Method for reducing content of volatile basic nitrogen in aquatic product and aquatic product processed product
阅读说明：本技术 降低水产品中挥发性盐基氮含量的方法和水产品加工物 (Method for reducing content of volatile basic nitrogen in aquatic product and aquatic product processed product ) 是由 马超 夏培浩 陈磊 黄小青 于 2021-09-27 设计创作，主要内容包括：本发明涉及一种降低水产品中挥发性盐基氮含量的方法,构建包括液相的体系,通过添加碱性助剂将液相pH调至碱性,采用低温真空蒸发技术,在50℃～70℃低温条件下脱氨,可以有效地降低水产品中挥发性盐基氮的含量,然后经添加酸性助剂回调液相pH。本发明还提供根据前述的方法制备而成的水产品加工物。(The invention relates to a method for reducing the content of volatile basic nitrogen in aquatic products, which comprises the steps of constructing a system comprising a liquid phase, adjusting the pH of the liquid phase to be alkaline by adding an alkaline auxiliary agent, deaminating at the low temperature of 50-70 ℃ by adopting a low-temperature vacuum evaporation technology, effectively reducing the content of volatile basic nitrogen in the aquatic products, and then adjusting back the pH of the liquid phase by adding an acidic auxiliary agent. The invention also provides the processed aquatic product prepared by the method.)
1. A method for reducing the content of volatile basic nitrogen in aquatic products is characterized by comprising the following steps:
providing raw materials: providing an aquatic product raw material, wherein the aquatic product raw material contains volatile basic nitrogen, and the pH value of the aquatic product raw material is recorded as an initial pH;
adjustment to alkaline pH: mixing the aquatic product raw material, a first auxiliary agent and a proper amount of aqueous solvent, wherein the first auxiliary agent is an alkaline auxiliary agent, and adjusting the pH value of a liquid phase to 7-9 to prepare a first intermediate product;
vacuum heating: carrying out vacuum heating treatment on the first intermediate product for 20min to 4h under the conditions that the heating temperature is 50 ℃ to 70 ℃ and the vacuum degree is-0.06 MPa to-0.1 MPa, and preparing a second intermediate product;
and (4) adjusting the pH value: mixing the second intermediate product with a second auxiliary agent, wherein the second auxiliary agent is an acidic auxiliary agent, and adjusting the pH value of a liquid phase to be +/-0.2 of the initial pH value to prepare an aquatic product processed product;
the aquatic product process has a reduced content of volatile basic nitrogen relative to the aquatic product feedstock.
2. The method of reducing the volatile basic nitrogen content of a marine product of claim 1, wherein the volatile basic nitrogen content of the marine product process is reduced by at least 50% relative to the marine product feedstock.
3. The method of reducing the content of volatile basic nitrogen in a marine product of claim 1, wherein the content of volatile basic nitrogen in the marine product process is reduced to no more than 30mg/100 g.
4. The method for reducing the content of volatile basic nitrogen in aquatic products according to claim 1, wherein the first auxiliary agent is at least one of sodium bicarbonate and sodium hydroxide;
the aqueous solvent is at least one of water;
the second auxiliary agent is hydrogen chloride.
5. The method of claim 1, wherein the step of adjusting to alkaline pH adjusts the pH of the liquid phase to 8-9.
6. The method of reducing volatile basic nitrogen in aquatic products according to claim 1, wherein the vacuum heat treatment conditions are as follows: the heating temperature is 55-65 ℃, and/or the vacuum degree is-0.06 MPa-0.09 MPa, and/or the vacuum heating treatment time is 1-2 h.
7. A method of reducing the content of volatile salt-based nitrogen in marine product according to any one of claims 1 to 6, wherein the pH of the marine product process is ± 0.1 of the starting pH.
8. A method for reducing the content of volatile basic nitrogen in marine products according to any one of claims 1 to 6, wherein the step of adjusting the pH back further comprises adding water in an amount such that the difference between the solids content of the marine product raw material and the solids content of the processed marine product is not more than 5g/100g, preferably not more than 0.5g/100 g.
9. A method for reducing the content of volatile basic nitrogen in aquatic products is characterized by comprising the following steps:
providing an aquatic product raw material, wherein the content of volatile basic nitrogen in the aquatic product raw material is above a set threshold value, and the pH value of the aquatic product raw material is recorded as an initial pH;
mixing the aquatic product raw material, a first auxiliary agent and a proper amount of aqueous solvent, wherein the first auxiliary agent is an alkaline auxiliary agent, and adjusting the pH value of a liquid phase to 7-9 to prepare a first intermediate product;
carrying out vacuum heating treatment on the first intermediate product at 50-70 ℃ and-0.06-0.1 MPa, and controlling the duration of the vacuum heating treatment to enable the content of volatile basic nitrogen in the aquatic product intermediate product to be below a set threshold value so as to prepare a second intermediate product;
and mixing the second intermediate product with a second auxiliary agent, wherein the second auxiliary agent is an acidic auxiliary agent, and adjusting the pH value of the liquid phase to be +/-0.2 of the initial pH value to prepare the aquatic product processed product.
10. A processed aquatic product produced by the method according to any one of claims 1 to 9.
Technical Field
The invention relates to the technical field of food processing, in particular to a method for reducing the content of volatile basic nitrogen in aquatic products and an aquatic product processed product.
Background
In the process of processing and storing aquatic products, the aquatic products are easily rotten and deteriorated due to the influence of factors such as enzymes and microorganisms, and the freshness is reduced. In the putrefaction process, basic nitrogen-containing substances such as ammonia and amines are generated by decomposition of proteins, so that putrefaction and/or freshness of aquatic products are often reflected by the content of volatile basic nitrogen (TVBN), and a higher TVBN content indicates a more serious putrefaction and a lower freshness. The volatile basic nitrogen is a basic nitrogen-containing substance with stronger volatility, and the content of the volatile basic nitrogen can be calculated by adopting a standard acid titration method after the volatile basic nitrogen is evaporated in a basic solution. The method for measuring the content of volatile basic nitrogen can refer to GB 5009.228-2016 (national food safety Standard) for measuring volatile basic nitrogen in food, and the like. There are reports on methods for measuring the content of volatile basic nitrogen in aquatic products such as fish and shrimp.
The content of volatile basic nitrogen specified in the food standard GB 2733-.
In view of the foregoing background, it is desirable to provide a method for reducing the content of volatile basic nitrogen.
Disclosure of Invention
Based on the above background, one of the objectives of the present invention is to provide a method for reducing the content of volatile basic nitrogen in aquatic products, which can effectively reduce the content of volatile basic nitrogen in aquatic products to meet the food-related standards.
