Effect of hydrogen peroxide treatment on the quality of epsilon-poly-L-lysine products

Abstract e-poly-L-lysine (e-PL) is a novel biopreservative with wide antibacterial spectrum, high safety, and stable property. However, the color of e-PL generating from manufacturing process lowers its appearance and limits its application. This work aimed to decolorize e-PL by hydrogen peroxide. Impacts of hydrogen peroxide concentration, pH, duration time and temperature were discussed. Physicochemical property and bioactivity of e-PL were explored. Results indicated that 43.2% color saturation and 94.54% recovery rate were reached when the concentration of hydrogen peroxide, pH, duration time and temperature were 3.0%, 7.0, 1.5 h and 70℃ respectively. Furthermore, the MIC (minimal inhibitory concentration) of the hydrogen peroxide treated e-PL for Bacillus subtilis, Escherichia coli, and Staphylococcus aureus were 2 mg/mL, 0.1 mg/mL, and 0.1 mg/mL respectively, which was similar with untreated e-PL. At last, cytotoxicity test indicated that no cytotoxicity could be observed at concentration lower than 2 mg/mL e-PL. As a result, hydrogen peroxide treatment on e-PL could significantly decolorize e-PL without impairing the antibacterial performance and changing the cytotoxicity. Hydrogen peroxide treatment is a promising method to improve the appearance of products, to reduce the cost of decoloration, and to enlarge the application in food and cosmetics industry.