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Extraction of Chitosan from Shrimp Shells

In this extraction of chitosan from shrimp shells post we have briefly explained about chitosan extraction principle, extraction of chitosan procedure, requirements, chitosan uses and limitations.

Extraction of Chitosan from Shrimp Shells

Chitosan is a biodegradable and biocompatible polymer generated from the deacetylation of chitin (a carbohydrate found in crustaceans and insects’ exoskeletons).

Chitosan is commonly considered as a non-toxic and biocompatible polymer. It has been approved by the FDA for use in wound dressings and is approved for dietary use in Japan, Italy, and Finland.

Principle

The extraction of chitosan was carried out in three steps: demineralization, deproteination, and deacetylation. The ion exchange technique is used to remove mineral salts from chitosan during demineralization process in extraction of chitosan.

Deproteinization is the act or process of eliminating protein from a substance. Deacetylation is the hydrolysis of acetamide groups in chitin with a strong NaOH solution at high temperatures (100°C or higher) to create the amino group of new compounds (chitosan).

Requirements

Materials

1. Industrial grinder

2. Sieve

3. Hotplate with magnetic stirrer

4. pH meter

5. Hot air oven

Chemicals

1. 2N Hydrochloric acid

2. 2N Sodium hydroxide

3. 50% NaOH

4. Double distilled water

Preparation

1. To eliminate soil and foreign materials, samples were obtained and thoroughly cleaned with running tap water.

2. For 2-3 days, a well cleaned sample was dried at 80°C in a hot air oven. In a grinding machine, the dried sample was finely powdered and stored in an airtight container.

Procedure

1. For demineralization in extraction of chitosan procedure, 10 g of sample was treated with 2N hydrochloric acid at a solid-to-solvent ratio of 1:15 in an incubator shaker at room temperature for 2 hours with constant stirring at 150 rpm.

2. Following demineralization in extraction of chitosan procedure, the sample was rinsed with tap water until it reached a pH of neutral. After a final wash with hot distilled water, the sample was dried overnight at 80°C.

3. Demineralised shrimp shell powder in extraction of chitosan procedure was treated with 2N NaOH at a solid-to-solvent ratio of 1:20 in an incubator shaker for 2 hours with constant stirring at 150 rpm at 50°C, followed by thorough washing and drying as described in step 2.

4. Chitin was treated with a high alkali for deacetylation, i.e., 1 g of chitin was introduced to 50 percent NaOH for 1 hour at 121°C, 15 psi, followed by washing until it reached neutral pH. Chitosan was the last substance recovered after drying.

Chitosan Uses

1. A wide range of chemicals can be deproteinization reagents including NaOH, Na2CO3, NaHCO3, KOH, K2CO3, Ca(OH)2, Na2SO3, NaHSO3, CaHSO3, Na3PO4and Na2

2. Demineralization is generally performed by acid treatment using HCl, HNO3, H2SO4, CH3COOH and HCOOH.

Limitations

1. Extraction of chitosan has disadvantages such as energy consumption; waste of concentrated alkaline solution, thus an increase of environmental pollution, broad and heterogeneous range of soluble and insoluble products.

Further Readings

Reference