阅读说明：本技术 一种复合酶解罗非鱼内脏水解液的制备方法 (Preparation method of composite enzymatic hydrolysis tilapia mossambica viscera hydrolysate ) 是由 周尽学 郭红星 于 2021-08-31 设计创作，主要内容包括：本发明公开了一种复合酶解罗非鱼内脏水解液的制备方法,依次包括以下步骤：初次除腥、肉糜制备、脱脂、内源酶水解、外源酶水解、灭酶处理和脱色脱腥,最后制得罗非鱼内脏水解液。本发明所述的复合酶解罗非鱼内脏水解液制备方法,解决了罗非鱼内脏水解液的腥苦问题,同时可以控制成本,且便于工业化生产。(The invention discloses a preparation method of compound enzymatic hydrolysis tilapia mossambica viscera hydrolysate, which sequentially comprises the following steps: primarily removing fishy smell, preparing minced meat, degreasing, hydrolyzing endogenous enzyme, hydrolyzing exogenous enzyme, inactivating enzyme, decoloring and removing fishy smell, and finally preparing the tilapia mossambica viscera hydrolysate. The preparation method of the compound enzymatic hydrolysis tilapia mossambica viscera hydrolysate solves the problem of fishy smell and bitter taste of the tilapia mossambica viscera hydrolysate, can control the cost and is convenient for industrial production.)

1. A preparation method of compound enzymatic hydrolysis tilapia mossambica viscera hydrolysate is characterized by comprising the following steps: the method sequentially comprises the following steps:

(1) removing fishy smell for the first time: squeezing viscera of tilapia, rinsing with water, and dehydrating;

(2) preparing meat paste: adding water into the tilapia mossambica viscera after primary fishy smell removal, and mixing and mashing into meat paste;

(3) degreasing: adding a degreasing agent into the meat paste for rinsing and dewatering, and then adding water for rinsing and dewatering to prepare degreased meat paste;

(4) endogenous enzymatic hydrolysis: adding water and a pH regulator into the defatted meat paste to regulate the pH value, and hydrolyzing to prepare a first hydrolysate;

(5) and (3) exogenous enzyme hydrolysis: adding a complex enzyme into the first hydrolysate, adding a pH regulator to regulate the pH value, and hydrolyzing to prepare a second hydrolysate;

(6) enzyme deactivation treatment: heating the second hydrolysate to 80-85 deg.C, maintaining for 15-30min, and filtering to obtain hydrolyzed mother liquor;

(7) decoloring and removing fishy smell: adding polystyrene-divinylbenzene resin and ethanol into the hydrolysis mother liquor, keeping stirring for 2-3h, and filtering at 70-80 ℃ to obtain tilapia mossambica viscera hydrolysate.

2. The preparation method of the compound enzymatic hydrolysis tilapia mossambica viscera hydrolysate according to claim 1, characterized in that: the temperature of the water in the step (1) is 40-45 ℃, the weight ratio of the viscera of the tilapia mossambica to the water is 1:3-5, and the rinsing times with the water are 1-3.

3. The preparation method of the compound enzymatic hydrolysis tilapia mossambica viscera hydrolysate according to claim 1, characterized in that: the weight ratio of the viscera of the tilapia mossambica to the water in the step (2) is 1: 1.

4. The preparation method of the compound enzymatic hydrolysis tilapia mossambica viscera hydrolysate according to claim 1, characterized in that: the degreasing agent in the step (3) is NaCl and NaHCO₃Mixed aqueous solution, NaCl mass concentration 0.8-1.2%, NaHCO₃The mass concentration of (A) is 0.3-0.5%.

5. The method for preparing the compound enzymatic hydrolysis tilapia mossambica viscera hydrolysate according to claim 1 or 4, which is characterized in that: in the step (3), the rinsing times of the degreasing agent are 1-3, and the weight ratio of the degreasing agent to the minced meat is 1-3: 1; the rinsing times of the water in the step (3) are 1-3 times, and the weight ratio of the water to the minced meat is 3-5: 1.