In a first aspect, the present invention provides a method for reducing the content of volatile basic nitrogen in aquatic products, comprising the steps of:
providing raw materials: providing an aquatic product raw material, wherein the aquatic product raw material contains volatile basic nitrogen, and the pH value of the aquatic product raw material is recorded as an initial pH;
adjustment to alkaline pH: mixing the aquatic product raw material, a first auxiliary agent and a proper amount of aqueous solvent, wherein the first auxiliary agent is an alkaline auxiliary agent, and adjusting the pH value of a liquid phase to 7-9 to prepare a first intermediate product;
vacuum heating: carrying out vacuum heating treatment on the first intermediate product for 20min to 4h under the conditions that the heating temperature is 50 ℃ to 70 ℃ and the vacuum degree is-0.06 MPa to-0.1 MPa, and preparing a second intermediate product;
and (4) adjusting the pH value: mixing the second intermediate product with a second auxiliary agent, wherein the second auxiliary agent is an acidic auxiliary agent, and adjusting the pH value of a liquid phase to be +/-0.2 of the initial pH value to prepare an aquatic product processed product;
the aquatic product process has a reduced content of volatile basic nitrogen relative to the aquatic product feedstock.
In some embodiments of the invention, the content of volatile salt-based nitrogen in the aquatic product process is reduced by at least 50%, preferably by at least 70%, more preferably by at least 80%, more preferably by at least 90% relative to the aquatic product feedstock.
In some embodiments of the invention, the content of volatile salt-based nitrogen in the seafood process is reduced to no more than 30mg/100 g.
In some embodiments of the present invention, the first auxiliary agent is at least one of sodium bicarbonate, sodium hydroxide, and the like; and/or the aqueous solvent is at least one of water and the like; and/or the second auxiliary agent is hydrogen chloride.
In some embodiments of the present invention, the first auxiliary agent is at least one of sodium bicarbonate, sodium hydroxide, and the like; the aqueous solvent is at least one of water and the like; the second auxiliary agent is hydrogen chloride.
In some embodiments of the present invention, in the step of adjusting to alkaline pH, the pH of the liquid phase is adjusted to 8-9.
In some embodiments of the invention, the vacuum heat treatment conditions are: the heating temperature is 55-65 ℃, and/or the vacuum degree is-0.06 MPa-0.09 MPa, and/or the vacuum heating treatment time is 1-2 h.
In some embodiments of the invention, the vacuum heat treatment conditions are: the heating temperature is 55-65 ℃, the vacuum degree is-0.06 MPa-0.09 MPa, and the vacuum heating treatment time is 1-2 h.
In some embodiments of the invention, the pH of the processed seafood is ± 0.1 of the starting pH.
In some embodiments of the present invention, the step of adjusting the pH further comprises adding water in an amount such that the difference between the solids content of the raw seafood and the solids content of the processed seafood is not more than 5g/100g, preferably not more than 0.5g/100 g.
In a second aspect, the present invention provides a method for reducing the content of volatile basic nitrogen in aquatic products, comprising the steps of:
providing an aquatic product raw material, wherein the content of volatile basic nitrogen in the aquatic product raw material is above a set threshold value, and the pH value of the aquatic product raw material is recorded as an initial pH;
mixing the aquatic product raw material, a first auxiliary agent and a proper amount of aqueous solvent, wherein the first auxiliary agent is an alkaline auxiliary agent, and adjusting the pH value of a liquid phase to 7-9 to prepare a first intermediate product;
carrying out vacuum heating treatment on the first intermediate product at 50-70 ℃ and-0.06-0.1 MPa, and controlling the duration of the vacuum heating treatment to reduce the content of volatile basic nitrogen in the aquatic product intermediate product to be below a set threshold value to prepare a second intermediate product;
and mixing the second intermediate product with a second auxiliary agent, wherein the second auxiliary agent is an acidic auxiliary agent, and adjusting the pH value of the liquid phase to be +/-0.2 of the initial pH value to prepare the aquatic product processed product.
In a third aspect, the invention provides a processed aquatic product produced by the method according to the first or second aspect.
The technical scheme provided by the invention at least comprises the following beneficial effects:
(1) the method for reducing the content of the volatile basic nitrogen of the aquatic products provided by the invention mainly utilizes a chemical means, converts the volatile basic nitrogen components (mainly ammonium ions) into an ammonia molecular form in an alkaline environment, and evaporates ammonia in a high-temperature environment to achieve the aim of removing the volatile basic nitrogen. The method can effectively reduce the content of volatile basic nitrogen in the aquatic product. Although the volatile basic nitrogen index (TVBN index) is an index reflecting the deterioration degree, the TVBN index is not a unique index, and the deterioration degree needs to be comprehensively judged by other indexes such as sensory evaluation; moreover, the high content of volatile basic nitrogen does not necessarily indicate that the putrefaction degree is necessarily high, because some products after enzymolysis and fermentation also have the characteristics of volatile basic nitrogen, and certain errors exist in reflecting the putrefaction degree by using the TVBN index. Therefore, if the food is judged to be not according to the TVBN index, a lot of food which can be safely eaten is judged to be unqualified, and the food is wasted. The method provided by the invention can provide technical reference for optimizing food comprehensive indexes and detection methods thereof.
(2) The invention provides a method for reducing the content of volatile basic nitrogen in aquatic products, which comprises the steps of constructing a system comprising a liquid phase, adjusting the pH of the liquid phase to be alkaline by adding an alkaline auxiliary agent, heating for deamination in vacuum, and then adding an acidic auxiliary agent to adjust back the pH of the liquid phase.
(3) The method for reducing the content of volatile basic nitrogen in the aquatic products provided by the invention adopts a low-temperature vacuum evaporation technology, can deaminate at a low temperature of 50-70 ℃ to reduce the TVBN content, can prevent loss of nutrient substances and generation of bad flavor at a high temperature, and can furthest retain the flavor, nutritional ingredients and the like of food.
(4) The invention provides another method for reducing the content of volatile basic nitrogen in an aquatic product, which can be referred to the method for reducing the content of volatile basic nitrogen in an aquatic product, can monitor the content of volatile basic nitrogen in an aquatic product intermediate product in a vacuum heating treatment step, and determines a proper threshold value according to the content index of volatile basic nitrogen so as to flexibly control the duration of the vacuum heating treatment.
(5) By adopting the method for reducing the content of volatile basic nitrogen in the aquatic products, the processed aquatic products (aquatic product processed products) can be obtained, and the volatile basic nitrogen in the aquatic products can be effectively removed or controlled.
Drawings
FIG. 1 is a line graph of the percent decrease in volatile basic nitrogen content using different pH conditions for the "adjust pH to basic" step of example 1;
FIG. 2 shows the results of the removal rate of volatile salt-based nitrogen under different experimental conditions in example 2.
