CN118556816A - Method for preparing rice paste matrix powder by combining cooking enzymolysis and microbial fermentation and product - Google Patents

Abstract

The invention provides a method for preparing rice paste matrix powder by combining cooking enzymolysis and microbial fermentation, which comprises the following steps: 1) Steaming raw rice with water to obtain cooked rice; steaming rice, adding alpha-amylase for stirring and enzymolysis, drying, and grinding after the rice is dried; 2) Adding bacteria powder into the rice flour obtained in the step 1) for fermentation, and then freeze-drying to form rice paste matrix powder. Compared with the processing process of rice paste matrix powder in the prior art, the invention adds the processes of stewing, enzymolysis and microbial compound fermentation, and the combination of the processes improves the brewing characteristic of the powder, so that the rice paste is easier to digest and absorb, and the taste of the rice paste is obviously improved. The cooking process changes the starch structure in the rice by high temperature treatment, and improves the hardness and taste of the powder.

Description

Method for preparing rice paste matrix powder by combining cooking enzymolysis and microbial fermentation and product

Technical Field

The invention belongs to the technical field of foods, and particularly relates to an instant food prepared from rice.

Background

At present, the social life rhythm is continuously accelerated, the demand of the instant food market is steadily increased, the demand of the brewing cereal food is also increased, and the rice paste is one of typical brewing products. The instant rice paste food can be directly brewed and eaten without complex cooking process, and is very convenient and quick. The brewed rice paste can be eaten by people with bad teeth, such as infants, the elderly, etc. The rice contains 6% -9% of protein and less than

1.5% Of crude fat, and substances such as sugar, protein, fat and dietary fiber contained in rice provide needed nutrition for human body, but rice paste directly prepared from rice has rough texture and relatively flat flavor; in addition, products that are easier to digest are needed for infants and the elderly.

The rice slurry is prepared by grinding long-shaped rice, adding Saccharomyces cerevisiae and Lactobacillus plantarum for fermentation, the quality of the rice slurry after fermentation is obviously better, and 18 kinds of aromatic substances (Jiang Ping U. The optimization of the process conditions of the fermented rice flour and the research of aromatic components [ D ] Nanchang university, 2016) which are higher than those of natural fermentation are obtained.

The combined action of multiple microorganisms can produce a significant synergistic effect during fermentation. Multiple microbial fermentation has many advantages over single strain fermentation. The cooperation of various microorganisms makes the strain have higher activity and can transform the nutritional ingredients in the raw materials more efficiently. Meanwhile, the proper fermentation mode can produce more abundant nutrient substances, and the nutritive value of the product is improved. In addition, the proper inoculation amount can effectively shorten the fermentation period, and simultaneously endow the product with unique and excellent flavor and taste (Hu Lihua, su Donghai, soviet Union and Eastern Europe people. Influence of multi-strain mixed fermentation on main food flavor [ J ]. Food science and technology, 2010,35 (3): 149-152.).

The fermentation of rice products is generally used for the preparation of traditional foods such as rice wine, rice cake and the like, and there is a blank of research on how to adopt a proper fermentation process in the preparation of rice paste.

Disclosure of Invention

In view of the shortcomings of the prior art, a first object of the present invention is to provide a method for preparing rice paste base powder by combining cooking enzymolysis and microbial fermentation.

It is a second object of the present invention to provide the product of the process.

The technical scheme for realizing the purposes of the invention is as follows:

A method for preparing rice paste matrix powder by combining cooking enzymolysis and microbial fermentation comprises the following steps:

1) Steaming raw rice with water to obtain cooked rice; steaming rice, adding alpha-amylase for stirring and enzymolysis, drying, and grinding after the rice is dried;

2) Adding bacteria powder into the rice flour prepared in the step 1) for fermentation, and then freeze-drying to form rice paste matrix powder; the bacterial powder is one or more of saccharomycetes, lactobacillus plantarum, lactobacillus acidophilus, lactobacillus lactis, lactobacillus casei and lactobacillus bulgaricus.

Wherein, when rice is steamed by rice, the volume ratio of water to raw rice is 0.9-1.7:1.

