Preparation technology of chickpea plant-based milk

Abstract

The invention discloses a preparation technology of chickpea plant-based milk, and relates to the technical field of food processing. Comprising the following steps of cooking, crushing, homogenizing, first-time enzymolysis, pH adjustment, second-time enzymolysis, enzyme deactivation, filtering, ingredient blending, high-speed shearing, homogenizing, sterilizing and canning. According to the chickpea plant-based milk with the low glycemic index prepared on the basis of the enzymolysis technology, the protein content reaches 1.86 + / -0.05 g / 100g, the protein utilization rate is increased by 38.4%, and the fat content is 0.85 + / -0.13 g / 100g; the content of dietary fibers is 1.51 + / -0.29 g / 100g; the eGI value is 57.27 + / -1.35; the average particle size of the chickpea plant milk is 124.49 microns; the absolute value of the Zeta potential is 55.67 + / -2.16 mV; 11 flavor substances contributing to sense organs are detected in the plant milk, the content of beany flavor substances such as hexanal is reduced, other flavor substances are enhanced, and the plant milk is endowed with mellow fragrance, light fruit fragrance and more distinct layering sense.

Description

Technical Field

[0001] The invention belongs to the technical field of food processing, and particularly relates to a preparation process of chickpea plant-based milk. Background Art

[0002] Milk is popular among the public due to its high protein content, but some people cannot drink it due to lactose intolerance. Dairy cow farming also has certain negative impacts on the ecological environment, including occupation of land resources, pollution caused by feed and excrement, etc.

[0003] However, plant milk currently has low protein content and poor stability, and often needs to be improved by adding food additives, which is inconsistent with consumers' pursuit of natural health and difficult to meet daily nutritional needs. Many companies are actively engaged in the research and development of plant milk, which uses plants as raw materials, is both environmentally friendly and can meet the needs of lactose intolerant groups.

[0004] Therefore, innovative technical solutions are urgently needed to resolve this dilemma, and the chickpea plant-based milk preparation process has come into being. It is expected to overcome the protein and stability problems, enrich the product flavor, provide consumers with high-quality plant-based beverages, and promote the healthy development of the plant milk industry by optimizing chickpeas, processing technology and product formula. Summary of the invention

[0005] The purpose of the present invention is to solve the problems of low protein content, poor stability and single flavor of existing plant milk, and provide a preparation process of chickpea plant-based milk.

[0006] In order to achieve the above object, the present invention provides the following technical solution: a preparation process of chickpea plant-based milk, characterized in that it comprises the following steps:

[0007] S1. Preparation of raw materials

[0008] S11. Wash and soak the chickpeas and steam them under high pressure;

[0009] S12. The cooked chickpeas were crushed and homogenized in an ultrasonic cell disruptor;

[0010] S2. Preparation of enzymatic solution by step-by-step enzymatic hydrolysis

[0011] S21. Add α-amylase and β-amylase to the homogenized mixture, stir and enzymolyze in a water bath at 50-55° C. for 25-40 min with magnetic ion stirring to perform the first stage of enzymolysis, and add sodium bicarbonate to adjust the pH to 8.0;

[0012] S22. After the first stage of enzymatic hydrolysis, alkaline protease was added and enzymatic hydrolysis was carried out in a water bath at 40-50° C. with magnetic ion stirring for 25-40 min;

[0013] S23. The mixture after enzymatic hydrolysis was inactivated in a water bath and filtered to obtain an enzymatic hydrolyzate;

[0014] S3. Formulate plant-based milk products

[0015] S31. The enzymatic hydrolysate is heated, and weighed xylitol, sucralose, acesulfame potassium, stabilizer, perilla oil, and dietary fiber are evenly added;

[0016] S4. Shearing and homogenizing the prepared mixture;

[0017] S5. Sterilize the homogenized mixed solution by ultra-high temperature instantaneous sterilization;

[0018] S6. Cool and fill the sterilized product.

[0019] Preferably, the formula of the enzymatic hydrolyzate prepared in step S2 comprises: 8-12% chickpea, 0.2%-1.0% β-amylase, 0.2%-1.2% α-amylase, 0.1%-0.3% alkaline protease, and the rest is purified water.

[0020] Preferably, the formula of the plant-based milk prepared in step S3 includes: 93%-95% enzymatic hydrolyzate, 0.2%-0.8% composite stabilizer, 0.4%-0.6% xylitol, 0.001%-0.004% sucralose, 0.006%-0.01% acesulfame potassium, 0.2%-0.8% perilla oil, and 3%-3.5% dietary fiber.

[0021] Preferably, in step S22, the alkaline protease is hydrolyzed in a water bath at 46° C. with magnetic ion stirring for 25-40 minutes.

[0022] Preferably, the specific steps of preparing in step S31 are: heating the enzymatic hydrolyzate to 55-60° C., adding evenly mixed xylitol, sucralose, acesulfame potassium, stabilizer, and dietary fiber, stirring while adding, and finally adding perilla oil.

[0023] Preferably, the specific steps of soaking and high-pressure cooking in step S11 are: adding clean water with a weight of 9 times that of the raw material for soaking for 2 hours, and high-pressure cooking for 50 minutes.

[0024] Preferably, the specific steps of crushing and homogenizing in step S12 are: crushing the chickpeas in a wall crusher for 8-15 minutes at a power of 800 W; and homogenizing the mixed solution obtained after crushing in an ultrasonic cell disruptor at 420 W for 20-40 minutes.

[0025] Preferably, in step S2, the addition ratio of α-amylase, β-amylase and alkaline protease is 5:4:1.

[0026] The beneficial effects of the present invention are:

[0027] The present invention adds 3%-3.5% dietary fiber, which can improve the intestinal microenvironment. The composition of the intestinal flora can determine the effectiveness of obtaining energy from food, and changes in dietary composition are related to changes in the composition of the intestinal microbial community. Diet can regulate the composition and function of the intestinal flora. When the diet undergoes a huge and rapid change, the microbial community will change rapidly, and long-term dietary habits can shape the composition of the intestinal flora. A fiber-rich diet has been shown to improve insulin resistance in thin people and obese diabetic patients.