6. The preparation method of the compound enzymatic hydrolysis tilapia mossambica viscera hydrolysate according to claim 1, characterized in that: the pH regulator is one or more of phosphoric acid, citric acid, tartaric acid, maleic acid, acidic amino acid, malic acid, ethanolamine, ethylenediamine, basic amino acid, phosphate buffer solution and borate buffer solution.

7. The method for preparing the compound enzymatic hydrolysis tilapia mossambica viscera hydrolysate according to claim 1 or 6, which is characterized in that: the step (4) is specifically as follows: adding a pH regulator into the defatted meat paste to regulate the pH to 6-7, and hydrolyzing for 2-3h at the temperature of 40-45 ℃; adding 1-2 times of water, adjusting pH2-3 with pH regulator, and hydrolyzing at 35-42 deg.C for 2-3 h; to produce a first hydrolysate.

8. The preparation method of the compound enzymatic hydrolysis tilapia mossambica viscera hydrolysate according to claim 1, characterized in that: the compound enzyme is a compound enzyme of flavourzyme and neutral protease, the weight ratio of the flavourzyme to the neutral protease is 1.5-2:0.5-1, and the weight ratio of the compound enzyme to the first hydrolysate is 1.5-3: 100.

9. The method for preparing the compound enzymatic hydrolysis tilapia mossambica viscera hydrolysate according to the claim 1, 6 or 8, characterized in that: the step (5) is specifically as follows: and adding complex enzyme into the first hydrolysate, adjusting the pH to 7-8 with a pH regulator, and hydrolyzing at 40-50 deg.C for 4-5h to obtain a second hydrolysate.

10. The preparation method of the compound enzymatic hydrolysis tilapia mossambica viscera hydrolysate according to claim 1, characterized in that: the weight ratio of the polystyrene-divinylbenzene resin to the hydrolysis mother liquor in the step (7) is 1: 100-.

Technical Field

The application relates to the field of aquatic product processing, in particular to a preparation method of compound enzymatic hydrolysis tilapia mossambica viscera hydrolysate.

Background

Tilapia (Oreochromys, Tilapia) is a warm-water fish native to tropical and subtropical regions, has more than ten varieties of nile, Mosangbike, Orimula, Milaixi and the like, has the advantages of strong fertility, high growth speed, coarse food resistance, strong disease resistance and the like, and is one of important breeding varieties in the current fresh water breeding industry. The processed tilapia fillets have meat percentage of 32-35% generally, leftovers with weight more than 60% are not fully utilized, and particularly viscera with high protein content are used. These process leftovers, if not effectively treated, not only pollute the environment, but also waste a large amount of nutrients. In the prior art, tilapia viscera processing is mainly used for feeds and is rarely used in other fields, the main reason is that the earthy taste of tilapia viscera is difficult to remove, and the earthy taste substances are mainly aldehyde, alcohol, ketone and other fishy taste substances which can generate short peptides after the visceral fat is decomposed. A great deal of research shows that the main source of the alditones is unsaturated fatty acid, the oxidation of the unsaturated fatty acid is free radical chain reaction, free radical initiation is required, and the free radical can be generated only by catalysis. The catalysts for catalyzing the generation of free radicals in meat mainly include hemoglobin, Lipoxygenase (loxyme), metal ions, and the like.

In addition, bitter peptides and other bitter substances are generally generated after the hydrolysis of proteins, and the bitter intensity of bitter peptides in the hydrolyzed proteins is influenced by many factors, including the length of peptide chains, the content and spatial structure of hydrophobic amino acids, and the like.

Disclosure of Invention

Therefore, the application provides a preparation method of the compound enzymatic hydrolysis tilapia mossambica viscera hydrolysate, which aims to solve the problem of fishy smell and bitter taste of the enzymatic hydrolysis preparation tilapia mossambica viscera hydrolysate, simultaneously controls the cost and is convenient for industrial production.

