RU2000066C1 - Method for processing small crustaceans to produce chitosan - Google Patents

Abstract

Using the invention: a method for processing small crustaceans to produce chitoean belongs to the fishing industry and can be used in food, microbiological industry, agriculture, medicine and environmental protection. Summary of the invention: to improve the quality of the product, expanding the range of raw materials, raw frozen krill is used, which is subjected to single pressing after thawing and heating by pressing on press separators with a diameter of the drum openings of 2 mm, the resulting pulp is washed, alkaline treatment is carried out with a 1% solution of NaOH and KOH and demineralization by adding concentrated hydrochloric acid to the suspension, the obtained chitin is subjected to freezing, grinding in a frozen state, and deacetylation in a wet state and a 60% alkali solution at a temperature of 90-110 ° C for 1-2 hours, 1 tablet, 1 silt.

Description

The invention relates to the fishing industry, in particular to a method for producing chitosan, and can be used in the fish processing, food, microbiological industry, agriculture, medicine and environmental protection.

At present, a significant part of the laid krill is prepared in ice cream, delivered to the shore and without further deep processing is sold directly to poultry farms, fur farms and pig farms for use as a protein feed additive. Another part of the caught krill raw material in its entirety, without separating shells under fishing conditions, is used to produce feed flour,

Raw krill are known to contain up to 30% of the shell consisting of chitin, a protein

and mineral salts (mainly calcium carbonate). Feeding whole krill and flour from animals in amounts exceeding 4% of the feed weight negatively affects their condition, since the shell is not absorbed by the animal and is an irritant to the stomach and intestines.

In turn, the shell is a raw material for the production of a whole series of very valuable products having a wide range of fields of their application; feeding shells to animals is irrational. Known methods of processing krill and other crustaceans, taking into account the separation of the shell, as a rule, do not provide for its further processing into chitin and chitosan. On the other hand, known methods for producing chitin and chitosan from the shells of crustaceans

they envisage the use of production of pansir-containing waste (PSO) as raw material, that is, material with a stable chemical composition.

A known method for producing chitin from shell-containing krill wastes by duhstage alkaline hydrolysis of the feedstock, its neutralization, acid hydrolysis, washing and drying. In this case, the stages of alkaline hydrolysis are carried out south-directly, one after another, and each of vfnx is carried out with a 2-4% alkali solution at a temperature of 65 to 80 ° C until complete removal of proteins, and acid hydrolysis is carried out 0.8 - 2% solution of hydrochloric or phosphoric acid at a temperature of from 50 to 90 ° C for 10 to 20 minutes until complete demineralization of the target product.

The main disadvantage of this method is too hard alkaline and acid hydrolysis, which leads to a decrease in the biological value of the resulting feed protein, and also reduces molecular weight and worsens the viscosity characteristics of the target product. In addition, the alternation of alkaline and acid treatments of the feed is more rational. The first stage of alkaline hydrolysis is aimed at removing muscle protein residues from raw materials, without affecting mainly inaccessible skeletal shell proteins. Conducting an acid treatment then removing the mineral part of the carapace, loosens its structure and increases the availability of carapace proteins, which are removed by repeated alkaline treatment.

The closest in technical essence to the claimed invention is a method for producing chitin from crustacean shells, including twice alternating treatment with solutions of sodium alkali and hydrochloric acid, as well as washing the semi-finished product after each operation with 4-6% sodium chloride solution to neutral wash water reactions. The disadvantages of this method include rather stringent conditions of alkaline hydrolysis, leading to a decrease in the biological value of the resulting feed protein, a decrease in the molecular weight of chitin and the viscosity characteristics of the chitosan obtained from it, as well as an increased consumption of reagents, and the use of sodium chloride. A common disadvantage of the described methods for producing chitin is the use of unstable chemical composition as a raw material for shell-containing wastes, as well as the fact that they

provide for the possibility of processing only PSO crustaceans that have undergone heat treatment.

