Physico-chemical properties of chitosan extracted from Whiteleg shrimp (Litopenaeus vannamei) processing shell waste in Sri Lanka

Abstract

The present study investigated the potential of whiteleg shrimp shell waste to use as a source of chitosan which has a limited focus on previous Sri Lankan studies. Comparatively higher amount of chitosan yield (33.53%) was obtained in the study with 91.78 ± 0.66 (%) of dry matter content, 8.22 ± 0.66 (%) of moisture content, 1.08 ± 0.24 (%) of ash content, 80.43% of the degree of deacetylation, 435.87 ± 1.03 cP dynamic viscosity and a good thermal stability up to 312 °C. Fourier transform infrared spectroscopy (FTIR) analysis confirmed the structure of chitin and chitosan by the presence of their characteristic IR bands and X-ray diffraction analysis further verified the crystalline structure of the extracted chitin and chitosan. Scanning electron microscopic (SEM) images of the extracted chitosan recognized the layers of flakes with porous and fibril structures. According to the energy-dispersive X-ray spectroscopy image, carbon, oxygen and nitrogen were observed as the major elements in the extracted chitosan and no calcium peaks were detected confirming effective demineralization in the extraction process. Further, DPPH (2,2-diphenyl-1-picryl hydrazy) assay revealed that the chitosan solution with the concentration of 10 mg/mL was having 66.45% of free radical scavenging activity. Thus, the present study reveals that the chitosan with high quantity and quality can be extracted from whiteleg shrimp ( Litopenaeus vannamei ) processing shell waste in Sri Lanka suggesting a solution to the waste accumulation in processing factories while proposing an alternative income generation strategy from waste.