Quality assessment and shelf-life of processed tilapia (Oreochromis niloticus) fish sticks: Laboratory based study

Abstract

Customers prefer tilapia (Oreochromis niloticus), one of the most popular freshwater fish species farmed in Bangladesh, because of its flavor and affordable market pricing. This study aimed to develop value-added tilapia fish sticks and evaluate the quality changes, shelf life, and storage stability of the developed tilapia fish sticks in order to investigate the possibilities of better utilizing low-value tilapia fish and to satisfy consumers' growing demand for quality ready-to-eat food products. For this regard, storage characteristics in room (28ºC) and refrigerator (5ºC) temperatures were assessed in terms of microbiological, chemical, proximate, and sensory attributes. The moisture, lipid, protein, and ash contents of the fish sticks were observed to be 56.23±0.62, 7.62±0.27, 26.01±0.39, and 2.93±0.23%, respectively, at fresh condition. As storage time increased, it was discovered that ash content at room temperature increased while moisture, lipid, and protein levels steadily declined. On the other hand, it was discovered that at refrigeration temperatures, ash and fat content increased while moisture and protein content decreased. Compared to fish sticks held at ambient temperature, changes in the proximate composition of fish sticks stored in a refrigerator were found to be more stable. TVB-N was initially measured as 12.38±0.45 mg/100 g. After 24 hours of room storage, the TVB-N value exceeded the acceptable level; however, after 72 hours of refrigeration, it did not exceed the acceptable limit and was deemed fit for consumption. TPC was observed in fresh fish sticks as 3.74±0.31 Log CFU/g. In 48 hours at room temperature, the bacterial load of tilapia fish sticks increased sharply (p<0.05) during the course of the storage period and went above the microbiological threshold for fishery products (7 Log CFU/g of flesh). The bacterial growth trend was slower and, after 72 hours, was within the permitted limit at refrigerated storage temperature. All fresh products had the highest initial sensory ratings. At ambient temperature, all of the products sensory qualities significantly declined with time (p<0.05), however at refrigeration temperature, the product was determined to be more stable. The overall acceptability score assessed for appearance, flavor, taste, and texture was within acceptable limits for up to 24 hours at room temperature, but not for 72 hours at refrigeration temperature. According to the study's findings, tilapia fish sticks have a very limited shelf life at room temperature (28°C), only lasting around 24 hours, whereas they can last up to 72 hours at 5°C in the refrigerator.