Detailed Description
The method for reducing the content of volatile basic nitrogen in aquatic products and the processed aquatic product of the present invention will be described in further detail with reference to the following embodiments and examples. In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. It will be apparent, however, to one skilled in the art, that the present invention may be practiced without one or more of these specific details. These embodiments and examples are provided so that this disclosure will be thorough and complete. It should be understood that the present invention may be embodied in many different forms and is not limited to the embodiments and specific examples described herein. Rather, these embodiments and examples are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments and examples only and is not intended to be limiting of the invention.
Term(s) for
Unless otherwise stated or contradicted, terms or phrases used herein have the following meanings:
the term "and/or", "and/or" as used herein is intended to be inclusive of any one of the two or more items listed in association, and also to include any and all combinations of the items listed in association, including any two or more of the items listed in association, any more of the items listed in association, or all combinations of the items listed in association.
As used herein, "at least one of, and the like, includes any one, any two, or any more of the listed items, as well as all of the listed items.
As used herein, "a combination thereof," "any combination thereof," and the like, includes all suitable combinations of any two or more of the listed items.
In the present specification, the term "suitable" in "a suitable combination, a suitable manner," any suitable manner "and the like shall be construed to mean that the technical solution of the present invention can be implemented, the technical problem of the present invention can be solved, and the technical effect of the present invention can be achieved.
The terms "preferably", "preferably" and "preferably" are used herein only to describe preferred embodiments or examples, and it should be understood that the scope of the present invention is not limited by these terms. If multiple "preferences" are present in a claim, each "preference" is independent of the other "preferences" unless specifically stated otherwise, and there are no contradictory or limiting relationships or special indications to each other.
In the present invention, "optionally" and "optionally" refer to both being optional, that is, to either "having" or "not having" one of the two parallel schemes. If multiple optional items are present in a technical scheme, if no special description is provided, and no contradiction or mutual restriction or special indication exists, each optional item is independent.
In the present invention, the terms "first", "second", "third", "first auxiliary", "second auxiliary", etc. are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or quantity, nor as implying an importance or quantity indicating a technical feature indicated. Also, "first," "second," "third," etc. are for non-exhaustive enumeration and description purposes only and should not be construed as constituting a closed limitation to the number.
In the present invention, the numerical range is defined to include both end points of the numerical range unless otherwise specified. Including but not limited to the numerical intervals defined by "±".
The temperature parameter in the present invention is not particularly limited, and may be a constant temperature treatment or a treatment within a certain temperature range. The constant temperature process allows the temperature to fluctuate within the accuracy of the instrument control.
The percentage contents referred to in the present invention refer to wt% by mass for a solid-solid phase mixture, wt% by volume for a liquid-liquid phase mixture (v/v), wt% by mass or wt% solid-liquid for a solid-liquid mixture (w/v), unless otherwise specified.
Aquatic products including, but not limited to, fish, shrimp, crab, shellfish, and the like.
The aquatic product raw material can be food materials, semi-finished products, edible finished products and other different forms, and is within the meaning range of the aquatic product raw material as long as volatile basic nitrogen can be generated due to corruption. Examples of raw materials for seafood include, but are not limited to, fresh (frozen) meat from which skin, fat, bone, and tendons are removed and lean meat is obtained, fresh (frozen) seafood and seafood from which skin, head, viscera, and bone spurs are removed and edible parts are obtained and ground and homogenized. The finished product can be directly minced and stirred evenly. The meat paste, meat powder, dried meat floss, fish meal, dried fish floss and liquid sample can be directly used for standby.
In the "low-temperature vacuum evaporation technology", the low temperature is 50 ℃ to 70 ℃ relative to the high temperature condition of 90 ℃ to 100 ℃. The low-temperature vacuum evaporation technology is used in the application to realize deamination and reduce the content of volatile basic nitrogen in the raw material. Traditional deamination usually needs to be carried out under the high temperature condition of 90-100 ℃. The low-temperature vacuum evaporation technique in the present application can be carried out at a low temperature of 50 ℃ to 70 ℃ and is advantageous for maintaining the quality of food materials in terms of flavor, texture, nutrition, and the like.
In the present invention, "normal temperature" mainly means that no temperature control means is applied, and if not otherwise stated, it is preferably 20 to 35 ℃.
In the present invention, the "degree of vacuum" is expressed by a relative pressure with respect to a standard atmospheric pressure, and is expressed by a negative value, and the larger the absolute value thereof, the larger the degree of vacuum, the smaller the absolute pressure. For example, a vacuum of-0.09 MPa corresponds to an absolute pressure equal to the standard atmospheric pressure minus 0.09 MPa.
Deammoniation, which refers to the reduction of volatile nitrogen-containing components in the system. The deamination referred to in this application is primarily to reduce the volatile basic nitrogen content of the system by means including, but not limited to, removing ammonia gas to indirectly reduce the TVBN content, and directly removing TVBN to reduce its content.
The content of volatile basic nitrogen, also denoted as TVBN content or TVBN value in the present invention, is defined as: mass of volatile basic nitrogen per 100 grams of sample. For liquid samples, the sample weight can be directly weighed. For solid samples, it is preferred to weigh the sample after mincing, homogenizing, filtering with gauze.
In the invention, the meaning of removing TVBN and reducing TVBN content are the same, and the TVBN can be used interchangeably. The references to "removing" and "reducing" include complete removal (reduced to no residue) and incomplete removal (residue remaining after reduction).
The food standards related to the present invention, including but not limited to food quality standards, food safety standards, food processing standards, and other food-related standards, may be international standards, national standards, local standards, industry standards, published enterprise standards, and may be other standards recognized by those skilled in the art.
The raw materials of the first auxiliary agent, the second auxiliary agent, the water-based solvent and the like in the invention adopt raw materials meeting food safety specifications.
In the present invention, the technical features described in the open type include a closed technical solution composed of the listed features, and also include an open technical solution including the listed features.
In a first aspect, the present invention provides a method for reducing the content of volatile basic nitrogen in aquatic products, comprising the steps of:
s100 (providing raw materials): providing a raw aquatic product material, wherein the raw aquatic product material contains volatile basic nitrogen, and the pH value of the raw aquatic product material is recorded as an initial pH;
s110 (adjusted to basic pH): mixing the aquatic product raw material, a first auxiliary agent and a proper amount of aqueous solvent, wherein the first auxiliary agent is an alkaline auxiliary agent, and adjusting the pH value of a liquid phase to 7-9 to prepare a first intermediate product;
s120 (vacuum heating): carrying out vacuum heating treatment on the first intermediate product for 20min to 4h under the conditions that the heating temperature is 50 ℃ to 70 ℃ and the vacuum degree is-0.06 MPa to-0.1 MPa, and preparing a second intermediate product;
s130 (pH adjustment): mixing the second intermediate product with a second auxiliary agent, wherein the second auxiliary agent is an acidic auxiliary agent, and adjusting the pH value of a liquid phase to be +/-0.2 of the initial pH value to prepare an aquatic product processed product;
the aquatic product process has a reduced content of volatile basic nitrogen relative to the aquatic product feedstock.
