Microbial quality of Nile perch (Lates niloticus) and physico-chemical properties of salted sun-dried products sold at regional markets, Tanzania

Abstract

This study was conducted to investigate the microbial and physico-chemical qualities of salted sundried Nile perch (Lates niloticus) products and frozen fish from various storage facilities in Mwanza, Tanzania. The bacterial flora, moisture contents (MCs), and water activity (A w ) were investigated using standard methods. A total of 120 samples were collected for microbiological analysis with 90 of the samples additionally analysed for MC and A w . Findings showed that the mean total viable counts (TVCs) in salted sun-dried products sampled during rainy season was 4.5 log cfu/g in fish heads with MCs of 38.0% and A w of 0.682. This was significantly higher (P<0.05) than what was recorded during the dry season with mean TVCs of 3.0 log cfu/g at MCs of 24.6% and A w of 0.625. Fish chests had TVCs of 3.3 log cfu/g and MCs of 27.6% and A w of 0.659 in rainy season with no significant seasonal difference (P>0.05). Fish belly flaps had TVCs of 3.3 log cfu/g at 26.4% MCs and 0.669 A w in rainy season which were comparable (P>0.05) to those dried in the dry season. The microbial species recovered were Staphylococcus spp., Enterobacter spp., Psychrobacter spp., and Bacillus spp. Neither Escherichia coli nor extended-spectrum beta-lactamase producing Enterobacteriaceae were detected. Frozen Nile perch had TVCs of 5.7 log cfu/g on skin, 5.4 log cfu/g in gills and 2.9 log cfu/g in flesh and were within acceptable limit set by Tanzanian standards. These results reveal that dried Nile perch products are generally safe for human consumption; however, the recovered bacteria indicate a need of implementing hygienic procedures during processing of products for improved quality and safety.

Assessment of Quality and Safety of Some Imported and Locally Sourced Fish in the Egyptian Markets

“…Previous research on various fish products also indicates diverse bacterial loads [73,74]. Notably, salted sun-dried Nile perch showcased higher counts during the rainy season [74]. Importantly, in our study, 33.33% of smoked fish samples violated the Egyptian standard (ES 288/2005) for TBC and TCC, highlighting potential safety risks [37].…”

“…Our findings raise concerns about potential bacterial contamination in smoked fish, mirroring results observed in our salted fish samples. Previous research on various fish products also indicates diverse bacterial loads [73,74]. Notably, salted sun-dried Nile perch showcased higher counts during the rainy season [74].…”