Compared to other amylases, such as beta-amylase, gamma-amylase, etc., alpha-amylase can randomly hydrolyze alpha-1, 4 glycosidic bonds of starch molecular chains, thereby increasing the gelatinization degree of starch. Gelatinization refers to the process by which starch granules swell and break up upon absorption of water, and is an important factor affecting the mouthfeel and digestive characteristics of rice paste. The short-chain dextrin generated by the hydrolysis of the alpha-amylase has good solubility and viscosity, so that the rice paste is finer and smoother and is easy to digest and absorb. In terms of viscosity, beta-amylase and gamma-amylase act mainly on the inner side and the outer side of starch branches, and the viscosity of products produced by hydrolysis is high. The viscosity of short-chain dextrin generated by the hydrolysis of the alpha-amylase is lower, so that the viscosity of the rice paste can be reduced, and the rice paste is more fresh.

In addition, the action site and action mode of the alpha-amylase are relatively simple, the hydrolysis degree is easier to control, and the required gelatinization degree and viscosity are obtained. The production cost of the alpha-amylase is relatively low, and the alpha-amylase has high cost performance in practical application.

Preferably, the enzyme addition amount of the alpha-amylase in the step 1) is 0.6-1.4 g enzyme/200 mL raw rice, and the enzyme activity of the alpha-amylase is 3000-4000U/g.

Starch in rice paste is a major carbohydrate source and is of vital importance for the energy supply of the consumer, and the addition of amylase in proper amounts can help to break down the starch and convert it into smaller carbohydrate molecules, such as glucose, which make it easier for the consumer to digest and absorb the nutrients therein. Meanwhile, the sugar molecules can also interact with other nutrient substances in the rice paste, so that the bioavailability of the rice paste is improved, and the food has more comprehensive nutrition. Secondly, the addition of amylase can improve the taste and the texture of the rice paste, produce fine and smooth food and is beneficial to brewing.

Further preferably, the enzymolysis time in step 1) is 2 to 6 minutes. The enzymolysis temperature is 50-70 ℃.

Wherein, the drying mode in the step 1) is as follows: firstly, drying for 1 to 1.5 hours at the temperature of between 100 and 110 ℃ by hot air, and then drying to a state of being capable of grinding at the temperature of between 55 and 65 ℃.

The drying time of samples under different enzymolysis conditions is different, and the drying time is longer as the enzymolysis degree is larger. The drying time at 55-65 ℃ can be 18-28 h, more preferably, rice in the tray is turned over once every 1h, so that the drying uniformity is ensured.

In the step 2), the bacterial powder is yeast and lactobacillus plantarum composite bacterial powder compounded according to the mass ratio of 9:1.

The similar growth conditions of the lactobacillus and the saccharomycete promote the cooperative relationship of the lactobacillus and the saccharomycete, acid substances such as lactic acid produced by the lactobacillus can inhibit the growth of other bacteria in the fermentation process, and the saccharomycete can produce growth factors such as vitamins, amino acids and the like so as to provide nutrition for the growth of the lactobacillus. The flavor of the rice and flour products can be greatly improved by utilizing the yeast and lactobacillus for co-fermentation.

Wherein, in the step 2), the fermentation time is 12-24 hours.

Wherein, in the step 2), the fermentation temperature is 25-34 ℃.

Wherein, in the step 2), the inoculation amount of the bacterial powder is 3-5% (mass percent).

Still another preferred embodiment of the present invention includes the steps of:

1) Adding water into raw rice according to the volume ratio of 1.2-1.4:1 water/meter, steaming the rice, adding alpha-amylase according to the enzyme adding amount of 1.2-1.3 amylase (g)/meter (200 mL), stirring and carrying out enzymolysis for 4min; drying and grinding rice after enzymolysis, and sieving with 100 mesh sieve;

2) Adding yeast and lactobacillus plantarum composite bacteria powder compounded according to the mass ratio of 9:1 into the rice flour prepared in the step 1) for fermentation, wherein the fermentation time is 11-14 h, the fermentation temperature is 26-29 ℃, and the inoculation amount is 4%; after fermentation, the rice paste is lyophilized into rice paste matrix powder.

The lyophilization conditions may be: the temperature is-50 to-70 ℃, the vacuum degree is 5-10 Pa, and the time is 40-60 h.

The rice paste matrix powder prepared by the method of the invention.

