Modified corn protein additive as well as preparation method and application thereof

Abstract

The invention provides a modified corn protein additive as well as a preparation method and application thereof, and belongs to the field of feed additives. The invention provides a bio-enzyme modified corn protein additive and a preparation method thereof. The bio-enzyme modified corn protein additive can be applied to preparation of feed for improving intestinal tracts of pigs. Protein in traditional corn protein powder is structurally modified through an enzymolysis technology, so that the original defects of poor water solubility and low digestibility of the protein are overcome, the content of acid soluble protein and small peptide is remarkably increased, the digestible absorption utilization rate of nutritional ingredients is comprehensively increased, and the nutritional value of the corn protein powder is increased. The high-quality protein raw material is high in digestibility and free of antinutritional factors, can replace high-quality protein raw materials including imported fish meal, soybean meal and the like, and is widely applied to various types of feeds. The problem that the cost of animal protein source feed is high is solved, and the problems that existing plant protein source feed is not easy to absorb by intestinal tracts and cannot improve the health level of the intestinal tracts are solved.

Description

Technical Field

[0001] This invention belongs to the field of feed additives, and in particular relates to a corn protein feed additive modified by biological enzymes, which is suitable for piglet nursery feed and can improve the intestinal health of piglets. Background Technology

[0002] my country has the world's largest pig farming industry. With the improvement of the industry's scale, raising the level of pig farming is crucial. Compared to adult pigs, piglets have smaller stomach capacity, higher gastric juice pH, shorter intestines, and insufficient digestive enzyme secretion, making them prone to indigestion. Furthermore, piglets are in a rapid growth stage and have higher requirements for nutrients in their feed, increasing farming costs. Therefore, in the piglet farming process, using high-quality feed and employing enzymatic hydrolysis and other methods can increase the digestibility of nutrients in the feed and improve the piglets' intestinal health. The use of protein source additives in feed plays a vital role. Fishmeal is a common animal protein source with high nutritional value, palatability, and digestibility, but its high price necessitates finding suitable alternative proteins. Plant-based protein feeds such as corn protein are inexpensive and have stable prices, making them suitable alternatives. However, natural corn protein has a complex molecular structure and is a large molecule protein, making it difficult for animal intestines to absorb, resulting in low digestibility. High toxin content and anti-nutritional factors also limit its use, and its poor palatability restricts its application in piglet feed. Therefore, there is an urgent need for a small-molecule plant-based protein feed additive that can replace animal protein feed. Summary of the Invention

[0003] This invention provides a modified corn protein additive using enzymatic hydrolysis technology, which solves the problem of high feed costs for animal protein sources. Furthermore, the modified corn protein additive of this invention addresses the issues of poor intestinal absorption and failure to improve intestinal health in current plant protein feeds.

[0004] A method for modifying corn protein using bioenzymes, the method comprising:

[0005] Step 1: Adjust the pH of the corn flotation solution to 5.5-6.5 and heat it to 70-85℃. Add α-amylase and hydrolyze for 30 minutes. Then add a mixed enzyme of cellulase and xylanase and hydrolyze for 20 minutes. Finally, add neutral protease and hydrolyze for 20 minutes.

[0006] Step 2: Adjust the temperature to 55-58℃ and the pH value to 8.0-9.0. Add a mixture of alkaline protease and keratinase and perform enzymatic hydrolysis for 2 hours, maintaining the pH value at 8.0-9.0 during this period.

[0007] Step 3: Decolorization;

[0008] Step 4: Spray drying to obtain enzymatically hydrolyzed corn protein.

[0009] The α-amylase has an enzyme activity of 50,000 U / g, and the amount added is 0.3 to 0.6% of the dry matter mass.

[0010] The mixed enzyme of cellulase and xylanase is prepared by adding 0.1-0.3% of cellulase with an enzyme activity of 200,000 U / g and xylanase with an enzyme activity of 100,000 U / g at a dry matter mass, and mixing them together.

