Abstract
Today in the wine industry, oenological tannins are widely used to improve wine quality and prevent oxidation in wine aging. With the development of tannin products, new oenological tannins are developed with many specific functions, such as modifying antioxidant effect, colour stabilization and aroma modifications. The aim of this work is to investigate effects of pre-fermentative addition of oenological tannins on wine colour, anthocyanins, volatile compounds and sensorial properties. In this case, Syrah juice was extracted with classic flash thermovinification from fresh must in order to release more colour and tannins. Three types of oenological tannins, which are, respectively, derived from grape skin, seed (Vitis vinifera) and French oak (Quercus robur and Querrus petraea), were selected to carry out the experiments with seven treatments. Results indicated that tannin treatments significantly improved wine aroma complexity and sensorial properties. However, the concentration of some stable pigments such as Vitisin A, Vitisin A-Ac and Vitisin B was negatively affected by tannin additions. Nevertheless, by means of cluster analysis and principal component analysis, it was observed that higher alcohols were significantly promoted by grape seed tannin while most anthocyanins can be improved by addition of grape tannins. In conclusion, low amount of oenological tannin derived from grape seed is a promising method to be applied especially for young red wine making.
Highlights
It is well known that oenological tannins and other phenolic compounds potentially influence wine components and contribute to the sensorial properties during red winemaking [1,2,3]
The gelatine index highlights the capacity of wine tannins to react with salivary proteins, which is responsible for the sensation of astringency experienced when tasting red wine [23]
HCL index reflects the state of polymerization of tannins in red wines [8], tannin treatment showed high values compared with the control, and the degree of tannin polymerization of Tanicol Vintage (TV) is positively correlated with addition volume, opposite to the effects of Robletan Estructura (RE) and Tan Sutil (TS)
Summary
It is well known that oenological tannins and other phenolic compounds potentially influence wine components and contribute to the sensorial properties during red winemaking [1,2,3]. Tannins play an important role during the aging process, modify aromatic complexity, prevent colour loss, create a balanced proportion of anthocyanins and improve wine structure [3,4,5]. Appropriate pre-fermentative addition of oenological tannin can positively contribute to colour stabilization and aroma protection during red wine aging [6,7]. Depending on different fermentation scenario and grape varieties, single implement or hybrid application of oenological tannins can improve wine quality and correct must flaws [9]. Hydrolysable tannins originating from oak possess higher antioxidant activity than some tannins extracted from
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