Background
At present, with the development of the aquaculture industry in China and the popularization of modern fishing technology, fish resources are damaged, low-value aquatic products such as small fish, small shrimps and the like are rapidly bred, the aquatic product processing industry is relatively slowly developed in developed countries, the number of primary products in the aquatic products is large, the number of deep processing products and fine processing products is small, a large amount of leftovers are generated, the ratio reaches about 28%, a large amount of byproducts (about 390 ten thousand tons) are generated after the aquatic products are roughly processed, and about 800 ten thousand tons of high-protein wastewater is generated after the processing and steaming. These low value fish processing by-products, particularly the high protein water fraction after processing cooking, are discarded and the remainder is used to produce fish meal and other products.
The externally dependence of protein feed resources in China is improved year by year, while various fish protein resources in China are rich, but for a long time, the feeding value of low-value fish and fish meal is not high, the coefficient of low-value fish bait is up to more than 10, the coefficient of fish meal bait is about 2.0, the food calling capacity is insufficient, the breeding cost is high, the quality of the fish is not high, the disease resistance is poor, and in addition, the water quality pollution is caused. This situation is far from the actual needs of the feed industry and the breeding industry. Therefore, the key technical research on development and efficient utilization of protein feed raw materials is urgently needed to be deeply developed, and how to develop novel high-quality aquatic protein feed resources, improve the utilization rate of the existing protein resources and relieve the shortage of protein feed resources in China becomes a development hotspot and key point.
Microbial fermentation and enzymatic hydrolysis have been gaining attention because of their unique advantages. Compared with the conventional fish meal protein feed, the fermented and enzymolyzed aquatic protein feed contains more easily digestible and absorbable substances such as small peptides, amino acids and the like, and also contains rich bioactive substances such as phagostimulants, enzymes, probiotics and the like, and the substances greatly improve the utilization rate and the nutritional value of the feed, can also improve the intestinal flora structure of the aquatic products and improve the immunity of the aquatic products. Therefore, the product can well replace the conventional protein powder feed, promote the growth of animals, improve the feed conversion efficiency, enhance the immunity of the animals and the like.
In 2018, the total yield of the feed in China is 22788 ten thousand tons, and the yield of the aquatic feed is 2211 ten thousand tons; the total amount of feed additive products is 1094 ten thousand tons, wherein the yield of amino acid peptide, enzyme preparation, microbial preparation and other products respectively reaches 285 ten thousand tons, 17 ten thousand tons and 15 ten thousand tons, the yield is increased by 21.5 percent, 55.8 percent and 36.9 percent respectively in the same ratio, and biological feed products such as enzyme preparation, microbial preparation and the like show strong rising momentum. The bioactive peptide has wide nutrition and physiological regulation effects on aquatic organisms, can be completely degraded in the aquatic organisms, has the characteristics of no residue and no toxic or side effect, improves the quality of the aquatic products, meets the requirements of modern feed industry development and aquatic product healthy culture, and is a novel green functional feed additive with great potential. Therefore, by means of biotechnology such as microbial fermentation and decomposition, oligopeptide resources are reasonably utilized and developed, and the method has great practical significance for making up the shortage of protein feed, especially high-quality protein resources in China, reducing the production cost of aquaculture industry, and promoting the yield increase and the efficiency increase of aquaculture industry.
Disclosure of Invention
The invention aims to provide a method for recovering low-value fish processing byproducts, which can convert the low-value fish processing byproducts into biological peptides with good feeding value and nutritional value.
In order to solve the technical problems, the technical scheme of the invention is as follows:
a method for recovering low value fish processing by-products comprises the following steps:
(1) adding the low-value fish processing byproducts into water, uniformly stirring to obtain a mixed solution, adjusting the pH value of the mixed solution to 6-7, adding compound protease in a vacuum environment, heating to 40 ℃, performing enzymolysis for 3-5 hours to obtain an enzymolysis solution, heating the enzymolysis solution to inactivate enzyme, cooling, filtering to obtain a filtrate, and drying the filtrate to obtain an zymolyte;
(2) crushing the zymolyte, sieving the crushed zymolyte with a 80-mesh sieve to obtain zymolyte powder, stirring the zymolyte powder, zymophyte and water until the zymolyte powder, the zymolyte and the water are uniformly mixed to obtain a mixed material, fermenting the mixed material in a closed environment at the temperature of 35 ℃ for 50-60 hours to obtain a fermented product, and performing vacuum concentration and drying on the fermented product to obtain the biological peptide.