The aim of the invention is to provide a method for producing chitosan from raw-frozen krill, providing processing of raw materials under mild conditions, preserving to the greatest extent the native properties of both the target product and the resulting feed protein, and thereby improving their quality.

This is achieved by a single pressing of thawed and warmed krill to 10-15 ° C on press separators with a hole diameter of 0.5-5 mm. providing maximum separation of the protein fraction and removal of the complex of chitinolytic and proteolytic enzymes krill and lipids;

washing the pulp and removing muscle soluble proteins, lipids and the residual amount of enzymes with constant stirring at 40-60 rpm for 10 minutes, the ratio of pulp and water 1: 2, water temperature not higher than 25 ° C; alkaline hydrolysis of pulp with a 0.2 - 2% (with an optimum of 1%) solution of sodium hydroxide or potassium hydroxide with a ratio of pulp: alkali solution 1: 1 - 1: 8 and a temperature of 20 - 80 ° C for 0.5 - 2 h;

demineralization of the carapace suspended in water in a carapace ratio of 1: 2-1: 5 by adding concentrated hydrochloric acid to the suspension in a carapace: acid ratio of 1: 1-1: 3 at room temperature for 1 hour;

alkaline tertification of chitin with a 0.2 - 2% (1%) solution of sodium hydroxide or potassium hydroxide at a ratio of chitin: alkali solution 1: 1-1: 8 and a temperature of 20-80 ° C for 0.5 - 2 hours;

freezing chitin to minus 12 ° C, followed by crushing to 2-4 mm particles;

chitin deacetylation with a 50 - solution of alkali at a temperature of 90: 110 ° C for 1.5-2 hours.

The essence of the proposed method is as follows.

Raw frozen krill is thawed and heated to a temperature of 10-15 ° C and pressed on a press separator with a drum opening diameter of preferably 2 mm to maximize protein separation of the krill and a complex of chitinolytic and proteolytic enzymes. With a juice yield of 31%, the activity of chitonolytic enzymes in bagasse is 26 conventional units. The increase in juice yield up to 90% leads to a decrease in the activity of chitinolytic enzymes to 0.5 srvc. The isolated protein fraction is used as a feed additive to formulate feed mixtures. preparation of feed flour or feed protein concentrate. The pulp obtained after separation of the ground meat, containing the remains of muscle tissue, the carapace, up to 5% lipids, has a residual activity of chitinolytic and proteolytic enzymes. In order to remove the residual amount of enzymes, lipids and soluble muscle proteins that negatively affect the properties of the target chitosan product, the pulp is washed with water in solution with constant stirring for 10 minutes at a ratio of pulp and water of 1: 2. water temperature not higher than 25 ° С. In this case, the lipid content in the pulp is reduced to 1%, chitinolytic and proteolytic activity is absent, the protein content is reduced by 30% and, accordingly, the content of shells is increased. The washed pulp is subjected to alkaline hydrolysis by treating it with a 1% solution of sodium hydroxide or potassium hydroxide at a ratio of pulp: alkali solution of 1: 5, and both fresh and sea water can be used to prepare the alkali solution. The hydrolysis temperature is 70-75 ° C, the duration is 1 hour. The process is carried out with constant stirring. After the indicated hydrolysis time has elapsed, the suspension is separated in a precipitation horizontal centrifuge of the OGSh type, thereby obtaining a liquid protein hydrolyzate and a deproteinized shell. The protein hydrolyzate is subjected to isoelectric precipitation at pH 6.5-7.5. The protein released in this case is separated by thermocoagulation at 90-100 ° C for 10-15 minutes, followed by separation. It is possible to use a protein hydrolyzate after isoelectric precipitation directly into animal feed. The deproteinated carapace containing 5-10% protein, 18-30% minerals, 2-3% coloring matter and 50-60% chitin (in terms of dry matter) is sent for demineralization. For this purpose, the deproteinated carapace is suspended in water at a ratio of carapace: water predominantly 1: 5 and with constant stirring, concentrated hydrochloric acid in a ratio of hydrochloric acid: carapace predominantly 1: 2 is added to the reactor. Hydrolysis is carried out at a temperature of 15-40 ° C for 25-60 minutes. At the end of the demineralization process, the suspension is separated into precipitation

