MICROBIOLOGICAL QUALITY ATTRIBUTES OF NILE PERCH LATES NILOTICUS FISH FILLETS TREATED WITH AQUEOUS EXTRACT OF LEPIDIUM SATIVUM L. CRESS SEEDS

Abstract

The antimicrobial activity of the aqueous and methanol extracts of Lepidium sativum cress seeds at various concentrations (1, 2 and 3 %) against four strains of gramnegative bacteria including Escherichia coli, E. coli 157, Salmonella typhimurium and Kelbsiella pneumonia, four strains of gram–positive bacteria including Staphylococcus aureus, Bacillus subtilus, Bacillus megaterium and Listeria moncytogenes serotype, two yeasts including Candida albicans and Sacchromyces cerevisiae and one fungi (Aspergillus niger) was assessed. Also, the effect of spraying with aqueous cress seeds extract on microbiological attributes and shelf life of Nile perch fish fillets was also studied. The results indicated that all concentrations of aqueous extract were active against all tested microorganisms except Klebsiella pneumonae. On the other hand, the methanol Lepidium sativum extract at 1 and 2 % had no effect on the growth of all gram-negative bacteria. Meanwhile, the above mentioned concentrations of methanol extract had detectable effects on the gram–positive bacteria, yeasts and fungi. Also, the antimicrobial effect of aqueous and methanol extracts was increased with increasing the concentrations. The results also showed that the distilled water was better than methanol for extracting antimicrobial substances from this seeds. Therefore, spraying of Nile perch fish fillets with various concentrations (1, 2 and 3%).of the aqueous extract was the suggested treatment to reduce the microbial load and extend the shelf life.