Non-thermal processing of milk: Principles, mechanisms and effect on milk components

The conventional thermal treatment causes chemical modifications to milk constituents such as protein denaturation, loss of vitamins and flavoring compounds, depression at freezing point, and nonenzymatic browning, which may result in adverse changes to the flavor, color, and nutritional value of milk. This review looks into the emerging non-thermal processing techniques such as high-pressure processing (HPP), pulsed electric field (PEF), ultrasonication and hydrodynamic, UV-irradiation and plasma technology, cavitation, and their effects on milk components and bioactive compounds. For consumer acceptability and safety, simultaneous and crucial needs exist: microbial safety, fresh like quality and preservation of bioactive compounds. Technologies like HPP and PEF have been capable of achieving microbial reduction with moderate thermal inputs. Ultrasonication and hydrodynamic cavitation have the dual functions of deactivating microorganisms and homogenizing, and plasma and UV-C radiation could ensure minimal loss of heat-sensitive components. These processing techniques could be an alternative to pasteurization and sterilization of milk with assured microbial inactivation and maximal retention of nutrients in dairy.