Influence of microwave treatments on viability and vitality of wine-origin microorganisms

Microwave has been used in food industries to enhance or replace conventional techniques. In Enology, its potential use is not clear since references indicate that can be intended for both inactivation of microorganisms and maceration treatments. In this context, it is important to know the effect of microwaves on microorganisms. This study focuses on the application of microwave (MW) on Saccharomyces and non-Saccharomyces yeasts and Lactiplantibacillus plantarum (from oenological ecosystems) to evaluate their behaviour under different conditions of power, duration and presence of pulses on; viability and vitality were studied. MW affected microorganisms in different ways. In general, yeasts were less resistant than L. plantarum. Counts after treatments showed inactivation in some cases. Nevertheless, ODmax after 96 h presented values closer to the controls. This effect shows that in some cases the treatment exerts an antimicrobial effect after application, but after some time, microorganisms can restore their biological structures and growth, which is reflected in an increase in the lag phase. On a few occasions, treatments were able to improve the kinetic parameters. Thus, this technique could be useful for inactivation, attenuation or even activation of associated food microorganisms.