Influence of pressing conditions on the chemical composition, oxygen consumption rate, and tyrosinase activity of the grape must

Identifier:  imarina:9577448

Handle: https://hdl.handle.net/20.500.11797/imarina9577448

Authors:  Garcia-Roldan, Aitor; Canalda-Sabate, Antoni; Gregori, Nadia; Gombau, Jordi; Bustamante-Quinones, Marco; Fort, Francesca; Marchal, Richard; Tillement, Theodore; Duroux, Coraline; Canals, Joan Miquel; Zamora, Fernando

Abstract:
Pressing is a key step in white winemaking that directly influences juice yield, chemical composition, and the oxidative stability of grape must. Among commonly used techniques, direct pressing (DP) and pressing after crushing (PaC) differ in their mechanical treatment and impact on must quality. This study compares these two methods. Our results show that PaC achieved a higher juice yield and greater mechanisation efficiency but also produced musts with higher turbidity, increased phenolic content, lower potential ethanol levels, lower titratable acidity, and greater oxidability. Specifically, PaC musts showed higher concentrations of hydroxycinnamic acids and a faster oxygen consumption rate despite exhibiting lower tyrosinase activity than DP musts. The results suggest that substrate availability plays a more critical role in must oxidation than enzyme activity alone.