centrifuge type OGSh, while receiving chitin and acid hydrolyzate. After demineralization, the resulting chitin contains a residual amount of protein (3-4%), which 5 must be removed by alkaline purification with a 1% solution of sodium hydroxide or potassium at a ratio of chitin: alkali solution of 1: 5 with constant stirring. The process temperature is maintained at a level of 70 to 75 ° C. duration 1.5 hours. At the end of the process, the suspension is separated in an OGSh-type precipitation centrifuge. These conditions for the production of chitin ensure the preservation of its natium structure. 5 practically the absence of residual protein and mineral salts, which in turn determines a high degree of purity and reactivity of chitosan. In addition, the completion of the chitin purification process at the alkaline treatment stage allows the deacetylation process to be carried out under relatively milder conditions. Alkaline treatment promotes swelling and activation of chitin, which makes it possible

5, a decrease in the deacetylation temperature, which in turn reduces the degree of chitosan degradation and allows one to obtain a product with high viscosity characteristics. Acidic and alkaline hydrolysates obtained

0 at the stages of demineralization and alkaline purification, mutually neutralize, and the resulting suspension is separated to obtain a protein-mineral feed pass. Washed until neutral

5, chitin is subjected to freezing, in which, under the influence of ice formation, loosening of its structure occurs, which facilitates further deacetylation. Freezing is carried out to a temperature not exceeding -12 ° C. Frozen chitin is subjected to grinding to a particle size of 2-4 mm which makes it possible to obtain subsequently a more uniform chitosan in particle size, since the grinding of dry chitosan

5 is difficult due to its resistance to abrasion and high electrification. The crushed thawed chitin or chitin in a swollen state after alkaline treatment is suspended in a 50-60% solution

0 alkali (NaOH or KOH) with a mass ratio of chitin and alkali solution of 1:10 and subjected to deacetylation at 90-110 ° C. within 1.5 - 2 hours. At the end of the process, the suspension is separated on a suction filter and half the chitosan under study is thoroughly washed with distilled water to pH 7, after which it is dried at 40-60 ° C to a residual moisture content of 5-8%.

The indicated conditions for the production of chitosan or whole frozen ice cream krill guarantee / purulent removal of a complex of chitinolytic enzymes affecting the destruction of chitin; mild conditions of proteination and demineralization predetermine the high quality of chitin, preservation of its native structure, which in turn provides high reactivity of chitosan, a high degree of deacetylation (over 85%), and viscosity at the level of 2000-2500 cps. its complete solubility in weak solutions of acids. This reduces the consumption of reagents for the production of chitosan and simplifies the scheme of waste disposal.

The drawing shows a diagram of the method.

Example 1. 1000 kg of ice cream krill are thawed and then heated to a temperature in the center of the block of 15 ° C and fed to the filling hopper. When thawed, krill blocks are destroyed. Thawed krill is sent for separation to separate muscle proteins from the carapace. Separation is carried out on press separators of type Forcemeat 4/500 with a diameter of the holes of the working drum of 2 ml. 750 kg of the resulting krill minced meat is sent to feed production.

250 kg of pulp obtained after press separation are loaded into a reactor equipped with a jacket and stirrer, 500 l of water are poured and the pulp is washed to remove additional proteins, as well as lipids and enzymes. Washing is carried out with constant stirring at a temperature of 25 ° C once. The suspension is separated, whereby the fat fraction is sent to feed and the pulp is further processed.

200 kg of pulp are loaded into a reactor equipped with a jacket and a stirrer, 600 l of water are poured and the suspension is heated to 45 ° C with stirring. Then, 6.5 kg of NaOH was added to the suspension, thereby obtaining a shell suspension in a 1% NaOH solution. The deproteination of the carapace is carried out at 70 ° C for 1 hour to obtain a protein hydrolyzate and carapace. At the end of the determination, the suspension is separated in an OGSh-type horizontal sedimentation centrifuge.

