New oat plant-based freeze-dried yogurt block and preparation method therefor

Abstract

The present invention belongs to the technical field of plant-based yogurt processing. Provided in the present invention are a new oat plant-based freeze-dried yogurt block and a preparation method therefor. The method for preparing the new oat plant-based freeze-dried yogurt block of the present invention comprises: preparing oat core flour into oat concentrated slurry, performing enzymatic hydrolysis, homogenization, sterilization, fermentation, blending, vacuum freeze drying and coating with chocolate to obtain the oat plant-based freeze-dried yogurt block. In the present invention, the oat core flour produced from pure oats is used as a raw material, and after fermentation, the product has yogurt flavor and characteristic fragrance of oats. The product is rich in terms of nutrition and easy to digest and absorb, and the performance of oats can also be improved, so that the requirements of people for physiological health and nutrition and dietary balance are met, and the added value of the oat product is greatly improved. In the present invention, the problems such as short shelf life, poor taste and monotonous flavor of the oat yogurt are solved. The product is not only crispy and delicious and contains active lactic acid bacteria, but also improves the utilization rate and added value of oats.

Description

Novel oat plant-based freeze-dried yogurt block and preparation method thereof Technical Field

[0001] The present invention relates to the technical field of plant-based yogurt processing, and in particular to a novel oat plant-based freeze-dried yogurt block and a preparation method thereof. Background Art

[0002] Inner Mongolia is one of the world's origins of oats and is also my country's largest oat production base. Oats are a highly nutritious, high-energy, low-sugar food. According to data from the China Food and Drug Administration (CFDA), there are 47 domestic health foods and 4 imported health foods that use oats as a functional ingredient. Oats are nutritionally comprehensive, ranking first in protein, fat, soluble dietary fiber (β-glucan), vitamins, and minerals compared to more common grains like wheat, rice, and corn. Compared to other cereal proteins, oat protein has a higher bioavailability in the body, and its essential amino acid composition is essentially consistent with the recommended daily intake, making it one of the most amino acid-balanced cereals. Oat oil is rich in high-quality fatty acids, with unsaturated fatty acids accounting for over 80% of the total fatty acids. It has significant benefits in lowering blood lipids and total cholesterol levels, and protecting cardiovascular and cerebrovascular systems. Oats contain 17% to 21% total dietary fiber, with soluble dietary fiber primarily comprising beta-glucan, which accounts for approximately one-third of the total dietary fiber and is seven times the beta-glucan content in rice and wheat. Beta-glucan is one of the components that distinguishes oats from other cereals and is a key component of their nutritional value. Numerous reports confirm that oat β-glucan has the potential to lower blood sugar, soften blood vessels, prevent hypertension, enhance immunity, and protect against cardiovascular disease. Furthermore, oat β-glucan exhibits beneficial effects by promoting the growth of beneficial bacteria such as bifidobacteria and lactic acid bacteria, while inhibiting the growth of harmful intestinal bacteria such as Escherichia coli. Oats are also a good source of antioxidants such as phenols, primarily phenolic acids, vitamin E, flavonoids, sitosterol, avenanthramides (anthraquinones), and phytic acid. Oat phenols possess excellent antioxidant properties and strong free radical scavenging ability. They also inhibit the oxidation of low-density lipoprotein (LDL), lower blood lipids, and protect against cardiovascular disease. The rich nutrients in oats provide a good foundation for the growth of lactic acid bacteria.

[0003] Currently, most fermented oat products reported domestically and internationally use oats as their primary raw material, adding milk, sterilizing, and inoculating with lactic acid bacteria to produce a range of products, including oat yogurt. However, products that produce yogurt blocks solely from oats are extremely rare. This is because lactic acid fermented yogurt blocks made from oats alone lack flavor and are unpopular with consumers. Therefore, there is an urgent need for a fermented oat product that addresses these technical issues.

