Antimicrobial effect of apple polyphenols.

In order to provide some evidence for new natural safe food bacteriostat, we investigated the antimicrobial effect of apple polyphenols on bacteria, yeast and molds and their minimum inhibitory concentration. Six kinds of bacteria, three kinds of yeast and three kinds of mold were selected to investigate the antimicrobial effect of apple polyphenols (2, 6, 10 g/L) by using an agar diffusion method. Eight different concentrations of apple polyphenols, i.e. 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 1.0, 2.0 g/L, were screened to investigate the minimum inhibitory concentration of tested strains. The results showed that apple polyphenols significantly inhibited the growth of all six tested bacterial strains. The minimum inhibition concentration of the polyphenols in the test range was 0.6 g/L for Flavobacterium SHL45, 0.7 g/L for Escherichia coli, 0.6 g/L for Pseudomonas fluorescens SHL5, 0.6 g/L for P. fluorescens SHL7, 0.8 g/L for Bacillus subtilis, and 0.5 g/L for Staphyloccocus aureus. Apple polyphenols are applicable as a natural antimicrobial agent in improving food safety.