[0028] The present invention adopts chickpea as raw material. Chickpea has health care functions such as lowering blood sugar, lowering blood lipids, anti-oxidation and regulating intestinal flora as a low blood sugar food, and is therefore suitable as an auxiliary treatment food for diabetes and the like. The present invention is based on the glycemic index theory and low glycemic index (GI) raw materials, and a stable chickpea enzymolyzate with a protein content of 1.9g / 100g is prepared as a base material for subsequent product development. The chickpea plant-based milk prepared by the present invention adds a stabilizer to improve the stability of the product, and adds vegetable oil to improve the saturation of the plant milk taste, thereby achieving the effect of comparing animal milk. At the same time, the present invention selects low glycemic index (GI) food as raw material, which can delay the rapid rise of blood sugar after a meal to a certain extent. The glycemic index of the chickpea plant milk prepared by the formula and method of the present invention can reach 50-58, which is suitable for drinking by diabetic patients.

[0029] The enzymatic hydrolysis process of the present invention has a significant effect on odor substances. The contents of ethyl acetate, (E)-2-butenal, n-butanol, β-pinene and other substances show an upward trend as the enzymatic hydrolysis process proceeds. These flavor substances give the chickpea enzymatic hydrolyzate a mellow aroma, a light fruity aroma and a more distinct sense of hierarchy. The enzymatic hydrolysis process is also conducive to improving the stability of the product and extending the storage period of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a flow chart of the preparation process of the present invention.

[0031] Figure 2 This is a graph showing the experimental results of the effects of different enzyme preparation combinations on the enzymatic hydrolysis effect in the preparation process of the present invention.

[0032] Figure 3 This is a graph showing the experimental results of the effects of different material-liquid ratios on the enzymatic hydrolysis effect in the preparation process of the present invention.

[0033] Figure 4 This is a graph showing the experimental results of the effects of different enzyme-substrate ratios on the enzymatic hydrolysis effect in the preparation process of the present invention.

[0034] Figure 5This is a graph showing the experimental results of the effects of different enzymatic hydrolysis times on the enzymatic hydrolysis effect in the preparation process of the present invention.

[0035] Figure 6 This is a graph showing the experimental results of the effects of different enzymatic hydrolysis temperatures on the enzymatic hydrolyzate in the preparation process of the present invention.

[0036] Figure 7 This is a graph showing experimental results comparing the predicted values ​​and true values ​​in the RSM model in the process selection of the present invention.

[0037] Figure 8 This is a graph showing the experimental results of the effect of the interaction between various factors on turbidity in the process selection of the present invention.

[0038] Fig. 9 This is a graph showing the experimental results of the effects of the interactions among various factors on protein content in the process selection of the present invention.

[0039] Fig.10 This is the differential scanning calorimetry (DSC) spectrum of the chickpea plant milk prepared in the present invention.

[0040] Fig.11 It is the principal component analysis diagram of the chickpea flour, chickpea puree and enzymatic hydrolyzate samples of the present invention.

[0041] Fig.12 It is a bar graph of the differential compound contents of chickpea flour, puree and enzymatic hydrolyzate samples of the present invention.

[0042] Fig.13 The figure is a comparison result of the particle sizes of the chickpea enzymatic hydrolysate and the original puree of the present invention.

[0043] Fig.14 The following is a photograph comparing the stratification of the chickpea enzymatic hydrolysate and the original puree of the present invention.

[0044] Fig.15 The figure is a comparison of the microstructures of the chickpea enzymatic hydrolysate and the original pulp of the present invention.

[0045] Fig.16 The figure is a comparison chart of the coagulation index of the chickpea enzymatic hydrolysate and the original pulp of the present invention.

[0046] Fig.17 The figure is a comparison chart of the flocculation index of the chickpea enzymatic hydrolysate and the original pulp of the present invention.

[0047] Fig.18 The figure is a comparison chart of the protein concentration at the interface between the chickpea enzymatic hydrolysate and the original pulp of the present invention.

[0048] Fig.19 The figure is a comparison chart of the protein content at the interface between the chickpea enzymatic hydrolysate and the original pulp of the present invention.

[0049] Fig. 20The figure is a comparison of the rheological properties of the chickpea enzymatic hydrolyzate flow and the original pulp of the present invention. DETAILED DESCRIPTION

[0050] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with specific embodiments.

[0051] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0052] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0053] 1. Chickpea plant-based milk and its preparation process

[0054] A low glycemic index chickpea plant-based milk, comprising the following substances in percentage by weight:

[0055] The formula of the enzymatic hydrolysate is: 8-12% chickpea, 0.2%-1.0% beta-amylase, 0.2%-1.2% alpha-amylase, 0.1%-0.3% alkaline protease, and the rest is purified water; sodium bicarbonate is used to adjust the pH to 8.0;

[0056] The formula of chickpea plant-based milk: 93%-95% chickpea enzymatic hydrolysate (protein content 1.89±0.12g / 100g), 0.2%-0.8% composite stabilizer, 0.4%-0.6% xylitol, 0.001%-0.004% sucralose, 0.006%-0.01% acesulfame potassium, 0.2%-0.8% perilla oil, and 3%-3.5% cellulose.

[0057] The preparation process of the chickpea plant-based milk is to use the above-mentioned substances as raw materials and mix them according to the percentage content ratio. The process flow of the enzymatic hydrolyzate is as follows: cleaning, removing impurities, soaking, cooking, crushing, homogenizing, enzymatic hydrolysis, pH adjustment, enzymatic hydrolysis, enzyme inactivation, and filtration; cooking → crushing → homogenizing → first enzymatic hydrolysis → pH adjustment → second enzymatic hydrolysis → enzyme inactivation → filtration; the process flow of the chickpea plant-based milk is as follows: ingredient preparation → high-speed shearing → homogenizing → sterilization → canning.

