Antimicrobial Effects of Grape and Pomegranate Waste Extracts against two Foodborne Pathogens

In recent years, increasing in the level of public health consciousness has led to a drastic decrease in the use of synthetic food preservatives. Therefore, there has been a growing demand for novel antimicrobials. Apart from that, finding low cost sources has been always an important issue for food marketers. The present study was designed to investigate in-vitro antibacterial activities of grape and pomegranate waste separately and in combination with broth dilution methods against two bacteria (Staphylococcus aureus and Escherichia coli). The utilized solvent, as an extractant, was hot water. The total phenolic contents of grape and pomegranate wastes were also evaluated. Results revealed that the hot-water extract of the mixed wastes was the most potent, with the MIC / MBC of 52 / 286 mg/ml against E. coli and 75/98 mg/ml against S. aureus. It was also observed that the pomegranate waste contained higher level of phenolic compounds (439±0.82 mg GAE/L) as compared to the grape waste (333.6±1.25 mg GAE/L). It also exhibited higher antibacterial activity (lower MIC and MBC against tested bacteria) than the extract of grape waste. These results suggest that by-products of grape and pomegranate that are inexpensive and available can be employed as a potential source of antibacterial compounds.