Winegrape tannin and colour specification

Abstract

Winegrape tannin and colour specification

 

Summary

This project aimed to provide a better understanding of the types of compounds important to red wine colour and mouthfeel and of conditions favouring their presence in wine; to determine whether the interaction of proanthocyanidins (tannins) with other grape and wine compounds, especially polysaccharides, modifies their sensory properties; and to establish viticultural and oenological techniques that enhance wine colour and desirable mouthfeel.

Effects of pre-fermentation (cold soak) and post-fermentation extended maceration treatments on the tannin composition of red wines. The cold soak and cold soak with plunging treatments obtaining the highest chroma values. Maceration treatments had no effect on the total amount of anthocyanins, but did affect pigmented polymer concentrations with the three week extended maceration treatment having the lowest content. Neither of these two was correlated with the spectral measurements. Total tannin content was affected by maceration treatment and catechin and epicatechin concentrations increased dramatically as a function of time on skins after alcoholic fermentation. Despite the differences, a trained sensory panel did not rate the wines as significantly different with regards to bitterness or astringency.