Chitosan gel in extending the shelf-life of Nga-pi: A fermented fish product of Bangladesh

Nga-pi, a fermented fish product of cultural and nutritional importance in Bangladesh, frequently experiences quality degradation due to a lack of sufficient storage facilities, leading to oxidation and lower shelf life. Chitosan is recognized for its antioxidant properties and efficacy as a natural food preservative, and it was employed to extend the shelf life of Nga-pi. Various concentrations of chitosan gel (0 % (CG-0), 0.125 % (CG-1), 0.25 % (CG-2), 0.50 % (CG-3), and 1 % (CG-4)) (w/v) were applied in Nga-pi and evaluated physicochemical (pH, moisture loss), microbiological, oxidative, and sensory properties for 180 days. Incorporating chitosan gel resulted in a considerable (p < 0.05) decrease in pH and facilitated the compacting of the moisture, thereby reducing moisture loss. Furthermore, oxidative stability, assessed by thiobarbituric acid reactive substances (TBARS), improved markedly, with a reduction in oxidation compared to control. CG-4 also had the lowest mean TBARS value at 2.37 ± 0.07 mg MDA/kg, resulting in 54 % lower oxidation than the control. Microbiological quality was also enhanced, as total plate count (TPC) remained lower in chitosan-treated groups. Additionally, sensory analysis showed no adverse effect by adding chitosan gel into Nga-pi. Hence, Nga-pi treated with chitosan gel enhanced the shelf-life and, specifically with 1 % chitosan gel addition, holds the best quality for up to 180 days, highlighting its potentiality in Nga-pi preservation.