The invention has the beneficial effects that:

Compared with the processing process of rice paste matrix powder in the prior art, the invention adds the processes of stewing, enzymolysis and microbial compound fermentation, and the combination of the processes improves the brewing characteristic of the powder, so that the rice paste is easier to digest and absorb, and the taste of the rice paste is obviously improved. The cooking process changes the starch structure in the rice by high temperature treatment, and improves the hardness and taste of the powder. The enzymolysis technology uses alpha-amylase as a catalyst, accelerates the hydrolysis reaction of starch on the basis of gelatinization, generates oligosaccharide and monosaccharide, and the starch is easier to be absorbed by human bodies. In addition, the microbial compound fermentation process further degrades starch and protein and generates flavor substances and other nutritional ingredients by introducing saccharomycetes and lactobacillus plantarum, so that the flavor and the nutritional value of the food are enhanced.

The research ensures the high quality of the product and the satisfaction of consumers through an objective sensory evaluation method, and lays a foundation for the subsequent market popularization of the product.

Drawings

FIG. 1 is a graph showing comparison of experimental results of single factors under the condition of enzymolysis in examples.

FIG. 2 is a graph showing comparison of results of in vitro digestibility of starch and protein in a sample.

FIG. 3 is a graph showing the comparison of the processed rice with the comparison result of the control group.

FIG. 4 is a flow chart of the present method for preparing a rice paste base powder by combining cooking enzymolysis with microbial fermentation.

Detailed Description

The following examples are illustrative of the invention and are not intended to limit the scope of the invention.

In order to make the objects, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below.

The specific conditions are not noted in the examples and are carried out according to conventional conditions or conditions recommended by the manufacturer. The raw materials or equipment used are conventional products available commercially without identifying the manufacturer.

In the examples, the method for measuring the content of the reducing sugar comprises the following steps: the method comprises the steps of using an oxidant 3, 5-dinitrosalicylic acid, wherein the amount of reducing sugar is in direct proportion to the color of a substance reduced to be brownish red, measuring the optical density value at the wavelength of 540nm by using a spectrophotometer, checking a standard curve, and calculating to obtain the content of the reducing sugar and the total sugar in a sample.

Water solubility index determination: the greater the water solubility index, the more readily the powder is bound to water, i.e., the better the product is flushability. The determination method is to pour the quantitative powder into water, centrifuge and calculate the ratio of the supernatant residue mass to the total mass.

WSI (%) = (residue mass after supernatant evaporated to dryness/dry weight of sample) ×100%

Determination of caking Rate: the smaller the index, the less likely the rice powder is to agglomerate in water, i.e. the better the consistency. The measurement mode is that quantitative powder is poured into water, stirred, kept stand and sieved by a 20-mesh sieve, and the ratio of the mass of the oversize material to the total mass is calculated.

Caking ratio = [ (mass of screen and caking-mass of screen)/dry weight of sample ] ×100%

Sensory evaluation: for the rice paste product subjected to enzymolysis only, the following investigation indexes and scoring standards are designed:

(1) Color (before brewing), full 15 minutes: dark, yellowish, uneven (0-4 minutes); the color is darker, slightly yellow and basically uniform (5-9 minutes); bright, white, uniform (10-15 minutes).

(2) Smell (before brewing), 15 minutes per full: has unpleasant smell and no rice smell (0-4 minutes); substantially free of unpleasant odors, slightly rice-flavored (5-9 minutes); no unpleasant smell, and obvious rice flavor (10-15 minutes).

(3) Tissue state (before brewing), full 20 minutes: coarse particles, uneven size, multi-junction blocks (0-7 minutes); the particles are finer and finer, the size is uniform, and caking is less (8-14 minutes); fine and smooth particles, relatively uniform, loose and no caking (15-20 minutes).

(4) Brewing (after brewing), the full score is 25: more caking and serious delamination (0-8 min); with minor caking, slight delamination (9-17 min); no or almost no caking and no delamination (18-25 min).

(5) Taste (after brewing), the full score is 25: obviously has granular feel and has peculiar smell (0-8 minutes); no granular feel and no peculiar smell (9-17 minutes); no granular feel, and the rice taste and the amylase taste are better fused (18-25 minutes).

For rice paste products which are subjected to combination of steaming enzymolysis and microbial fermentation, the investigation indexes and the scoring standards are basically the same, and the difference is that: (2) smell (before brewing), 15 minutes per full: has unpleasant smell, no fermented smell, no rice smell (0-4 min); basically has no unpleasant smell, slightly has fermented flavor and slightly has rice flavor (5-9 minutes); has no unpleasant smell, obvious fermented flavor and rice flavor and better fusion (10-15 minutes). (5) taste (after brewing), the full score is 25: obviously has granular feel and has peculiar smell (0-8 minutes); no granular feel and no peculiar smell (9-17 minutes); has no granular feel, and the rice taste and the zymophyte taste are better fused (18-25 minutes).

