CN115245193B - Method for producing corn whole meal by cooperation of bacterial enzymes - Google Patents

Abstract

The invention discloses a method for producing corn whole powder by synergism of bacterial enzymes, which belongs to the technical field of food processing. The invention mainly aims at the problems that corn flour does not contain gluten, starch is too tightly coated with protein, the prepared product has poor viscoelasticity, ductility, water retention and the like, and the texture recombination of starch, protein and fiber in corn is realized by taking whole corn kernels which are not peeled and degerminated as raw materials through the technology of combining enzyme preparation and lactobacillus implantation and extrusion, so that all nutritional ingredients of the corn are maintained, and the high-quality texture characteristic of the corn flour is endowed.

Description

A method for producing whole corn flour by bacterial enzyme synergism

Technical Field

The invention relates to the technical field of food processing, in particular to a method for producing whole corn flour in a bacterial and enzyme-assisted manner.

Background technique

Corn is an annual grass plant, also known as corn, maize, and corn. It is an important food crop and an important source of feed. It is also the food crop with the highest total output in the world and is rich in nutrition. Dry corn kernels contain protein, fat, starch, as well as rich dietary fiber, vitamin B, vitamin E, and trace elements necessary for the human body. Corn is widely favored by consumers for its rich nutrients and strong aroma, and has a large market.

Although corn has many advantages as a coarse grain and is increasingly sought after, it is limited by its own characteristics and cannot give corn flour dough excellent processing characteristics: due to the lack of gluten protein in corn protein, the dough made directly from corn flour cannot form a network structure, and the resulting corn dough has poor plasticity; in addition, the starch and protein in corn flour are wrapped too tightly, and the starch cannot absorb water and expand well, so the viscoelasticity of the corn dough is poor; this also makes the corn flour have a rough taste, which greatly limits the application of corn flour in staple food processing.

Moreover, the main processing method of corn flour at present is to dry-peel and degerminate mature corn kernels and then dry-grind them to obtain corn flour, a primary processed product of grain, or to peel and degerminate corn kernels, remove hornyness, and only retain the starch part to grind finer corn flour. However, since these methods all use pre-treatment processes such as peeling and degerming, the process is cumbersome, the raw materials are wasted, and the obtained products have problems such as low viscoelasticity, rough taste, and poor palatability.

Summary of the invention

The purpose of the present invention is to provide a method for producing whole corn flour by using bacteria and enzymes to solve the problems existing in the above-mentioned prior art. The present invention mainly aims at the problems that corn flour does not contain gluten protein, starch wraps protein too tightly, and the prepared product has poor viscoelasticity, ductility, and water holding capacity. By implanting enzyme preparations and lactic acid bacteria in combination with extrusion puffing technology, and using whole corn kernels that have not been peeled or degermed as raw materials, the texture reconstruction of starch, protein, and fiber in corn is achieved, all the nutrients of corn are maintained, and the corn flour is endowed with high-quality texture characteristics.

To achieve the above object, the present invention provides the following solutions:

The present invention provides a method for producing whole corn flour by bacterial enzyme synergism, comprising the following steps:

The whole corn kernels are used as raw materials, and the whole corn flour is obtained by extruding and puffing, crushing, anaerobic fermentation, washing, grinding, homogenization, dehydration and drying.

Furthermore, the extrusion puffing conditions are: water content 16-24wt%, temperature 100-180°C, screw speed 324-486r/min, material feeding speed 162-378r/min.

During the extrusion and puffing process, the corn flour is extruded by rollers, and the high temperature and high pressure environment inside the cavity makes the corn flour expand, turning the corn flour into countless fine and porous sponges, increasing the specific surface area and the pore size of the corn flour. This increases the fermentation area of lactic acid bacteria and corn flour, accelerates the production of lactic acid bacteria, and shortens the time to reach the pH requirement of fermentation. The microporous structure formed on the surface of the powder during the puffing process is also conducive to the outflow of nutrients and promotes the production rate of lactic acid bacteria. Due to the high proportion of corn starch content, about 60%, and starch is a large molecule, it is difficult to release all the vitamins and minerals wrapped in starch, so that the prepared corn has a poor taste, the nutrients cannot be released, and the nutritional value is very low. The corn flour is pretreated by extrusion and puffing, so that the starch is separated from the various substances wrapped around it. At the same time, the high temperature and high pressure environment also has a sterilizing effect on the corn flour, which provides a guarantee for reducing the fermentation time and avoiding the probability of the production of miscellaneous bacteria in the next step, and improves the nutritional value of the whole corn flour.