[0011] The neutral protease has an enzyme activity of 200,000 U / g, and the amount added is 0.3 to 0.5% of the dry matter mass.

[0012] The mixed enzyme of alkaline protease and keratinase is prepared by adding an alkaline protease with an enzyme activity of 200,000 U / g at an amount of 1-1.5% of the dry matter mass and a keratinase with an enzyme activity of 100,000 U / g at an amount of 0.1-0.2% of the dry matter mass, and then mixing them together.

[0013] The decolorization process involves adding 95% ethanol after enzymatic hydrolysis and stirring for 3 hours.

[0014] A modified corn protein additive was prepared using the method described above.

[0015] Application of a modified corn protein additive in the preparation of pig gut-improving feed.

[0016] The modified corn protein additive is added to the feed at a rate of 5% to 15%.

[0017] Beneficial effects

[0018] Corn flotation liquid is a corn by-product produced from corn gluten meal. It structurally modifies the protein in traditional corn gluten meal through enzymatic hydrolysis. This not only overcomes its original shortcomings of poor water solubility and low digestibility, but also significantly increases the content of acid-soluble proteins and small peptides. It comprehensively improves the digestibility and absorption of nutrients, making it a high-quality protein raw material with high digestibility and no anti-nutritional factors. It can replace high-quality protein raw materials such as imported fishmeal and soybean meal and is widely used in various types of feed.

[0019] This invention provides a method for enzymatic hydrolysis of a compound enzyme preparation that can effectively improve the protein structure of corn gluten meal. This method can significantly increase the content of acid-soluble proteins in corn gluten, making it easier for animals to absorb when used as a feed additive. It is a high-quality feed additive. Furthermore, the decolorization in this method is carried out by adding 95% ethanol after enzymatic hydrolysis. The process is simple, low-cost, and does not easily cause losses.

[0020] The protein feed additive provided in this invention increased the activity of intestinal digestive enzymes, especially proteases, at a certain addition level in feeding experiments on piglets. Furthermore, intestinal morphology analysis showed that the protein feed additive of this invention effectively promoted intestinal growth and development, thereby promoting mucosal maturation, improving its secretory capacity, and enhancing intestinal health.

[0021] The protein feed additives provided in this invention affect different groups of intestinal microorganisms than fishmeal, but both can increase the abundance of probiotics and stabilize the intestinal flora structure, thereby promoting the growth of piglets. Attached Figure Description

[0022] Figure 1 HE staining images of duodenal mucosa, where A is FM, B is CGM, C is MCGM (5%), D is MCGM (10%), and E is MCGM (15%).

[0023] Figure 2 HE staining images of jejunal mucosa, where A is FM, B is CGM, C is MCGM (5%), D is MCGM (10%), and E is MCGM (15%).

[0024] Figure 3 HE staining images of ileal mucosa, where A represents FM, B represents CGM, C represents MCGM (5%), D represents MCGM (10%), and E represents MCGM (15%).

[0025] Figure 4 HE staining images of cecal mucosa, where A represents FM, B represents CGM, C represents MCGM (5%), D represents MCGM (10%), and E represents MCGM (15%).

[0026] Figure 5 The diagram shows the composition of the ileum microbial community, where A represents the phylum level (Phylum) and B represents the genus level (Genus).

[0027] Figure 6 The diagram shows the composition of the cecal microbial community, where A represents the phylum level (Phylum) and B represents the genus level (Genus).

[0028] Figure 7 A graph showing the results of differential bacterial genera (>2%) in the ileum;

[0029] Figure 8 This is a comparison of the differential bacterial species (>2%) in the cecum. Detailed Implementation

[0030] Comparative Example 1.

