Grape Processing by High Hydrostatic Pressure: Effect on Microbial Populations, Phenol Extraction and Wine Quality

© 2014, Springer Science+Business Media New York. Vitis vinifera (variety Tempranillo) grapes were subjected to high hydrostatic pressure (HHP) treatments of 200, 400 and 550 MPa for 10 min, and its effect on microbial populations, phenol extraction and wine quality was examined. At ≥400 MPa, the wild yeast population was strongly reduced from 104 to <10 cfu/ml. Bacteria showed greater resistance, and a residual load remained even after the treatment at 550 MPa. The extraction of phenolic compounds from the HHP-treated grapes was improved, with higher concentrations of total phenols obtained compared to crushing alone. Anthocyanin extraction was also increased, producing wines with better colour intensity. These wines also had higher methanol and ethanol contents and returned higher aromatic quality and colour scores. The HHP treatment of grapes may assist in the use of yeast starters, increase phenol extraction from grape skins and improve wine quality.This work was funded by the Ministerio de Economía y Competitividad (AGL2013-40503-R).Peer Reviewe

J Agric Food Chem

Pulsed electric field (PEF) treatment is an emerging technology that is arousing increasing interest in vinification processes for its ability to enhance polyphenol extraction performance. The aim of this study was to investigate the effects of PEF treatment on grape skin histocytological structures and on the organization of skin cell wall polysaccharides and tannins, which, until now, have been little investigated. This study relates to the effects of two PEF treatments on harvested Cabernet Sauvignon berries: PEF1 (medium strength (4 kV/cm); short duration (1 ms)) and PEF2 (low intensity (0.7 kV/cm); longer duration (200 ms)). Histocytological observations and the study of levels of polysaccharidic fractions and total amounts of tannins allowed differentiation between the two treatments. Whereas PEF1 had little effect on the polyphenol structure and pectic fraction, PEF2 profoundly modified the organization of skin cell walls. Depending on the PEF parameters, cell wall structure was differently affected, providing variable performance in terms of polyphenol extraction and wine quality