Further, in the step (1) of the present invention, the mass concentration of the mixed solution is 15%.
Further, in the step (1) of the invention, the compound protease is formed by mixing neutral protease, alkaline protease and acid protease in a mass ratio of 1:3:2, and the ratio of the compound protease to the mixed solution is 100U/g.
Further, in the step (1), the heating and enzyme deactivation process of the enzymatic hydrolysate is to heat the enzymatic hydrolysate to 60 ℃ and then perform enzymolysis for 40 minutes.
Further, in the step (2), the fermentation bacteria are formed by mixing lactobacillus plantarum, lactobacillus rhamnosus and mung bean hull extracts in a mass ratio of 1:1:0.2, and the mass ratio of the zymolyte powder to the fermentation bacteria to the water is 1:0.05: 20.
Further, the preparation method of the mung bean hull extract comprises the following steps:
drying mung bean hull, crushing, sieving with a 40-mesh sieve to obtain mung bean hull powder, adding the mung bean hull powder into an ethanol aqueous solution, stirring for 1 hour, washing out ethanol to obtain defatted mung bean hull, adding the defatted mung bean hull into deionized water, stirring uniformly, adding alpha-amylase and neutral protease, bathing for 30 minutes at 90 ℃ and drying to obtain pretreated mung bean hull, adding the pretreated mung bean hull into a sodium hydroxide solution, extracting for 3 hours at 60 ℃ to obtain an extracting solution, centrifuging the extracting solution to obtain a supernatant, adding ethanol into the supernatant until the volume concentration of the ethanol reaches 65%, stirring for 30 minutes, standing overnight at 4 ℃ to obtain a mixed solution, centrifuging the mixed solution to obtain a precipitate, and freeze-drying the precipitate to obtain a mung bean hull extract.
Further, the volume concentration of the ethanol aqueous solution is 90%, the mass ratio of the mung bean hull powder to the ethanol aqueous solution is 1:12, the mass ratio of the defatted mung bean hull, the deionized water, the alpha-amylase and the neutral protease is 1:10:0.05:0.02, the mass concentration of the sodium hydroxide solution is 2%, and the mass ratio of the pretreated mung bean hull to the sodium hydroxide solution is 1: 30.
Compared with the prior art, the invention has the following beneficial effects:
1) the invention takes low-value fish processing by-products and high-protein waste water after processing and cooking as raw materials, carries out enzymolysis by using a compound enzyme of neutral protease, alkaline protease and acidic protease under the vacuum condition, degrades the protein into low-molecular-weight polypeptide, can improve the hydrolysis degree of the protein and increase the content of the low-molecular-weight polypeptide in the product, and adds zymophyte for fermentation after the enzymolysis, thereby producing fermentation fragrance of acid, sweet, alcohol and the like, improving the food calling property, simultaneously regulating the intestinal microecology and enhancing the immunity and the anti-stress capability of aquaculture. The invention fully utilizes respective advantages of microbial fermentation and enzymolysis, exerts the synergistic action of the microbes and the protease to ensure that the protein degradation of the low-value fish processing by-product is more sufficient and the small peptide degree is higher, simultaneously avoids the bitter taste of an enzymolysis product, improves the fishy smell, the flavor and the palatability of the product, and further improves the feeding value and the nutritive value of the product.
2) The recovery method has mild operation conditions, stable product quality, easily controlled hydrolysis conditions such as temperature, time and the like, avoids the product from being damaged by heat and fat oxidation, and furthest retains the probiotics, enzyme and flavor of the product.
3) The invention pretreats the skin part of mung bean, namely the mung bean skin, and then carries out alkali extraction through a sodium hydroxide solution to obtain the mung bean skin extract, the mung bean skin extract can effectively improve the fermentation degree, shorten the fermentation time, further improve the palatability of a biological peptide product, and when the biological peptide product is used for aquatic feed, the intestinal function of aquatic products can be effectively improved, and the death rate can be reduced.
4) The invention can well promote the comprehensive utilization of a large amount of low-value fish processing byproducts, can effectively replace fish meal processing, greatly improves the value of the low-value fish byproducts, solves the problems of environmental pollution and the like, and well promotes the development of local economy.
Detailed Description
The present invention will be described in detail with reference to specific embodiments, which are illustrative of the invention and are not to be construed as limiting the invention.
