Novel approaches with acetic acid, liquid smoke, and Lactobacillus rhamnosus for mitigating some heavy metals in Nile fish.

Abstract

Mercury and cadmium are toxic heavy metals that can bioaccumulate in freshwater fish, posing a health risk to human consumers. This study analyzed residue levels of these metals in 105 randomly sampled fish of three common species -Clarias lazera, Oreochromis niloticus, and Bagrus bayad -(35 each) from markets in Gharbia, Egypt. Concentrations were compared to national and international standards to evaluate suitability for human consumption. Further interventions using acetic acid, liquid smoke, and Lactobacillus rhamnosus probiotic cultures were tested for their efficacy in reducing or controlling these toxic residues in farmed fish. The results showed that 44.8% of all Nile fish samples exceeded mercury's maximum residue limit (MRL), while 25.7% exceeded the MRL for cadmium based on Egyptian standards. Single applications of 5% acetic acid and 3% liquid smoke reduced experimentally inoculated mercury by 52.8% and 64.2%, respectively. L. rhamnosus treatment achieved 71.6% reduction. For cadmium, the reduction was 43.5% for acetic acid, 56.0% for liquid smoke, and 61.5% with L. rhamnosus, respectively.