At the same time, extrusion puffing also ensures the palatability and processability of the whole corn flour obtained after subsequent fermentation and pulping process without peeling, germining and horny removal of whole corn kernels. At the same time, due to the lack of peeling, germining and horny removal, the cellulose utilization rate is improved. The moisture content of the extruded material, the sleeve temperature, the screw speed, and the material feeding speed have a great influence on the gelatinization degree, water absorption index, water solubility index texture characteristics, rheological properties, and the retention of fiber in corn flakes. If the puffing temperature is too high or the moisture content is too low, the fiber will be decomposed and lost during the puffing process, thereby affecting the fiber utilization rate in the corn flour. If the puffing temperature is too low, the corn husk cannot be softened well, thereby affecting the subsequent steps, and then affecting the palatability and processability of the corn flour.

Furthermore, the crushing is to crush the extruded and puffed corn flour into 60-100 meshes;

The anaerobic fermentation comprises the following steps: the crushed material is inoculated with lactic acid bacteria at an inoculation rate of 0.01-0.02%, and then anaerobic fermentation is performed at a fermentation temperature of 36-38°C and a fermentation time of 14-16 hours. Preferably, at the end of the fermentation, the pH value of the fermentation liquid is 4-5.

The palatability and processing characteristics of corn flour can be improved by using microbial fermentation. Lactic acid bacteria fermentation is to ferment corn flour with bacteria. These microorganisms contain rich enzyme systems. The combined action of these enzymes can destroy the tight structure of macromolecular substances such as starch, cellulose and protein, change the structure of macromolecular substances such as starch, protein, cellulose and so on in corn flour, and change the composition of corn flour. After fermentation, the starch content in corn flour has increased, and the relative content of other substances has decreased (mainly crude fiber and ash). The decrease in protein content indicates that microorganisms have destroyed the protein molecules wrapped around starch and purified the starch molecules. In addition, the content of amylose in fermented corn increases, and the fermentation of lactic acid bacteria hydrolyzes the side chains of some amylopectin. Therefore, the average molecular weight of the macromolecular starch region dominated by amylopectin decreases, while the average molecular weight of the small molecular starch region dominated by amylose increases, and the relative content of amylopectin decreases. In addition, fermentation and modification of corn flour stabilizes the structure of corn protein Zein, which also increases the stability of corn dough. Exogenous addition of enzyme systems, such as proteases and cellulases, can more effectively improve the properties of corn flour. Finally, fermented corn flour exhibited better toughness and viscosity, thereby improving its processing properties, such as palatability, chewiness, and tensile properties.

Furthermore, the washing comprises: after solid-liquid separation of the anaerobic fermentation product, washing the solid material with high-pressure spray water until the pH value reaches 6.8 to 7.2.

Furthermore, the refining comprises: mixing the washed solid fermentation powder and water to obtain a refining material, and simultaneously filing and grinding the refining material until the particle size of the solid fermentation powder is 120-140 meshes, and the mass ratio of water to solid fermentation powder is (2-4):1.

The solid fermented powder after lactic acid bacteria fermentation is subjected to a mixed treatment of filing and tooth grinding. Filing takes a long time and consumes a lot of energy. The combination of the two can reduce the number of grinding times and save energy.

Furthermore, the homogenization pressure is 15-20 MPa, 3-5 min/time, and the homogenization is 3-8 times; the dehydration and drying adopts flash evaporation after filtration.

Furthermore, an enzyme preparation is added during the anaerobic fermentation process.

Furthermore, the enzyme preparation is added 110-130 minutes before the end of fermentation; and the enzyme preparation is cellulase and/or hemicellulase.

