Molecular approaches for understanding and modulating wine taste

Abstract

Wine consumers generally demand wines having a perception of softer tannins and less ripe, having a heaviness and richness on palate (full-body wine) with a limpid and stable color. However, polyphenol (tannins)-rich wines have been also correlated with unpleasant taste properties such as astringency and bitterness when perceived at high intensities. Modulating these unpleasant properties could be important for consumer’s approval of wines.
Indeed, polyphenols are usually associated with flavor, and particularly with astringency, due to their ability to complex with salivary proteins [1]. Saliva is rich in different SP families described to be involved in astringency, namely basic PRPs, glycosylated PRPs, acidic PRPs, statherin/P-B peptide and cystatins. However, due to saliva being a complex fluid, its protein profile may quantitatively and qualitatively vary under different conditions. Currently, astringency is recognized as a trigeminal sensation although the molecular pathway responsible for its onset is yet to be fully established. Moreover, it is unknown if the many different astringency mouthfeel sub-qualities such as velvet, puckering, harsh, among others, are perceived by different mechanisms. Besides the structural factors and medium conditions, there are some endogenous factors that affect astringency perception such as the physiological response, circadian rhythms, salivary flow rate and time of exposure. Indeed, astringency is perceived as a diffuse stimulus and dynamic process in the oral cavity that requires time to be elicited. It is known that astringency increases upon successive exposures to tannins [2,3].
Wine industry has some strategies to balance astringency and bitterness such as the use of some fining agents and also some winemaking practices (e.g. oak aging, batonnage and microoxygenations) leading to the loss of phenolics and also promoting the chemical change of some of them. While removing phenolic compounds is necessary to fulfill some organoleptic requirements of a beverage, the process must be controlled to avoid some collateral effects such as the loss of flavor [4]. Polysaccharides have been an emerging natural and sustainable option to be used on the modulation of taste properties. In fact, polysaccharides can influence salivary protein-tannin interactions and they could be used to modulate astringency and bitterness.

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