The method provided by the first aspect of the invention can effectively reduce the content of volatile basic nitrogen in the aquatic product.
The principle of reducing the content of volatile basic nitrogen in aquatic products in the invention is as follows: in a neutral environment, the following dynamic chemical equilibria exist in the food product:in an acidic environment, the equilibrium tends to shift to the left, and the basic nitrogen is generally present as ammonium ions, and thusIt is difficult to completely remove it using conventional methods; in the alkaline environment, the basic nitrogen can exist in the form of ammonia molecules, and the generated ammonia can be evaporated in the form of gas through heating treatment, so that the whole chemical balance is shifted to the right, and the aim of gradually reducing the volatile basic nitrogen is fulfilled. And the vacuum heating treatment in the step S120 is low-temperature vacuum heating treatment. Taking aquatic products as an example, the raw materials of the aquatic products are easy to change in aspects of fragrance, texture and the like in the heating process, so the raw materials of the aquatic products can be deaminated at the low temperature of 50-70 ℃ through low-temperature vacuum heating treatment, and the stability of the raw materials of the aquatic products in aspects of flavor, texture, nutrition and the like can be ensured; the 120 steps can also be recorded as a low-temperature vacuum heating step and a vacuum deamination step. It should be noted that, by using low-temperature vacuum heating, ammonia gas can be distilled out to remove ammonia, and the content of volatile basic nitrogen is reduced, but it is not excluded that volatile basic nitrogen components are directly volatilized, that is, distilled out and/or volatilized components in the S120 low-temperature vacuum heating step, including but not limited to ammonia gas and TVBN components.
In the method for reducing the content of volatile basic nitrogen in the aquatic product, the pH value control before and after the low-temperature vacuum heating treatment can be realized by adding a first auxiliary agent and a second auxiliary agent, wherein the first auxiliary agent and the second auxiliary agent are both pH regulators. The first auxiliary agent is an alkaline auxiliary agent and is used for adjusting the environment of the aquatic product raw material to be alkaline, so that subsequent low-temperature vacuum heating treatment is facilitated. The second auxiliary agent is an acidic auxiliary agent and is used for adjusting the pH value back after the low-temperature vacuum heating treatment so as to better maintain the flavor, texture, nutrition and other properties of the raw materials.
In some embodiments of the invention, the first aid and the second aid are each independently preferably approved substances for use in food processing, and the respective standard may be an international standard, a national standard, a local standard, an industry standard, a published enterprise standard, or other standard recognized by one skilled in the art.
In some preferred embodiments of the invention, the first aid and the second aid, each independently, preferably do not introduce other material constituents into the seafood process (no introduction of other material constituents, meaning no introduction of new elements as a whole).
In some preferred embodiments of the present invention, the first auxiliary agent is at least one of sodium bicarbonate, sodium hydroxide, and the like; and/or the second auxiliary agent is hydrogen chloride. Sodium ions and chloride ions are one of metal elements of the edible salt, and bicarbonate radical and hydroxyl radical can be converted into water without introducing new elements into raw materials of aquatic products.
In some preferred embodiments of the present invention, the first auxiliary agent is at least one of sodium bicarbonate, sodium hydroxide, and the like, and the second auxiliary agent is hydrogen chloride.
S100: providing raw materials of aquatic products.
S100 (providing raw materials): providing a raw aquatic product material, wherein the raw aquatic product material contains volatile basic nitrogen, and the pH value of the raw aquatic product material is recorded as an initial pH.
The aquatic product raw material can be food materials, semi-finished products, edible finished products and other different forms, and is within the meaning range of the aquatic product raw material.
When aquatic products are rotten, proteins are decomposed to generate basic nitrogen-containing substances such as ammonia and amines, and therefore, the volatile basic nitrogen mainly includes components such as primary amines, secondary amines, and tertiary amines.
In some preferred embodiments of the invention, the aquatic products include, but are not limited to, fish, shrimp, crab, and the like. The indicators of the content of volatile basic nitrogen in food products from different sources vary.
When the content of volatile basic nitrogen in the raw material of the aquatic product is high, the content of volatile basic nitrogen can be effectively reduced by adopting the aspect provided by the first aspect.
In some embodiments of the invention, the amount of volatile basic nitrogen in the aquatic product feedstock does not exceed a set threshold; the set threshold value preferably does not exceed a specified value in a food-related standard. In some preferred embodiments of the invention, the set threshold is preferably a defined value in a food-related standard.
In some embodiments of the invention, the content of volatile basic nitrogen in the seafood stock exceeds food-related standards.
In some embodiments of the invention, the amount of volatile basic nitrogen in the seafood stock exceeds the specified value in the food-related standards, for example GB 2733-.
In some embodiments of the invention, the aquatic product feedstock has a volatile basic nitrogen content of greater than 30mg/100 g.
In some embodiments of the invention, the aquatic product feedstock has a volatile basic nitrogen content of greater than 25mg/100 g.
In some embodiments of the invention, the aquatic product feedstock has a volatile basic nitrogen content of greater than 20mg/100 g.
In some embodiments of the invention, the aquatic product feedstock has a volatile basic nitrogen content of greater than 15mg/100 g.
The pH value of the aquatic product raw material can be measured by adopting methods such as a pH meter or pH test paper.
The pH value of the aquatic product raw material varies with the species of animal source, and may be related to the animal part.
The form of the animal food material is not particularly limited, but is preferably a meat paste.
S110: adjusting pH and providing alkaline environment.
S110 (adjusted to basic pH): mixing the aquatic product raw material, a first auxiliary agent and a proper amount of aqueous solvent, wherein the first auxiliary agent is an alkaline auxiliary agent, adjusting the pH value of a liquid phase to 7-9 (preferably pH 7.5-9, more preferably pH 8-9), and preparing a first intermediate product.
The first auxiliary agent is an alkaline auxiliary agent and is used for adjusting the environment of the aquatic product raw material to be alkaline, so that subsequent low-temperature vacuum heating treatment is facilitated.
In some preferred embodiments of the present invention, the first auxiliary agent is at least one of sodium bicarbonate, sodium hydroxide, and the like, and may be one of the ingredients or any suitable combination of the listed ingredients.
The proper amount of the aqueous solvent is determined by the principle that the aqueous solvent can be optionally added, can be added or not added, and is beneficial to removing volatile salt-based nitrogen. If the raw materials of the aquatic products originally contain enough free water, the water-based solvent is not required to be added. If the content of free water in the raw materials of the aquatic products is low and is not enough to evaporate volatile components such as ammonia gas, an aqueous solvent is necessary to be added to assist in evaporating the volatile components.