Although lactic acid bacteria fermentation can improve the structure of corn flour, so that the processing performance and palatability of the obtained corn flour are improved, simple lactic acid bacteria fermentation cannot fully degrade substances such as starch and cellulose in corn, and the present invention does not remove corn husk before fermentation, which leads to limited improvement of processing performance and palatability of corn flour by lactic acid bacteria fermentation, and corn flour after simple lactic acid bacteria fermentation still cannot achieve elasticity, toughness, agglomeration and chewiness comparable to wheat flour. Therefore, in the technical scheme of the present invention, an enzyme preparation is added in the late stage of lactic acid bacteria anaerobic fermentation. On the one hand, the enzyme preparation can further degrade starch and cellulose that lactic acid bacteria cannot fully decompose, thereby improving the performance of fermented corn flour. On the other hand, the degradation of cellulose by the enzyme preparation provides new fermentation substrates for lactic acid bacteria, so that the fermentation activity of lactic acid bacteria in the late stage of anaerobic fermentation is enhanced, and the two produce a synergistic effect, so that the anaerobic fermentation efficiency of lactic acid bacteria is significantly improved, thereby overcoming the technical problem that corn flour obtained by using a single lactic acid bacteria in the prior art cannot be comparable to wheat flour. The time of adding the enzyme preparation is also based on the consideration of promoting the maximum synergistic effect between the two. If the enzyme preparation is added too early, it will participate in the fermentation and degradation process of corn too early, and will not have enough effect on the difficult-to-degrade substances in the later stage of fermentation. At the same time, the synergistic effect with lactic acid bacteria will be significantly weakened. If the enzyme preparation is added too late, the synergistic effect between the enzyme preparation and lactic acid bacteria will have little room to play, which is not conducive to improving the fermentation efficiency.

At the same time, the lactic acid bacteria fermentation time is long and difficult to control. At present, the prior art requires at least 24 hours of fermentation. How to use effective means to control the fermentation process and shorten the fermentation time is the key to achieving industrial-scale production of whole corn flour. The present invention adds enzyme preparations during the fermentation process, so that the two produce a synergistic effect, improve the fermentation efficiency, shorten the fermentation time, increase the fermentation termination pH, and avoid the problem of poor flavor caused by too low pH.

The present invention also provides whole corn flour produced by the method for producing whole corn flour by cooperating with bacteria and enzymes.

The present invention also provides a product processed from the whole corn flour, which is used for controlling diabetes or obesity.

Corn starch is composed of two glucose polymers, amylose and amylopectin, of which the amylose content is about 25%. The ratio of amylose to amylopectin has a decisive influence on the health benefits and final quality of corn starch. The resistant starch content is higher in high-amylose starch. Resistant starch is a starch that cannot be digested and absorbed in the small intestine, but can reach the colon and be fermented by the microbial flora in the colon 2 hours after eating, and then play a beneficial physiological role. It is regarded as one of the components of dietary fiber. Resistant starch plays an important role in promoting intestinal health and preventing diseases such as colorectal cancer, type 2 diabetes, obesity, heart disease and osteoporosis. In addition, resistant starch can increase satiety and reduce food intake, which is important for obese people. Most processed starch-containing foods contain a small amount of resistant starch, but the content of resistant starch in foods such as bread that generally use conventional wheat flour or corn flour is less than 1%. After being processed by the present invention, the amylose content in whole corn flour can reach about 48-73%, and the resistant starch content can reach about 33-65%, which has the physiological effect of effectively controlling weight.

The present invention discloses the following technical effects:

The production method of the invention improves the processing characteristics and palatability of corn flour by implanting enzyme preparations and lactic acid bacteria, and pretreats the corn flour by applying extrusion puffing technology, thereby greatly shortening the time of microbial fermentation, reducing the probability of miscellaneous bacteria generation during the fermentation process, and improving industrial production efficiency; all nutrients in the whole corn flour can be retained by combining extrusion puffing with microbial fermentation, and the flour has good processing performance and rich nutrition.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

Figure 1 is a comparison chart of pH changes during the fermentation process.

Detailed ways

Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe methods and/or materials related to the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

Example 1

A method for producing whole corn flour by bacterial enzyme synergism comprises the following steps:

(1) Cleaning corn: Using commercially available corn kernels as raw materials, the corn is cleaned of impurities, stones and cleaning.

(2) Extrusion and puffing: After cleaning the corn, dry it in the sun and control the moisture content of the corn to 20wt%. Use a twin-screw extruder (Tianjin Test) to extrude and puff the whole corn kernels. The extrusion temperature is controlled at 140℃, the screw speed is 486r/min, and the material feeding speed is 270r/min.

(3) Crushing: The extruded corn flour is conveyed to the crusher and crushed to 80 mesh.

