Identification of phenolic compounds, antibacterial and antioxidant activities of raisin extracts

In this study, antibacterial, antioxidant and phenolic compounds of raisin extracts was evaluated. Different solvent extraction methods were utilized to extract phenolic compounds from raisin. The phenolic compounds of raisin extracts was determined using HPLC and three compounds were found, catechin, quercetin and rutin. The antibacterial activity of the acetonic extract was tested against four bacterial pathogens viz. Staphylococcus aureus, Pseudomonas aeroginosa, Salmonella typhimurium and Escherichia coli using both disk diffusion and minimum inhibitory concentration (MIC) methods. The acetonic extract exhibited the highest activity against Staphylococcus aureus with zone of inhibition of 14mm and the MIC of 25 mg/ml. However, there was a little activity against E. coli and S. typhimurium. The methanolic extract showed good antioxidant activity as indicated by 2,2-diphenyl-1-picrylhydrazyl free radical assay (DPPH). In conclusion, raisin contains potent phenolic compounds and their application might function as promising natural preservative and antimicrobial agents in food industry and also good antioxidant food that helps to minimize the risk of degenerative diseases.