Determination of minimum inhibitory concentration of the ethanolic extract of orange peel and the effects on the growth inhibition of Huso huso filet bacteria during refrigerated storage

Using natural extracts, as a source of anti-microbial, to improve the quality of fish is increasing. In this study, the ethanolic extract of orange (Citrus sinensis L.) was used due to having this property. Agar dilution method was employed in order to determine the minimum inhibitory concentration (MIC) of the ethanolic extract of orange peel on Pseudomonas aeruginosa, E. coli and Aeromonas hydrophila bacteria. The fish fillets were treated with aqueous solution of orange peel extract (5, 6 and 7% w/w) and dipped in distilled water for 30 minutes. These samples were analyzed during storage (0, 5, 10 and 15 days) for the total viable count (TVC), psychrotrophic count, coliform count. The MIC of the ethanolic extract of orange peel on the bacteria was 5%. The results of the microbial analysis indicated that the orange peel extracts reduced the growth of the bacterial counts in contrast control sample (p<0.01). The ethanol extract of orange peel as a natural preservative could increase shelf life during refrigerated storage because of having antimicrobial properties.