Shrimp waste management Use of dried papaya milk in chitosan manufacture

Abstract

Chitin is the second most abundant carbon biopolymer on earth, next to cellulose. It is the majorconstituent in the exo-skeleton of crustacean water animals such as shrimps, crabs etc. Shrimp wasteis a major cause for environmental pollution in shrimp cultivating areas such as Puttalam. Currentannual shrimp production in Sri Lanka is about 4000 MT and the shrimp waste produced is about1200 MT. This shrimp waste at present is discharged into environment or buried without any treatment,thereby causing serious environmental pollution problems.

Chitosan, which can be obtained from chitin by chemical treatment, is a polysaccharide of very higheconorn ic importance with a wide range of industrial applications. If Sri Lanka can convert its shrimpwaste in to chitosan, it can be a major foreign exchange earner, in addition to solving the problem ofenvironmental pollution caused by shrimp waste.

A method for the production of chitosan from shrimp waste using dried papaya milk (OPM) has beendeveloped (Sri Lanka Patent No 13544,2005). It involves the treatment of demineralised (with 4%HCI) shrimp waste with OPM followed by deproteinization with 3% NaOH and deacetylation with50% NaOH. The use ofOPM brings about a 25% reduction in the amount ofNaOH, which is knownto cause environmental pollution problems. Typically, the degree of deacetylation (~O) of resultingchitosan was 66% comparable to DO of conventional methods. Moisture content (11.2%) and ashcontent (0.69%) of resulting chitosan were also comparable to those obtained by 100% chemicalmethods.