The technical scheme of the application is realized as follows:

a preparation method of compound enzymatic hydrolysis tilapia mossambica viscera hydrolysate sequentially comprises the following steps:

(1) removing fishy smell for the first time: squeezing viscera of tilapia, rinsing with water, and dehydrating to remove metal ions, part of hemoglobin A and part of endogenous lipoxidase;

(2) preparing meat paste: adding water into the tilapia mossambica viscera after primary fishy smell removal, and mixing and mashing into meat paste;

(3) degreasing: the fat removing agent is added into the meat paste for rinsing and dehydration, and then water is added for rinsing and dehydration to prepare the fat-removed meat paste, so that the catalytic action of the lipoxidase in the meat paste on fat is reduced, the generation of fishy smell is further reduced, and the influence of the lipid in the meat paste on subsequent enzymolysis is also reduced;

(4) endogenous enzymatic hydrolysis: adding water and a pH regulator into the defatted meat paste to regulate the pH value, and hydrolyzing to prepare a first hydrolysate; firstly, endogenous enzymolysis of the viscera of the tilapia is utilized, so that the hydrolysis degree of the defatted meat paste can be improved, and the cost of using exogenous enzyme is reduced;

(5) and (3) exogenous enzyme hydrolysis: adding a complex enzyme into the first hydrolysate, adding a pH regulator to regulate the pH value, and hydrolyzing to prepare a second hydrolysate; the degree of hydrolysis of the meat emulsion is improved by combining exogenous enzymes with endogenous enzymes;

(6) enzyme deactivation treatment: heating the second hydrolysate to 80-85 deg.C, maintaining for 15-30min, and filtering to obtain hydrolyzed mother liquor;

(7) decoloring and removing fishy smell: adding polystyrene-divinylbenzene resin and ethanol into the hydrolysis mother liquor, keeping stirring for 2-3h, and filtering at 70-80 ℃ (completely volatilizing ethanol at the temperature) to obtain tilapia mossambica viscera hydrolysate.

The further technical scheme is that the temperature of water in the step (1) is 40-45 ℃, the weight ratio of the viscera of the tilapia mossambica to the water is 1:3-5, and the rinsing times with the water are 1-3.

The further technical scheme is that the weight ratio of the tilapia viscera to water in the step (2) is 1: 1.

The further technical proposal is that the degreasing agent in the step (3) is NaCl and NaHCO₃Mixed aqueous solution, NaCl mass concentration 0.8-1.2%, NaHCO₃The mass concentration of (A) is 0.3-0.5%.

The further technical scheme is that the rinsing times of the degreasing agent in the step (3) are 1-3, and the weight ratio of the degreasing agent to the minced meat is 1-3: 1; the rinsing times of the water in the step (3) are 1-3 times, and the weight ratio of the water to the minced meat is 3-5: 1.

The further technical scheme is that the pH regulator is one or more of phosphoric acid, citric acid, tartaric acid, maleic acid, acidic amino acid, malic acid, ethanolamine, ethylenediamine, basic amino acid, phosphate buffer and borate buffer.

The further technical scheme is that the step (4) is specifically as follows: adding a pH regulator into the defatted meat paste to regulate the pH to 6-7, and hydrolyzing for 2-3h at the temperature of 40-45 ℃; adding 1-2 times of water, adjusting pH2-3 with pH regulator, and hydrolyzing at 35-42 deg.C for 2-3h to facilitate enzymolysis with pepsin of defatted meat paste; then, the degreased meat paste is subjected to enzymolysis by trypsin and the like, so that a first hydrolysate is prepared.

The technical scheme is that the compound enzyme is a compound enzyme of flavourzyme and neutral protease, the weight ratio of the flavourzyme to the neutral protease is 1.5-2:0.5-1, and the weight ratio of the compound enzyme to the first hydrolysate is 1.5-3: 100. The hydrolysis pH of the neutral protease is similar to that of the flavourzyme, and the protein in the first hydrolysate can be further hydrolyzed; the flavourzyme is an endo-and exo-protease, can thoroughly hydrolyze proteins and small molecular polypeptides on the basis of the hydrolysis of endogenous enzymes and neutral proteases in the previous period, and further reduces the bitter taste generated in the first hydrolysate.