[0058] Specifically, the preparation steps of the chickpea plant-based milk are as follows:

[0059] Step 1: Steaming: Wash the chickpeas, remove impurities, add 9 times the weight of the raw materials into clean water and soak for 2 hours, and steam under high pressure (the equipment can be the SY-50YC9086 electric pressure cooker produced by the company) for 50 minutes; the steaming process is to remove the bean smell of the chickpeas.

[0060] Step 2: Crushing: crush the chickpeas in a wall breaking machine (the equipment can be SP605R wall breaking machine produced by Supor Group Co., Ltd.) for 8-15 minutes, with a power of 800W; crush the steamed chickpeas to prepare for extracting internal nutrients.

[0061] Step 3: Homogenize the mixture obtained in the previous step in an ultrasonic cell disruptor at 420W for 20-40min.

[0062] Step 4: Enzymatic hydrolysis: Enzymatic hydrolysis is divided into two stages:

[0063] The first stage of enzymolysis: add α-amylase and β-amylase shown in the enzymolysis liquid ingredients to the mixed solution obtained in the previous step, and perform enzymolysis for 25-40 minutes in a water bath at 50-55°C with magnetic ion stirring. The amount of α-amylase and β-amylase added in this step can effectively improve the stability and rheological properties of chickpea plant-based milk, degrade α-galactose into small molecules of glucose, thereby improving the stability of the product, solving the bottleneck problem of easy precipitation of plant-based milk, and effectively controlling the glycemic index of the final product; then use sodium bicarbonate to adjust the pH to 8.0.

[0064] The second stage of enzymatic hydrolysis: add alkaline protease as shown in the enzymatic hydrolysis liquid ingredients, and perform enzymatic hydrolysis for 25-40 minutes in a water bath at 46°C with magnetic ion stirring. The protein content in chickpeas accounts for 25% to 30% of the total dry basis of the grain, which is twice that of oat protein. Chickpea protein is mainly composed of globulin (56%), gluten (15%-25%), albumin (12%) and alcohol-soluble protein (2.8%). Gluten is an insoluble protein. The action of alkaline protease can effectively improve the solubility of gluten, thereby increasing the protein content in plant-based milk, which can be as high as 1.9g / 100g.

[0065] Step 5: Inactivate enzyme: Heat the mixture in a water bath until it reaches 90°C and start timing, maintaining for 10 minutes.

[0066] Step 6: Filtration: Filter with a 100-mesh filter and retain the filtrate as the enzymatic hydrolysate.

[0067] In the above steps, the corresponding substances are added in accordance with the formula of the enzymatic solution.

[0068] Step 7: Preparation: According to the formula of chickpea plant-based milk, weigh xylitol, sucralose, acesulfame potassium, stabilizer, perilla oil, and dietary fiber. First, heat the enzymatic solution, and when it reaches 55-60°C, add the evenly mixed xylitol, sucralose, acesulfame potassium, stabilizer, and dietary fiber, stirring while adding, and finally add perilla oil. Xylitol, sucralose, and acesulfame potassium are added to the ingredients to increase the sweetness of the plant milk, and stabilizers are added to further increase the stability of the final product, plant-based milk, on the basis of the enzymatic solution, and delay the shelf life of the product; dietary fiber is added to improve the intestinal microenvironment.

[0069] Step 8: Shearing: Shear the prepared mixed liquid at 1800 rpm / min for 10 minutes.

[0070] Step 9: Homogenization: Homogenize the mixture obtained in the previous step in an ultrasonic cell disruptor at 420W for 30min;

[0071] Step 10: Sterilization: Use ultra-high temperature instantaneous sterilization at 123°C for 3-5 seconds;

[0072] Step 11: Cooling and canning: Cool to room temperature before packaging.

[0073] 2. Analysis of the creativity of the reaction conditions in the process of the present invention

[0074] The present invention is an innovative design for the selection of enzyme preparation combination, material-liquid ratio (the amount of chickpea added), enzyme-substrate ratio, total enzymolysis time, and enzymolysis temperature. Corresponding experiments have been conducted for screening, determination and verification. The specific screening and verification methods are as follows:

[0075] 1. Single Factor Experiment

[0076] Combined with the preliminary experimental results, single-factor experiments were conducted on enzyme preparation combination, material-liquid ratio, enzyme-substrate ratio, total enzymolysis time, and enzymolysis temperature using turbidity and protein content as indicators.

[0077] 1.1 Effect of different enzyme preparation combinations on enzymatic hydrolysis

[0078] The chickpeas were weighed and mixed with distilled water in a ratio of 1:9 (w / w), soaked for 4 h, then placed in a juicer, ground at gear 8 (800 W) for 10 min, and homogenized using an ultrasonic cell disruptor (420 W, 30 min). The liquid obtained in this step was the chickpea puree, which was set aside.

[0079] Combination I: amylase, hemicellulase and alkaline protease. Keep the chickpea puree in a 55°C water bath. Add 1% amylase and 0.7% hemicellulase, mix well and place in a 55°C water bath for 30 minutes. Adjust the pH of the liquid to 8 with sodium bicarbonate, add 0.20% alkaline protease and stir in a 53°C water bath for 30 minutes, heat to 90°C and maintain for 10 minutes to inactivate the enzyme, cool to room temperature and filter through a 100-mesh filter, use the filtrate as the aqueous phase for later use.

[0080] Combination II: hemicellulase, pectinase, amylase and alkaline protease. Place the chickpea puree in a 55°C water bath to keep warm. Add 1% amylase, 0.7% hemicellulase, and 0.2% pectinase, mix well, and place in a 53°C water bath for 30 minutes. The subsequent treatment method is the same as combination I.

[0081] Combination III: hemicellulase, pectinase, α-amylase, β-amylase and alkaline protease. Place chickpea puree in a 55°C water bath to keep warm. Add 1% amylase, 0.8% β-amylase, 0.7% hemicellulase, and 0.2% pectinase, mix well, and place in a 53°C water bath for 30 minutes of stirring and enzymolysis. The subsequent treatment method is the same as combination I.

