Application of atmospheric cold plasma (ACP) for processing of raw bovine colostrum: Investigation of antimicrobial efficacy of different ACP treatments

As a rich source of bioactive components, bovine colostrum (BC)¹ can be used to produce valuable nutraceuticals. Achieving this goal with common thermal pasteurization processes is challenging due to the heat-sensitive nature of raw BC. This research aimed to investigate the potential of atmospheric cold plasma (ACP) as a novel non-thermal process in inactivating the microbial population in BC. Raw BC was treated with different ACP treatments, including direct dielectric barrier discharge (DBD) in both static and continuous modes, indirect DBD, corona discharge, and gliding arc discharge. The occurrence of creaming and curdling of BC during the treatments was one of the challenges of this research, which was the most and least severe during static and continuous treatments, respectively. The continuous and the indirect DBD treatments were the most and least effective in terms of microbial inactivation. The inactivation of natural microflora with the continuous ACP at the voltage of 15 kV for 20 min was approximately 98%. The indirect DBD treatment led to an increase in the microbial population of BC. In addition, the initial microbial population significantly affected the antimicrobial efficacy of ACP. Treatment voltage and time had a significant effect on the creaming and curdling, natural microflora population, and the total coliform population of the treated samples. The voltage of 14.5 kV and the exposure time of 14.2 min were determined as optimal treatment conditions by response surface methodology (RSM) to achieve the maximum reduction of microbial population, without pH changing of ACP-treated BC. The optimal treatment conditions of ACP reduced the total plate count and total coliform count of raw BC by 1.41 and 3.55 log CFU/ml, respectively, with a minor change in pH. These results promise the potential of ACP technology for BC processing.