Effect of thermal and non-thermal techniques for microbial safety in food powder: Recent advances

Food powders are appreciated worldwide, as it enables food to be preserved for an extended period without significant loss of quality, even under the ambient storage condition. However, it is evidenced that the development of resistant microbial spore and viable microbial cells is a matter of concern even in low moisture foods like food powders. For microbial inactivation, the strategy generally applied is the implication of conventional preservation methods, such as heat treatment which is greatly accompanied by degradation of nutritional organoleptic properties. To overcome the shortcomings of conventional thermal processing, a set of advanced or emerging technologies are being developed which can inactivate the microbial spores and viable microbial cells capable of surviving with maximum retention in the nutritional or organoleptic profile. The examples include infrared heating, microwave heating, radiofrequency heating, instant control pressure drop technology, high-pressure processing, pulsed electric field, pulsed light, ozone processing, and cold plasma. In this review, the potential of different advanced thermal and non-thermal technologies towards the inactivation of spores and viable cells of microorganisms in food powders has been highlighted precisely along with their mechanism of action. The summary of the literature encompassing the use of different processing techniques will help the readers to understand the underlying mechanism of microbial inactivation associated with each processing techniques applied to powders. Eventually, this information will help them to select the suitable technique (individual or in combination with another counterpart) to inactivate spores and viable cells in a specific food powder.