(4) Fermentation: The crushed corn flour is added to a constant temperature sealed fermentation tank, and the mass ratio of corn flour dry matter to water is controlled to be 1:2; then anaerobic fermentation is carried out, and lactic acid bacteria (Lactobacillus plantarum, obtained through commercial channels) is inoculated in the fermentation tank at an inoculation rate of 0.01% for fermentation, and the fermentation temperature is controlled at 36°C, and the sealed anaerobic fermentation is carried out for 14 hours. Plant cellulase (a mixture of cellulase and hemicellulase in equal proportions) is added 110 minutes before the end of fermentation, and the added amount is 1% of the mass of the corn flour dry matter; the fermentation is terminated, and the pH value is maintained at 4.5; after the fermentation product is filtered, the solid and liquid are separated to obtain a solid fermentation product and a liquid fermentation product, and the liquid fermentation product is returned to the fermentation tank and used as a yeast liquid to continue anaerobic fermentation and reuse.

(5) Washing: Wash the solid fermentation product obtained in step (4) with high-pressure spray cold water to a pH value of 6.8, and then dry.

(6) Refining: The fermentation product treated in step (5) is mixed with water in a solid mass to water ratio of 1:2, and then refined for 1 hour using a mixed pulper (a file grinder and a toothed pulper in one). At this time, the corn flour particle size is 120 mesh.

(7) High-pressure homogenization: The product after treatment in step (6) was subjected to high-pressure homogenization at a condition of 15 MPa, 3 times of high-pressure homogenization, and each time of high-pressure homogenization for 3 minutes.

(8) Dehydration and drying: The slurry subjected to the high pressure homogenization treatment in step (7) is filtered through a plate and frame filter to remove water, and then flash evaporated at 170° C. for 5 seconds to obtain the product corn flour.

Example 2

The only difference from Example 1 is that during the anaerobic fermentation in step (4), plant cellulase was not added.

Example 3

The only difference from Example 1 is that the mixed pulp machine in step (6) is replaced by a rasp grinder.

Example 4

The only difference from Example 1 is that the mixed pulper in step (6) is replaced by a toothed pulper.

Example 5

The only difference from Example 1 is that the mixed pulping process in step (6) is replaced by first grinding with a file grinder for 0.5 h and then grinding with a tooth grinder until the corn particle size is 120 mesh.

Example 6

The only difference from Example 1 is that in step (4), the plant cellulase is added at the beginning of anaerobic fermentation.

Example 7

The only difference from Example 1 is that during the anaerobic fermentation process, the plant cellulase is added 60 minutes before the end of the fermentation.

Example 8

The only difference from Example 1 is that the cellulase is replaced with cellulase and pepsin in a mass ratio of 1:1.

The pH changes during the fermentation process of Example 2 and Example 8 were recorded, and the results are shown in Figure 1. As can be seen from the figure, within 24 hours, the fermentation pH shows a downward trend with the increase of time. The pH decline trend of lactic acid bacteria fermentation alone is relatively slow. The combined use of cellulase and protease advances the acidity decline time, shortens the fermentation time, and improves the palatability and processability of corn flour.

Example 9

The only difference from Example 1 is that the plant lactobacillus used in the anaerobic fermentation is domesticated before addition, and the specific steps are as follows:

(1) Prepare MRS solid culture medium and MRS liquid culture medium respectively;

(2) Different amounts of lactic acid were added to 100 mL of MRS medium to obtain acidic MRS medium with lactic acid concentrations of 5 g/L, 10 g/L, and 15 g/L, respectively.

(3) The plant lactobacillus was taken out of the refrigerator, activated and separated by streaking in a solid MRS medium, a single bacterial colony was picked and inoculated into 100 mL of MRS liquid medium, and cultured anaerobically at 37°C for 24 h. Then, 2% of the bacterial liquid was inoculated into an acidic MRS medium with a concentration of 5 g/L, and cultured anaerobically at 37°C until the growth was stable. Then, 2% of the bacterial liquid was inoculated into an acidic MRS medium with a concentration of 10 g/L, and cultured anaerobically at 37°C until the growth was stable. Then, 2% of the bacterial liquid was inoculated into an acidic MRS medium with a concentration of 15 g/L, and cultured anaerobically at 37°C until the growth was stable. Then, 2% of the bacterial liquid was inoculated into an MRS liquid medium supplemented with a liquid fermentation product (the liquid fermentation product mentioned in step (4) of Example 1) (the mixed volume ratio of the liquid fermentation product to the MRS liquid medium was 2:2), and cultured anaerobically at 37°C until the growth was stable to obtain domesticated plant lactobacillus.