The further technical scheme is that the step (5) is specifically as follows: and adding complex enzyme into the first hydrolysate, adjusting the pH to 7-8 with a pH regulator, and hydrolyzing at 40-50 deg.C for 4-5h to obtain a second hydrolysate.

The further technical scheme is that the weight ratio of the polystyrene-divinylbenzene resin to the hydrolysis mother liquor in the step (7) is 1:100-200, the ethanol is a 75% ethanol solution with the mass concentration, and the weight ratio of the 75% ethanol solution to the hydrolysis mother liquor is 1: 300-500. The polystyrene-divinylbenzene resin can play a role in debitterizing, decoloring and deodorizing at the same time; the ethanol can dissolve aldehyde, ketone and sulfur-containing compounds in the hydrolyzed mother liquor, volatilize the aldehyde and remove fishy smell after heating, and simultaneously the ethanol can react with the aldehyde to generate an aroma substance, namely acetal, or combine with organic acid to generate ester, and the combined action of the two can remove fishy smell and increase flavor of the tilapia mossambica viscera hydrolysate.

Compared with the prior art, the beneficial effects of this application are:

(1) according to the method, through the steps of primary fishy smell removal and degreasing, metal ions, partial hemoglobin A and endogenous lipoxidase in the viscera of the tilapia are removed, the catalytic decomposition effect of the metal ions, the hemoglobin A and the lipoxidase in the meat paste on fat is reduced, the generation of fishy smell is further reduced, and meanwhile, the influence of lipid in the meat paste on subsequent protein enzymolysis is also reduced.

(2) According to the method, endogenous enzyme and exogenous enzyme are used in a matched manner, so that sufficient hydrolysis of protein and polypeptide in the viscera of the tilapia mossambica is guaranteed, the hydrolysis degree is improved, and meanwhile, the enzymolysis cost is reduced due to the use of the endogenous enzyme.

(3) The polystyrene-divinylbenzene resin used in the application can play a role in decoloring, deodorizing and debitterizing tilapia mossambica viscera hydrolysate, and has the effect of deodorizing and fragrance by being matched with ethanol.

(4) The hydrolysis degree of the composite enzymolysis tilapia mossambica viscera hydrolysate is 25.45-25.69%, the nitrogen yield is 79.68-80.84%, and the composite enzymolysis tilapia mossambica viscera hydrolysate can be used for industrial production.

Detailed Description

In order to better understand the technical content of the application, specific examples are provided below and the application is further described.

Example 1

A preparation method of compound enzymatic hydrolysis tilapia mossambica viscera hydrolysate sequentially comprises the following steps:

(1) removing fishy smell for the first time: squeezing viscera of tilapia, rinsing with 45 deg.C water for 3 times, and dewatering; the weight ratio of the Luofia indica viscera to water is 1: 3.

(2) Preparing meat paste: and adding 1 time of water by weight into the tilapia viscera after the primary fishy smell removal, mixing and mashing into meat paste.

(3) Degreasing: adding a degreasing agent with the weight of 1 time into the meat paste, rinsing for 3 times for dehydration, and then adding water with the weight of 5 times for rinsing for 3 times for dehydration to prepare defatted meat paste; the degreasing agent is NaCl and NaHCO₃Mixed aqueous solution, NaCl mass concentration 0.8%, NaHCO₃The mass concentration of (2) is 0.3%.

(4) Endogenous enzymatic hydrolysis: adding a pH regulator into the defatted meat paste to regulate the pH value of 6, hydrolyzing for 3h at 45 ℃, adding 1 time of water by weight, regulating the pH value of 2 by using the pH regulator, and hydrolyzing for 2h at 35 ℃; to produce a first hydrolysate.

