Effect of some essential oils against Aeromonas hydrophila artificially inoculated into raw Nile Tilapia fish fillets during refrigeration storage.

Abstract

Aeromonas spp. is one of the emerging foodborne pathogens that gained importance during the last decades because of its zoonotic potential and as one of the specific spoilage organisms in seafood products. Agar well-diffusion assay revealed that cinnamon EO-Trans Cinnamaldehyde- (TC) and garlic Eos (GEO) showed the highest zone of inhibition against Aeromonas strains 18 mm for each at 0.5 % followed by thyme EO (TEO) (12 mm). While Clove EO (CEO) and onion EO (OEO) didn’t inhibit the growth of Aeromonas spp. Resazurin microtiter plate assay indicated that the MIC values were 3.125 mg/ml for GEO, 6.25 mg/ml for TC, 12.5 mg/ml for CEO, 50 mg/ml for TEO, and 75 mg/ml for OEO. The application of cinnamon, clove, garlic, thyme, and onion Eos against Aeromonas spp. on tilapia fish fillets stored at 4oC showed that among the low concentration of Eos (25 mg/ml), cinnamon and clove Eos showed a significant reduction in Aeromonas counts. Also, the higher concentration of CEO (25 mg/ml) caused a significant reduction rate. Counts of A. hydrophila in tilapia fish fillets of Eos treated samples were significantly different compared to the initial counts. EOS showed a significant reduction in the PH value of fish fillets except for the lower concentrations of TEO & OEO (alpha =0.052, P>0.05). A shelf-life extension of 2-3 days was achieved with essential oils treatment. They could be recommended as natural antimicrobial control of A. hydrophila in fish fillets.

Keywords

• essential oils
• a. hydrophila
• natural antimicrobials
• fish fillets