[0031] According to patent CN102911992, the enzymatic hydrolysis scheme provided in a method for preparing corn oligopeptide chelates by enzymatic hydrolysis of corn protein is as follows:

[0032] 1. Adjust the pH of the corn flotation solution (dry matter content between 7% and 9%) to between 8.5 and 9.5 with 3 mol / L sodium hydroxide solution, and adjust the temperature to 62-68℃. Add 0.3-0.5% of the weight of corn gluten meal of alkaline protease with an enzyme activity of 200,000 U / g, and enzymatically hydrolyze for 3-4 hours. During the process, continuously maintain the pH value with 3 mol / L sodium hydroxide solution.

[0033] 2. Then lower the temperature to 40-50℃, adjust the pH value to between 5 and 7 with 3mol / L HCl solution, add 0.3-0.5% by mass of dry matter of neutral protease with an enzyme activity of 200,000 U / g, and enzymatically hydrolyze for 0.5-1h;

[0034] 3. Adjust the temperature to 50-70℃, add 0.2-0.8% of the dry matter mass of flavor protease with an enzyme activity of 200,000 U / g, and enzymatically hydrolyze for 3-5 hours;

[0035] 4. Decolorization: Use hydrogen peroxide for decolorization. Control the amount of food-grade hydrogen peroxide used to be between 10% and 30% of the dry matter, the temperature to be between 60 and 80°C, the pH value to be between 7 and 9, and the decolorization time to be between 1 and 3 hours.

[0036] 5. Add 0.04-0.06% catalase by dry matter mass, control the temperature at 40-60℃, and hydrolyze for 1-2 hours. Then, inactivate the enzyme at 85-95℃ for 15-20 minutes.

[0037] 6. Spray dry to obtain corn protein.

[0038] Comparative Example 2.

[0039] According to patent CN102994598, the enzymatic hydrolysis scheme for weakly bitter corn oligopeptides with high alanine and leucine content and their preparation method is as follows:

[0040] 1. Adjust the pH of the corn flotation solution (dry matter between 7 and 9%) to 6.0 with 3 mol / L sodium hydroxide solution, heat to 82℃ and maintain for 40 min, add 0.5% of the dry matter mass of α-high temperature amylase with an enzyme activity of 50000 U / g, enzymatically hydrolyze for 45 min, raise the temperature to 95℃ and maintain for 15 min, cool to 60℃ and centrifuge, discarding the supernatant;

[0041] 2. Resuspend in deionized water at 55℃, with a dry matter content of 10%. Adjust the pH to 6.5 with 3 mol / L sodium hydroxide solution, add 1% of the dry matter mass of neutral protease with an enzyme activity of 200,000 U / g at a constant temperature of 55℃, and enzymatically hydrolyze for 1.5 hours. Then add 1% of the dry matter mass of acidic protease and enzymatically hydrolyze for 6 hours.

[0042] 3. Decolorization: After enzymatic hydrolysis, heat to 85℃, add 0.6% (by dry matter weight) of 200-mesh activated carbon and stir for 45 minutes;

[0043] 4. Spray dry to obtain corn protein.

[0044] Example 1.

[0045] 1. Adjust the pH of the corn flotation solution (dry matter content between 7% and 9%) to 5.5–6.5 using liquid ammonia, heat to 70–85°C, add 0.3–0.6% (by weight of dry matter) of α-amylase with an enzyme activity of 50,000 U / g, and hydrolyze for 30 minutes. Then, lower the temperature to 58–65°C, add 0.3–0.5% (by weight of dry matter) of neutral protease with an enzyme activity of 200,000 U / g, and hydrolyze for 20 minutes.

[0046] 2. Control the temperature at 55-58℃, adjust the pH to between 8.0 and 9.0 using liquid ammonia, and add premixed protease, which includes: 1-1.5% (dry matter weight) of alkaline protease with an enzyme activity of 200,000 U / g, and 0.1-0.2% (dry matter weight) of keratinase with an enzyme activity of 100,000 U / g. Incubate for 2 hours, maintaining the pH using liquid ammonia during this time.