[0004] Summary of the Invention

[0005] The purpose of the present invention is to provide a novel oat plant-based freeze-dried yogurt block and a preparation method thereof, which solves the problems of short shelf life, poor taste and single flavor of oat yogurt. The product is not only crispy and delicious, contains active lactic acid bacteria, but also improves the utilization rate and added value of oats.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing a novel oat plant-based freeze-dried yogurt block, comprising the following steps:

[0008] A. Preparation of oat slurry: oat core powder, K2HPO4, Ca3PO4, high-temperature amylase and water are mixed, heated to 95°C, and wet-grinded to obtain oat slurry;

[0009] B. Enzymatic hydrolysis: Mix the oat slurry with α-amylase and debittering enzyme, adjust the pH to 6.80-7.00, and perform enzymatic hydrolysis at 60°C for 1 hour to obtain an enzymatic hydrolyzate;

[0010] C. Homogenization: Add oat oil to the enzymatic hydrolyzate, stir for 5 minutes, and homogenize at 60-70°C and 20 MPa;

[0011] D. pasteurization;

[0012] E. Fermentation: Inoculate the sterilized liquid with composite microorganisms and ferment at 41-43°C for 4-6 hours;

[0013] F. Preparation: Mix the fermented liquid with freeze-dried oatmeal, jam and water to obtain a prepared liquid;

[0014] G. Vacuum freeze drying: Pour into a mold and pre-freeze and freeze-dry to obtain a semi-finished freeze-dried yogurt block;

[0015] H. Chocolate coating: The semi-finished product is coated with natural cocoa butter chocolate to obtain the finished product.

[0016] Preferably, the mass ratio of the oatmeal powder, K2HPO4, Ca3PO4, high-temperature amylase and water is 35:1:1:0.1:100.

[0017] Preferably, the mass ratio of the α-amylase and debittering enzyme to the oat core powder is 0.05:0.1:100.

[0018] Preferably, the oat oil accounts for 10% of the mass of the oat core powder.

[0019] Preferably, the pasteurization temperature is 95° C. and the time is 5 minutes.

[0020] Preferably, the composite microorganisms are Lactobacillus delbrueckii, Streptococcus thermophilus and Lactobacillus plantarum; the mass ratio of Lactobacillus delbrueckii, Streptococcus thermophilus and Lactobacillus plantarum is 1:1:1; and the inoculation amount of the composite microorganisms is 0.05%.

[0021] Preferably, the oat solid content in the prepared liquid is 15%; the volume of the jam is 20% of the prepared liquid, and the volume of the freeze-dried oat rice is 20% of the prepared liquid.

[0022] Preferably, the pre-freezing temperature is -35°C to -45°C, and the time is 4 to 6 hours; the freeze-drying is vacuum freeze-drying, the sublimation temperature is -25°C to 0°C, and the time is 24 hours; the analytical drying temperature is 0°C to 35°C, and the time is 24 hours.

[0023] The present invention also provides novel oat plant-based freeze-dried yogurt blocks obtained by the above preparation method.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention provides a method for preparing a novel oat plant-based freeze-dried yogurt block, comprising: preparing oat core powder into an oat slurry, and then subjecting the mixture to enzymatic hydrolysis, homogenization, sterilization, fermentation, blending, vacuum freeze drying, and chocolate coating to obtain an oat plant-based freeze-dried yogurt block. The present invention uses oat core powder produced from pure oats as raw material. The various volatile flavor components formed during the fermentation process, such as acetic acid and butyric acid, can reflect the unique taste of fermentation, so that the product has a yogurt flavor and a unique aroma of oats, is nutritious, easy to digest and absorb, and can improve the performance of oats, meet people's needs for physiological health and nutritional dietary balance, and greatly increase the added value of oat products. The present invention solves the problems of oat yogurt with a short shelf life, poor taste, and a single taste. The product is not only crispy and delicious, contains active lactic acid bacteria, but also increases the utilization and added value of oats. DETAILED DESCRIPTION

