Innovative physical techniques in freeze-drying

Malnutrition is a global problem that is caused by insufficient sources of vitamins, microelements, and other nutrients. This creates a need for developing long-term preservation techniques. One of the solutions is to pre-treat food materials before freeze-drying by applying advanced and safe electrophysical techniques instead of traditional thermomechanical methods. We reviewed three of the most promising electrophysical techniques (low-temperature plasma, ultrasound, and pulsed electric field) which have proven effective for a wide range of food materials. In particular, we focused on their mechanism of action and the equipment required, drawing on successful laboratory and large-scale studies in Russia and abroad. The electrophysical techniques under review had an etching effect on the material, caused electroporation, and changed the material's internal structure. In addition to these effects, we described their process and technology, as well as their advantages and disadvantages in industrial applications. Based on literature analysis, we stressed the importance of developing innovative electrophysical techniques for the food industry. These techniques should ensure high energy efficiency of the freeze-drying process and maintain good quality characteristics of food products.