Crab (Portunus pelagicus) is a fishery export commodity, especially to Japan, the European Union and the United States. On the other hand, the crab part, namely the shell, is still not utilized optimally so it becomes waste. To make crab shells valuable, several studies have revealed the presence of useful substances known as chitin and chitosan. Therefore, this research was carried out with the aim of knowing the effect of deacetylation temperature on the quality of chitosan and the optimal deacetylation temperature so as to produce good quality chitosan. Method: This study employs an experimental methodology based on Fully Randomized Design (CRD) analysis. Several deacetylation temperature treatments (0⁰C, 90⁰C, 950C, 100⁰C, 105⁰C, 110⁰C, 115⁰C, 120⁰C) were repeated three times in this study's design. Analyses of yield, moisture content, ash content, protein content, and acetyl content serve as test parameters. Result: The results showed that the treatment using different deacetylation temperatures had a very significant effect (F_crit > F_table 1%) on water content, ash content, protein content, acetyl content and had no significant effect (F_crit > F_table 5%) on the yield. The optimal deacetylation temperature was 120⁰C, with a yield of 19.050%, water content of 8.340%, ash content of 0.022%, protein content of 0.198%, and acetyl content of 84.870%. Conclusion: The conclusion based on analysis that the best temperature deacetylation in producing quality chitosan crab is 120⁰C.

Swimming crab shell waste is a fishery byproduct that has the potential to pollute the environment if not utilized properly. One alternative utilization is to process it into chitosan, which is then formulated into liquid fertilizer. This study aimed to determine the effect of chitosan concentration based on swimming crab shells on the chemical properties of liquid fertilizer. The study was conducted from February to March 2025. Chitosan and liquid fertilizer production was conducted at the Fishery Products Biochemistry Laboratory, Pangkep State Agricultural Polytechnic. The method used was an experimental laboratory with a Completely Randomized Design (CRD), with three treatments and three replications, with chitosan concentrations of 2%, 4%, and 6%. Data were analyzed using One-Way ANOVA and the W-Tukey HSD test. If the assumption of homogeneity of variance was not met, Welch ANOVA with the Games-Howell test was used to determine differences in effects between treatments. The results showed that the treatment had a significant effect (P<0.05) on most of the chemical properties of liquid fertilizer. The chemical properties of pH were (2.90 3.00 3.23), C-organic were (1.08% 2.72% 4.21%), macronutrients N + P₂O₅ + K₂O were (0.76% 0.64% 1.19%). In conclusion, increasing the concentration of chitosan improves the chemical properties of liquid fertilizer, so that crab shell chitosan has the potential as a material for liquid organic fertilizer formulation.

Writing this scientific paper aims to determine the economic value of the potential waste of crab shells produced by PT. Toba Surimi Industry in Tanjungpinang City, Riau Islands Province. The company has not utilized crab shell waste. In contrast, crab shell waste can provide economic value that provides a lot of additional value. Crab shell waste can be processed into chitosan, which has many functions in various sectors, both in the fisheries, automotive and health industries, and other sectors. Chitosan is produced from the chitin substance contained in crab shells through deproteination, demineralization, and deacetylation. The economic value that can generate from the utilization of crab shell waste PT. Toba Surimi Industry when processed into chitosan with a crab shell weight of 270 kg/day, which is Rp. 40.500.000/day.