Example 1
The method for recovering the low-value fish processing by-products comprises the following steps:
(1) adding the low-value fish processing by-product into water, uniformly stirring to obtain a mixed solution with the mass concentration of 15%, adjusting the pH value of the mixed solution to 6-7, adding compound protease into a vacuum environment, heating to 40 ℃, performing enzymolysis for 4 hours to obtain an enzymolysis solution, mixing the compound protease with neutral protease, alkaline protease and acidic protease in a mass ratio of 1:3:2, heating the enzymolysis solution to 60 ℃, performing enzymolysis for 40 minutes, cooling, filtering to obtain a filtrate, and drying the filtrate to obtain an zymolyte;
(2) crushing the zymolyte, sieving the crushed zymolyte with a 80-mesh sieve to obtain zymolyte powder, stirring the zymolyte powder, zymophyte and water until the zymolyte powder, the zymophyte and the water are uniformly mixed to obtain a mixed material, mixing the zymolyte powder, the zymophyte and the water according to the mass ratio of 1:1:0.2, performing closed fermentation on the mixed material at 35 ℃ for 55 hours to obtain a fermented product, and performing vacuum concentration and drying on the fermented product to obtain the biological peptide; the preparation method of the mung bean hull extract comprises the following steps:
drying mung bean hull, crushing, sieving with a 40-mesh sieve to obtain mung bean hull powder, adding the mung bean hull powder into 90 vol% ethanol water solution, wherein the mass ratio of the mung bean hull powder to the ethanol water solution is 1:12, stirring for 1 hour, washing away ethanol to obtain defatted mung bean hull, adding the defatted mung bean hull into deionized water, uniformly stirring, adding alpha-amylase and neutral protease, wherein the mass ratio of the defatted mung bean hull to the deionized water, the alpha-amylase and the neutral protease is 1:10:0.05:0.02, carrying out water bath at 90 ℃ for 30 minutes, drying to obtain pretreated mung bean hull, adding the pretreated mung bean hull into 2 vol% sodium hydroxide solution, extracting at 60 ℃ for 3 hours to obtain an extracting solution, centrifuging the extracting solution to obtain a supernatant, adding ethanol into the supernatant until the volume concentration of the ethanol reaches 65%, stirring for 30 min, standing at 4 deg.C overnight to obtain mixed solution, centrifuging to obtain precipitate, and freeze drying to obtain testa Phaseoli Radiati extract.
Example 2
The method for recovering the low-value fish processing by-products comprises the following steps:
(1) adding the low-value fish processing by-product into water, uniformly stirring to obtain a mixed solution with the mass concentration of 15%, adjusting the pH value of the mixed solution to 6-7, adding compound protease into a vacuum environment, heating to 40 ℃, performing enzymolysis for 3 hours to obtain an enzymolysis solution, mixing the compound protease with neutral protease, alkaline protease and acidic protease in a mass ratio of 1:3:2, heating the enzymolysis solution to 60 ℃, performing enzymolysis for 40 minutes, cooling, filtering to obtain a filtrate, and drying the filtrate to obtain an zymolyte;
(2) crushing the zymolyte, sieving the crushed zymolyte with a 80-mesh sieve to obtain zymolyte powder, stirring the zymolyte powder, zymophyte and water until the zymolyte powder, the zymophyte and the water are uniformly mixed to obtain a mixed material, mixing the zymolyte powder, the zymophyte and the water according to the mass ratio of 1:1:0.2, and performing closed fermentation on the mixed material at 35 ℃ for 50 hours to obtain a fermented product, and performing vacuum concentration and drying on the fermented product to obtain the biological peptide; the preparation method of the mung bean hull extract comprises the following steps:
drying mung bean hull, crushing, sieving with a 40-mesh sieve to obtain mung bean hull powder, adding the mung bean hull powder into 90 vol% ethanol water solution, wherein the mass ratio of the mung bean hull powder to the ethanol water solution is 1:12, stirring for 1 hour, washing away ethanol to obtain defatted mung bean hull, adding the defatted mung bean hull into deionized water, uniformly stirring, adding alpha-amylase and neutral protease, wherein the mass ratio of the defatted mung bean hull to the deionized water, the alpha-amylase and the neutral protease is 1:10:0.05:0.02, carrying out water bath at 90 ℃ for 30 minutes, drying to obtain pretreated mung bean hull, adding the pretreated mung bean hull into 2 vol% sodium hydroxide solution, extracting at 60 ℃ for 3 hours to obtain an extracting solution, centrifuging the extracting solution to obtain a supernatant, adding ethanol into the supernatant until the volume concentration of the ethanol reaches 65%, stirring for 30 min, standing at 4 deg.C overnight to obtain mixed solution, centrifuging to obtain precipitate, and freeze drying to obtain testa Phaseoli Radiati extract.
