Method for preparing chitin and process for preparing chitosan by using chitin

Abstract

The invention discloses a method for making crust element which comprises the following steps that: a crab shell which is cleaned and soaked for the first time is put into a sodium hydrate solution for heat preservation; the crab shell which is washed by tap water to the neutral is soaked for the second time, the acid liquor is scoured off by the tap water; the curst element soaked by hydrochloric acid is put into the sodium hydrate solution for heat preservation and then is fished out as well as is washed by the tap water to the neutral, and the crust element is obtained. The method for making chitosan by the crust element comprises the following steps that: the crust element is put into the sodium hydrate solution and is sealed, after temperature preservation and the reaction, the mixture is soaked by the tap water and is washed by the tap water; the processed chitosan is taken out to be dried and put into the sodium hydrate solution as well as be sealed while preserving the temperature, after the reaction, the chitosan is taken out and is soaked in the tap water as well as is taken out and dried, thereby obtaining the chitosan. By processing by the method, the reaction speed is increased by 30 times, the alkali liquor dosage is reduced by 50 percent; the made crust element has white color, the crust element is washed by water and soaked to produce the chitosan, the molecular weight is great, the deacetylation is more than or equal to 95 percent, and the viscosity coefficient is more than or equal to 2000MPa.S.

Description

technical field [0001] The invention relates to aquatic product biotechnology, in particular to a method for preparing chitin and a method for preparing chitosan from chitin. Background technique [0002] Chitin is widely used in medicine and health, food, chemical industry, agriculture, textile, papermaking, printing and other fields. The current method of preparing chitin is to decalcify crab shells and then pass through KMnO 4 Oxidation, washed with NaHSO 3 Reduction, washing and drying to obtain chitin or hydrolyzing papain to prepare chitin. [0003] At present, there are mainly the following methods for preparing polysaccharides in most enterprises at home and abroad: [0004] 1. Alkali fusion method, chitin and KOH are eutectically melted in a nickel crucible at a ratio of 1:5, heated and stirred at 180°C for 30 minutes to obtain crude chitosan, and a relatively pure product is obtained through repeated purification and washing, but this Chitosan has a lower molecu...

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Problems solved by technology

[0004] 1. Alkali fusion method, chitin and KOH are eutectically melted in a nickel crucible at a ratio of 1:5, heated and stirred at 180°C for 30 minutes to obtain crude chitosan, and a relatively pure product is obtained through repeated purification and washing, but this low molecular weight chitosan

[0005] 2. Alkaline method: mainly have two kinds of techniques: 1) produce chitosan product for a long time with lower temperature, as soaking in 40-41% NaOH solution at room temperature for 7 days, the product viscosity is relatively high. High, simple production process, low production cost but long production cycle; 2) short-term high temperature operation, such as deacetylation treatment with 40-41% concentrated lye at 100-180 ° C, this production process is difficult to master and easy Out of waste

[0006] 3. Enzymatic hydrolysis: Chitin deacetylase reacts with chitin in TES-NaOH solution for 48 hours at 30°C to obtain chitosan products. This method saves energy, avoids expensive chemical raw materials, and has simple equipment, but Chitin deacetylase extraction process is more complicated

This kind of deficiency: the cost of the method is higher, and the process is not easy to control

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