The rice paste is prepared by the following steps: the ratio of rice flour to water is 15g:150mL. Taking rice flour into a container, firstly taking 2/3 of purified water with the temperature of about 60 ℃, adding the purified water while stirring rapidly in the same direction for 30s, then adding the rest water again, and stirring continuously in the same direction until the mixture is semi-fluid and pasty. The total number of subjects was 15.

Starch in vitro digestibility assay: in vitro digestion experiments are used to evaluate the digestibility, bioavailability, release kinetics, structural changes, etc. of food ingredients during digestion. The experiment can predict the digestion and absorption condition of rice flour in human body, thereby helping research and development personnel optimize the formula and processing technology of rice flour to improve the nutritional value and edible quality of rice flour.

The soluble sugar in the sample can be separated from the starch by using 80% ethanol, the starch is further decomposed into glucose by an acid hydrolysis method, and the content of the starch can be calculated by measuring the content of the glucose by using an anthrone colorimetric method. The glucose content was determined using the Soxhobao BC2505 glucose content detection kit.

The calculation formula of the in-vitro digestion rate of the starch is as follows: sh=0.9×gp/Si,

Where SH is the starch hydrolysis rate (total), gp is the amount of glucose produced by digestion of the sample, and Si is the initial amount of starch.

Protein in vitro digestibility assay: first, the initial protein concentration of the sample was measured using the soribao PC0020 BCA protein concentration measurement kit. Thereafter, 1.000g of the sample was placed in a sample bottle, 4mL of deionized water was added thereto, and the temperature was kept constant at 37℃for 3 minutes. 4mL of simulated gastric fluid (containing 3mL of pepsin solution with a mass concentration of 7mg/mL and an enzyme activity of 2.5X10 ⁵ U/g, 0.25. Mu.L of 0.3mol/L calcium chloride solution) was poured into a sample bottle and mixed, and the pH was adjusted to 1.7.+ -. 0.1. The mixed sample is added with water to 10mL of total volume, kept at 37 ℃ for 2 hours, sampled at the time point of 120min in the gastric digestion stage, and the enzyme is deactivated in a boiling water bath.

The liquid samples were mixed with simulated intestinal fluid (containing 2mL of 8mg/mL by mass concentration and 8 XUSP pancreatin solution with enzyme activity, 20. Mu.L of 0.3mol/L calcium chloride solution) at the 120min time point during the intestinal digestion phase. The samples of gastric and intestinal digesta were taken out and the mass of undegraded macromolecular protein in the pellet was determined using BCA kit.

The calculation formula of the in vitro digestibility of the protein is as follows: dp= (mT-mC)/mT

Wherein DP is the in vitro digestibility of the protein of the sample; mT is the total protein mass of the sample; mC is the mass of protein that the sample has not been digested during the gastric and intestinal digestion phases.

Pre-test 1:

reducing sugar is generated in the enzymolysis process, and if the fermenting is not performed directly, the sour taste generated by the fermenting cannot be neutralized by the sweet taste of the reducing sugar, so that the sensory score of the sample can be reduced. Under the same fermentation conditions, the enzymatic hydrolysis parameters of sample 9 of example 2 were on average 6.51 points higher than the non-enzymatic sensory scores.

From the aspect of component analysis, the reducing sugar generated by enzymolysis is small molecular sugar which is more beneficial to microorganism utilization and can promote fermentation.

In summary, the importance of performing the enzymatic hydrolysis prior to fermentation has been demonstrated, so that no process optimization test for non-enzymatic hydrolysis, i.e., fermentation, has been set.

Pre-test 2:

lactobacillus plantarum fermentation can generate sour taste of a sample, and in the early pre-experiment, sensory evaluation experiments show that under the same fermentation condition, when lactobacillus plantarum accounts for more than 15%, the sour taste in the sample can bring unpleasant feeling to a subject in terms of smell and taste, and sensory scores are reduced (average reduction of 10.2 minutes). When lactobacillus plantarum is at a ratio of 10%, most subjects indicate that the sourness imparted by fermentation is acceptable and that the aroma imparted by fermentation is perceived.