[0047] 3. Decolorization: After enzymatic hydrolysis, add 95% ethanol for decolorization and stir for 3 hours;

[0048] 4. Spray dry to obtain enzymatically modified corn protein.

[0049] Example 2.

[0050] 1. Adjust the pH of the corn flotation solution (dry matter content between 7% and 9%) to 5.5 to 6.5 with liquid ammonia, heat to 70 to 85°C, add 0.3 to 0.5% of the dry matter mass of neutral protease with an enzyme activity of 200,000 U / g, and enzymatically hydrolyze for 20 minutes.

[0051] 2. Control the temperature at 55-58℃, adjust the pH to between 8.0 and 9.0 using liquid ammonia, and add the premixed protease, which includes 1-1.5% (by dry matter) of alkaline protease with an enzyme activity of 200,000 U / g and 0.1-0.2% (by dry matter) of keratinase with an enzyme activity of 100,000 U / g. Incubate for 2 hours, maintaining the pH using liquid ammonia during this time.

[0052] 3. Decolorization: After enzymatic hydrolysis, add 95% ethanol for decolorization and stir for 3 hours;

[0053] 4. Spray dry to obtain enzymatically modified corn protein.

[0054] Example 3.

[0055] 1. Adjust the pH of the corn flotation solution (dry matter content between 7% and 9%) to 5.5–6.5 using liquid ammonia, heat to 70–85°C, add α-amylase with an activity of 50,000 U / g (0.3–0.6% of dry matter mass), and hydrolyze for 30 minutes. Then lower the temperature to 58–65°C, add premixed protease A, which includes: cellulase with an activity of 200,000 U / g (0.1–0.3% of dry matter mass) and xylanase with an activity of 100,000 U / g (0.05–0.15% of dry matter mass), and hydrolyze for 20 minutes. Finally, add neutral protease with an activity of 200,000 U / g (0.3–0.5% of dry matter mass), and hydrolyze for 20 minutes.

[0056] 2. Control the temperature at 55-58℃, adjust the pH value to between 8.0 and 9.0 with liquid ammonia, add premixed proteinase B, which includes: 1-1.5% of dry matter by weight of alkaline proteinase with an enzyme activity of 200,000 U / g and 0.1-0.2% of dry matter by weight of keratinase with an enzyme activity of 100,000 U / g. Enzymatic hydrolysis for 2 hours, during which the pH value is maintained with liquid ammonia.

[0057] 3. Decolorization: After enzymatic hydrolysis, add 95% ethanol for decolorization and stir for 3 hours;

[0058] 4. Spray dry to obtain enzymatically modified corn protein.

[0059] Example 4.

[0060] The nutritional indicators of corn protein in the above examples and comparative examples were tested. The control group consisted of corn protein obtained by direct spray drying of raw corn flotation liquid (dry matter between 7% and 9%), and fishmeal, an animal protein source, was used as a comparison. The results are shown in Table 1. All experimental results are on a dry basis.

[0061] Table 1

[0062] Nutritional indicators control group Comparative Example 1 Comparative Example 2 Example 1 Example 2 Example 3 fish meal Crude protein % 62.88 65.37 64.89 66.06 64.78 62.97 65.13 Acid-soluble protein % 15.94 48.37 50.33 50.57 47.22 52.55 14.84 Ash content % 4.86 4.66 5.96 5.23 5.56 4.72 20.35 Moisture% 1.66 1.74 1.78 1.57 1.69 1.97 12.93 Digestibility % 88.68 90.18 89.18 93.21 92.15 93.51 78.54 Acid-soluble protein / crude protein % 25.35 73.99 77.56 76.55 72.89 83.45 22.79 18 amino acids / crude protein % 92.14 93.45 94.13 93.25 92.56 93.12 95.45