[0026] The present invention provides a method for preparing a novel oat plant-based freeze-dried yogurt block, comprising the following steps:

[0027] A. Preparation of oat slurry: oat core powder, K2HPO4, Ca3PO4, high-temperature amylase and water are mixed, heated to 95°C, and wet-grinded to obtain oat slurry;

[0028] B. Enzymatic hydrolysis: Mix the oat slurry with α-amylase and debittering enzyme, adjust the pH to 6.80-7.00, and perform enzymatic hydrolysis at 60°C for 1 hour to obtain an enzymatic hydrolyzate;

[0029] C. Homogenization: Add oat oil to the enzymatic hydrolyzate, stir for 5 minutes, and homogenize at 60-70°C and 20 MPa;

[0030] D. pasteurization;

[0031] E. Fermentation: Inoculate the sterilized liquid with composite microorganisms and ferment at 41-43°C for 4-6 hours;

[0032] F. Preparation: Mix the fermented liquid with freeze-dried oatmeal, jam and water to obtain a prepared liquid;

[0033] G. Vacuum freeze drying: Pour into a mold and pre-freeze and freeze-dry to obtain a semi-finished freeze-dried yogurt block;

[0034] H. Chocolate coating: The semi-finished product is coated with natural cocoa butter chocolate to obtain the finished product.

[0035] The mass ratio of the oat core powder, K2HPO4, Ca3PO4, high-temperature amylase and water of the present invention is preferably 35:1:1:0.1:100.

[0036] In the present invention, the mass ratio of the α-amylase and debittering enzyme to the oat core powder is preferably 0.05:0.1:100; the oat oil is preferably 10% of the mass of the oat core powder; the pasteurization temperature is preferably 95°C and the time is preferably 5 minutes; and the oat core powder is Wuchuan naked oat oat core powder. The enzymatic hydrolysis step of the present invention can hydrolyze sugars and remove the bitterness of the Wuchuan naked oat oat core powder. The homogenization step of the present invention can improve color (whiten) and enhance taste and flavor.

[0037] In the present invention, the composite microorganisms are Lactobacillus delbrueckii, Streptococcus thermophilus, and Lactobacillus plantarum; the mass ratio of Lactobacillus delbrueckii, Streptococcus thermophilus, and Lactobacillus plantarum is preferably 1:1:1; the inoculum amount of the composite microorganisms is preferably 0.05%; and the fermentation endpoint is preferably determined to be pH ≤ 4.6. The Lactobacillus delbrueckii, Streptococcus thermophilus, and Lactobacillus plantarum described in the present invention were purchased from Chr. Hansen.

[0038] The Lactobacillus delbrueckii and Streptococcus thermophilus described in the present invention can lower the pH value and increase viscosity, while the Lactobacillus plantarum can improve flavor, produce acid and active substances, and enhance the mouthfeel of yogurt blocks. The composite microorganisms of the present invention act synergistically, and the various volatile flavor components, such as acetic acid and butyric acid, formed during the fermentation process contribute to the unique fermentation mouthfeel, giving the product a yogurt flavor and the distinctive aroma of oats. The product is nutritious, easily digestible, and improves the properties of oats, meeting people's needs for physical health and a balanced nutritional diet, significantly increasing the added value of oat products.

[0039] The oat solid content in the prepared liquid is 15%, the volume of the jam is 20% of the prepared liquid, and the volume of the freeze-dried oat rice is 20% of the prepared liquid. The prepared liquid can improve the taste and texture of the freeze-dried yogurt blocks.

[0040] In the present invention, the pre-freezing temperature is preferably -35°C to -45°C, and the time is preferably 4 to 6 hours; the freeze-drying is performed in a vacuum freeze-drying process, and the sublimation temperature is preferably -25°C to 0°C, and the time is 24 hours (the sublimation temperature increases linearly from -25°C to 0°C within 24 hours); the desorption drying temperature is 0°C to 35°C, and the time is 24 hours (the drying temperature increases linearly from 0°C to 35°C within 24 hours). The vacuum freeze-drying step of the present invention can achieve a crispy taste, good melt-in-mouth properties, and a rich taste.