In the process of using lactic acid bacteria to ferment corn flour, the fermentation environment is continuously acidified as the lactic acid bacteria produce acid anaerobicly, which gradually deviates from the optimal fermentation environment for lactic acid bacteria. When lactic acid bacteria are in an acid stress environment, it will affect the lactic acid bacteria's absorption of nutrients and protein synthesis process, and will also produce certain stress reactions, which will have an adverse effect on the taste and processability of corn. This is another important reason why it is not ideal to ferment corn with lactic acid bacteria alone. In order to solve this technical problem, before the lactic acid bacteria are anaerobic fermented, they are tamed to improve the acid resistance of the lactic acid bacteria, prompt the lactic acid bacteria to maintain a high fermentation activity, and improve the anaerobic fermentation efficiency and the performance of corn flour.

Example 10

A method for producing whole corn flour by bacterial enzyme synergism comprises the following steps:

(1) Cleaning corn: Using commercially available corn kernels as raw materials, the corn is cleaned of impurities, stones and cleaning.

(2) Extrusion and puffing: After cleaning the corn, dry it in the sun and control the moisture content of the corn to 22 wt%. Use a twin-screw extruder (Tianjin Test) to extrude and puff the whole corn kernels. The extrusion temperature is controlled at 150 °C, the screw speed is 486 r/min, and the material feeding speed is 270 r/min.

(3) Crushing: The extruded corn flour is conveyed to the crusher and crushed to 70 mesh.

(4) Fermentation: The crushed corn flour is added to a constant temperature sealed fermentation tank, and the mass ratio of corn flour dry matter to water is controlled to be 1:3; then anaerobic fermentation is carried out, and lactic acid bacteria (Lactobacillus plantarum) are inoculated in the fermentation tank at an inoculation rate of 0.015% for fermentation. The fermentation temperature is controlled at 37°C, and the sealed anaerobic fermentation is carried out for 15 hours. 120 minutes before the end of the fermentation, isolated plant cellulase (a mixture of cellulase and hemicellulase in equal proportions) is added, and the added amount is 1% of the mass of the corn flour dry matter; the fermentation is terminated, and the pH value is maintained at 4.6; after the fermentation product is filtered, the solid and liquid are separated to obtain solid fermentation products and liquid fermentation products, and the liquid fermentation product is returned to the fermentation tank and used as the yeast liquid to continue anaerobic fermentation and reuse.

(5) Washing: Wash the solid fermentation product obtained in step (4) with high-pressure spray cold water to a pH value of 7.2, and then dry.

(6) Refining: The fermentation product treated in step (5) is mixed with water at a solid mass to water ratio of 1:3, and then refined for 1 h using a mixed pulper (a file grinder and a toothed pulper in one). At this time, the corn flour particle size is 130 mesh.

(7) High-pressure homogenization: The product after treatment in step (6) was subjected to high-pressure homogenization. The high-pressure homogenization condition was 17 MPa, the high-pressure homogenization was repeated 4 times, and the high-pressure homogenization time was 4 min each time.

(8) Dehydration and drying: The slurry subjected to the high pressure homogenization treatment in step (7) is filtered through a plate and frame filter to remove water, and then flash evaporated at 170° C. for 5 seconds to obtain the product corn flour.

Embodiment 11

A method for producing whole corn flour by bacterial enzyme synergism comprises the following steps:

(1) Cleaning corn: Using commercially available corn kernels as raw materials, the corn is cleaned of impurities, stones and cleaning.

(2) Extrusion and puffing: After cleaning the corn, dry it in the sun and control the moisture content of the corn to 24 wt%. Use a twin-screw extruder (Tianjin Test) to extrude and puff the whole corn kernels. The extrusion temperature is controlled at 160 °C, the screw speed is 486 r/min, and the material feeding speed is 270 r/min.

(3) Crushing: The extruded corn flour is conveyed to the crusher and crushed to 80 mesh.

