Antioxidant and antimicrobial activities of ginseng extract, ferulic acid, and noni juice: Evaluation of their potential to be incorporated in food

Ginseng extract (GE), ferulic acid (≥99%) (FA), and a fermented noni juice powder (FNJP), were investigated for their antioxidant and antimicrobial activities in vitro. Half inhibitory concentration (IC50) was 29.87, 0.45 and 3.82 mg/mL, for GE, FA, and FNJP, respectively. The capacity of the three extracts to inhibit polyphenol oxidase from three vegetable matrices ranged between no inhibition and 95.1 % (depending on the extract and PPO source). In the study of peroxidation prevention of three types fats, only ferulic acid delayed lipid peroxidation of olive oil when applied at 10 mg/mL. The extracts’ antimicrobial activity was studied on thirteen bacterial strains using the disk diffusion assay and the microdilution assay. Minimal inhibitory concentration (MIC) values were 5.5 mg/mL of GE for Listeria monocytogenes, 1.7 mg/mL of FA for Staphylococcus aureus, L. monocytogenes 1/2 and 4b, and 4.2 mg/mL of FNJP for Bacillus cereus. The increases in lag phase, and decreases in growth rate and in asymptotic value of the bacteria growing under different concentrations of the three compounds were described. The results obtained suggest the potential of GE, FA and FNJP for its further application in food industries.