Example 3
The method for recovering the low-value fish processing by-products comprises the following steps:
(1) adding the low-value fish processing by-product into water, uniformly stirring to obtain a mixed solution with the mass concentration of 15%, adjusting the pH value of the mixed solution to 6-7, adding compound protease into a vacuum environment, heating to 40 ℃, performing enzymolysis for 5 hours to obtain an enzymolysis solution, mixing the compound protease with neutral protease, alkaline protease and acidic protease in a mass ratio of 1:3:2, heating the enzymolysis solution to 60 ℃, performing enzymolysis for 40 minutes, cooling, filtering to obtain a filtrate, and drying the filtrate to obtain an zymolyte;
(2) crushing the zymolyte, sieving the crushed zymolyte with a 80-mesh sieve to obtain zymolyte powder, stirring the zymolyte powder, zymophyte and water until the zymolyte powder, the zymophyte and the water are uniformly mixed to obtain a mixed material, mixing the zymolyte powder, the zymophyte and the water according to the mass ratio of 1:1:0.2, performing closed fermentation on the mixed material at 35 ℃ for 60 hours to obtain a fermented product, and performing vacuum concentration and drying on the fermented product to obtain the biological peptide; the preparation method of the mung bean hull extract comprises the following steps:
drying mung bean hull, crushing, sieving with a 40-mesh sieve to obtain mung bean hull powder, adding the mung bean hull powder into 90 vol% ethanol water solution, wherein the mass ratio of the mung bean hull powder to the ethanol water solution is 1:12, stirring for 1 hour, washing away ethanol to obtain defatted mung bean hull, adding the defatted mung bean hull into deionized water, uniformly stirring, adding alpha-amylase and neutral protease, wherein the mass ratio of the defatted mung bean hull to the deionized water, the alpha-amylase and the neutral protease is 1:10:0.05:0.02, carrying out water bath at 90 ℃ for 30 minutes, drying to obtain pretreated mung bean hull, adding the pretreated mung bean hull into 2 vol% sodium hydroxide solution, extracting at 60 ℃ for 3 hours to obtain an extracting solution, centrifuging the extracting solution to obtain a supernatant, adding ethanol into the supernatant until the volume concentration of the ethanol reaches 65%, stirring for 30 min, standing at 4 deg.C overnight to obtain mixed solution, centrifuging to obtain precipitate, and freeze drying to obtain testa Phaseoli Radiati extract.
Example 4
The method for recovering the low-value fish processing by-products comprises the following steps:
(1) adding the low-value fish processing by-product into water, uniformly stirring to obtain a mixed solution with the mass concentration of 15%, adjusting the pH value of the mixed solution to 6-7, adding compound protease into the vacuum environment, heating to 40 ℃, performing enzymolysis for 4.5 hours to obtain an enzymolysis solution, mixing the compound protease with neutral protease, alkaline protease and acidic protease in a mass ratio of 1:3:2, heating the enzymolysis solution to 60 ℃, performing enzymolysis for 40 minutes, cooling, filtering to obtain a filtrate, and drying the filtrate to obtain an zymolyte;
(2) crushing the zymolyte, sieving the crushed zymolyte with a 80-mesh sieve to obtain zymolyte powder, stirring the zymolyte powder, zymophyte and water until the zymolyte powder, the zymophyte and the water are uniformly mixed to obtain a mixed material, mixing the zymolyte powder, the zymophyte and the water according to the mass ratio of 1:1:0.2, performing closed fermentation on the mixed material at 35 ℃ for 57 hours to obtain a fermented product, and performing vacuum concentration and drying on the fermented product to obtain the biological peptide; the preparation method of the mung bean hull extract comprises the following steps:
drying mung bean hull, crushing, sieving with a 40-mesh sieve to obtain mung bean hull powder, adding the mung bean hull powder into 90 vol% ethanol water solution, wherein the mass ratio of the mung bean hull powder to the ethanol water solution is 1:12, stirring for 1 hour, washing away ethanol to obtain defatted mung bean hull, adding the defatted mung bean hull into deionized water, uniformly stirring, adding alpha-amylase and neutral protease, wherein the mass ratio of the defatted mung bean hull to the deionized water, the alpha-amylase and the neutral protease is 1:10:0.05:0.02, carrying out water bath at 90 ℃ for 30 minutes, drying to obtain pretreated mung bean hull, adding the pretreated mung bean hull into 2 vol% sodium hydroxide solution, extracting at 60 ℃ for 3 hours to obtain an extracting solution, centrifuging the extracting solution to obtain a supernatant, adding ethanol into the supernatant until the volume concentration of the ethanol reaches 65%, stirring for 30 min, standing at 4 deg.C overnight to obtain mixed solution, centrifuging to obtain precipitate, and freeze drying to obtain testa Phaseoli Radiati extract.