[0041] The present invention also provides novel oat plant-based freeze-dried yogurt blocks obtained by the above preparation method.

[0042] In the present invention, unless otherwise specified, all raw material components are commercially available products well known to those skilled in the art.

[0043] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0044] The composite microorganisms used in Examples 1-5 and Comparative Examples 1-6 are Lactobacillus delbrueckii, Streptococcus thermophilus and Lactobacillus plantarum; the mass ratio of Lactobacillus delbrueckii, Streptococcus thermophilus and Lactobacillus plantarum is 1:1:1.

[0045] Example 1

[0046] Preparation of novel oat plant-based freeze-dried yogurt blocks

[0047] A. Prepare oat slurry: 3500g oat core powder, 35g K2HPO4, 35g Ca3PO4, 3.5g high-temperature amylase and 10000g purified water, heat to 95°C, and then wet grind for 20min until smooth and free of grains to obtain oat slurry;

[0048] B. Enzymatic hydrolysis: Mix oat slurry with 1.75 g α-amylase and 3.5 g debittering enzyme, adjust pH to 6.80, cool to 60°C, stir at 400 rpm, and keep warm for 1 h;

[0049] C. Homogenization: Add 350 g oat oil to the enzymatic hydrolysate, stir at 800 rpm for 5 min, keep the temperature at 65°C, and homogenize under a pressure of 20 MPa;

[0050] D. Pasteurization: Heat the liquid to 95°C and keep it warm for 5 minutes;

[0051] E. Fermentation: The mixed liquid after pasteurization was cooled to 42°C and then inoculated with composite microorganisms, mixed and stirred to obtain a pre-fermented liquid, and then fermented at a constant temperature of 42°C for 6.5 hours and a pH of 4.55;

[0052] F. Preparation: After the constant temperature fermentation is completed, 1.5kg freeze-dried oat rice, 3kg mango jam and 6.66kg water are added to the feed liquid and stirred at 800rpm;

[0053] G. Vacuum freeze drying: Pour into a mold and pre-freeze at -43 to -45°C for 6 hours, then freeze-dry in a vacuum freeze drying chamber at a sublimation temperature of -25 to 0°C for 24 hours, and a desorption drying temperature of 0 to 35°C for 24 hours; after freeze drying, manually demould to obtain the semi-finished product;

[0054] H. Chocolate coating: The semi-finished product is coated with natural cocoa butter chocolate to obtain a finished product. The coating thickness is 0.3 mm. The finished product is obtained after the chocolate is cooled.

[0055] Example 2

[0056] Preparation of novel oat plant-based freeze-dried yogurt blocks

[0057] A. Prepare oat slurry: 3500g oat core powder, 35g K2HPO4, 35g Ca3PO4, 3.5g high-temperature amylase and 10000g purified water, heat to 97°C, and then wet grind for 10min until smooth and free of grains to obtain oat slurry;

[0058] B. Enzymatic hydrolysis: Mix oat slurry with 1.75 g α-amylase and 3.5 g debittering enzyme, adjust pH to 6.90, cool to 60°C, stir at 500 rpm, and keep warm for 1 h;

[0059] C. Homogenization: Add 350 g oat oil to the enzymatic hydrolysate, stir at 800 rpm for 15 min, keep the temperature at 65°C, and homogenize under a pressure of 18 MPa;

[0060] D. Pasteurization: Heat the liquid to 95°C and keep it warm for 15 minutes;

[0061] E. Fermentation: The pasteurized mixed liquid was cooled to 42° C. and inoculated with 6.75 g of composite microorganisms. The mixture was mixed and stirred to obtain a pre-fermented liquid, which was then fermented at a constant temperature of 42° C. for 4.5 h and a pH of 4.55.