(5) And (3) exogenous enzyme hydrolysis: adding complex enzyme into the first hydrolysate, adjusting pH to 7 with pH regulator, and hydrolyzing at 40 deg.C for 4 hr to obtain second hydrolysate; the compound enzyme is a compound enzyme of flavourzyme and neutral protease, the weight ratio of the flavourzyme to the neutral protease is 1.5:0.5, and the weight ratio of the compound enzyme to the first hydrolysate is 1.5: 100.

(6) Enzyme deactivation treatment: heating the second hydrolysate to 80 deg.C, maintaining for 15min, and filtering to obtain hydrolyzed mother liquor.

(7) Decoloring and removing fishy smell: and adding polystyrene-divinylbenzene resin and 75% ethanol solution in mass concentration into the hydrolysis mother liquor, keeping stirring for 2h, and filtering at 70 ℃ to obtain tilapia mossambica viscera hydrolysate.

The pH regulator is tartaric acid.

In the step (7), the weight ratio of the polystyrene-divinylbenzene resin to the hydrolysis mother liquor is 1:100, and the weight ratio of the 75% ethanol solution to the hydrolysis mother liquor is 1: 500.

Example 2

A preparation method of compound enzymatic hydrolysis tilapia mossambica viscera hydrolysate sequentially comprises the following steps:

(1) removing fishy smell for the first time: squeezing viscera of tilapia, rinsing with 45 deg.C water for 1 time, and dewatering; the weight ratio of the Luofia indica viscera to water is 1: 3.

(2) Preparing meat paste: and adding 1 time of water by weight into the tilapia viscera after the primary fishy smell removal, mixing and mashing into meat paste.

(3) Degreasing: adding a degreasing agent with the weight of 3 times into the meat paste, rinsing for 1 time for dehydration, and then adding water with the weight of 3 times, rinsing for 1 time for dehydration to prepare defatted meat paste; the degreasing agent is NaCl and NaHCO₃Mixed aqueous solution, NaCl mass concentration 1.2%, NaHCO₃The mass concentration of (2) is 0.5%.

(4) Endogenous enzymatic hydrolysis: adding a pH regulator into the defatted meat paste to regulate the pH value of 7, hydrolyzing for 3h at 45 ℃, adding 2 times of water by weight, regulating the pH value of 3 by using the pH regulator, and hydrolyzing for 3h at 42 ℃; to produce a first hydrolysate.

(5) And (3) exogenous enzyme hydrolysis: adding complex enzyme into the first hydrolysate, adjusting pH to 8 with pH regulator, and hydrolyzing at 50 deg.C for 5 hr to obtain second hydrolysate; the compound enzyme is a compound enzyme of flavourzyme and neutral protease, the weight ratio of the flavourzyme to the neutral protease is 2:1, and the weight ratio of the compound enzyme to the first hydrolysate is 3: 100.

(6) Enzyme deactivation treatment: heating the second hydrolysate to 80 deg.C, maintaining for 30min, and filtering to obtain hydrolyzed mother liquor.

(7) Decoloring and removing fishy smell: and adding polystyrene-divinylbenzene resin and 75% ethanol solution in mass concentration into the hydrolysis mother liquor, keeping stirring for 2h, and filtering at 70 ℃ to obtain tilapia mossambica viscera hydrolysate.

The pH regulator is phosphate buffer solution.

In the step (7), the weight ratio of the polystyrene-divinylbenzene resin to the hydrolysis mother liquor is 1:200, and the weight ratio of the 75% ethanol solution to the hydrolysis mother liquor is 1: 300.

Example 3

A preparation method of compound enzymatic hydrolysis tilapia mossambica viscera hydrolysate sequentially comprises the following steps:

(1) removing fishy smell for the first time: squeezing viscera of Tilapia mossambica, rinsing with 42 deg.C water for 2 times, and dewatering; the weight ratio of the Luofia indica viscera to water is 1: 4.

(2) Preparing meat paste: and adding 1 time of water by weight into the tilapia viscera after the primary fishy smell removal, mixing and mashing into meat paste.