Comparative example 1
Different from the example 1, in the step (1), the mass ratio of the neutral protease, the alkaline protease and the acidic protease is 1:1: 1.
Comparative example 2
Different from the embodiment 1, in the step (2), the zymocyte is formed by mixing the extracts of lactobacillus plantarum, lactobacillus rhamnosus and mung bean hull in a mass ratio of 1:1: 1.
Comparative example 3
Different from the embodiment 1, in the step (2), the zymocyte is formed by combining lactobacillus plantarum and lactobacillus rhamnosus in a mass ratio of 1:1, and the preparation step of the mung bean hull extract is not included.
Comparative example 4
Different from the example 1, in the step (2), the mass ratio of the zymolyte powder, the zymophyte and the water is 1:0.1: 20.
Test example: experiment of feeding crucian
The test is completed in a laboratory of Xinhong ocean Biotechnology Limited in Zhejiang. Selecting 180 tails of healthy crucian carps with basically consistent specifications and weights, wherein the initial weight of each crucian carp is 20 +/-0.5 g, randomly and averagely dividing the crucian carps into 6 groups of 30 tails, and feeding the crucian carps in net cages with the length, width and height of 1 m. The basal feed was formulated with reference to SC/T07-2004, and the control group was fed with the basal feed (10% fish meal), the test group was made by adding the bio-peptide to the basal feed and subtracting the corresponding amount of fish meal, 6% fish meal + 4% bio-peptide from example 1 in test 1, 6% fish meal + 4% bio-peptide from comparative example 1 in test 2, 6% fish meal + 4% bio-peptide from comparative example 2 in test 3, 6% fish meal + 4% bio-peptide from comparative example 3 in test 4, and 6% fish meal + 4% bio-peptide from comparative example 4 in test 5. Feeding crucian carp in a net cage for 30 days, wherein the feeding amount is 3% of the weight of the crucian carp, feeding is carried out for 4 times every day, the water temperature is kept at 25 +/-1 ℃, the dissolved oxygen is not less than 6mg/L, the pH value is 6.6-7.0 during the test period, the feeding and death conditions of the crucian carp are observed every day, the total weight of each net cage crucian carp is weighed after 70 days, each growth index and each feed utilization index are calculated, and the test results are shown in the following table:
|
weight gain (%)
|
Protein efficiency (%)
|
Mortality (%)
|
Control group
|
0.71
|
58.56
|
3.33
|
Test 1 group
|
0.92
|
69.35
|
0.56
|
Test 2 groups
|
0.85
|
69.08
|
0.56
|
Test 3 groups
|
0.83
|
69.15
|
0.56
|
Test 4 groups
|
0.80
|
68.93
|
2.22
|
Test 5 groups
|
0.82
|
69.27
|
0.56 |
As can be seen from the table above, the daily weight gain rate and the protein efficiency of the test groups 1 to 5 are obviously higher than those of the control group, and the mortality rate is obviously lower than that of the control group, which indicates that the biological peptide prepared by the invention has higher feeding value and nutritional value. Compared with the test 1 group, the daily weight gain rate and the protein efficiency of the test 2 group to the test 5 group are reduced, which shows that the effect of the biological peptide prepared from the complex enzyme and the zymophyte which are composed of specific components in specific proportion is optimal, and the effect is reduced by changing the proportion or the components; the mortality rate of the test group 4 was significantly higher than that of the other test groups, indicating that the testa Phaseoli Radiati extract used in the present invention can effectively reduce the mortality rate of aquatic products.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.