Pulsed Electric Fields to Improve the Use of Non-Saccharomyces Starters in Red Wines
Cristian Vaquero, Iris Loira, Javier Raso, Ignacio Ãlvarez, Carlota Delso, António Morata
Abstract
New nonthermal technologies, including pulsed electric fields (PEF), open a new way to generate more natural foods while respecting their organoleptic qualities. PEF can reduce wild yeasts to improve the implantation of other yeasts and generate more desired metabolites. Two PEF treatments were applied; one with an intensity of 5 kV/cm was applied continuously to the must for further colour extraction, and a second treatment only to the must (without skins) after a 24-hour maceration of 17.5 kV/cm intensity, reducing its wild yeast load by up to 2 log CFU/mL, thus comparing the implantation and fermentation of inoculated non-Saccharomyces yeasts. In general, those treated with PEF preserved more total esters and formed more anthocyanins, including vitisin A, due to better implantation of the inoculated yeasts. It should be noted that the yeast Lachancea thermotolerans that had received PEF treatment produced four-fold more lactic acid (3.62 ± 0.84 g/L) than the control of the same yeast, and Hanseniaspora vineae with PEF produced almost three-fold more 2-phenylethyl acetate than the rest. On the other hand, 3-ethoxy-1-propanol was not observed at the end of the fermentation with a Torulaspora delbrueckii (Td) control but in the Td PEF, it was observed (3.17 ± 0.58 mg/L).