Extraction and analysis of natural antibacterial components from peanut hulls

The investigation reported here deals with a bioactivity guided extraction of natural antibacterial components from powdered dried peanut hulls. By orthogonal experiment and single factor experiments, the extraction was optimized with regard to solvents and operational parameters, such as temperature, solid-to-liquid ratio, and extraction time. Ethyl acetate solvent was found to be optimum in combination with extraction time of 5.0h, leaching temperature of 60°C, and solidto-liquid ratio of 1∶35. The extracts showed distinct antibiotic activity against Staphylococcus aureus, Bacillus subtilis, and Escherichia coli. The minimum inhibitory concentrations (MICs) were 0.063 mg/mL, 0.500 mg/mL, and 0.250 mg/mL respectively, and the minimum bactericidal concentrations (MBCs) were 0.125 mg/mL, 1.000 mg/mL, and 0.500 mg/mL respectively. The antibacterial activity was stable under various conditions such as heat treatment (60°C to 121°C) and pH range 4–9.