The aqueous solvent contains at least water, and other solvents are permissible, but solvents other than water are preferable in order not to adversely affect the properties of the processed marine product in terms of flavor, texture, nutrition, and the like, and further, the solvent components originally present in the raw marine product are preferable.
In some preferred embodiments of the present invention, the aqueous solvent preferably does not introduce other material constituents into the processed seafood.
In some embodiments of the invention, the aqueous solvent is water.
The liquid phase in the system can be ensured by controlling the using amount of the aqueous solvent, so that the pH can be controlled by controlling the pH value of the liquid phase. Volatile basic nitrogen in the raw materials of the aquatic products is dissolved in a liquid phase, and ammonia gas can be evaporated out after low-temperature vacuum heating treatment, so that the chemical balance is shifted to the right, and the volatile basic nitrogen in the raw materials is continuously dissolved in the liquid phase and deamination is removed.
In the step S110, the pH value of the liquid phase is preferably 7-9. Under alkaline conditions, the higher the pH, the easier the chemical equilibrium described above shifts to the right and the easier the volatile basic nitrogen is removed. (too high a pH will result in waste of material and it is not necessary to adjust to too high a pH).
In some embodiments of the present invention, the pH of the liquid phase is 7.5 to 9, preferably 8 to 9.
In some embodiments of the invention, in the step of adjusting to basic pH, the pH of the liquid phase is adjusted to pH7.2, pH7.4, pH7.5, pH7.6, pH7.8, pH8.0, pH8.2, pH8.4, pH8.5, pH8.6, pH8.8, pH 9.0.
In some embodiments of the present invention, the raw material for aquatic products is in the form of meat paste, and in the step S110, a first treatment solution is formed by a first auxiliary agent and an appropriate amount of an aqueous solvent, and the raw material is immersed in the first treatment solution, and the content of the first auxiliary agent is adjusted to adjust the pH of the liquid phase to 7 to 9 (preferably, pH7.5 to 9, and more preferably, pH8 to 9).
S120: low-temperature vacuum heating treatment is carried out to reduce the content of volatile basic nitrogen.
S120 (low temperature vacuum heating): and carrying out vacuum heating treatment on the first intermediate product for 20min to 4h under the conditions that the heating temperature is 50 ℃ to 70 ℃ and the vacuum degree is-0.06 MPa to-0.1 MPa, and preparing a second intermediate product.
By controlling a certain vacuum degree, deamination can be carried out at a lower temperature of 50-70 ℃, and the stability of the flavor, texture, nutrition and the like of the aquatic raw materials can be ensured. Further controlling the duration of the vacuum heating treatment can control the removal degree of the volatile basic nitrogen. After the low-temperature vacuum heating treatment, the content of volatile basic nitrogen in the system is reduced.
Examples of the heating temperature include, but are not limited to, 50 ℃, 55 ℃, 60 ℃, 65 ℃, 70 ℃, 55 ℃ to 65 ℃, 55 ℃ to 60 ℃, 50 ℃ to 65 ℃, 50 ℃ to 60 ℃, and 50 ℃ to 55 ℃.
Examples of vacuum include, but are not limited to, -0.06MPa, -0.07MPa, -0.08MPa, -0.09MPa, -0.1MPa, -0.07 MPa-0.09 MPa, -0.08 MPa-0.1 MPa, -0.08 MPa-0.09 MPa, -0.06 MPa-0.08 MPa, -0.06MPa, -0.06 MPa-0.07 MPa.
Examples of the vacuum heat treatment time include, but are not limited to, 20min, 30min, 40min, 50min, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 20min to 60min, 20min to 4h, 30min to 2h, and 1h to 2 h.
In some preferred embodiments of the invention, the heating temperature is from 55 ℃ to 70 ℃, more preferably 55 ℃.
In some preferred embodiments of the invention, the heating temperature is from 55 ℃ to 65 ℃, more preferably 60 ℃ (as shown in example 2).
In some preferred embodiments of the invention, the vacuum is between-0.06 MPa and-0.09 MPa.
In some preferred embodiments of the invention, the vacuum is between-0.07 MPa and-0.1 MPa.
In some preferred embodiments of the invention, the vacuum is-0.09 MPa.
In some preferred embodiments of the present invention, the vacuum heat treatment time is 30min to 3 hours, more preferably 1 hour to 3 hours, and more preferably 1 hour to 2 hours.
The technical features may be combined in any suitable manner, as exemplified below.
In some preferred embodiments of the present invention, the vacuum heat treatment conditions are: the heating temperature is 55-70 ℃, and/or the vacuum degree is-0.06 MPa to-0.1 MPa, and/or the vacuum heating treatment time is 30 min-2 h.
In some preferred embodiments of the present invention, the vacuum heat treatment conditions are: the heating temperature is 55-65 ℃, and/or the vacuum degree is-0.06 MPa to-0.09 MPa (preferably-0.07 MPa to-0.09 MPa), and/or the vacuum heating treatment time is 1-2 h.
In some preferred embodiments of the present invention, the vacuum heat treatment conditions are: the heating temperature is 55-65 ℃, the vacuum degree is-0.06 MPa to-0.09 MPa (preferably-0.07 MPa to-0.09 MPa), and the vacuum heating treatment time is 1-2 h.
In some preferred embodiments of the present invention, the vacuum heat treatment conditions are: the heating temperature is 60 ℃, the vacuum degree is-0.09 MPa, and the vacuum heating treatment time is 2 h.
S130: and (5) adjusting the pH value.
The step 130: and adding a second auxiliary agent into the second intermediate product to prepare an aquatic product processed product, wherein the pH value of the aquatic product processed product is 7-9, and the second auxiliary agent is an acidic auxiliary agent.
The purpose of the step of adjusting the pH back is to adjust the pH value of the aquatic product processed product to be basically consistent with the pH value of the aquatic product raw material. This is to better maintain the flavor, texture, nutritional, etc. properties of the raw materials. The pH value between the pH value (initial pH) of the raw aquatic product and the pH value of the processed aquatic product is not particularly limited.
In some preferred embodiments of the invention, the pH of the processed seafood is ± 0.2 of the starting pH, more preferably ± 0.1 of the starting pH.
The second auxiliary agent is an acidic auxiliary agent and is used for adjusting the pH value back after low-temperature vacuum heating treatment so as to better maintain the properties of the raw materials in aspects of flavor, texture, nutrition and the like.
In some preferred embodiments of the present invention, the second auxiliary agent is hydrogen chloride.
After the pH is adjusted back, a processed aquatic product from which volatile basic nitrogen is removed can be obtained. The TVBN content is regulated in food standard GB 2733-: sea water fish and shrimp is less than or equal to 30mg/100g, sea crab is less than or equal to 25mg/100g, fresh water fish and shrimp is less than or equal to 20mg/100g, and frozen shellfish is less than or equal to 15mg/100 g. Therefore, for the different types of aquatic products, the TVBN content is preferably reduced to the above-described index range, that is, the TVBN content in the processed aquatic product is preferably controlled to be within the above-described index range.