[0082] Combination IV: hemicellulase, α-amylase, β-amylase and alkaline protease. Place chickpea puree in a 55°C water bath to keep warm. Add 1% α-amylase, 0.8% β-amylase, and 0.7% hemicellulase, mix well, and place in a 53°C water bath for 30 minutes of stirring and enzymolysis. The subsequent treatment method is the same as combination I.

[0083] Combination V: α-amylase, β-amylase and alkaline protease. The treated mixture was placed in a water bath at 55°C for heat preservation. 1% α-amylase and 0.8% β-starch were added, mixed and placed in a 53°C water bath for 30 minutes of stirring and enzymolysis, and the subsequent treatment method was combination I.

[0084] 1.2 Effect of feed-liquid ratio on chickpea enzymatic hydrolysis

[0085] The material-liquid ratio is 6:100, 8:100, 10:100, 12:100, 14:100, and 16:100, the fixed enzyme-substrate ratio is 2:100 (α-amylase: β-amylase: alkaline protease = 5:4:1, i.e., the addition amounts of α-amylase, β-amylase, and alkaline protease are 1%, 0.8%, and 0.2%, respectively), the total enzymatic hydrolysis time is 60 min (stage I enzymatic hydrolysis time: stage II enzymatic hydrolysis time = 1:1, i.e., stage I and stage II enzymatic hydrolysis times are 30 min, respectively), and the stage II enzymatic hydrolysis temperature is 53°C.

[0086] 1.3 Effect of enzyme-substrate ratio on enzymatic hydrolysis of chickpea

[0087] The enzyme-substrate ratios were 0:100, 1:100, 2:100, 3:100, and 4:100, the material-liquid ratio was fixed at 10:100, the total enzymatic hydrolysis time was 60 min, and the enzymatic hydrolysis temperature of stage II was 53°C.

[0088] 1.4 Effect of enzymatic hydrolysis time on chickpea enzymatic hydrolysis effect

[0089] Preliminary experiments showed that the best enzymatic hydrolysis effect was achieved when the ratio of stage I enzymatic hydrolysis time to stage II enzymatic hydrolysis time was 1:1. The total enzymatic hydrolysis time was 40min, 50min, 60min, 70min, and 80min. The fixed material-liquid ratio was 10:100, the enzyme-substrate ratio was 2:100, and the stage II enzymatic hydrolysis temperature was 53°C.

[0090] 1.5 Effect of enzymatic hydrolysis temperature on chickpea enzymatic hydrolysis

[0091] The enzymatic hydrolysis temperatures in stage II were 43°C, 46°C, 49°C, 52°C, and 55°C, the material-liquid ratio was fixed at 10:100, the enzyme-substrate ratio was 2:100, and the total enzymatic hydrolysis time was 70 min.

[0092] 2. Single factor experimental verification and analysis

[0093] 2.1 Effects of different enzyme preparation combinations on enzymatic hydrolysis

[0094] The substrate is the same, and different enzyme preparations act on different sites. Turbidity can well reflect the effect of enzyme preparations on the dissolution of chickpeas. The greater the turbidity, the higher the dissolution of chickpeas and the less precipitation. At the same time, stability is an important indicator for evaluating a food base. Secondly, the gluten in chickpeas is an insoluble protein. Alkaline protease can act on the peptide bonds in amino acids such as alanine and leucine in gluten, thereby increasing the content of soluble protein in the enzymatic hydrolysate. Therefore, under the same other conditions, the chickpea enzymatic hydrolysate hydrolyzed by different enzyme preparation combinations was subjected to turbidity, protein content determination and static test, such as Figure 2 shown.

[0095] like Figure 2 It can be seen that the protein content in chickpea enzymatic hydrolysate is greater than 0.76±0.0245g / 100g, with the highest value being 1.32±0.0102g / 100g. Alkaline protease has a significant effect on improving the soluble protein content (p<0.05). Among the five groups of enzyme preparations, the turbidity of the enzymatic hydrolysate in group I is the lowest, at 0.86±0.0078NTU; the turbidity of the enzymatic hydrolysate in groups III and V is 1.34±0.0078NTU and 1.43±0.0137NTU, respectively. There is no significant difference in the results, but it is significantly higher than other combinations. It can be seen that the enzymatic hydrolysis effect of group III and V enzyme preparations is good.

[0096] The chickpea hydrolysates prepared by combining five different enzyme preparations were placed at room temperature for 24 hours. A small amount of precipitation appeared in the hydrolysates of groups II and IV, a slight stratification phenomenon appeared in group I, and the hydrolysates of groups III and V were stable and uniform.

[0097] In summary, the enzyme preparations in group V had the best enzymatic hydrolysis effect, the highest protein content, the largest content of dissolved substances, a uniform and stable solution, and no precipitation or stratification.

[0098] 2.2 Effect of material-liquid ratio on enzymatic hydrolysis effect

[0099] The enzyme-substrate ratio was 2:100, the enzymatic hydrolysis time was 60 min, and the enzymatic hydrolysis temperature in stage II was 53 °C. The effects of the feed-liquid ratio on turbidity and protein content were investigated. The results are as follows: Figure 3 shown.

[0100] Depend on Figure 3 It can be seen that as the chickpea content increases, the turbidity shows a trend of first increasing and then flattening. This may be due to the increase in the material-liquid ratio and the enzymatic hydrolysis, and the increase in the substance in the enzymatic hydrolyzate. However, when the chickpea content reaches a certain amount, the enzymatic hydrolysis effect of the enzyme preparation reaches the maximum value. When the material-liquid ratio is greater than 10:100, the degree of enzymatic hydrolysis is on a downward trend, and the turbidity change tends to be flat. The protein content shows an upward trend. In the range of 6:100-10:100 of the material-liquid ratio, the alkaline protease has a significant enzymatic hydrolysis effect on gluten in chickpeas, and even reaches the maximum enzymatic hydrolysis degree. When the material-liquid ratio is greater than 10:100, the only thing that contributes to the protein content in the chickpea enzymatic hydrolyzate is the albumin and globulin in the chickpea, and the increase in protein content tends to be flat.

