Cuticular Chitin of the Wild Silkworm Saturnia Pyri: A Renewable Source for Applications Across Industrial Sectors

Abstract

In the context of a developing sustainable bioeconomy, the search for renewable sources of biopolymers as alternatives to traditional ones is of crucial importance. In this regard, insect cuticular waste represents a promising yet insufficiently explored raw material for obtaining chitin and chitosan. This study aimed to perform a comparative assessment of the extraction efficiency and quality of chitin and chitosan derived from larval and pupal exuviae of the wild silkworm Saturnia pyri in order to determine the optimal source of raw material. Standard chemical extraction methods were employed, including deproteinisation, decalcification, and deacetylation. Chemical analysis of the initial material revealed that the exuviae contained 70% more chitin fibres (17.5% compared with 10.5%) and a significantly lower fat content (3% compared with 27.9%). The yield of purified chitin from the exuviae reached 28.5%, which was more than twice that obtained from pupae (12.8%). The deacetylation process demonstrated higher efficiency for chitin derived from exuviae, with a conversion rate to chitosan of 87.7%, compared with 78.1% in the case of pupae. The resulting chitosan was characterised by a high degree of deacetylation (89.5±1.2%) and favourable rheological properties, with the viscosity of a 1% solution reaching 345 cP. The findings confirmed that the exuviae of Saturnia pyri constitute a high-quality and technologically efficient source of chitosan that surpasses, in key performance parameters, the material obtained from pupae. The results of this study provide a basis for developing an environmentally oriented technology for processing insect moulting waste into valuable biopolymers with potential applications in biomedicine, agriculture, and the food industry, thereby contributing to the implementation of circular economy principles.