Effect of chitosan coating and drying on quality of Bombay duck (Harpodon nehereus)

Abstract

Bombay duck (Harpadon nehereus) is one of the most abundant and preferable marine species in the Maharashtra and Gujrat regions. While Bombay duck is mostly consumed in dried form, the major problems associated with traditionally sun-dried Bombay duck are contamination by insects or pests; uneven drying which leads to spoilage; and poor quality of the end product. Chitosan and its derivatives are used as an edible coating in food applications due to its antioxidant and antimicrobial actions. In the present work, the effect of chitosan coating and drying on the quality of Bombay duck was studied. Five different samples were prepared as follows: (i) control (without any treatment); (ii) dip-treated in 1% acetic acid (AA); (iii) dip-treated in 0.5% chitosan dissolved in 1% acetic acid (CAA); (iv) dip-treated in 1% malic acid (MA); and (v) dip-treated in 0.5% chitosan dissolved in 1% malic acid (CMA). All samples were dried at 50°C. When biochemical, microbiological, and sensory analyses were assessed for four months, results indicated the sample coated with chitosan pre-dissolved in either acetic acid or malic acid had lower TVB-N (86.5 - 115.25 mg/100 g) and TPC (5.3 - 5.5 log10 CFU/g) than the control (TVB = 163 mg/100 g; TPC = 7.4 log10 CFU/g); a similar trend was also observed for TBA values. Even though the microbial analysis revealed that TPC crossed the limit of acceptability (5.2 log10 CFU/g) by the second month in the control, AA, CAA, MA, and CMA levels were acceptable up to three months. Sensory analysis showed that the overall acceptability score was higher for sample coated with chitosan. These results suggested that chitosan coating and drying could improve the quality of dried Bombay duck.