(3) Degreasing: adding a degreasing agent with the weight of 2 times into the meat paste, rinsing for 2 times for dehydration, and then adding water with the weight of 4 times for rinsing for 2 times for dehydration to prepare defatted meat paste; the degreasing agent is NaCl and NaHCO₃Mixed aqueous solution, NaCl mass concentration 1.0%, NaHCO₃The mass concentration of (2) is 0.4%.

(4) Endogenous enzymatic hydrolysis: adding a pH regulator into the defatted meat paste to regulate the pH value of 6, hydrolyzing for 3h at 40 ℃, adding 2 times of water by weight, regulating the pH value of 3 by using the pH regulator, and hydrolyzing for 3h at 38 ℃; to produce a first hydrolysate.

(5) And (3) exogenous enzyme hydrolysis: adding complex enzyme into the first hydrolysate, adjusting pH to 8 with pH regulator, and hydrolyzing at 45 deg.C for 4 hr to obtain second hydrolysate; the compound enzyme is a compound enzyme of flavourzyme and neutral protease, the weight ratio of the flavourzyme to the neutral protease is 1.5:1, and the weight ratio of the compound enzyme to the first hydrolysate is 2: 100.

(6) Enzyme deactivation treatment: heating the second hydrolysate to 80 deg.C, maintaining for 20min, and filtering to obtain hydrolyzed mother liquor.

(7) Decoloring and removing fishy smell: and adding polystyrene-divinylbenzene resin and 75% ethanol solution in mass concentration into the hydrolysis mother liquor, keeping stirring for 3h, and filtering at 75 ℃ to obtain tilapia mossambica viscera hydrolysate.

The pH regulator is ethylenediamine.

In the step (7), the weight ratio of the polystyrene-divinylbenzene resin to the hydrolysis mother liquor is 1:150, and the weight ratio of the 75% ethanol solution to the hydrolysis mother liquor is 1: 400.

Comparative example 1

Degreasing in step (3) was omitted, and the procedure was otherwise the same as in example 1.

Comparative example 2

There is no step (4) of endogenous enzymatic hydrolysis, otherwise the same as in example 1.

Comparative example 3

The compound enzyme has no flavourzyme, and the rest is the same as the example 1.

Comparative example 4

The compound enzyme has no neutral protease, and the rest is the same as the example 1.

Comparative example 5

In the step (7), the polystyrene-divinylbenzene resin was replaced with activated carbon, and the rest was the same as in example 1.

Comparative example 6

The step (7) is free of ethanol and specifically comprises the following steps: adding polystyrene-divinylbenzene resin into the hydrolyzed mother liquor, keeping stirring for 2 hours, and filtering at 70 ℃ to obtain tilapia mossambica viscera hydrolysate; the rest is the same as in example 1.

Sensory evaluation

The color, the transparency, the fishy smell and the bitter taste of the hydrolysate are comprehensively evaluated by 10 fixed persons, and are classified and compared according to the grade of 1-5 (5 represents the best, 1 represents the worst), 20 points are full points, 4 points are the lowest points, and the average score of a 10-person evaluation group with a sensory evaluation value is shown in table 2.

TABLE 1 sensory evaluation scoring criteria

TABLE 2 sensory evaluation results

	Colour(s)	Transparency of solution	Fishy smell	Bitter taste	Sensory value
						Example 1	4.8	4.7	4.7	4.8	19.0
Example 2	4.7	4.8	4.6	4.8	18.9
						Example 3	4.8	4.7	4.7	4.8	19
Comparative example 1	4.8	4.7	3.5	4.8	17.8
						Comparative example 2	4.7	4.7	4.7	4.0	18.1
Comparative example 3	3.6	3.2	3.7	2.3	12.8
						Comparative example 4	4.2	4.0	4.3	4.1	16.6
Comparative example 5	1.4	4.5	3.9	4.2	14
						Comparative example 6	4.8	4.7	4.5	4.8	18.8

