Antibacterial and antioxidant properties of clove extract applied in the production of dry-cured duck

The clove extract showed the best inhibitory effect on all the five spoilage bacteria of dry-cured ducks among eight commonly used spices. The proliferation of Staphylococcus simulans 2 was inhibited significantly with no logarithmic phase following the treatment of the clove extract. The MIC of clove extract against Staphylococcus simulans 2 was 9 mg/mL. The clove extract had remarkable effects on inhibiting proteins synthesis and enhancing the permeability of the cell membrane, which induced the inactivation of the spoilage bacteria and the irregular, pitted, and shriveled bacterial morphology. Besides, the clove extract showed the strongest antioxidant capacity in vitro than the other seven spices. The clove extract had the highest scavenging activity on DPPH·, OH· and O2−·, which were 95.28%, 95.88% and 62.63%, respectively. It had the unique antioxidant capacity in duck grease, which was almost equivalent to TBHQ. As the clove extract was applied in the manufacture of dry-cured duck, the peroxide value, acid value, and total bacterial colony count declined significantly, and the shelf-life extended from 3 months to 6 months. It confirmed that the clove extract had distinguished antibacterial and antioxidant properties in the manufacture of traditional dry-cured duck.