EVALUATION OF FLORAL HONEY FOR INHIBITION OF POLYPHENOL OXIDASE-MEDIATED BROWNING, ANTIOXIDANT AND ANTIMICROBIAL ACTIVITIES

Inhibition of polyphenol oxidase (PPO)-mediated browning in apple juice using different concentrations of floral honey was evaluated by performing the kinetics of PPO inhibition, effect of honey concentrations on activity of PPO and rate of quinone formation (browning) in apple juice. The antioxidant status of honey was demonstrated by 2, 2-diphenyl-1-picryl hydrazine (DPPH) radical-scavenging assay. Agar diffusion assay was carried out to demonstrate the antimicrobial activity of honey. Kinetic experiment suggests that honey is a noncompetitive inhibitor of PPO having K-m = 3.33 mM. There exist a negative correlation (gamma = -0.65) between different concentrations (50-100%, v/v) of honey and PPO activity with significant retardation in rate of browning reaction in apple juice. The DPPH radical-scavenging activity showed that the antioxidant potential of honey strongly depends on its concentration with a positive correlation (gamma = +0.96). Assessment of the antimicrobial activity of honey using agar diffusion assay demonstrated the significant inhibition of Candida albicans (Microbial Technology & Culture Collection [MTCC-3018]), Escherichia coli (MTCC-1588), Pseudomonas aeruginosa (MTCC-2488) and Staphylococcus aureus (MTCC-96) as compared to standard antibiotics. PRACTICAL APPLICATIONS Consumer demands for freshness in the minimally processed fruits and vegetables is a priority by the food processing industries. Alternate strategies for prevention of enzymatic browning in fruits and vegetables are necessary to maintain the quality and value of these produces. This study demonstrates that honey is an effective inhibitor of enzymatic browning in apple juice. Honey studied in this research also has antimicrobial and antioxidative properties; thus, its use as a browning inhibitor may have additional health and therapeutic properties.