[0101] 2.3 Effect of enzyme-substrate ratio on enzymatic hydrolysis effect

[0102] The material-liquid ratio was 10:100, the enzymatic hydrolysis time was 60 min, and the enzymatic hydrolysis temperature in stage II was 53 °C. The effects of the enzyme-substrate ratio on turbidity and protein content were investigated. The results are as follows: Figure 4 shown.

[0103] Depend on Figure 4It can be seen that with the increase of enzyme-substrate ratio, the turbidity shows a trend of first rising and then falling. This is because α-amylase acts on the α-1-4-glycosidic bond inside the starch molecule, hydrolyzing the starch into dextrin and small molecular reducing sugars; alkaline protease acts on gluten, the molecular weight and disulfide bond content are significantly reduced, and the soluble protein content is increased, both of which have a certain positive effect on the increase of turbidity. When the enzyme-substrate ratio is greater than 2:100, the turbidity decreases, which may be due to the increase in the content of the enzyme preparation, excessive enzymatic hydrolysis, and some small molecular substances are filtered out during the filtration process, resulting in less substances in the enzymatic solution. When the enzyme-substrate ratio is less than 2:100, the enzyme preparation content fully reacts with the substrate, and the protein content increases significantly. When the enzyme-substrate ratio is greater than 2:100, the gluten is fully enzymatically hydrolyzed, and the accumulation of enzymatic hydrolysis products will also inhibit the enzyme preparation, so the protein content shows a slow upward trend.

[0104] 2.4 Effect of enzymatic hydrolysis time on enzymatic hydrolysis effect

[0105] The material-liquid ratio was 10:100, the enzyme-substrate ratio was 2:100, and the enzymatic hydrolysis temperature in stage II was 53°C. The effect of enzymatic hydrolysis time on turbidity and protein content was investigated. The results are as follows: Figure 5 shown.

[0106] Depend on Figure 5 It can be seen that with the passage of enzymatic hydrolysis time, the turbidity and protein content showed a trend of first increasing and then decreasing. When the enzymatic hydrolysis time was 70 minutes, the turbidity and protein content both reached a peak. After 70 minutes, the contents of both began to gradually decrease. With the extension of enzymatic hydrolysis time, the enzymatic hydrolysis was sufficient, and the turbidity and protein content both increased. When the enzymatic hydrolysis time was longer than 70 minutes, there was no obvious effect on the hydrolysis of chickpea starch, and the accumulation of enzymatic hydrolysis products would also inhibit the enzyme preparation.

[0107] 2.5 Effect of enzymatic hydrolysis temperature on enzymatic hydrolysate

[0108] The material-liquid ratio was 10:100, the enzyme-substrate ratio was 2:100, and the enzymatic hydrolysis time was 70 min. The effect of the enzymatic hydrolysis temperature in stage II on the turbidity and protein content was investigated. The results are as follows: Figure 6 shown.

[0109] from Figure 6 It can be seen that as the temperature of the enzymatic hydrolysis in stage II increases, the turbidity rises slowly without significant changes, because the enzymatic hydrolysis of α-amylase and β-amylase plays a dominant role in the turbidity, and the enzymatic hydrolysis of alkaline protease has no significant effect on the turbidity. When the enzymatic hydrolysis temperature is greater than 46°C, the protein content begins to decrease. This may be because the optimal enzymatic hydrolysis temperature of the alkaline protease used in the experiment is around 46°C, at which time the enzyme activity is the highest and the degree of hydrolysis of insoluble protein is greater. As the enzymatic hydrolysis temperature increases, the degree of hydrolysis of insoluble protein also decreases, and the protein content in the chickpea enzymatic hydrolysate also decreases.

[0110] Based on the results of the above single factor experiments, four factors that have a greater impact on the enzymatic hydrolysis effect of chickpeas, namely, the ratio of solid to liquid, the ratio of enzyme to substrate, the total enzymatic hydrolysis time, and the temperature of stage II enzymatic hydrolysis, were selected to design a response surface optimization experiment, with turbidity and protein content as the evaluation indicators of the enzymatic hydrolysis effect. The factor level table of the response surface experiment is shown in Table 1.

[0111] Table 1 CEH process factor level table

[0112]

[0113] 3. Response surface test results and analysis

[0114] 3.1 Response surface optimization experiment plan and results

[0115] Based on the results of single factor experiment, this study used RSM optimization method to analyze the influence of independent variables (A: feed-liquid ratio, B: enzyme-substrate ratio, C: enzymatic hydrolysis time, D: stage II enzymatic hydrolysis temperature) on dependent variables (Y1: turbidity, Y2: protein content). A four-factor three-level Box-Behnken experimental design was used to further determine the influence of enzymatic hydrolysis process parameters on the turbidity and protein content of chickpea enzymatic hydrolysate. The response surface optimization test and its results are shown in Table 2.

[0116] Table 2 Response surface design and results

[0117]

[0118] As shown in Table 2, the turbidity in the RSM optimization test group was between 1.35 NTU and 1.90 NTU, and the protein content was between 1.35 g / 100 g and 1.92 g / 100 g. The experimental values ​​fit well with the predicted values ​​(e.g. Figure 7 shown).

