Application of Quality Index Method, TVB-N and Histamine content to evaluate the quality of Indian Scad (Decapterus russelli) and Frigate Tuna (Auxis thazard) at different market conditions in selected suburbs of Colombo district.

Abstract

Assessing the quality of fresh fish is vital for several reasons, including ensuring consumer safety, maintaining product quality, complying with regulations, and achieving success in the competitive seafood market. This study aimed to explore how market conditions affect the freshness of Indian Scad (Decapterus russelli) and Frigate Tuna (Auxis thazard) in various suburbs (Peliyagoda, Mattakkuliya, and Kelaniya) of the Colombo District which were received fresh fish stuff daily. Indian Scad and Frigate Tuna were selected for 0th day of ice storage due to their demand, availability, and affordability. A total of 48 fresh fish samples from both species were collected randomly from retail stores and supermarkets in the mentioned suburbs. The samples were uniformly sized and transported through a freezing channel, then stored at -18°C until analysis. Physical parameters like weight and length were measured, and sensory analysis using the Quality Index Method (QIM) was conducted by trained panelists to assess fish freshness at the date of purchase. As soon as the sample was taken to the laboratory, the TVB-N test was conducted, and it was subsequently extracted for the histamine test. Supermarket samples consistently exhibited superior sensory attributes across quality parameters in each suburb. Sensory evaluation indicated that local market samples of both species had a better appearance compared to supermarket samples. TVB-N levels were lower in retail markets compared to supermarkets for both fish species. Among retail markets, Peliyagoda and Mattakkuliya had lower TVB-N values than Kelaniya. Despite significant differences (P<0.05), TVB-N levels in both markets remained within acceptable limits (30-35 mg/kg). Histamine content was significantly (p>0.05) higher in local markets than in supermarkets for both species, with Peliyagoda and Mattakkuliya showing lower levels than Kelaniya. The mean Histamine content of both fish markets showed a significant difference (P<0.05) in both fish species. However, all Histamine values remained below the permissible limit (< 100 ppm). The study concluded that TVB-N levels were notably higher in supermarket-sourced Indian Scad and Frigate Tuna, while local market samples had lower TVB-N content. Histamine content was higher in local markets, but still below the maximum limit. Therefore, while there were variations in TVB-N and histamine levels between different markets and species, overall, the quality of Indian Scad and Frigate Tuna remained within safe limits for consumption in referred suburbs of the Colombo district.