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Direct method of chitosan extraction from shrimp waste for production of biodegradable films

Abstract:

Using shrimp shells, a direct method for chitosan isolation was developed, which eliminates the intermediate step of chitin extraction as in the so-called indirect method. Films were made using chitosan suspensions extracted by the direct and by the indirect method at 0.50 and 0.75% chitosan, 3% acetic acid or 1% lactic acid, with and without glycerol as plasticizer. The films were characterized for their moisture content, water vapor permeability, tensile strength and elongation, phase properties, color and opacity. The average viscosimetric molecular weight and the apparent viscosity of the film forming suspensions were higher for the chitosan samples from the direct method. For both methods, the viscosity increased with the increment of the chitosan concentration. The main statistical differences were related to the type of acid used in the solutions and the presence of glycerol as plasticizer. A minor effect was observed in relation to the method of chitosan extraction and in less extent to the chitosan concentration; therefore the chitosan extraction by the direct method assists the production of films with similar properties to those containing commercial chitosan.