Reference has also been made to prior studies which have shown (e.g., fu Yaping. Technical study of lactic acid bacteria fermentation to eliminate cadmium in rice [ D ] Hunan university of agriculture, 2016; wang Lei, chen Yuwei, wang Yingjie, etc.. Microbiological method to eliminate cadmium in rice flour [ J ] technical study and quality analysis of light university of Wuhan university, 2018,132 (02): 5-12.), lactobacillus plantarum can help to adjust pH during rice fermentation to enhance shelf life of foods, and may also increase some beneficial bioactive ingredients such as vitamins and minerals, thereby providing further health benefits. In addition, lactobacillus plantarum fermentation can reduce the content of metal cadmium in rice.

In the test, the saccharomycetes and the lactobacillus plantarum are compounded according to the ratio of 9:1.

Example 1 conditions for digestion and enzymolysis were searched for by single factor experiments

Steaming raw rice with water to obtain cooked rice; steaming rice, adding alpha-amylase, stirring for enzymolysis, and drying in oven. The drying method comprises the following steps: first, the mixture is dried by hot air at 105 ℃ for 1h, and then dried to a state of being capable of being milled at 60 ℃. Grinding after the sample is dried, and sieving the powder through a 100-mesh sieve to obtain the rice paste matrix powder.

And measuring the reducing sugar content, the water solubility index and the caking rate. In order to optimize the enzymolysis process design single factor experiment, the selected factors are as follows:

(1) Factor a—water addition: the hardness of cooked rice is affected, and the baking difficulty of the enzymolysis effect is affected. In addition, water is used as a production raw material, and the water addition amount can have an important influence on the product cost. The water volume is as follows: the volume of raw rice is measured in units of 0.9:1,1.1:1,1.3:1,1.5:1 and 1.7:1, and 5 gradients are arranged. When the volume ratio is lower than 0.9, the rice is too hard and the electric rice cooker is damaged; when the volume ratio is higher than 1.7, the cooked rice is too soft, approaches to porridge and is difficult to dry, so the experimental gradient is set to the above range.

(2) Factor B-enzyme addition: influence the enzymolysis effect of the rice; and because amylase has color and peculiar smell and has higher price, the enzyme adding amount influences the sensory evaluation of the product in terms of color and smell and influences the production cost.

Early experiments found that when 3700U/g of alpha-amylase was added at an addition level of 1g/200mL of raw rice, the rice paste did not produce significant color change and off-flavors and had a smooth mouthfeel and rice flavor that were able to taste different than the non-added sample. Based on this, experiments were performed with 5 gradients of 0.6,0.8,1.0,1.2,1.4g enzyme/200 mL raw rice.

(3) Factor C-enzymolysis time: influence the effect and the stoving degree of difficulty that rice was by enzymolysis, in addition, because the equipment is kept constant temperature in the enzymolysis process, consequently enzymolysis time can produce the influence to manufacturing cost through influencing the mill energy consumption. And setting 5 gradients of 2, 3, 4,5 and 6min according to the earlier test and the experimental conditions recorded in the factor B, and performing single factor investigation on the enzymolysis time. The enzymolysis temperature is 60 ℃.

Single factor experimental results: the alpha-amylase can hydrolyze starch in the rice flour to generate maltose and glucose with smaller molecular weight, and the two sugars belong to reducing sugar, and the starch is non-reducing sugar, so that the degree of enzymolysis of the sample can be known by measuring the content of the reducing sugar in the sample, namely, the higher the content of the reducing sugar, the higher the degree of enzymolysis of the sample. See fig. 1. With the increase of the water adding amount, the reducing sugar content and the water solubility index of the sample are gradually increased, and the caking rate is gradually reduced. Wherein the influence of the water addition amount on the content of the reducing sugar is obvious, and when the water-to-rice ratio is increased from 1.1:1 to 1.3:1, the content of the reducing sugar in the sample is increased to be close to 30 percent. However, it should be noted that the increase in the amount of water added increases the difficulty of drying, and if the drying is insufficient, the powder still tends to agglomerate after bagging.