[0062] F. Preparation: After the constant temperature fermentation is completed, 1.5 kg of freeze-dried oatmeal, 3 kg of blueberry jam and 6.66 kg of water are added to the liquid and stirred at 800 rpm;

[0063] G. Vacuum freeze drying: Pour into a mold and pre-freeze at -40 to -45°C for 6 hours, then freeze-dry in a vacuum freeze drying chamber at a sublimation temperature of -25 to 0°C for 24 hours, and at a desorption drying temperature of 0 to 35°C for 24 hours; after freeze drying, manually demould to obtain the semi-finished product;

[0064] H. Chocolate coating: The semi-finished product is coated with natural cocoa butter chocolate to obtain a finished product. The coating thickness is 0.3 mm. The finished product is obtained after the chocolate is cooled.

[0065] Example 3

[0066] Preparation of novel oat plant-based freeze-dried yogurt blocks

[0067] A. Preparation of oat slurry: 3500g oat core powder, 35g K2HPO4, 35g Ca3PO4, 3.5g high-temperature amylase and 10000g purified water were mixed, heated to 90°C, and then wet-milled for 10min until smooth and free of grains to obtain oat slurry;

[0068] B. Enzymatic hydrolysis: Mix oat slurry with 1.75 g α-amylase and 3.5 g debittering enzyme, adjust pH to 6.90, cool to 60°C, stir at 600 rpm, and keep warm for 1 h;

[0069] C. Homogenization: Add 350 g oat oil to the enzymatic hydrolysate, stir at 900 rpm for 15 min, keep the temperature at 65°C, and homogenize under a pressure of 22 MPa;

[0070] D. Pasteurization: Heat the liquid to 95°C and keep it warm for 15 minutes;

[0071] E. Fermentation: The mixed liquid after pasteurization was cooled to 42°C and inoculated with 6.75g of composite microorganisms, mixed and stirred to obtain a pre-fermented liquid, and then fermented at a constant temperature of 42°C for 4 hours at a pH of 4.55;

[0072] F. Preparation: After the constant temperature fermentation is completed, 1.5 kg of freeze-dried oatmeal, 3 kg of strawberry jam and 6.66 kg of water are added to the feed liquid and stirred at 800 rpm;

[0073] G. Vacuum freeze drying: Pour into a mold and pre-freeze at -40 to -45°C for 6 hours, then freeze-dry in a vacuum freeze drying chamber at a sublimation temperature of -25 to 0°C for 24 hours, and at a desorption drying temperature of 0 to 35°C for 24 hours; after freeze drying, manually demould to obtain the semi-finished product;

[0074] H. Chocolate coating: The semi-finished product is coated with natural cocoa butter chocolate to obtain a finished product. The coating thickness is 0.5 mm. The finished product is obtained after the chocolate is cooled.

[0075] Example 4

[0076] A. Preparation of oat slurry: 3500g oat core powder, 35g K2HPO4, 35g Ca3PO4, 3.5g high-temperature amylase and 10000g purified water were mixed, heated to 90°C, and then wet-milled for 10min until smooth and free of grains to obtain oat slurry;

[0077] B. Enzymatic hydrolysis: Mix oat slurry with 1.75 g α-amylase and 3.5 g debittering enzyme, adjust pH to 6.90, cool to 60°C, stir at 600 rpm, and keep warm for 1 h;

[0078] C. Homogenization: Add 350 g oat oil to the enzymatic hydrolysate, stir at 900 rpm for 15 min, keep the temperature at 65°C, and homogenize under a pressure of 22 MPa;

[0079] D. Pasteurization: Heat the liquid to 95°C and keep it warm for 15 minutes;

[0080] E. Fermentation: The pasteurized mixed liquid was cooled to 42° C. and inoculated with 1.35 g of the composite microorganisms. The mixture was mixed and stirred to obtain a pre-fermented liquid, which was then fermented at a constant temperature of 42° C. for 15 h and a pH of 4.55.