As can be seen from tables 1-2, the sensory values (about 19 cents) of the examples 1-3 are close to full score, and the comparative example 1 has no pre-degreasing and strong fishy smell mainly because the degreasing reduces the catalytic action of endogenous fat oxidase in the meat paste on fat, and further reduces the fishy smell substances such as aldehyde, ketone and the like which generate short peptides after the visceral fat is decomposed, so that the fishy smell is less, and the influence of the lipids in the meat paste on the subsequent enzymolysis is also reduced. Comparative example 2 no endogenous enzymatic hydrolysis was performed and the hydrolysate had some bitter taste, possibly the exogenous enzyme did not completely hydrolyze the polypeptide and some bitter peptides caused the bitter taste. Comparative example 3 is inferior to example 1 in color, solution transparency, fishy smell and bitter taste, so that the important role of the flavourzyme in the enzymolysis of the tilapia mossambica viscera hydrolysate can be seen, the flavourzyme can thoroughly hydrolyze proteins and small molecular polypeptides, and the flavourzyme is the best enzyme selection in the tilapia mossambica viscera hydrolysate. Comparative example 4 has no neutral protease, and compared with example 1, the hydrolysate is slightly inferior in color, solution transparency, fishy smell and bitter taste, so that the neutral protease and the flavourzyme are used together, and the protein and the polypeptide in the viscera of the tilapia can be hydrolyzed more fully. The tilapia mossambica viscera hydrolysate of comparative example 5 is inferior to example 1 in color, solution transparency, fishy smell and bitter taste, and it can be seen that the polystyrene-divinyl benzene resin has higher decoloring, fishy smell removing and debittering performances than activated carbon, thereby increasing the sensory value of the tilapia mossambica viscera hydrolysate. The tilapia mossambica viscera hydrolysate of comparative example 6 is slightly inferior to that of example 1 in fishy smell value, and the main reason is that ethanol can dissolve residual aldehyde, ketone and sulfur-containing compounds in the hydrolyzed mother liquor, and volatilize and remove fishy smell after heating, and simultaneously, the ethanol can react with the aldehyde to generate an aroma substance, namely acetal, or combine with organic acid to generate ester, and the result of the combined action of the two can remove fishy smell and enhance flavor of the tilapia mossambica viscera hydrolysate.

Degree of hydrolysis and Nitrogen yield determination

The amino nitrogen is measured by a formaldehyde potentiometric titration method, and the hydrolysis degree is calculated according to the following formula:

degree of hydrolysis: DH ═ AN (AN-AN)₀)/N×100％

In the formula, AN is the content of free amino nitrogen in the raw material enzymolysis liquid, 10^-2g/g；AN₀Content of free amino nitrogen before enzymolysis of raw material, 10^-2g/g; n is the content of total protein nitrogen in the viscera raw materials of tilapia mossambica, 10^-2g/g。

The nitrogen content of the hydrolysate is determined by a Kjeldahl method, and the nitrogen yield is calculated according to the following formula:

the nitrogen yield (%) - (% of the total nitrogen content in the hydrolysate/the total nitrogen content of the meat emulsion x 100%.

TABLE 3

	Degree of hydrolysis (%)	Nitrogen yield (%)
			Example 1	25.58	80.12
Example 2	25.45	79.68
			Example 3	25.69	80.84
Comparative example 1	25.57	80.14
			Comparative example 2	18.37	68.43
Comparative example 3	12.25	62.77
			Comparative example 4	17.32	67.21
Comparative example 5	25.34	79.27
			Comparative example 6	25.57	80.11

As can be seen from Table 3, the hydrolysis degree of the tilapia mossambica viscera hydrolysate of examples 1-3 is between 25.45% and 25.69%, and the nitrogen yield is between 79.68% and 80.84%, while the hydrolysis degree and the nitrogen yield of the tilapia mossambica viscera hydrolysate can be directly influenced without single component hydrolysis of endogenous enzyme or exogenous enzyme.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.