(4) Fermentation: The crushed corn flour is added to a constant temperature sealed fermentation tank, and the mass ratio of corn flour dry matter to water is controlled to be 1:4; then anaerobic fermentation is carried out, and lactic acid bacteria (Lactobacillus plantarum) are inoculated in the fermentation tank at an inoculation rate of 0.02% for fermentation. The fermentation temperature is controlled at 38°C, and the sealed anaerobic fermentation is carried out for 16 hours. 130 minutes before the end of the fermentation, isolated plant cellulase (a mixture of cellulase and hemicellulase in equal proportions) is added, and the amount added is 1% of the mass of the corn flour dry matter; the fermentation is terminated, and the pH value is maintained at 4.7; after the fermentation product is filtered, the solid and liquid are separated to obtain solid fermentation products and liquid fermentation products, and the liquid fermentation product is returned to the fermentation tank and used as the yeast liquid to continue anaerobic fermentation and reuse.

(5) Washing: Wash the solid fermentation product obtained in step (4) with high-pressure spray cold water to a pH value of 7.2, and then dry.

(6) Refining: The fermentation product treated in step (5) is mixed with water at a solid mass to water ratio of 1:4, and then refined for 1 h using a mixed pulper (a file grinder and a toothed pulper in one). At this time, the corn flour particle size is 140 mesh.

(7) High-pressure homogenization: The product after treatment in step (6) was subjected to high-pressure homogenization. The high-pressure homogenization condition was 20 MPa, the high-pressure homogenization times were 5 times, and the high-pressure homogenization time was 5 min each time.

(8) Dehydration and drying: The slurry subjected to the high pressure homogenization treatment in step (7) is filtered through a plate and frame filter to remove water, and then flash evaporated at 170° C. for 5 seconds to obtain the product corn flour.

Example 12

The only difference from Example 9 is that after washing to a pH value of 7.2 in step (5), starch branching enzyme is added to the solid fermentation product at an amount of 1%, incubated at 30°C for 30 min, and then 1% maltogenic amylase is added, treated at 50°C for 40 min, and then dried.

Starch branching enzyme, one of the glycosyltransferases, has transferase activity, that is, it cuts the α-1,4-glucan linear donor (the linear region of amylose and amylopectin) and connects the cut short chain to the acceptor chain (original chain or other chain) through the formation of α-1,6 glycosidic bonds. This enzyme reaction not only produces branches, but also the non-reducing end can be used for further extension of the α-1,4-glucan chain. The starch branching enzyme can hydrolyze the connection between the fragments of the amylose clusters in the starch to produce amylose clusters. At the same time, the branching enzyme connects the branched side chains to the amylose to produce branched amylose. Then, the product is treated with maltose amylase to cut the long side chains into short side chains and transfer glucose to the side chains to increase the branching degree of amylose in the starch. The increase in the degree of branching can make the hydrolysis of starch slower, avoiding the rapid increase of blood sugar in diabetics in a short time after ingestion. In addition, the slow hydrolysis can enable it to continuously supply energy and make blood sugar more stable.

Example 13

The difference from Example 1 is that, while inoculating Lactobacillus plantarum, 1% of pullulanase-producing bacteria is also inoculated, and the fermentation temperature is increased to 39°C.

Embodiment 14

The difference from Example 12 is that, while inoculating Lactobacillus plantarum, 1% pullulanase-producing bacteria was also inoculated, and the fermentation temperature was increased to 39°C.

Pullulanase is an important industrial enzyme. The synergistic effect of pullulanase with other enzymes can greatly improve the utilization rate and production efficiency of starch. It can specifically hydrolyze the α-1,6-glycosidic bonds in the branch points of amylopectin to form amylose and increase the content of resistant starch.

Test Example 1

A performance verification experiment was conducted on Examples 1-14 (marked as Samples 1-14) and unfermented peeled corn flour purchased from the market (marked as Sample 15) to compare the technical effects; the specific process is as follows:

1.1 Determination of basic nutritional components of corn flour

Commercially available corn kernels were used as raw materials, stones and bad kernels were removed, and the corn flour was ground and sieved. The protein content (determined by GB/T5009.5-2016 Kjeldahl method), fat (determined by GB/T 14772-2008 Soxhlet extraction method), starch content (determined by GB/T5009.9-2016 acid hydrolysis method), cellulose content (determined by GB/T5009.88-2014 enzyme weight method), ash (determined by GB/T5009.4-2016 burning method), amylose content (determined by dual wavelength method), and resistant starch content (determined by Megazyme resistant starch kit method) of the corn flour were measured. The results are shown in Table 1.