[0081] F. Preparation: After the constant temperature fermentation is completed, 0.75 kg of freeze-dried oatmeal, 1.5 kg of strawberry jam and 6.66 kg of water are added to the feed liquid and stirred at 800 rpm;

[0082] G. Vacuum freeze drying: Pour into a mold and pre-freeze at -40 to -45°C for 6 hours, then freeze-dry in a vacuum freeze drying chamber at a sublimation temperature of -25 to 0°C for 24 hours, and a desorption drying temperature of 0 to 35°C for 24 hours; after freeze drying, manually demould to obtain the semi-finished product.

[0083] H. Chocolate coating: The semi-finished product is coated with natural cocoa butter chocolate to obtain a finished product. The coating thickness is 1 mm. The finished product is obtained after the chocolate is cooled.

[0084] Example 5

[0085] A. Preparation of oat slurry: 3500g oat core powder, 35g K2HPO4, 35g Ca3PO4, 3.5g high-temperature amylase and 10000g purified water were mixed, heated to 80°C, and then wet-milled for 30min until smooth and free of grains to obtain oat slurry;

[0086] B. Enzymatic hydrolysis: Mix oat slurry with 1.75 g α-amylase and 3.5 g debittering enzyme, adjust pH to 6.90, cool to 60°C, stir at 600 rpm, and keep warm for 1 h;

[0087] C. Homogenization: Add 350 g oat oil to the enzymatic hydrolysate, stir at 900 rpm for 15 min, keep the temperature at 65°C, and homogenize under a pressure of 22 MPa;

[0088] D. Pasteurization: Heat the liquid to 95°C and keep it warm for 15 minutes;

[0089] E. Fermentation: The pasteurized mixed liquid was cooled to 42° C. and inoculated with 1.35 g of the composite microorganisms. The mixture was mixed and stirred to obtain a pre-fermented liquid, which was then fermented at a constant temperature of 42° C. for 20 h and a pH of 4.55.

[0090] F. Preparation: After the constant temperature fermentation is completed, 0.75 kg of freeze-dried oatmeal and 1.5 kg of strawberry jam are added to the liquid and stirred at 800 rpm to mix;

[0091] G. Vacuum freeze drying: Pour into a mold and pre-freeze at -40 to -45°C for 6 hours, then freeze-dry in a vacuum freeze drying chamber at a sublimation temperature of -25 to 0°C for 24 hours, and a desorption drying temperature of 0 to 35°C for 24 hours; after freeze drying, manually demould to obtain the semi-finished product.

[0092] H. Chocolate coating: The semi-finished product is coated with natural cocoa butter chocolate to obtain a finished product. The coating thickness is 0.1 mm. The finished product is obtained after the chocolate is cooled.

[0093] Comparative Example 1

[0094] The specific implementation is the same as that of Example 1, except that when A prepares oatmeal slurry, the amount of raw materials used is: 3500g oatmeal powder, 35g K2HPO4, and 35g Ca3PO4.

[0095] Comparative Example 2

[0096] The specific implementation is the same as that of Example 1, except that the enzymatic hydrolysis B is as follows: the oat slurry is mixed with 5.25 g of debittering enzyme, the pH is adjusted to 6.8, the temperature is lowered to 60° C., stirred at 400 rpm, and kept warm for 1 hour.

[0097] Comparative Example 3

[0098] The specific implementation is the same as that of Example 1, except that enzymatic hydrolysis B is as follows: oat slurry is mixed with 5.25 g α-amylase, the pH is adjusted to 6.8, the temperature is lowered to 60° C., stirred at 400 rpm, and kept warm for 1 hour.