In some embodiments of the invention, the TVBN content in the processed seafood is reduced to no more than 30mg/100g, more preferably no more than 25mg/100g, more preferably no more than 20mg/100g, more preferably no more than 15mg/100 g.
In one embodiment of the invention, the volatile basic nitrogen in the aquatic product raw material is reduced from 310mg/100g to 26mg/100g by more than 90%.
In one embodiment of the invention, the volatile basic nitrogen in the aquatic product raw material can be reduced to below 20mg/100g (reduced by more than 85%) from 173mg/100g, and can also be reduced to 16mg/100g (TVBN removal rate is more than 90%).
In some preferred embodiments of the invention, the TVBN content in the seafood stock is reduced by 12.26%, 52.58% or 91.61% from 310mg/100g
In some preferred embodiments of the invention, the TVBN content in the processed seafood is reduced to 16mg/100g to 25mg/100 g.
In some embodiments of the present invention, the volatile salt-based nitrogen content (TVBN content or TVBN value) in the aquatic product process is reduced by at least 50%, preferably by at least 70%, more preferably by at least 75%, more preferably by at least 80%, more preferably by at least 85%, more preferably by at least 90% relative to the aquatic product feedstock.
In some embodiments of the invention, the TVBN content of the aquatic product feedstock is greater than 300mg/100g, and the TVBN content of the aquatic product process is reduced by at least 80%, preferably by at least 90%, relative to the aquatic product feedstock.
In order to ensure that the properties of the aquatic products such as flavor, texture, nutrition and the like are basically stable before and after the low-temperature vacuum heating treatment, the changes of physicochemical indexes such as salt, amino acid nitrogen, volatile basic nitrogen, pH, total acid, total solid and the like can be compared.
The sample preparation method can adopt the existing standard. For example, the solid sample can be stirred up by a stirrer to be homogenized, and then is weighed after being filtered by gauze; the liquid sample can be directly weighed. For example, the sample preparation method of part 5.2 of GB 5009.228-2016 (determination of volatile basic nitrogen in national food safety standards) can be adopted.
Volatile basic nitrogen may be measured by or with reference to GB 5009.228-2016. The pH can be measured by a pH meter or a pH strip. The salt content, total acid content, amino acid nitrogen content and salt-free solid content can be determined by the method described in SB/T11191-2017. The total solid content can be calculated by taking X + X according to the formula of the salt-free solid in 5.2.4 in SB/T11191-once 20171The value is obtained.
In order to maintain the stability of the solid content before and after the low-temperature vacuum heating treatment, in the step S130, an appropriate amount of water may be added to the second intermediate product in addition to the second auxiliary agent. The appropriate amount of water is that whether water is added or not is optional, and water can be added or not, so that the solid content of the aquatic product raw material and the aquatic product processed product is basically stable.
In some embodiments of the invention, the step of adding a second auxiliary agent to the second intermediate product to produce a processed seafood product further comprises adding an amount of water such that the difference between the solids content of the seafood raw material and the solids content of the processed seafood product is not more than 5g/100 g. The difference is further preferably not more than 1g/100g, more preferably not more than 0.8g/100g, more preferably not more than 0.7g/100g, more preferably not more than 0.5g/100g, more preferably not more than 0.4g/100 g.
In one embodiment of the present invention, the difference between the solid content of the raw aquatic product and the solid content of the processed aquatic product is 0.62g/100g, 0.49g/100g, or 0.36g/100 g.
In a second aspect, the present invention provides a method for reducing the content of volatile basic nitrogen in aquatic products, comprising the steps of:
providing an aquatic product raw material, wherein the content of volatile basic nitrogen in the aquatic product raw material is above a set threshold value, and the pH value of the aquatic product raw material is recorded as an initial pH;
mixing the aquatic product raw material, a first auxiliary agent and a proper amount of aqueous solvent, wherein the first auxiliary agent is an alkaline auxiliary agent, adjusting the pH value of a liquid phase to 7-9 (for a preferable example, 7.5-9 is preferable, and 8-9 is more preferable), and preparing a first intermediate product;
carrying out vacuum heating treatment on the first intermediate product at 50-70 ℃ and-0.06-0.1 MPa, and controlling the treatment time to enable the content of volatile basic nitrogen in the aquatic product intermediate product to be below a set threshold value so as to prepare a second intermediate product;
and mixing the second intermediate product with a second auxiliary agent, wherein the second auxiliary agent is an acidic auxiliary agent, and adjusting the pH value of the liquid phase to be +/-0.2 of the initial pH value to prepare the aquatic product processed product.
The set threshold may be a predetermined value in a food standard, or may be selected to be equal to or lower than the predetermined value in the food standard. Reference can be made to the index value of the food standard GB 2733-.
The content of volatile basic nitrogen in the aquatic product intermediate product can be determined by referring to the method for determining TVBN in the aquatic product raw material and the aquatic product processed product.
The definitions, examples, preferences, combinations and the like of the features of the second aspect cover the definitions, examples, preferences, combinations and the like of the rest of the invention.
In a third aspect, the invention provides a processed aquatic product produced by the method according to the first or second aspect.
The following are specific examples.
Experimental parameters not described in the following specific examples, preferably with reference to the guidelines given in the present application, may also be referred to in the art experimental manuals, food standards (including but not limited to food processing standards) or other experimental methods known in the art, or to the manufacturer's recommended experimental conditions.
The starting materials and reagents referred to in the following specific examples are either commercially available or known to those skilled in the art how to obtain or prepare them.
Testing indexes are as follows: volatile basic nitrogen, pH, salt, amino acid nitrogen, total acid, total solid and other indexes.
1. Volatile basic nitrogen determination
The sample is stirred by a stirrer to be uniform, and the liquid sample can be directly weighed.
Weighing 10g of sample, accurately weighing to 0.005g, adding 75mL of water into a distillation tube, shaking to uniformly disperse the sample in the sample solution, and soaking for 30 min. After the instrument is cleaned, 75mL of water is added into a distillation tube, reagent blank measurement is carried out to obtain a blank value, 1g of magnesium oxide is added into the distillation tube filled with the processed sample, the distillation tube is immediately connected to a distiller for distillation, an automatic potentiometric titrator sets the titration end point pH to be 4.65, and the volume of the consumed sulfuric acid standard solution is recorded.
The following examples were measured according to "automatic Kjeldahl method" 11 of GB 5009.228-2016.
2. Determination of pH
The sample is stirred by a stirrer to be even and uniform, and the pH value is measured by a pH meter after being filtered by a gauze. The liquid sample can be measured directly.