1.2 Preparation of whole corn cake

Samples 1-15 were used to prepare whole corn cakes, and the specific preparation process was as follows:

a Take 200g corn flour, 90mL baking oil, 100g eggs, and 90g white sugar;

b. Stir the baking oil and egg yolk until they are milky white and fine bubbles;

c. Beat the egg white and sugar together;

d. Add corn flour into step b and mix well to make a paste;

e. Add the material from step c to step d in three portions and mix well to form a paste;

f. Brush the cake cup with oil in advance to prevent sticking, add product e into the cake cup;

g Preheat the oven to 180℃ for 5 minutes, bake at 150℃ on top and 160℃ on bottom for 17 minutes.

The hardness, elasticity, resilience and chewiness of the whole corn cake made of corn flour were compared using a texture analyzer. The testing parameters of the texture analyzer were as follows: test distance 10 mm, test speed 0.5 mm/s, trigger point load 7 g, probe type P/20, and test times 2. The results are shown in Table 2.

1.3 Sensory evaluation

Invite 20 volunteers (10 men and 10 women) to rate the whole corn cake made of corn flour from four perspectives: smell, color, taste and mouthfeel. The full score is 10 points. The four indicators are weighted and calculated using the following formula:

Total score = smell × 0.1 + color × 0.2 + taste × 0.3 + mouthfeel × 0.4.

The statistical results are recorded in Table 3.

Table 1 Nutrient content of corn flour

Note: The percentages of protein, fat, starch, fiber and ash are based on corn flour, while the percentages of amylose and resistant starch are based on starch.

Table 2 Whole corn cake texture results

Table 3 Sensory evaluation results of whole corn cake

1.4 Glycemic Index of Whole Corn Cake

The glycemic index, also known as the glycemic index, refers to the relative ability of sugary foods to raise blood sugar levels compared to the change in blood sugar concentration after the intake of foods such as glucose or white bread.

The calculation formula is as follows: GI = (2-hour blood glucose response to a food containing 50g of carbohydrates/2-hour blood glucose response to 50g of glucose) × 100%.

The glycemic index (GI) of the cake samples was measured in vitro and the results are shown in Table 4.

Table 4 Glycemic Index

Mice were fed with corn flour produced by Examples 1-15 of the present invention and commercially available amylopectin, and the insulin resistance of the mice was observed. The test showed that from 12 to 16 weeks, the mice fed with amylopectin began to develop irreversible insulin resistance, while the mice fed with corn flour of the present invention did not develop insulin resistance.

The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims (4)

1. The method for producing the whole corn flour by the cooperation of the bacterial enzymes is characterized by comprising the following steps of:

Taking whole corn grains as a raw material, crushing after extrusion and puffing, carrying out anaerobic fermentation, washing, pulping, homogenizing, dehydrating and drying to obtain the whole corn powder;

the extrusion and puffing conditions are as follows: the water content is 16-24wt%, the temperature is 100-180 ℃, the screw rotating speed is 324-486r/min, and the material feeding speed is 162-378r/min;

crushing, namely crushing the extruded and puffed corn flour to 60-100 meshes;

The anaerobic fermentation comprises the following steps: inoculating lactobacillus to the crushed material according to the inoculum size of 0.01-0.02%, and performing anaerobic fermentation at 36-38deg.C for 14-16 hr;

adding an enzyme preparation in the anaerobic fermentation process;

the addition time of the enzyme preparation is 110-130min before fermentation is terminated; the enzyme preparation is cellulase and/or hemicellulase;

The refining comprises: mixing the washed solid fermentation powder with water to obtain a pulp, and simultaneously filing and tooth-milling the pulp until the particle size of the solid fermentation powder is 120-140 meshes, wherein the mass ratio of the water to the solid fermentation powder is (2-4): 1.

2. The method for co-producing corn meal with bacterial enzymes according to claim 1, wherein the washing comprises: and (3) after solid-liquid separation of anaerobic fermentation products, washing the solid materials by using high-pressure spray water until the pH value is 6.8-7.2.

3. The method for producing corn whole meal by the synergistic action of the bacterial enzymes according to claim 1, wherein the homogenizing pressure is 15-20 mpa, 3-5 min/time, 3-8 times of homogenizing; the dehydration and drying are carried out by adopting flash evaporation after filtration.

4. A whole corn flour produced by the method for co-producing whole corn flour with the bacterial enzyme of any one of claims 1-3.