[0063] Significance of acid-soluble protein index detection: It can serve as an indicator to clarify the content of small peptides. Its value depends on the size of the polypeptide fragments and the hydrophobicity of amino acids and polypeptides, representing the content of protein hydrolysates with relatively small molecular weights. In feed formulation, acid-soluble protein can help assess the protein quality and nutritional value in feed, understand the digestibility and absorption of protein, and is an important indicator for feed quality assessment. This experiment used two control groups: one was corn flotation liquid directly sprayed into dry powder as the control group, and fishmeal was selected as the animal source protein for comparison to clarify the nutritional indicators of enzymatically hydrolyzed protein powder. The experimental data shows that the proportion of acid-soluble protein in the control group and fishmeal, as natural protein sources, was generally low, reaching only 25.35% and 22.79% of crude protein, respectively. The results of Comparative Examples 1-2 and Examples 1-3 show that after enzymatic hydrolysis with various enzyme preparations, the polypeptide chains were hydrolyzed into small peptides, and the content of acid-soluble protein increased dramatically. Among them, the enzymatic hydrolysis scheme involved in Example 3 had the highest proportion of acid-soluble protein, increasing the proportion of acid-soluble protein to crude protein to 83.45%. From the perspective of feed quality assessment, it can be evaluated as a high-quality feed additive.

[0064] Analysis of digestibility results: Combined with the ash content analysis, ash is an indigestible component. Excluding ash, the digestibility is close to 100%. Compared with the control group, the digestibility of Comparative Examples 1-2 and Examples 1-3 is improved, generally increasing from 88.68% to over 90%. Comparative Examples 1 and 2 are enzymatic hydrolysis schemes mentioned in the authorized corn gluten meal enzymatic hydrolysis patent, while Examples 1-3 are enzymatic hydrolysis schemes designed in this study. The digestibility results show that the enzymatic hydrolysis scheme in this study is more effective than the reference patent, with Example 3 showing the best digestibility at 93.51%.

[0065] Ash content analysis: When the ash content is generally below 5%, it can be determined that it is a high-quality protein, that is, the corn protein obtained in Example 3 is a high-quality protein;

[0066] Analysis of 18 Amino Acids: The 18 amino acids detected in this study have significant impacts in the agricultural field. These 18 amino acids are glycine, arginine, glutamic acid, tyrosine, alanine, valine, aspartic acid, threonine, tryptophan, histidine, proline, lysine, phenylalanine, cysteine, methionine, methionine, and isoleucine. The sum of the contents of these 18 common amino acids, along with the crude protein content, all exceeded 90%. This indicates that enzymatically modified corn protein is a high-quality protein source feed additive. As shown in Table 1, the proportion of the 18 amino acids in the modified corn protein source is close to that of fishmeal; therefore, it can replace animal-derived protein in feed.

[0067] Example 7. Feeding Trial for Piglets

[0068] Experimental Objective: This experiment aimed to evaluate the effects of enzymatically modified corn protein, used as a substitute for other protein ingredients in piglet feed, on piglet growth performance and gut health. The enzymatic hydrolysis of the corn protein was performed using the method described in Example 3 above.

[0069] Experimental Design: Twenty sows of similar weight and parity were selected and, after farrowing, were evenly distributed to each pen of 12 piglets based on their average weight, for a total of 240 piglets (20 litters). These piglets were randomly divided into 5 groups, with 4 replicates per group. The grouping details are shown in Table 2. Different protein feed ingredients were added to the basal diet of each experimental group. The different protein feed ingredients were: ordinary corn gluten meal (CGM), fish meal (FM), and enzymatically modified corn gluten meal (MCGM). The basal diet consisted of 40–45% corn, 25–27% soybean meal, 13–15% whey powder, 1.2–1.5% dicalcium phosphate, 0.8–1% limestone powder, 0.3–0.4% salt, and 1.7–2% premix.