3. Salinity determination
The sample is stirred by a stirrer to be uniform, the homogenate is weighed after being filtered by a gauze, and the liquid sample can be directly weighed.
Weighing 5g (accurate to +/-0.005 g) of sample, placing in a 100mL beaker, adding 50mL of water, fully stirring and dissolving, transferring into a 100mL volumetric flask, washing the beaker with a small amount of water in a plurality of times, merging the washing liquid into the volumetric flask, adding water to the scale, and mixing uniformly. Sucking 2.0mL of the diluent into a conical flask of 150-200 mL, adding 100mL of water and 1mL of potassium chromate solution (50g/L), mixing uniformly, and titrating with silver nitrate standard solution (0.100mol/L) until orange red appears.
The following specific examples were tested according to 5.2.3 "edible salt" in SB/T11191-2017.
4. Measurement of Total acid and amino acid Nitrogen
The sample is stirred by a stirrer to be uniform, the homogenate is weighed after being filtered by a gauze, and the liquid sample can be directly weighed.
Weighing 5g (accurate to +/-0.005 g) of sample, placing the sample in a 100mL beaker, adding 50mL of water, fully stirring and dissolving, transferring the sample into a 100mL volumetric flask, washing the beaker with a small amount of water in a fractional manner, adding the washing liquid into the volumetric flask, adding water to a scale, uniformly mixing, absorbing 20mL of the sample, adding 60mL of water into a 200mL beaker, titrating the mixture to the pH value of 8.2 by using a sodium hydroxide standard solution (0.050mol/L) by using an automatic potentiometric titrator, recording the number of milliliters of the consumed sodium hydroxide standard solution, and calculating the total acid content.
Adding 10mL of formaldehyde solution, uniformly mixing, titrating with a sodium hydroxide standard solution (0.050mol/L) until the pH value is 9.2, recording the number of milliliters of the sodium hydroxide standard solution consumed, and calculating the content of amino acid nitrogen.
And simultaneously, 80mL of water is taken, firstly, sodium hydroxide standard solution (0.050mol/L) is used for titration until the pH value is 8.2, then 10mL of formaldehyde solution is added, after uniform mixing, the sodium hydroxide standard solution (0.050mol/L) is used for titration until the pH value is 9.2, and a reagent blank test is carried out.
The following specific examples were measured according to 5.2.2 "total acid" and 5.2.1 "amino nitrogen" in SB/T11191-2017.
5. Determination of Total solid content
Sea sand: the sea sand or river sand washed with water to remove mud is taken, boiled with 6mol/L hydrochloric acid for 0.5h, washed with water to be neutral, boiled with 6mol/L sodium hydroxide solution for 0.5h, washed with water to be neutral and dried at 105 ℃ for later use.
Taking a clean evaporating dish, adding 100g of sea sand and a small glass rod into the evaporating dish, placing the evaporating dish in a drying box at the temperature of 95-105 ℃, taking out the evaporating dish after drying for 0.5-1.0 h, placing the evaporating dish in a dryer for cooling for 0.5h, weighing the evaporating dish, and repeatedly drying the evaporating dish to a constant weight. And precisely weighing 1g to 2g of sample, placing the sample in an evaporating dish, uniformly stirring the sample by using a small glass rod, placing the sample in a boiling water bath for drying by distillation, stirring the sample at any time, wiping off water drops at the bottom of the dish, placing the dish in a drying box at 95 ℃ to 105 ℃ for drying for 4 hours, covering the dish, taking the dish out, placing the dish in the drying box for cooling for 0.5 hour, and weighing the dish.
Then putting the mixture into a drying oven with the temperature of 95-105 ℃ for drying for 1h, taking the dried mixture out, putting the dried mixture into a dryer for cooling for 0.5h, and weighing the cooled mixture. The difference between the two masses is not more than 2mg, namely the constant mass. The total solids content was calculated as follows:
in the formula:
x-total solids in grams per hundred grams (g/100 g);
m1-mass in grams (g) of evaporating dish plus sea sand and glass rod;
m2-evaporating dish with sea sand, glass rod and sample mass before drying, in grams (g);
m3the mass of the evaporation dish after the addition of the sea sand, the glass rod and the sample have been dried, in grams (g).
The calculation results retain three significant digits.
Example 1 river shrimp was used as raw material for aquatic products
1.1. Raw material parameter determination
The method is characterized in that food materials of fresh shrimps which are placed for 2 days at normal temperature are taken as raw materials, the storage period of the raw materials at normal temperature is usually 0.5 day, and after the storage period, the phenomenon that volatile basic nitrogen exceeds the standard can occur, so that the fresh shrimps cannot be eaten. As raw materials of aquatic products, indexes such as volatile basic nitrogen, pH, salt, amino acid nitrogen, total acid, total solid and the like are measured by adopting the method. The results are shown in Table 1 as "raw materials". Where the starting pH was 4.67 (note that the starting pH was material dependent).
1.2. Providing raw materials of aquatic products: taking 20 g of shrimp raw material, and carrying out shelling, pulping and crushing treatment to obtain an aquatic product raw material for later use. The raw material of the aquatic product is in a solid-liquid mixed state comprising a liquid phase.
1.3. Adjusting the pH to be alkaline: taking the aquatic product raw materials prepared in the step 1.2, and dividing the raw materials into four groups, wherein the three groups are respectively added with a proper amount of sodium bicarbonate as an alkaline auxiliary agent (first auxiliary agent) to enable the pH of a liquid phase to respectively reach the pH of 7, 8 and 9, and the pH respectively corresponds to E1-1, E1-2 and E1-3; the other group of raw materials to be treated is used as a blank control group E1C without adding an alkaline assistant. Four groups of intermediate products with the pH value adjusted in advance are obtained for later use.
1.4. Vacuum deamination (low temperature vacuum heating): and (3) respectively carrying out low-temperature vacuum heating treatment on the intermediate product with the pre-adjusted pH value obtained in the step (1.3) under the deamination pH conditions of pH 4.67, pH7, pH8 and pH9, adjusting the vacuum degree of a pressure gauge to be-0.09 MPa, setting the temperature to be 50 ℃ and setting the treatment time to be 1.5 h. Four groups of intermediate products subjected to low-temperature vacuum heating treatment are obtained for later use.
1.5 pH Regulation: adding hydrogen chloride into the intermediate product obtained in the step 1.4 and subjected to low-temperature vacuum heating treatment, and adjusting the pH to the liquid phase pH to the initial pH (controlled within the range of +/-0.1). Obtaining an intermediate product with the adjusted pH value.
1.6. And (5) appropriately replenishing water to the intermediate product with the adjusted pH value obtained in the step (1.5) according to the change condition of physical and chemical indexes, and recovering the original solid content (controlled within the range of +/-0.5 g/100g) to obtain a processed product. Volatile base-based nitrogen indicators were determined for each of the groups of processed products, with the results for groups E1-3 shown in Table 1 as "processed products".
