Microbial and chemical quality assessment of different fresh water fish from two regions in Maramureș county

Abstract

The primary aim of the study was to evaluate the chemical composition and freshness of fish, using parameters such as ammonia, total volatile basic nitrogen (TVBN), and pH levels. A microbial assessment was also carried out at the Cluj County Sanitary Veterinary and Food Safety Laboratory, examining Total Viable Count (TVC), smear tests, and the presence of Enterobacteriaceae and E. coli. The research further investigated pathogens, specifically Listeria monocytogenes and Salmonella spp., which are known to pose significant health risks. Chemical composition analysis, conducted using a Foodscan lab analyzer, found no significant differences in protein and moisture content between the two species. However, rainbow trout had three times more lipid content than Crucian carp, while Crucian carp had four times more collagen than Rainbow Trout. The freshness assessment indicated that fish deterioration is evident without proper storage conditions, with 83.33% of the fish samples showing pH levels above the maximum acceptable limit. Ammonia levels exceeded the limit in 16.67% of Rainbow Trout samples, and elevated TVBN values were observed in one Rainbow Trout sample from a contaminated area and one Crucian Carp from a non-contaminated area. Both TVBN and ammonia levels showed a general upward trend, with many samples approaching the maximum allowable limit. The microbial analysis revealed that TVC levels were above the recommended limit (one million) in 31.25% of the fish samples. Enterobacteriaceae counts exceeded the recommended limit (1000) in all samples, suggesting ineffective evisceration. Although E. coli was detected in all samples, none of the strains were pathogenic to humans. The pathogen analysis for Salmonella spp. and Listeria monocytogenes showed no detection, but Listeria innocua colonies were found in rainbow trout samples from both contaminated and non-contaminated areas on ALOA and Oxford agar. From a freshness perspective, proper storage in melted ice is crucial. Microbiologically, Good Hygiene Practices (GHP) during evisceration are necessary to prevent cross-contamination.