oil is mixed with the slurry.

7. The preparation method according to claim 1, characterized in that, The oil-bearing plant seeds are any one or more of the following: peeled walnuts, peanuts, almonds, and sunflower seeds.

8. A plant-based yogurt, characterized in that, It is prepared by any one of claims 1 to 7.

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