Chitosan Decelerates Melanosis in Shrimp: A Novel Technique for Visual Quality Assessment Using Digital Image Analysis

Abstract

The study aimed to determine the effects of chitosan, sodium metabisulfite, and citric acid against melanosis, which causes significant economic losses during the storage of shrimps. For this purpose, two different types of chitosan were extracted from tiger prawn shell wastes. The extracted chitosan was characterized by viscosity, FT-IR, XRD, SEM imaging, and color analyses. Prevention of melanosis formation was investigated by testing chitosan, sodium metabisulfite, and citric acid. To achieve this, fresh deep-water pink shrimp samples immersed in different solutions were stored for 12 days at 4℃. Melanosis formation in the samples was observed via color measurement, sensory evaluation, and image analysis. According to the results of the research, the deacetylation degrees of chitosans were found to be 99.50 and 89.51% and 76.31 and 78.24% by two different methods, respectively. Viscosities were measured as 0.34 and 4.17 cSt, respectively. Regarding the color parameters, the L* values were 83.68 and 78.94, a* values were 0.55 and 2.71, and b* values were 10.33 and 13.85, respectively. According to the sensory evaluation conducted throughout the study, melanosis formation was observed in all groups starting from the 6th day. On the 8th day, the control groups exceeded the acceptability threshold, and on the 12th day, melanosis formation spread throughout the body in all groups. The sensory evaluation results were supported by the color measurement and image analysis implemented for the first time in this study. The present study’s results showed that chitosan obtained from shellfish wastes decelerates melanosis formation as an alternative to commercially used chemicals.