Anthocyanin composition and sensory properties of wines from Portuguese and international varieties cultivated in a hot and dry region of Portugal

Abstract

The study of anthocyanins in wines and grapes has been the subject of numerous research works over the years due to their important role in enology regarding their contribution to wine sensory properties. Anthocyanins confer colour to red wine and contribute to other organoleptic characteristics due to interactions with other polyphenols, proteins and polysaccharides. This group of compounds lends itself to varietal characterization; they are substances that, as secondary metabolites, are directly related to the genetic component. The environmental characteristics, namely the temperature and the water status under which the development of the berries takes place have a great influence on the quantity and composition of these compounds.The objective of this work was to study varietal differences in anthocyanins composition and the relation with some sensory properties, within selected international and Portuguese grape varieties cultivated in Alentejo region, one of Portugal largest quality wine producing regions but very hot and dry and extremely susceptible to climate change. The grape varieties were selected based on previous studies on their ecophysiological response and adaptability to severe environmental conditions and heatwaves. The grape varieties studied were 14 namely, Petit Verdot, Marselan, Merlot, Touriga Franca, Syrah, Vinhão, Bobal, Preto Martinho, Corropio, Trincadeira, Tinta Caiada, Alfrocheiro, Alicante Bouschet e Touriga Nacional. The varietal wines samples were evaluated by sensory analysis using quantitative descriptive analysis and the anthocyanins analysis by high-performance liquid chromatography-diode array (HPLC-DAD).The principal component analysis (PCA) results based on the correlation matrix between different anthocyanin groups according to acylation types, (nonacylated, acetate derivatives, coumarate derivatives and caffeoate derivatives) and total anthocyanins, showed that the first two principal components explained 98.24% of total variance. The PCA  show the discrimination of Touriga Nacional, Syrah, and Vinhão wines, that have high positive scores in PC1 strongly associated with nonacylated and total concentration of anthocyanins, related to their higher concentration and richer composition of anthocyanins, in the other hand wines from the varieties Preto Martinho, Bobal e Corropio are located on the opposite side of PC1, and they presented lower anthocyanins concentration. These results are in agreement with sensory analysis regarding specific sensory attributes such as astringency and colour quality.