[0070] The feeding trial began at 7 days of age and ended at 21 days of age. After the 35-day feeding trial, two piglets from each replicate were slaughtered (a total of 40 piglets). Intestinal tissue (mucosal and tissue samples from the duodenum, jejunum, ileum, and cecum) and intestinal contents (referring to the contents of the duodenum and jejunum) were collected to assess the effects of different treatments on intestinal development and health.

[0071] Table 2

[0072] Serial Number Processing group Number of repetitions Number of piglets 1 Basic feed + 5% CGM 4 48 2 Basic feed + 5% FM 4 48 3 Basic feed + 5% MCGM 4 48 4 Basic feed + 10% MCGM 4 48 5 Basic feed + 15% MCGM 4 48

[0073] I. Morphological analysis experiment of piglet intestinal tissue:

[0074] Sections of each intestinal segment were prepared and stained with hematoxylin and eosin (HE). Villus height and crypt depth were measured under a microscope in a fixed field of view, and the villus-crypt ratio was calculated (see Table 3). The sections from different intestinal segments showed no obvious pathological damage in any group. The duodenal and jejunal mucosa showed dense and orderly arrangement of single-layer columnar epithelial cells and goblet cells, with relatively intact villus structure (see Table 3). Figures 1-4 .

[0075] Table 3

[0076]

[0077] Note: Different values ​​for lowercase letters (a, b, c, or d) in the same row indicate significant differences between pairs (P < 0.05).

[0078] Results analysis:

[0079] Measurements taken by sectioning revealed that the crypt depths in the duodenum of the FM, MCGM (5%), and MCGM (15%) groups were 296.58 μm, 303.58 μm, and 240.67 μm, respectively, significantly lower than those in the CGM group (426.50 μm, P<0.05), indicating stronger secretory function in the former. The chorioretinopathy ratios were 2.36 for MCGM (5%) and 2.42 for MCGM (15%), significantly higher than those in the FM and CGM groups (1.89 and 1.71, P<0.05).

[0080] The jejunum and duodenum were similar in height, with the villus ratio (Villus-to-cryptocrypt ratio) of the MCGM (5%) group (2.26) and the MCGM (15%) group (2.24) being significantly higher than those of the FM and CGM groups (1.76 and 1.97, respectively, P<0.05). In the ileum, there were varying differences in villus height and crypt depth among the groups, but the difference in the villus-to-cryptocrypt ratio was not statistically significant (P>0.05). In the cecum, the crypt depth of the MCGM (5%) group was significantly lower than that of the MCGM (15%) group (P<0.05).

[0081] II. Experiment on the analysis of digestive enzyme activity in the esophagus of piglets:

[0082] The results of the experimental analysis of digestive enzyme activity in the esophagus of piglets are shown in Table 4.

[0083] Table 4

[0084]

[0085] Results analysis:

[0086] In the duodenum, there were no significant differences in amylase activity among the experimental groups (P>0.05); lipase activity in the FM, CGM, and MCGM (5%) groups was significantly higher than that in the MCGM (10%) and MCGM (15%) groups (P<0.05). Trypsin and chymotrypsin activities in the FM and MCGM (5%) groups were significantly higher than those in the CGM, MCGM (10%), and MCGM (15%) groups (P<0.01).

[0087] In the jejunum, amylase activity in the FM and MCGM (5%) groups was significantly higher than that in the CGM, MCGM (10%), and MCGM (15%) groups (P<0.05); lipase activity in the MCGM (5%) group was significantly higher than that in the CGM, MCGM (10%), and MCGM (15%) groups (P<0.05), but not significantly different from that in the FM group (P>0.05). Lipase activity in the FM group was significantly higher than that in the MCGM (10%) and MCGM (15%) groups (P<0.05). Trypsin and chymotrypsin activities in the FM and MCGM (5%) groups were significantly higher than those in the CGM, MCGM (10%), and MCGM (15%) groups (P<0.05), with trypsin activity in the MCGM (5%) group reaching a highly significant level compared to the CGM, MCGM (10%), and MCGM (15%) groups (P<0.01).

