Impact of UV-C processing of raw cow milk treated in a continuous flow coiled tube ultraviolet reactor

Abstract

Raw cow milk (RCM) was treated in a continuous flow coiled tube ultraviolet reactor at the Reynolds number (R_e) of 713 for a residence time of 17 s with cumulative UV-C dose of 16.822 mJ/cm².  SPC in RCM was reduced by 2.3logs at these conditions.  Sensory analysis of milk samples was conducted using triangle test.  UV-C treated RCM and untreated RCM was compared with the fresh RCM (control) using triangle test method of olfactory sensory analysis right after the UV treatment and during storage periods (1, 3, 7 d) at 4℃.  There were no significant differences among the odor of UV-light-treated, untreated, and control, right after the UV treatment.  Perceivable change in the odor of UV-treated and untreated RCM compared to the fresh RCM was observed on the 3^rd and 7^th days after treatment.  There was no significant difference between the malondialdehyde and other reactive substances (MORS) content in untreated and fresh milk right after the treatment and during storage.  Lipid oxidation products content of UV-treated RCM was significantly higher than that of the fresh or untreated RCM.

Keywords: raw cow milk, ultraviolet processing, UV-C treatment, sensory test, lipid oxidation substances