Table 1 shows the change of physicochemical indexes before and after treatment in E1-3 groups at pH9 of vacuum deamination.
Detection time point
pH
Total solids (g/100g)
Volatile basic nitrogen (mg/100g)
Percentage reduction of basic nitrogen
Raw materials
4.67
11.5
310
/
Processed product
4.65
11.5
26
91.6％
According to the comparison of physicochemical indexes of the aquatic product raw material and the processed product before and after the low-temperature vacuum heating treatment in table 1, it can be seen that the content of volatile basic nitrogen can be significantly reduced by starting from the aquatic product raw material, performing deamination by pre-adjusting the pH to alkalinity, performing low-temperature vacuum heating, adjusting the pH back, and replenishing water to obtain the processed product. In addition, the detection results of all indexes also show that parameters such as total solid, amino acid nitrogen, total acid, salt, pH and the like are basically kept unchanged, namely, the TVBN content can be effectively reduced under the condition of maintaining the quality in aspects such as flavor, texture, nutrition and the like.
The removal of TVBN when different pH conditions (pH 4.67, pH7, pH8, pH9) were used in the vacuum deamination step is shown in FIG. 1 and Table 2. It can be seen that in the vacuum deamination step, when the pH is acidic, the deamination efficiency is extremely poor, and when the pH is 7, a certain degree of deamination can be realized, but the deamination efficiency is less than 20%, and the deamination efficiency can exceed 90% in the range of pH 8-pH 9.
Table 2. feed to working stock TVBN content versus deamination pH.
Example 2 river crab as raw material for aquatic products
Taking food materials of fresh river crabs which are placed for 2 days at normal temperature as raw materials. As a raw material of an aquatic product, the content of volatile basic nitrogen was measured in the above manner, and the result was 173mg/100 g.
1.2. Providing raw materials of aquatic products: taking 20 g of river crab raw materials, and carrying out shelling, pulping and crushing treatment to obtain aquatic product raw materials for later use. The raw material of the aquatic product is in a solid-liquid mixed state comprising a liquid phase.
1.3. Adjusting the pH to be alkaline: taking the river crab raw material prepared in the step 1.2, respectively adding a proper amount of sodium bicarbonate as an alkaline auxiliary agent (first auxiliary agent), and adjusting the pH of a liquid phase according to the table 3 (corresponding to the deamination pH in the table 3) to obtain an intermediate product with the pH being adjusted in advance for later use.
1.4. Vacuum deamination (low temperature vacuum heating): and (3) respectively carrying out low-temperature vacuum heating treatment on the intermediate products with the pre-adjusted pH values obtained in the step (1.3) under the deamination pH condition shown in the table 3, and adjusting the vacuum degree, the heating temperature and the heating time of a pressure gauge according to the table 3. Obtaining the intermediate product after low-temperature vacuum heating treatment for later use.
1.5 pH Regulation: adding hydrogen chloride into the intermediate product obtained in the step 1.4 and subjected to low-temperature vacuum heating treatment, and adjusting the pH to the liquid phase pH to the initial pH (controlled within the range of +/-0.2). Obtaining an intermediate product with the adjusted pH value.
1.6. And (5) appropriately replenishing water to the intermediate product with the adjusted pH value obtained in the step (1.5) according to the change condition of physical and chemical indexes, and recovering the original solid content (controlled within the range of +/-0.5 g/100g) to obtain a processed product. The volatile basic nitrogen index was measured for each group of processed products, and the results are shown in table 4.
TABLE 3 different treatment parameters for Experimental examples E2-1 to E2-18
Examples of the experiments
pH of deamination
Degree of vacuum
Temperature of
Duration of time
E2-1
pH8.5
-0.09MPa
40℃
0.5h
E2-2
pH8.5
-0.08MPa
40℃
0.5h
E2-3
pH8.5
-0.06MPa
40℃
0.5h
E2-4
pH8.5
Atmospheric pressure
40℃
0.5h
E2-5
pH8
-0.08MPa
50℃
2h
E2-6
pH8
-0.08MPa
60℃
2h
E2-9
pH8
-0.08MPa
70℃
2h
E2-10
pH8
-0.08MPa
40℃
2h
E2-11
pH8
-0.08MPa
80℃
2h
E2-12
pH8
-0.08MPa
Boiling of water
2h
E2-13
pH8
Atmospheric pressure
Boiling of water
2h
E2-14
pH7.5
-0.06MPa
70℃
1h
E2-15
pH7.5
-0.06MPa
70℃
2h
E2-16
pH7.5
-0.06MPa
70℃
4h
E2-17
pH7.5
-0.06MPa
70℃
0.5h
E2-18
pH10
-0.08MPa
40℃
0.5h
The variation of the volatile basic nitrogen content in each of the above experimental groups according to the experimental parameters of table 2 is shown in table 4 below. As can be seen from the experimental results of E2-1 to E2-4 in Table 4, TVBN is removed by only 32.95% under normal pressure, and the removal effect is more remarkable as the vacuum degree is higher. From the experimental results of E2-5 to E2-13 in Table 4, it can be seen that the TVBN removal rate is 90% or more at a temperature of 60 ℃ to boiling (about 100 ℃), 85% or more at a temperature of 50 ℃ and 72.25% at a temperature of 40 ℃. From the experimental results of E2-14 to E2-17 in Table 4, it can be seen that the TVBN removal rate reaches 64.16% when the treatment time is 0.5h, about 85% of TVBN removal rate when the treatment time is 1h, about 90% of TVBN removal rate when the treatment time is 2h, 4 h.
As can be seen from the experimental results of E2-18 in table 4, the TVBN removal rate of 90% or more was also achieved at pH10, but at higher pH values, some nutrients such as proteins and saccharides in the aquatic product may be hydrolyzed, and flavor, texture, nutrients and the like in the food material may be destroyed, so it is preferable to control the pH to 7 to 9 (preferably pH7.5 to 9, more preferably pH8 to 9).
TABLE 4 Experimental results for TVBN removal according to different experimental conditions of TABLE 2
The technical features of the above embodiments and examples can be combined in any suitable manner, and for the sake of brevity, all possible combinations of the technical features of the above embodiments and examples are not described, however, as long as there is no contradiction between the combinations of the technical features, they should be considered to be within the scope of the present description.
The above examples only show some embodiments of the present invention, so as to facilitate the detailed and detailed understanding of the technical solutions of the present invention, but not to be construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. It should be understood that the technical solutions provided by the present invention, which are obtained by logical analysis, reasoning or limited experiments, are within the scope of the appended claims. Therefore, the protection scope of the present invention should be subject to the content of the appended claims, and the description and the drawings can be used for explaining the content of the claims.
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