See the second row of fig. 1. With the increase of the enzyme adding amount, the reducing sugar content and the water solubility index of the sample gradually increase, and the caking rate gradually decreases. Wherein the influence of the water adding amount on the water solubility index is obvious, and when the enzyme adding amount is increased from 0.4g/ml of raw rice to 0.6g/ml of raw rice, the water solubility index of the sample is increased by nearly 2 percent. Also, the enzyme adding amount has a larger influence on the enzymolysis effect, and the drying difficulty is increased due to the increase of the enzyme adding amount.

The smaller the caking ratio, the less likely the rice powder is to agglomerate in water, i.e. the better the brewing. The greater the water solubility index, the more readily the powder is bound to water, i.e., the better the product is flushability. See third row of fig. 1. With the increase of enzymolysis time, the reducing sugar content and the water solubility index of the sample gradually increase, and the caking rate gradually decreases. When the enzymolysis time is 6 minutes, the water solubility index of the sample enters a platform period, but the content of reducing sugar and the caking rate still have the tendency of changing. However, if the reducing sugar content is too high, a gel structure is easily generated in the sample in the drying stage, which is unfavorable for drying and subsequent crushing and sieving.

Example 2 conditions for preparation of a rice paste base powder by digestion and enzymolysis through orthogonal experiments

Steaming raw rice with water to obtain cooked rice; steaming rice, adding alpha-amylase, stirring for enzymolysis, and drying in oven. Grinding after the sample is dried, and sieving the powder through a 100-mesh sieve to obtain the rice paste matrix powder.

In this experiment, referring to the single factor experimental result of example 1, the following will be:

(1) The water addition amount is set as a factor A, and the 3 levels are respectively 0.9:1, 1.1:1 and 1.3:1 water/meter (v/v);

(2) The enzyme addition amount was set as factor B, and the 3 levels were 0.8, 1.0, 1.2 enzyme amounts (g)/meter (200 mL), respectively;

(3) Setting the enzymolysis time as a factor C, wherein the 3 levels are respectively 3min, 4min and 5min; the temperature of enzymolysis is 60 ℃.

Table 13 factor 3 horizontal orthogonal table

The measured indexes are respectively as follows: reducing sugar content (for evaluating enzymolysis degree), water solubility index and caking rate (for evaluating the brewing characteristics of rice paste), and sensory evaluation (for evaluating appearance, flavor and taste of the product).

The calculations were performed according to the results of table 2, the experimental results are as follows:

(1) The combination with the highest reducing sugar content and the optimal water solubility index is A ₃B₃C₂, namely, the water adding amount is 1.3:1 water/meter (v/v), the enzyme adding amount is 1.2 amylase (g)/meter (200 mL), and the enzymolysis time is 4min.

(2) The combination with the lowest caking rate is A ₃B₂C₃, namely the water adding amount is 1.3:1 water/meter (v/v), the enzyme adding amount is 1.0 amylase (g)/meter (200 mL), and the enzymolysis time is 5min.

(3) The combination with the highest total sensory evaluation score is A ₁B₂C₂, namely the water adding amount is 0.9:1 water/meter (v/v), the enzyme adding amount is 1.0 amylase (g)/meter (200 mL), and the enzymolysis time is 4min.

TABLE 2 results of orthogonal experiments on enzymatic hydrolysis conditions

The digestibility of rice flour is put in the first place in the product performance, and the factor combination which is most favorable for digestion (namely, the highest content of reducing sugar) is selected.

Example 3 orthogonal test of preparation of Rice paste matrix flour Using digestion enzymolysis and microbial fermentation

The embodiment provides a method for preparing rice paste matrix powder by combining cooking enzymolysis and microbial fermentation, which comprises the following steps:

1) Steaming raw rice with water to obtain cooked rice; steaming rice, adding alpha-amylase, stirring for enzymolysis, and drying in oven. Grinding after the sample is dried, and sieving with a 100-mesh sieve;

2) Adding yeast and lactobacillus plantarum composite bacteria powder compounded according to the mass ratio of 9:1 into the rice flour prepared in the step 1) for fermentation, and then freeze-drying to form rice paste matrix powder.

According to the result obtained in the example 2, in the step 1), a process of adding 1.3:1 water/meter (v/v), adding 1.2 amylase (g)/meter (200 mL) and carrying out enzymolysis for 4min is adopted to prepare a sample, then saccharomycetes and lactobacillus plantarum compound bacteria powder compounded according to the mass ratio of 9:1 are added for fermentation, and then the rice paste matrix powder is formed by freeze drying. The drying conditions of the step 1) are as follows: drying at 105℃for one hour and at 60℃for 24 hours. The conditions for lyophilization were-60℃and 8Pa vacuum for 48h.

