Interactions between wine components
Background
Wine contains a number of different chemical components that influence the sensory properties of the final product to varying degrees. A range of these components are well-known for the direct impact that they have on sensory properties. Wine and food in general, however, are compositionally very complex. It is therefore essential to consider the effect of interactions between different components on the sensory properties of the wine when consumed.
Interactions that influence the sensory properties of foods have been studied in the past. However, the interactions that have been studied have seldom gone beyond that of two components. While these simple models are useful in building an understanding of simple food systems, a question remains as to their usefulness in predicting the sensory properties of more complex foods and beverages such as wine. Understanding oral perception is particularly challenging as the general percept often referred to as ‘taste’ involves the major sensory modalities of olfaction (‘in mouth’ aroma), gustation (taste by mouth- sweet, sour, bitter, salty and umami) and chemesthesis (temperature, texture, astringency, irritation etc.). Furthermore, interactions may not only take place at the physical level, but also at the receptor and cognitive level.
Our previous work in this area of interactions focused on mouth-feel in red wines and assessed the impact of polysaccharides, grape pigments and ethanol on tannin astringency. Our current focus is on white wines.Progress
The key criteria for this current work is to present realistic ‘wine-like’ samples to trained evaluators, in such a way that key interactions between components can be identified. This was achieved by either adding wine components at wine realistic levels to a model wine base or by omitting them from the mixture. The complex wine macromolecules proteins and polysaccharides were purified from white wine, while the other components (ethanol, glycerol and volatiles) were obtained commercially. Interactions were examined by presenting various combinations of mixtures to a trained panel of assessors and asking them to assess the intensity of aroma, flavour, in-mouth textures and tastes.
The data from this study provides hints to what the key interactions may be. Not surprisingly, volatiles affected most aroma attribute ratings positively, however, this factor was also involved in interactions affecting hotness and acidity. Interactions between volatiles and protein also appeared to be important for several aroma attributes. Further experiments need to be conducted to confirm these and to ascertain the relative importance of them, particularly in light of the fact that white wines are generally fined to remove protein, but this process may also alter the level of volatiles in the wine. In many cases, interactions between effects involving volatiles were most prominent when the volatile level was low, suggesting that wines with naturally low levels of volatiles are affected more by changes to the factors more associated with wine structure, such as ethanol, glycerol and to a lesser extent polysaccharide level.
There appeared to be interactions involving ethanol and glycerol that affected aroma and mouth-feel attributes. Ethanol appeared to have the greatest enhancing impact on hotness, drying and roughing which are mouth-feel attributes that can be regarded as ‘unpleasant’ when perceived in white wine. The effect of glycerol, polysaccharides and protein was dependent on the combinations in which they were found, but in general the presence of glycerol in many cases appeared to reduce the intensity of ‘unpleasant’ characters such as bitterness. The generality of this statement warrants further study, however, before any firm conclusions can be made.
Highlights
In a reconstructed model white wine:
- Perceived hotness and acidity was affected by the level of volatiles
- Ethanol enhanced hotness, drying and roughing
- Glycerol reduced bitterness
Project leader: Dr Liz Waters
Project team members:
Publications:
1066 Jones, P.R., Gawel, R., Francis, I.L., Waters, E.J. The influence of interactions between major white wine components on the aroma, flavour and texture of model white wine. Food Qual. Pref. 19; 596-607: 2008 (click here to order).
964 Gawel, R.; van Sluyter, S.; Waters, E.J. The effects of ethanol and glycerol on the body and other sensory characteristics of Riesling wines. Aust. J. Grape Wine Res. 13; 38-45: 2007 (click here to order).
962 Gawel, R.; Francis, L.; Waters, E.J. Statistical correlations between the in-mouth textural characteristics and the chemical composition of Shiraz wines. J. Agric. Food Chem. 55; 2683-2687: 2007 (click here to order).
759 Vidal, S.; Francis, L.; Williams, P.; Kwiatkowski, M.; Gawel, R.; Cheynier, V.; Waters, E. The mouth feel properties of polysaccharides and anthocyanins in a wine like medium. Food Chem. 85; 519-525: 2004 (click here to order).
774 Vidal, S.; Courcoux, P.; Francis, L.; Kwiatkowski, M.; Gawel, R.; Williams, P.; Waters, E.; Cheynier, V. Use of an experimental design approach for evaluation of key wine components on mouth-feel perception. Food Qual. Pref. 15; 209-217: 2004 (click here to order).