[0119] 3.2 Regression model and variance analysis

[0120] Design expert 13.0.5 was used to perform variance analysis and data multivariate regression fitting to obtain the binary regression equation of turbidity and protein content. The regression equations of turbidity (Y1), protein content (Y2) and feed-liquid ratio (A), enzyme-substrate ratio (B), enzymatic hydrolysis time (C), and enzymatic hydrolysis temperature (D) are as follows:

[0121] Y1=32.37607+1.60981A+0.956415B+0.069596C+0.979722D+0.008675AB+0.000787AC-0.0011 46AD-0.002135BC-0.010275BD+0.000881CD-0.079140A20.009860B20.000811C2-0.010962D2

[0122] (2-1)

[0123] Y2=-35.97745+0.995773A+0.254368B+0.149009C+1.16407D+0.023750AB+0.000438AC-0.0033 33AD-0.00925BC+0.013417BD+0.001873CD-0.040955A2-0.114571B2-0.001532C2-0.014054D2

[0124] (2-2)

[0125] The above regression equation was subjected to model variance analysis, and the results are shown in Table 2. The response model was established, and the significance of the regression coefficient of the response surface model was evaluated by variance analysis. In the model, a larger regression coefficient and a smaller p value indicated a greater impact on the corresponding response variable. According to the results of variance analysis (Table 2-5), the regression model p<0.0001, indicating that the model fits well. The lack of fit term (p=0.0721 / 0.3036) was not significant, and turbidity (Y1) and protein content (Y2) were significantly correlated with the factors, which means that the model can be used with a low error probability. The correlation coefficients of turbidity (Y1) and protein content (Y2) were R2(Y1)=0.9726 and R2(Y2)=0.9537, respectively, and their correction coefficients were AdjR2(Y1)=0.9935 and AdjR2(Y2)=0.9624, respectively, indicating that the regression fit of the two models was good and had a good correlation. In addition, the acceptable signal-to-noise ratios (Adeq Precision) corresponding to turbidity (Y1) and protein content (Y2) were 53.02 and 22.27, respectively, both greater than 4, indicating that this model can perform preliminary analysis and prediction of response surface factors.

[0126] The strength of each parameter on the dependent variable was determined based on the F value. The influence on turbidity was A>B>C>D, and the influence on protein content was A>C>D>B.

[0127] Table 3 Analysis of variance for regression models

[0128]

[0129]

[0130] Note: * indicates significant difference, * represents p<0.05, ** represents p<0.01.

[0131] According to the results of variance analysis (Table 3), the linear and quadratic terms (A, A2) of the chickpea liquid-to-solid ratio and the linear and quadratic terms (B, B2) of the enzyme-substrate ratio have significant effects on turbidity (p<0.01), and the interaction terms (AB, AC) of the liquid-to-solid ratio, enzyme-substrate ratio, and enzymatic hydrolysis time have significant effects on turbidity (p<0.05). It can be seen that the liquid-to-solid ratio and enzyme-substrate ratio in the chickpea enzymatic hydrolysis process are the key factors affecting turbidity. The interaction terms (BC, BD) of the enzyme-substrate ratio, enzymatic hydrolysis time, and enzymatic hydrolysis temperature in stage II and the interaction term (CD) of the enzymatic hydrolysis time and enzymatic hydrolysis temperature have significant responses to turbidity (p<0.05). Enzymatic hydrolysis can change the structure of macromolecules in chickpea solution. The enzyme-substrate ratio, stage II enzymatic hydrolysis temperature, duration, and pH are all decisive factors affecting the enzymatic hydrolysis effect. Sufficient enzymatic hydrolysis is conducive to the improvement of turbidity. The linear and quadratic terms of the liquid-to-solid ratio (A, A2) and the linear and quadratic terms of the hydrolysis time (C, C2) have significant effects on protein content (p<0.01). The interaction terms of liquid-to-solid ratio and enzyme-substrate ratio (AB, AC) have significant effects on protein content (p<0.05). Alkaline protease can effectively increase the content of soluble protein in chickpeas. Therefore, the amount of enzyme preparation and substrate added plays a decisive role in the protein content in chickpea hydrolysate. The interaction terms among liquid-to-solid ratio, hydrolysis time and hydrolysis temperature (BC, BD, CD) have significant effects on protein content (p<0.05).

[0132] like Figure 8 As shown in the figure, ae are the effects of the interaction between the feed-liquid ratio and the enzyme-substrate ratio, the feed-liquid ratio and the enzymatic hydrolysis time, the enzyme-substrate ratio and the enzymatic hydrolysis time, the feed-liquid ratio and the enzymatic hydrolysis temperature of stage II, and the enzymatic hydrolysis temperature of stage II and the enzymatic hydrolysis time on turbidity. Fig. 9 As shown in the figure, ad respectively represents the effects of the interaction between the feed-liquid ratio and the enzyme-substrate ratio, the enzyme-substrate ratio and the enzymatic hydrolysis time, and the II stage enzymatic hydrolysis temperature and the enzymatic hydrolysis time on the protein content.

[0133] The figure shows the strength of the interaction between the two factors. The steeper the change in the response surface between the two factors in the figure, the greater the impact on the dependent variable, and vice versa. In addition, if the bottom contour between the two factors is elliptical, there is a strong interaction, and vice versa, the interaction is weak. Figure 8(d) The contour lines of the 3D response surface mapping of B-enzyme substrate ratio and D-II stage hydrolysis temperature are elliptical, and there is a strong interaction between the two factors, which is consistent with the results of variance analysis (p<0.01). Fig. 9 (c) The contour lines of the 3D response surface mapping of B-enzyme-substrate ratio and C-enzyme hydrolysis time are elliptical, and there is a strong interaction between the two factors, which is consistent with the variance results (p<0.01). The reason may be that the insoluble protein in chickpeas can be more fully bound and hydrolyzed at the leucine site under the appropriate amount of alkaline protease and appropriate enzymatic hydrolysis time, which is conducive to the increase of protein content in chickpea enzymatic hydrolysate.

[0134] 4. Optimal process determination and verification test

[0135] According to the results of the above single factor experiments or response surface analysis, combined with the regression model, the optimal process conditions for the preparation of chickpea enzymatic hydrolysate are predicted as shown in Table 4.

[0136] Table 4 Optimum process and validation test of the model

[0137]

[0138] Through the response surface optimization experiment, the best production process predicted by the model was obtained, as shown in the optimal group in Table 2-6. In order to ensure the feasibility and operability of actual production, the process parameters were fine-tuned. The optimal process parameters for the preparation of chickpea hydrolysate were: material-liquid ratio 10.5:100 (w / w), enzyme-substrate ratio 2:100 (w / w), hydrolysis time 70 min, and stage II hydrolysis temperature 46°C. At this time, the turbidity was 1.85±0.21NTU and the protein content was 1.89±0.12g / 100g, which were close to the predicted values. This shows that the model after response surface optimization can obtain the optimal production process of chickpea hydrolysate.