[0099] Comparative Example 4

[0100] The specific implementation is the same as that of Example 1, except that fermentation E is as follows: the pasteurized mixed liquid is cooled to 42° C. and then inoculated with a commercially available ordinary yogurt starter (Beijing Chuanxiu Technology Co., Ltd.), mixed and stirred to obtain a pre-fermented liquid, and then fermented at a constant temperature of 42° C. for 16 h and a pH of 4.50.

[0101] Comparative Example 5

[0102] The specific implementation is the same as that of Example 1, except that the preparation F is as follows: after the constant temperature fermentation is completed, 3 kg of mango jam is added to the liquid and then stirred at 800 rpm to mix.

[0103] Comparative Example 6

[0104] The specific implementation is the same as that of Example 1, except that vacuum freeze drying of G is as follows: after being poured into a mold and pre-frozen at -43 to -45°C for 6 hours, freeze drying is carried out in a vacuum freeze drying chamber at a sublimation temperature of 0°C to 45°C for 14 hours, and a desorption drying temperature of 45°C for 12 hours; after freeze drying, the semi-finished product is manually demoulded to obtain the semi-finished product.

[0105] Experimental Example 1

[0106] The bitterness of the oat slurry, the enzymatic hydrolyzate obtained after enzymatic hydrolysis of Example 1, and the enzymatic hydrolyzate obtained after enzymatic hydrolysis of Comparative Examples 2-3 were measured.

[0107] The testing method involves a month-long training session for 15 panelists on the sensory description and classification of taste substances. This familiarization training involves various bitter solutions, such as magnesium sulfate, salicylic acid, and caffeine solutions. Panelists who are unable to distinguish between bitterness intensity are eliminated. After training, a sensory evaluation panel consisting of 10 individuals (five men and five women) was formed. Sensory testing was conducted in a dedicated laboratory. Scoring was based on a 10-point scale: 0-2 indicates very weak (almost absent) taste intensity; 2-4 indicates weak; 4-6 indicates moderate; 6-8 indicates strong; and 8-10 indicates very strong. Taste intensity is scored on a scale of 0 to 10, with 0 representing the absence of a particular taste intensity and 10 indicating high taste intensity. During the sensory evaluation, samples were coded to minimize subjective influence. All samples were randomly presented to the panelists three times. Throughout the evaluation process, the panelists rinsed their mouths with purified water after each sample was evaluated and before the next. To avoid temperature differences, all test samples were kept at 25°C in a thermostat.

[0108] After testing, the bitterness sensory score of the oat concentrate in Example 1 was 8, the bitterness sensory score of the hydrolyzate after enzymatic hydrolysis was 0, the bitterness sensory score of the hydrolyzate in Comparative Example 2 was 2, and the sensory score in Comparative Example 3 was 6. This shows that the α-amylase and the debittering enzyme in the enzymatic hydrolysis step of the present invention have a synergistic effect, which can significantly reduce the bitterness in the oat concentrate, thereby improving the taste of the yogurt cubes.

[0109] Experimental Example 2

[0110] In the freeze-dried yogurt blocks of Examples 1-5 and Comparative Examples 1-6, the number of viable lactic acid bacteria, dietary fiber content, shelf life and sensory score were used as evaluation indicators.

[0111] Among them, the number of live lactic acid bacteria is counted according to the plate colony culture counting method in the national standard (GB4789.35-2016 Food Microbiology Inspection Lactic Acid Bacteria Inspection).

[0112] Dietary fiber was determined according to the second method of the national standard (GB / T22224-2008 Method 2 Determination of dietary fiber in foods).

[0113] The shelf life is determined according to the standard (T / CNFIA 001-2017 General Guidelines for the Shelf Life of Food).

[0114] Sensory evaluation: A scoring test method was used by a panel of 10 professionally trained individuals. The scorers evaluated the oat plant-based freeze-dried yogurt blocks based on appearance (smooth and smooth, without frosting or sanding), flavor (fruity, moderately sweet and sour, with no off-flavor), texture (presence of cavitation, breakage, or glassiness), and mouthfeel (crispness, stickiness, fruitiness, and sweetness). The final score was averaged out of 100. The sensory evaluation criteria are shown in Table 1.