In this embodiment, the following will be:

(1) The fermentation time is set as a factor A, and the 3 levels are respectively 12h, 18h and 24h;

(2) The fermentation temperature was set as factor B,3 levels were 28 ℃, 31 ℃, 34 ℃ respectively;

(3) The inoculation amount (mass percent) is set as a factor C, and 3 levels are respectively 3%, 4% and 5%;

table 33 factor 3 horizontal orthogonal table

As shown in FIG. 2A), the starch digestibility of each group increased with increasing digestion time, but the starch digestibility of the samples with longer fermentation time was higher, i.e., more digestible. This trend is also reflected in the in vitro digestion assay of proteins, as shown in FIG. 2B), there is no significant difference or trend in the degree of protein digestion between different samples during the gastric digestion phase, but the protein digestibility is higher for samples with longer fermentation times after the intestinal digestion phase is completed.

The calculations were performed according to the results of table 4, the experimental results are as follows:

(1) The highest in vitro digestibility of the starch is A ₃B₃C₃, namely the fermentation time is 18h, the fermentation temperature is 34 ℃ and the inoculum size is 5%.

(2) The highest in vitro digestibility of protein is A ₃B₃C₁, namely the fermentation time is 18h, the fermentation temperature is 34 ℃, and the inoculation amount is 3%.

(3) The highest combination of sensory evaluation total score was A ₁B₁C₂, namely fermentation time 12h, fermentation temperature 28℃and inoculum size 4%.

It should be noted that although the in vitro digestibility of the starch and protein of the sample increases with a high degree of microbial fermentation, the sourness imparted by the microorganisms also increases, and the unpleasant sensation is imparted to the subject during the sensory evaluation. Flavor mouthfeel is an important factor affecting food sales, and thus microbial fermentation conditions with the highest total sensory evaluation score are ultimately employed. The highest score of the sensory evaluation in the orthogonal experiment is the score of sample 2 in table 4, then a new sample is prepared according to the calculation result a ₁B₁C₂ of the orthogonal experiment, the sensory evaluation score is 72.65 score, which is higher than all samples of the orthogonal experiment, and the calculation result is proved to have credibility. Comparative example 2, the score was higher than all its samples.

Other parameter comparisons: in the case where the enzymatic conditions were the same (enzymatic conditions for sample 9 of example 2), the fermented sample was compared to the unfermented sample:

1) The reducing sugar content is reduced by 6.61%, the content is 34.45% before fermentation and 27.84% after fermentation, because the reducing sugar is consumed in the microbial fermentation process;

2) The in vitro digestibility of the starch is improved by 1.58 percent, and no obvious difference exists; 75.55% before fermentation and 77.13% after fermentation.

3) The in vitro digestibility of the protein is improved by 12.90 percent, the protein is 62.03 percent before fermentation and 74.93 percent after fermentation.

4) The water solubility index is improved by 1.06%, the water solubility index is 51.03% before fermentation and 52.09% after fermentation.

5) The caking rate is reduced by 0.93%, the caking rate is 2.59% before fermentation and 1.66% after fermentation.

TABLE 4 results of orthogonal experiments on microbial fermentation conditions

Example 4 preparation of Rice paste matrix flour Using digestion enzymolysis and microbial fermentation

The present example provides a method for preparing rice paste base powder by combining cooking enzymolysis and microbial fermentation, comprising the following steps (see fig. 4):

1) Adding water according to the volume ratio of raw rice to water of 1.3:1 water/meter (v/v), steaming rice, adding amylase (g)/meter (200 mL) with enzyme amount of 1.2, and performing enzymolysis for 4min, adding alpha-amylase with enzyme activity of 3700U/g, and performing stirring enzymolysis at 60deg.C; drying and grinding rice after enzymolysis, and sieving with 100 mesh sieve; the drying conditions were the same as in example 3.

2) Adding yeast and lactobacillus plantarum composite bacteria powder compounded according to the mass ratio of 9:1 into the rice flour prepared in the step 1) for fermentation, wherein the fermentation time is 12 hours, the fermentation temperature is 28 ℃, and the inoculation amount is 4%; after fermentation, the rice paste is lyophilized into rice paste matrix powder. Conditions for lyophilization: -60 ℃, 8Pa,48h vacuum.