[0139] Fig.10 This is the differential calorimetry (DSC) spectrum of chickpea plant milk. As can be seen from the figure, the differential calorimetry spectrum of chickpea plant milk has only one smooth endothermic peak, indicating that the purity of the chickpea plant milk components is relatively high. The denaturation temperature of chickpea plant milk is 129.92°C, which is relatively high. The denaturation state of protein can be reflected by the determination of enthalpy value (ΔH). The larger the enthalpy value, the greater the force maintaining the protein structure, the more ordered protein structures, that is, the better the thermal stability of the protein. The enthalpy value of chickpea plant milk is 1574.18mW / g, which shows that chickpea plant milk has good stability and is relatively insensitive to heat.

[0140] III. Performance analysis of the plant milk product prepared by the present invention

[0141] 1. Analyze the impact of enzymatic hydrolysis process on raw materials

[0142] The following materials were selected for experimental comparative analysis:

[0143] Soy flour: Chickpea flour, not processed in any way;

[0144] Puree: a product obtained by cooking, crushing and homogenizing chickpeas, which has only been subjected to the method of the present invention but not to enzymatic treatment;

[0145] Enzyme hydrolysate: The product is obtained by enzymatic hydrolysis and sterilization of the original pulp; the enzymatic hydrolysate base material has no added ingredients.

[0146] like Fig.11 As shown in the figure, the spatial relative distance values ​​and distance bar graphs of two samples are shown. The larger the distance, the greater the difference, and the farther the distance, the smaller the difference. Fig.11 It can be seen that the distance between chickpea flour and the original puree sample is the shortest, that is, the difference between chickpea flour and the original puree sample is the smallest, indicating that the process steps before enzymatic hydrolysis do not change the flavor substances much. The distance between chickpea flour and the enzymatic hydrolysate is the farthest, that is, the difference between chickpea flour and the enzymatic hydrolysate sample is the largest, indicating that the generation of flavor is related to the enzymatic hydrolysis process.

[0147] 2. Effect of enzymatic hydrolysis on the differences in flavor substances in chickpea-based milk

[0148] like Fig.12 It can be seen that this is a bar graph of the differential compound content of chickpea flour, puree, and hydrolyzate samples. From the figure, it can be clearly seen that there are differences in the compound content of the three samples. 12 and 11 flavor substances were detected from chickpea flour and chickpea hydrolyzate, respectively, and 10 flavor substances were detected from chickpea puree. 2-Propanone, hexanal, 2-butanone, and 2-heptanone are bean-flavor substances. Fig.12 It can be seen that the contents of 2-acetone, 2-butanone and hexanal rise linearly with the deepening of cooking, crushing and enzymolysis process. The contents of substances such as ethyl acetate, (E)-2-butenal, n-butanol, β-pinene show an upward trend with the progress of enzymolysis process, and these flavor substances give the chickpea enzymolysis liquid a mellow fragrance, a light fruity fragrance and a more distinct sense of hierarchy. At the same time, after being processed by the process of the present invention, the 2-butanone content in the enzymolysis liquid is significantly less than the content in the chickpea flour, and the beany smell in the chickpea plant milk can be effectively reduced by the process of the present invention.

[0149] 3. Product storage stability analysis

[0150] from Fig.13It can be seen that at the initial stage of storage, the chickpea enzymatic hydrolysate d(4,3)=51.7 μm, the average particle size of the original pulp is 70.99 μm, the particle size of the enzymatic hydrolysate is lower than that of the original pulp, and the smaller the particle size, the more conducive to the stability of the product. The stability of the enzymatic hydrolysate of the present invention is significantly increased compared with the original pulp.

[0151] Depend on Fig.14 , 15 It can be seen that the chickpea enzymatic hydrolysate prepared under the process conditions of the present invention is as follows Fig.14 (a) It can be seen that the chickpea enzymatic hydrolysate has good overall uniformity, the protein is in a flaky structure, and there is slight protein aggregation. Fig.14 It can be seen that the chickpea hydrolysate is light brown. After 4 days of storage, the system is uniform, with no precipitation or stratification. As the storage time increases, slight fracture marks appear on the 24th day. The chickpea puree is light yellow. At the beginning of storage, the system is relatively stable, with uniform color, no precipitation or stratification. Slight precipitation occurs after 16 days of storage, and the stratification phenomenon is obvious and continues to intensify on the 24th day. Fig.15 It can be seen from the microstructure that chickpea pulp has more macromolecules than enzymatic hydrolysate. This is because the enzymatic hydrolysis destroys the spherical structure of the protein, hydrolyzing it into soluble protein monomers or oligomers with smaller particle sizes, resulting in the conversion of insoluble protein to soluble protein, increasing the soluble protein content in the system; the conversion of straight-chain starch to branched starch, and the precipitation problem caused by adhesion. With the extension of storage time, the aggregation rate of macromolecules in the pulp is obviously higher than that of the enzymatic hydrolysate, which shows that the enzymatic hydrolysis has a significant improvement on the sedimentation problem caused by macromolecules.

[0152] Fig.16 , 17 It can be seen that the chickpea hydrolysate and puree were stored at 25°C for 28 days, and the data were monitored every 4 days. During the storage of the emulsion, the flocculation and coagulation of the droplets generally occur simultaneously. As can be seen from the figure, the CI and FI of the puree and hydrolysate showed an increasing trend. The CI of the puree increased from 100.4% to 108.2%, and the FI increased from 8.9% to 102.4%. The CI of the hydrolysate increased from 99% to 107.5%, and the FI increased from 8.7% to 93.5%. The enzymatic hydrolysis process not only increases the soluble protein content of the chickpea emulsion system, but also gives it better stability.

[0153] 4. Product interface protein content and concentration

[0154] Fig.18 , 19The changes of interface protein concentration (Γ) and interface protein content (AP) of chickpea hydrolysate and puree during storage were recorded respectively. As can be seen from the figure, the interface protein concentration and interface protein content of chickpea hydrolysate are greater than those of puree.