[0115] Table 1 Sensory evaluation criteria

[0116] The finished oat plant-based freeze-dried yogurt blocks prepared in Examples 1-5 and Comparative Examples 1-6 were stored at room temperature, and samples were taken regularly to determine the number of viable lactic acid bacteria, dietary fiber, shelf life, and sensory perception. The changes in the number of viable lactic acid bacteria and sensory perception of the oat plant-based freeze-dried yogurt blocks after storage at room temperature for half a year were examined. The specific test results are shown in Table 2.

[0117] Table 2 Quality of freeze-dried yogurt blocks with different treatments

[0118] It can be seen from the data in Table 2 that, compared with Comparative Examples 1-6, the freeze-dried yogurt blocks prepared by the present invention can significantly increase the number of viable lactic acid bacteria and the dietary fiber content, significantly extend the shelf life at room temperature, and improve the taste of the freeze-dried yogurt blocks.

[0119] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing a novel oat plant-based freeze-dried yogurt block, characterized in that: The following steps are involved: A. Preparation of oatmeal slurry: oatmeal core powder, K2HPO4, Ca3PO4, high temperature amylase and water are mixed, the temperature is raised to 95° C., and wet-grinded to obtain oatmeal slurry; B. Enzymatic hydrolysis: Mix oat concentrate with α-amylase and debittering enzyme, adjust the pH to 6.80-7.00, and perform enzymatic hydrolysis at 60°C for 1 hour to obtain enzymatic hydrolyzate; C. Homogenization: Add oat oil to the enzymatic hydrolyzate, stir for 5 minutes, and homogenize at 60-70℃ and 20MPa; D. pasteurization; E. Fermentation: Inoculate the sterilized liquid with composite microorganisms and ferment at 41-43°C for 4-6 hours; F. Preparation: Mix the fermented liquid with freeze-dried oatmeal, jam and water to obtain a prepared liquid; G. Vacuum freeze drying: pour into a mold, pre-freeze and freeze-dry to obtain a semi-finished freeze-dried yogurt block; H. Chocolate coating: coating the semi-finished product with natural cocoa butter chocolate to obtain the finished product.

2. The preparation method according to claim 1, characterized in that: The mass ratio of the oatmeal powder, K2HPO4, Ca3PO4, high-temperature amylase and water is 35:1:1:0.1:

100.

3. The preparation method according to claim 1, characterized in that: The mass ratio of the α-amylase and the debittering enzyme to the oat core powder is 0.05:0.1:

100.

4. The preparation method according to claim 1, characterized in that: The oat oil accounts for 10% of the mass of the oat core powder.

5. The preparation method according to claim 1, characterized in that: The pasteurization temperature is 95° C. and the time is 5 minutes.

6. The preparation method according to claim 1, characterized in that: The composite microorganisms are Lactobacillus delbrueckii, Streptococcus thermophilus and Lactobacillus plantarum; the mass ratio of Lactobacillus delbrueckii, Streptococcus thermophilus and Lactobacillus plantarum is 1:1:1; and the inoculation amount of the composite microorganisms is 0.05%.

7. The preparation method according to claim 1, characterized in that: The oat solid content in the prepared liquid is 15%; the volume of the jam is 20% of the prepared liquid, and the volume of the freeze-dried oat rice is 20% of the prepared liquid.

8. The preparation method according to claim 1, characterized in that: The pre-freezing temperature is -35°C to -45°C, and the time is 4 to 6 hours; the freeze-drying is vacuum freeze-drying, the sublimation temperature is -25°C to 0°C, the time is 24 hours, and the analytical drying temperature is 0°C to 35°C, and the time is 24 hours.

9. A novel oat plant-based freeze-dried yogurt block obtained according to the preparation method according to any one of claims 1 to 8.

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