In vitro antimicrobial effect of phenolic extracts and resistant starch on escherichia coli, streptococcus spp., bifidobacterium and lactobacillus spp.

Abstract

The present study aimed to evaluate the antimicrobial activity of Grape Pomace Extract (GPE), Pistachio Peel Extract (PsPE), and Pomegranate Pomace Extract (PPE) with or without Resistant Starch (RS) as a prebiotic on gut microflora representative"s in vitro conditions. For this purpose, the Resistant Starch (Fibersol2), grape pomace, pistachio peel, and pomegranate pomace were provided and the extracts of by-products were prepared. Folin-Ciocalteu method was used to determine the total phenolic content of extracts. The antimicrobial activity of extracts± Resistant Starch against Escherichia coli, Streptococcus spp., Lactobacillus spp. and Bifidobacterium spp. were evaluated using Minimum Inhibitory Concentration (MIC) method. The total tannin and phenolic compounds of pomegranate pomace were more than the others. The results of MIC showed that 1600 and 3200 ppm of pistachio peel extract inhibited the E. coli growth. The growth inhibition of Streptococcus spp. by Resistant Starch was equal to 400 ppm dilution. Streptococcus did not grow in 50, 100, and 200 ppm of pistachio peel extract + Resistant Starch treatment. The dilution of 800, 1600, and 3200 ppm of grape pomace extract could prevent the growth of Lactobacillus spp., while Bifidobacterium increased in all treatments dilution except in 3200 ppm pistachio peel extract and 50 and 100 ppm pistachio peel extract + resistant starch.

Keywords

• phenol
• resistant starch
• antimicrobial activity
• bacteria
• mic