[0155] 5. Comparison of product rheology

[0156] Effect of storage rheological properties of chickpea hydrolysate and puree Fig. 20 As shown, the apparent viscosity at shear frequency 0-100s after storage at 25°C for 4, 8, 12, 16, 20, 24, and 28 days respectively. -1 The change diagram between Fig. 20 It can be seen that with the extension of storage time of the enzymatic hydrolysate, the viscosity does not change significantly, indicating that the rheological properties of the chickpea enzymatic hydrolysate are relatively stable, while the rheological properties of the original pulp change significantly within 28 days.

[0157] Table 5 Basic indicators of chickpea plant milk Table 1 Basic indicators of CPBM

[0158] Physical and chemical indicators result unit protein 1.86±0.05 g / 100g Fat 0.85±0.13 g / 100g Dietary fiber 1.51±0.29 g / 100g Total colony count 0 cfu / mL Acidity 3±0.23 °T pH 8.12±0.02 - L* / a* / b* / E 66.91±0.03 / -2.00±0.08 / 20.52±0.07 / 85.43±0.04 - eGI 57.27±1.35 - Zeta Potential -55.68±2.16 mV

[0159] Note: The data in the table are expressed as “mean ± standard deviation”; - represents no unit.

[0160] From the above analysis, it can be seen that the basic storage time of the chickpea enzymatic hydrolysate prepared by the present invention can be maintained for more than 28 days. This storage time is simply due to the enzymatic hydrolysis process of the present invention and the product raw materials themselves, without adding any additives. After adding a stabilizer in the subsequent preparation, the stability of the finished plant-based milk will be higher. The low glycemic index chickpea plant-based milk prepared by the enzymatic hydrolysis technology of the present invention has a protein content of 1.86±0.05g / 100g, a protein utilization rate increased by 38.4%, a fat content of 0.85±0.13g / 100g, a dietary fiber content of 1.51±0.29g / 100g, an eGI value of 57.27±1.35, an average particle size of 124.49μm, and a Zeta potential absolute value of 55.67±2.16mV. A total of 11 flavor substances that contribute to the sensory organs are detected in the plant milk, and the content of beany smell substances such as hexanal is weakened, which strengthens other flavor substances and gives the plant milk a mellow aroma, a light fruity aroma and a more distinct sense of hierarchy.

[0161] In summary, the method of the present invention can prepare plant-based milk with a long shelf life, mellow flavor, light fruity aroma, high protein content and low glycemic index. It can replace animal milk and is suitable for consumption by people with lactose intolerance.

Claims

1. A process for preparing chickpea plant-based milk, characterized in that: The following steps are involved: S1. Preparation of raw materials S11. Wash and soak the chickpeas and steam them under high pressure; S12. The cooked chickpeas were crushed and homogenized in an ultrasonic cell disruptor; S2. Preparation of enzymatic solution by step-by-step enzymatic hydrolysis S21. Add α-amylase and β-amylase to the homogenized mixture, stir and enzymolyze in a water bath at 50-55° C. for 25-40 min with magnetic ion stirring to perform the first stage of enzymolysis, and add sodium bicarbonate to adjust the pH to 8.0; S22. After the first stage of enzymatic hydrolysis, alkaline protease was added and enzymatic hydrolysis was carried out in a water bath at 40-50° C. with magnetic ion stirring for 25-40 min; S23. The mixture after enzymatic hydrolysis was inactivated in a water bath and filtered to obtain an enzymatic hydrolyzate; S3. Formulate plant-based milk products S31. The enzymatic hydrolysate is heated, and weighed xylitol, sucralose, acesulfame potassium, stabilizer, perilla oil, and dietary fiber are evenly added; S4. Shearing and homogenizing the prepared mixture; S5. Sterilize the homogenized mixed solution by ultra-high temperature instantaneous sterilization; S6. Cool and fill the sterilized product.

2. The process for preparing chickpea plant-based milk according to claim 1, characterized in that: The formula of the enzymatic hydrolyzate prepared in step S2 includes: 8-12% chickpea, 0.2%-1.0% beta-amylase, 0.2%-1.2% alpha-amylase, 0.1%-0.3% alkaline protease, and the rest is purified water.

3. The process for preparing chickpea plant-based milk according to claim 1, characterized in that: The formula of the plant-based milk prepared in step S3 includes: 93%-95% of enzymatic hydrolyzate, 0.2%-0.8% of composite stabilizer, 0.4%-0.6% of xylitol, 0.001%-0.004% of sucralose, 0.006%-0.01% of acesulfame potassium, 0.2%-0.8% of perilla oil, and 3%-3.5% of dietary fiber.

4. The process for preparing chickpea plant-based milk according to claim 1, characterized in that: In the step S22, the alkaline protease is hydrolyzed in a water bath at 46° C. with magnetic ion stirring for 25-40 minutes.

5. The process for preparing chickpea plant-based milk according to claim 1, characterized in that: The specific steps of preparing in step S31 are: heating the enzymatic hydrolysate to 55-60° C., adding evenly mixed xylitol, sucralose, acesulfame potassium, stabilizer, and dietary fiber, stirring while adding, and finally adding perilla oil.

6. The process for preparing chickpea plant-based milk according to claim 1, characterized in that: The specific steps of soaking and high-pressure cooking in step S11 are: adding clean water with a weight of 9 times that of the raw material to soak for 2 hours, and high-pressure cooking for 50 minutes.

7. The process for preparing chickpea plant-based milk according to claim 1, characterized in that: The specific steps of crushing and homogenizing in step S12 are: crushing the chickpeas in a wall crusher for 8-15 minutes at a power of 800W; and homogenizing the mixed solution obtained after crushing in an ultrasonic cell disruptor at 420W for 20-40 minutes.

8. The process for preparing chickpea plant-based milk according to claim 1, characterized in that: The addition ratio of α-amylase, β-amylase and alkaline protease in step S2 is 5:4:1.

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