Study on low‐pressure plasma system for continuous decontamination of milk and its quality evaluation

Abstract

A low-pressure plasma system was used to study the continuous decontamination of milk flowing at atmospheric pressure in a quartz tube. The plasma discharge generated at 2 kV, 1.5 cm electrode gap was characterized by optical emission spectroscopy, and evaluated for microbial reduction at a flow rate of 6 and 3 ml/min. It accounted for a maximum of ~95% microbial (coliforms) reduction at 3 ml/min (5 min exposure time). No detrimental effects were detected during plasma interaction on physicochemical properties such as pH, conductivity, acidity and nutrient contents namely protein, calcium, and lactose. The findings from this study reveal that the low-pressure plasma system could be used for bulk processing of milk while reducing the microbial load without compromising the milk quality. This work on continuous plasma processing is an initiative for bulk processing of liquids, which could have a potential impact on industrial applications. Practical application The role of nonthermal plasma in food processing includes sterilization, decontamination, disinfestation, enzyme inactivation, allergen reduction, and property modification. The main application of this work is to provide an insight on alternative to batch-type plasma processing of liquid foods. A continuous-type plasma system for liquids was developed with an aim to increase the quantity of liquid foods used for decontamination. Maintenance of hygienic environment during processing in this plasma processing system is an added advantage which can be equivalent to hygiene maintenance on thermal in-line pasteurization units.