[0088] III. The effects of different feed additives on the composition of the intestinal microbiota of piglets:

[0089] Results analysis:

[0090] 1. In the ileum, Firmicutes accounted for over 96%, with FM and MCGM (5%) having a higher percentage than CGM, MCGM (10%), and MCGM (15%) groups. Figure 5 A. At the genus level, the top three most abundant species are *Lactobacillus*, *Clostridium sensu stricto*, and *Streptococcus*, such as... Figure 5 B;

[0091] 2. In the cecum, Firmicutes account for over 72%, followed by Bacteroidetes and Proteobacteria, such as... Figure 6 A. At the genus level, the top three most abundant species are Clostridium sensu stricto 1, Lactobacillus, and Terrisporobacter, such as... Figure 6 B;

[0092] 3. Using the Kruskal-Wallis test, pairwise comparisons were performed on differentially abundant genera with an abundance greater than 2%, such as... Figure 7As shown, the abundance of Lactobacillus and Terrisporobacter (mostly Bacillus species) was significantly increased in the FM group and MCGM (5%) group (P<0.05), suggesting that FM and MCGM may improve gut health by increasing the abundance of probiotics. Enterococcus, on the other hand, was significantly increased in the MCGM (10%) group (P<0.05).

[0093] 4. Differential bacterial genera in the cecum, for example... Figure 8 As shown, the addition of MCGM helped increase the abundance of Streptococcus. The abundance of Prevotella, an important cornerstone bacterium of the gut, was significantly decreased in both the MCGM (10%) and MCGM (15%) groups (P<0.05), while the abundance of Escherichia-Shigella, a potential pathogen, was significantly increased (P<0.05), suggesting a higher risk of intestinal inflammation and diarrhea in these two groups.

Claims

1. A method for modifying corn protein by biological enzymes, characterized in that: The method is: Step 1: adjust the pH value of corn aerosol to 5.5-6.5 and heat to 70-85°C, add α-amylase, enzymolyze for 30 minutes, then add a mixed enzyme of cellulase and xylanase, enzymolyze for 20 minutes, and then add neutral protease for enzymolyze for 20 minutes; Step 2: adjusting the temperature to 55-58°C, adjusting the pH value to 8.0-9.0, adding a mixture of alkaline protease and keratinase, and performing enzymolysis for 2 hours, during which the pH value is maintained at 8.0-9.0; Step 3: Decolorization; Step 4: Powder spraying and drying to obtain enzymatically modified corn protein.

2. The method according to claim 1, characterized in that The enzyme activity of the alpha-amylase is 50000 U / g, and the added amount is 0.3-0.6% of the dry matter mass.

3. The method according to claim 1, characterized in that The mixed enzyme of cellulase and xylanase is prepared by mixing 0.1-0.3% of the dry matter mass of cellulase with an enzyme activity of 200000 U / g and 0.05-0.15% of the dry matter mass of xylanase with an enzyme activity of 100000 U / g.

4. The method according to claim 1, characterized in that: The enzyme activity of the neutral protease is 200000 U / g, and the added amount is 0.3-0.5% of the dry matter mass.

5. The method according to claim 1, characterized in that The mixed enzyme of alkaline protease and keratinase is prepared by mixing alkaline protease with an enzyme activity of 200,000 U / g in an amount of 1-1.5% of the dry matter mass and keratinase with an enzyme activity of 100,000 U / g in an amount of 0.1-0.2% of the dry matter mass.

6. The method according to claim 1, characterized in that The decolorization step is to add 95% ethanol after the enzymatic hydrolysis and stir for 3 hours.

7. A modified corn protein additive, characterized in that: The corn protein additive is prepared by any one of claims 1-6.

8. Application of a modified corn protein additive in the preparation of feed for improving pig intestinal function.

9. The use according to claim 8, characterized in that: The modified corn protein additive is added in an amount of 5% to 15% in feed.

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