Effect of frozen storage on the biochemical, microbial and sensory attributes of skipjack tuna (Katsuwonus pelamis) fish loins

Abstract

Skipjack tuna (Katsuwonus pelamis) belongs to the Scombridae family to determine the consistency characteristics of tuna fish loins for 28th days at frozen (−18 ± 2°C) storage. The biochemical, microbial, and sensory quality were analyzed by association of official analytical chemists method, plate count, and Quality Index method (QIM), respectively. Protein, lipid, and moisture content were found to decrease significantly (p < 0.05) over the study period. Nonetheless, the values of ash, total volatile base nitrogen, tri-methyl amine nitrogen, pH, and peroxide increased significantly (p < 0.05). After 28 days of frozen storage, the total bacterial load in tuna fish loins was reduced from 3.8 × 105 to 3.3 × 104 colony forming unit/g. Total coliforms reduced from 113 to 5 Most Probable Number (MPN)/g, fecal coliforms declined to undetectable level from 13 MPN/g, and total Salmonella sp. also decreased from 1 MPN/g to unnoticeable, respectively. Organoleptically tuna loins were found in excellent condition up to 14th days although remained acceptable up to 28th days of the study period. The present findings should that the skipjack tuna loins can be retained under an acceptable limit for human consumption at frozen storage conditions up to 28th days.