Review: Characterization and role of grape solids during alcoholic fermentation under enological conditions

Abstract

During wine production, grape solids have a large impact on the fermentation characteristics and organoleptic qualities of the resulting wine. Here we review the research on grape solids. We begin by focusing on the origin, physical characteristics, and composition of these solids and on the changes in these factors that occur during fermentation. We then consider the impact of solids on fermentation, the role of sterols, the control of solids, and interactions between solids and other nutrients. Solids exert their effects on alcoholic fermentation mainly by modulating lipid supply. The balance between solids content and nitrogen is a key factor in fermentation control. The study of grape solids is in its infancy and requires further development. Knowledge of the composition of these solids and of sterol uptake mechanisms by yeast should facilitate improvements in fermentation control.