Shallot peel (Allium ascalonicum L.) extract, the antioxidative, antibacterial properties and fish preservation capacity

Abstract

This study aimed to extract and evaluate some properties and the capability of phenolic components from shallot (Allium ascalonicum L.) peels for usage as fish preservative. It was found that shallot peels extracted twice with 70% ethanol solvent, within 60 minutes, at 60°C and the ratio of solid/liquid 1/20 (g/mL) gave highest polyphenol and flavonoid yields. Total polyphenol content and total flavonoid content of the extract were 224.34±5.66 mg GAE/g DW and 255.11±4.35 µg QE/g DW, respectively. The extract demonstrated potent DPPH scavenging capacity with IC50 value of 16.77±0.23 µg/mL. and high antibacterial activities on Bacillus subtilis, Escherichia coli and Staphylococcus aureus with MIC values were 224, 160 and 224 µg/ml., respectively. Through measuring PV, TBARS values of basa catfish fillets coated with the extract suspension, it was observed that shallot peel extracts could strongly inhibit lipid oxidation. Suspension of 3% extract displayed inhibitory capacity comparable to that of 200 ppm BHT, a commercially employed antioxidant, after 3 days in refrigerator conditions (4°C) and up to 4 weeks in deep-freezing conditions (-18°C).