| Author: | Krishna Das |
| Roll: | BFH1902045F |
| Batch | 14th batch |
| Session | 2018-19 |
Abstract:
Soft-shell mud crab farming has recently replaced shrimp farming due to its gastronomic delicacy and more marginal return to farmers. This practice has resulted in the production of large amounts of discarded shells that could serve as a good source of raw materials for chitosan. Additionally, these shells could bring more economic value than a low-cost sale for animal feeds or be discarded completely as debris. The aim of the present study was to characterize the chitosan synthesized from mud crab (Scylla olivacea) shell wastes from soft-shell farming and to investigate the yield percentages of chitin and chitosan that vary with three different size groups: small size (S) crab shells (60–80 g), medium size (M) crab shells (81–100 g), and large size (L) crab shells (101–120 g) and evaluate the production costs of chitosan. Using two different hydrochloric acid (HCl) concentrations, 1 M (Treatment A) and 1.5 M (Treatment B), in the demineralization steps of chemical extraction methods, the remaining steps involved deproteinization and deacetylation. The 1 M HCl treated chitin yield percentages of large, medium, and small were 6.92±0.345%, 6.5±0.122%, and 6.34±0.413% respectively and 1 M HCl treated chitosan yield percentages of large, medium, and small were 4.29±1.554%, 4.07±0.110%, and 4±1.129%, respectively. Using 1.25 HCl treatment resulted in yields percentages of chitin of small, medium, and large were 6.08±0.884%, 6.64±0.940%, 7.19±0.685% and using same treatment chitosan of small, medium, and large were 4.38±0.171%. 4.39±0.796% and 6.32±1.319%, respectively. Extracted chitosan physicochemical properties were evident by using Fourier transform infrared spectroscopy (FTIR) and thermo gravimetric analysis (TGA). Across the growing demand for soft-shell mud crab farming in aquaculture, approximately 252 tons of the soft-shell mud crab shells are being lifted in Bangladesh by exporting, which can be a source of 1.512 million US dollars per year in utilization to produce 15.12 tons of chitosan. The prospect of setting up the chitosan industry on a small scale with new developments for waste management and creating extra income utilization from the sludge of minerals and proteins that result from demineralization and deproteinization processes and its production could be profitable, as its profit would be 50% higher than its production cost. The recycling economies of these shells will bring a new dimension to the economic sector of the nonconventional fisheries sector, creating working opportunities, especially for women, as less labor is needed to run these procedures, along with growing soft-shell farming systems