Pulsed electric fields for application to grape must: microbial modulation and extraction of bioactive compounds

Mild postharvest treatments, including pulsed electric fields (PEF), are increasingly required to meet high demand of shelf-stable fresh fruit worldwide and to produce fruit extracts of high quality without using chemical additives. Experimental treatments with a novel Pulsed Electric Fields generator were tested on 'Aglianico' grape must to investigate potential applications for red wine production. A wide range of PEF parameters, including electric field intensity, impulse width, treatment time, were tested with the aims i) to enrich the must content with valuable bioactive compounds; ii) to investigate the effect on the viability of oenological microbes (Saccharomyces cerevisiae, non-Saccharomyces spp., and lactic acid bacteria) in must artificially contaminated. Results indicated a different sensitivity of the microbial strains, suggesting that the optimization of PEF conditions might be useful to modulate the microbial oenological consortium, and at the same time to encourage the extraction of bioactive compounds during maceration. The experimental results have also emphasized the need of optimizing the software user interface of the PEF generator in order to allow a closed-loop control of the PEF parameters based on real-time measurement of workable parameters.