Nutritional and shelf-life studies of a ready-to-eat snack developed using by-products from Tilapia guineensis

Abstract

Ready-to-eat (RTE) snacks were produced from the head and fins of Tilapia guineensis. The snacks were fried using the conventional method and were analyzed for their nutritional composition and shelf-life using biochemical tests (Thiobarbituric Acid (TBA), Peroxide value (PV) and Free Fatty Acid (FFA)), sensory assessment, water activity tests, and microbial analysis. There was no significant difference (p>0.05) in the nutritional composition of the two snacks developed. The snacks developed from the head without gills (PA) and the fins (PC) were low in protein (9.50±0.19 and 10.03±0.71%) and high in carbohydrate (55.33±2.02 and 51.56±2.53%). There was a significant increase (p<0.05) in the PV, TBA and FFA values throughout the storage period. Although the values for FFA exceeded the 0.5-1.5% recommended level for a noticeable rancid taste, the result of the sensory assessment of PA and PC showed that both RTE snacks were acceptable by the taste panel throughout the storage period. The range of water activity values for PA (0.57-0.78) and PC (0.59-0.64) were high and this possibly favoured the survival and outgrowth of microbial spores. The absence of Salmonella sp, S. aureus and E. coli in PA and PC, showed good manufacturing practice in terms of hygiene and food handling while the presence of low counts of Enterobacteriaceae was indicative of inadequate frying of the snack. The bacteria species identified in both products was Bacillus sp. The value for total plate count and mould count in PA was within acceptable limits until the third week of storage while its values for PC were within the acceptable limit throughout the storage period. The results show that the head and fins of T. guineensis can be used to make a nutritious snack product that would be accepted by consumers. Although the RTE snacks developed in this study offers a new snack variety and adds value to the fish by-products generated during processing, there is need to conduct more research on optimization studies which would lead to the development of protein rich RTE snacks having a longer shelf-life.