Effect of light emitting diode treatment on inactivation of Escherichia coli in milk

• Effect of LED treatment on inactivation of Escherichia coli in milk was studied.
• Log reduction and colour change of the treated milk were measured.
• Maximum reduction was obtained at higher temperatures and lower wavelengths.
• No significant change was observed between treated and untreated milk samples.

The effect of blue monochromatic light emitting diode (LED) light treatment on inactivation of Escherichia coli ATCC 25922 in milk was investigated in the present study. Wave length (405 nm–460 nm), temperature (5 °C–15 °C), and treatment time (0 min–90 min) were considered as the independent variables and log reduction of E. coli and overall colour change of the treated milk were measured as the dependent variables. It was observed that the maximum microbial reduction was achieved at higher temperatures and lower wavelengths. The optimized values of wavelength, temperature, and treatment time corresponding to log reduction value of five (pasteurization), and minimum overall colour change were 406 nm, 13.8 °C, and 37.83 min, respectively. There was no significant difference (P > 0.05) in physico-chemical properties of the LED treated milk in comparison to untreated samples. The shelf-lives of the LED treated milk samples, packaged aseptically in low density polyethylene (LDPE) pouches and stored at 37 °C and 4 °C were 19 h and 9 days, respectively. The data obtained in the research are expected to form a platform for development of a continuous LED based pasteurization system.