The product of this example (processed group) was compared with the sample subjected to the cooking process alone (control group), as shown in fig. 3, reducing sugar content: control 19.69%, processed 27.84%, 8.15% improvement, water solubility index: 49.53% for the control group, 52.10% for the processing group, 2.57% improvement; caking ratio: control 3.60%, processing 1.66%, 1.94% lower; starch digestibility: control group 71.63%, processing group 77.13%, 5.5% improvement; protein digestibility: control group 65.91%, processing group 74.93%, 9.02% improvement; sensory score: control 60.80%, processing 72.65%, 11.85% improvement. Besides the water solubility index, the reducing sugar content, the starch digestibility, the protein digestibility and the sensory score of the processed group samples are obviously improved, and the caking rate is obviously reduced, so that the processing technology optimizes the quality of the rice paste matrix powder from the aspects of nutrition, brewing and sensory flavor.

Although the invention has been described by way of examples, it will be appreciated by those skilled in the art that modifications and variations may be made thereto without departing from the spirit and scope of the invention.

Claims (10)

1. The method for preparing the rice paste matrix powder by combining cooking enzymolysis and microbial fermentation is characterized by comprising the following steps of:

1) Steaming raw rice with water to obtain cooked rice; steaming rice, adding alpha-amylase for stirring and enzymolysis, drying, and grinding after the rice is dried;

2) Adding bacteria powder into the rice flour prepared in the step 1) for fermentation, and then freeze-drying to form rice paste matrix powder; the bacterial powder is one or more of saccharomycetes, lactobacillus plantarum, lactobacillus acidophilus, lactobacillus lactis, lactobacillus casei and lactobacillus bulgaricus.

2. The method for preparing rice paste base powder by combining cooking enzymolysis and microbial fermentation according to claim 1, wherein the volume ratio of water to raw rice is 0.9-1.7:1 when rice is steamed.

3. The method for preparing rice paste base powder by combining cooking enzymolysis and microbial fermentation according to claim 1, wherein the enzyme adding amount of alpha-amylase in the step 1) is 0.6-1.4 g enzyme/200 mL raw rice, and the enzyme activity of the alpha-amylase is 3000-4000U/g.

4. The method for preparing rice paste base powder by combining cooking enzymolysis and microbial fermentation according to claim 1, wherein the enzymolysis time in the step 1) is 2-6 min, and the enzymolysis temperature is 50-70 ℃.

5. The method for preparing rice paste base powder by combining cooking enzymolysis and microbial fermentation according to claim 1, wherein the drying mode in the step 1) is as follows: firstly, drying for 1 to 1.5 hours at the temperature of between 100 and 110 ℃ by hot air, and then drying to a state of being capable of grinding at the temperature of between 55 and 65 ℃.

6. The method for preparing rice paste matrix powder by combining cooking enzymolysis and microbial fermentation according to claim 1, wherein in the step 2), the bacterial powder is saccharomycete and lactobacillus plantarum composite bacterial powder compounded according to a mass ratio of 9:1.

7. The method for preparing rice paste base powder by combining cooking enzymolysis and microbial fermentation according to claim 1, wherein in the step 2), the fermentation time is 12-24 h, and the fermentation temperature is 25-34 ℃.

8. The method for preparing rice paste base powder by combining cooking enzymolysis and microbial fermentation according to claim 1, wherein in the step 2), the inoculation amount of the bacterial powder is 3-5% (mass percent).

9. The method for preparing rice paste base powder by combining cooking enzymolysis and microbial fermentation according to any one of claims 1 to 8, comprising the steps of:

1) Adding water into raw rice according to the volume ratio of 1.2-1.4:1 water/meter, steaming the rice, adding alpha-amylase according to the enzyme adding amount of 1.2-1.3 amylase (g)/meter (200 mL), stirring and carrying out enzymolysis for 4min; drying and grinding rice after enzymolysis, and sieving with 100 mesh sieve;

2) Adding yeast and lactobacillus plantarum composite bacteria powder compounded according to the mass ratio of 9:1 into the rice flour prepared in the step 1) for fermentation, wherein the fermentation time is 11-14 h, the fermentation temperature is 26-29 ℃, and the inoculation amount is 4%; after fermentation, the rice paste is lyophilized into rice paste matrix powder.

10. A rice paste base flour made by the method of any one of claims 1 to 9.