Antioxidant and antibacterial activities of dill extracts and their preservative effect on mackerel fillets during refrigerated storage

Abstract

In order to develop a natural extract using no organic solvent for extension of shelf life of mackerel fillets, juices were prepared from raw, water bath boiled (WBB) and microwave oven boiled (MOB) dill (Anethum sowa Kurz) plant. The MOB dill juice showed the highest percentage of inhibition in DPPH radical scavenging activity and also had high total phenolic content revealing the role of phenolic compounds in their antioxidant activity. The antibacterial activities of the dill juices were evaluated against 13 fish borne pathogens and fish spoilage bacteria using micro broth dilution methods. Among the dill juices, MOB dill juice showed lowest MIC and MBC values in the range of 250 to 500 µL/mL and 250 to 1000 µL/mL, respectively, demonstrating their potential antibacterial activity. Among the three dill juice extracts studied, MOB dill juice was selected for preservation of mackerel fillets based on its antioxidant and antibacterial activity exhibited against fish borne pathogens and fish spoilage bacteria. The MOB dill juice extended the shelf life of mackerel fillets by three days demonstrating its capacity as an excellent natural antioxidant and antibacterial agent which could be an effective alternative to synthetic antioxidant and antibacterial agents.