Evaluation of antimicrobial activity of water-soluble flavonoids extract from Vaccinium bracteatum Thunb. leaves.

Aqueous extract of Vaccinium bracteatum Thunb. leaves (VWFE) is traditionally used for food preservation in China, which is rich in flavonoids compounds. VWFE could effectively inhibit the growth of both Gram negative (Escherichia coli) and positive bacteria (Staphylococcus aureus and Bacillus subtilis), however, no inhibition effects were observed on mold and yeast. The minimum inhibitory concentration of VWFE were 2.06 mg/ml, 1.03 mg/ml, and 4.11 mg/ml for E. coli, S. aureus and B. subtilis, respectively, which were 13%, 13%, and 26% of sodium benzoate and 23%, 11%, and 46% of potassium sorbate. Cell membrane permeability assays indicated that cell membrane disruption was one of the antibacterial mechanisms of VWFE. VWFE showed a good thermal stability. The expiration date of VWFE was 6 months at 25 °C, which was predicted using the accelerated aging method. This present work indicated VWFE is a potential natural antibacterial preservative. © The Korean Society of Food Science and Technology 2019.