740 L of protein hydrolyzate is neutralized with hydrochloric acid to pH 7 and fed to animals without further processing. The hydrolyzate contains 6-8% solids, represented by 85% hydrolyzed digestible protein and amino acids. 60 kg of deproteinated carapace are suspended in 300 l of water and 120 l of concentrated hydrochloric acid are added in portions with constant stirring at ambient temperature. Demineralization is carried out for 60 minutes with constant stirring, after which

the suspension is separated in an OGSh type horizontal sedimentation centrifuge to produce chitin and an acid hydrolyzate. 35 kg of chitin is subjected to alkaline purification by suspending in 180 l of water and adding 1.8 kg of dry sodium hydroxide to a suspension, thereby obtaining a suspension of chitin in a 1% NaOH solution. Alkaline purification is carried out with constant stirring at 75 ° C for 1.5 hours. At the end

In the reaction 5, the suspension is separated in an OGSh type horizontal sedimentation centrifuge to obtain purified chitin and an alkaline hydrolyzate. The acid hydrolyzate from the demineralization step and the alkaline hydrolyzate from the alkaline chitin purification step are mutually neutralized by mixing them. In this case, the protein contained in the hydrolysates coagulates and is separated by separation to obtain a protein 5 mineral paste containing 8% protein and 12% ash (mainly calcium chloride) at a humidity of 80%. This paste is fed to animals as a mineral supplement in the wet form, or

0 is dried at 60-90 ° C to a moisture content of 8-10% and is used as a mineral additive in animal feed. The purified chitin in an important form is frozen and frozen and subjected to grinding and thawing. Thawed chitin is dispersed in a 60% sodium hydroxide solution and chitin is deacetylated at 100 ° C for 90 minutes. Chitosan is washed with distilled water to pH 7 and dried.

0 Other examples are given in the table.

Based on the claimed method for producing chitosan in 1993 on the basis of the Moscow state farm, the creation of

5 industrial production for the production of 10 tons of chitosan per year, as well as feed by-products.

Claims (1)

SUMMARY OF THE INVENTION A method for processing small crustaceans to produce chitosan. comprising treating the shell-containing pulp with an alkali solution, demineralizing it with acid to produce chitin, washing it to a neutral reaction of washings, and de5 acetylating chitin with alkali when heated, characterized in that raw frozen krill, which are previously thawed, are heated to 10 15 ° C and subjected to a single lrrgglv on a drum press separator with a diameter of 2 mm drum openings for separating muscle proteins from the pulp, the latter is washed with water at a pulp to water ratio of 1: 2 and a temperature not exceeding 25 ° C to remove soluble muscle proteins, lipids and residual enzymes, and the pulp is processed alkali is carried out with a 1% solution of NaOH or KOH for one hour at a ratio of pulp and alkali solution of 1: 3. the resulting deproteinated armored suspension It is washed in water at a shell-to-water ratio of 1: 5 and demineralized by concentrated hydrochloric acid at a shell-to-acid ratio of 1: 2 for one hour at room temperature, while the chitin is purified with a 1% solution of NaOH or KOH in 15 hours at 70 - 75 ° C and the ratio of chitin and alkali solution 1: 5 and freeze, and before deacetylation, chitin is crushed in a frozen state Table continuation Table continuation Table continuation j Kral cwpo-rake |, | Pressed 1 Minced meat j Alkaline hydrolyzate Belkhovo-szheral "a nacva Hmdrodieat sour gap hktozai J Eom water Deproteiimrovaya pa tskr Flushing. water D "pivram8ats" | + .1oda, net 7,  Hi sh i i | Promy | "-1oda Click and point 9x2. VaOH water Alkaline hydromeat ode | D (L0H Doc «tkdfo u1 Iammchtsyu |