Wine Chemistry and Biochemistry

(Steven Felgate) #1

430 M.A. Pozo-Bay ́ ́ on and G. Reineccius


Since yeast lees may adsorb some aroma compounds responsible of off-flavours


in wines (volatile phenols), these components have been also proposed such as a


cost-effective and efficient approach to remove or to decrease organoleptic defects


in wine (Chassagne et al. 2005).


In the case of wines aged in oak barrels with lees, aroma interactions with the


lees could modify how the wine interacts with the wood. One would expect a com-


petition between the wood and yeast derivatives for hydrophobic interactions with


aroma compounds (Ram ́ırez-Ram ́ırez et al. 2004). One of the most recent studies in


this field by Jimenez-Moreno and Anc ́ın-Azpilicueta (2007) investigated the effect


of lees extracted from wines on the binding of aroma compounds contributed by the


wood. As one would expect, most of thesewoodyaroma compounds decreased in


the wines when in the presence of lees, independent of their hydrophobicity and con-


centration (same effect for 10 g/L or 50 g/L). This finding suggested the saturation of


the binding sites at 10 g/L, and that the binding was likely due to non-hydrophobic


interactions. A summary conclusion is that wines aged in oak barrels in the presence


of lees could affect wine aroma giving wines with less woody, aromatic character.


Yeast cells can also influence wine flavour by binding aroma precursors such


as glycoconjugated terpenes. Moio et al. (2004) have shown that this binding by


yeast cells during fermentation could have important consequences on wine varietal


aroma.


The interaction between aroma compounds and other wine micro-organisms (e.g.


lactic acid bacteria) or with metabolites produced during malolactic fermentation


has been studied to a limited extent. Interactions between polysaccharides produced
by the most common wine lactic bacteria(Oenoccocus oeni)during malolactic fer-


mentation have been shown to be responsible for the reduced volatility of some


aroma compounds in wines (Boido et al. 2002). The possibility of direct interac-


tions between the surface of the bacteria cells and aroma compounds should also be


considered since this type of interaction has been found for other food lactic bacteria


(Ly et al. 2008).


8F.2.2.5 Other Wine Components


Glycerol is also one of the most abundant components in wine. It is mainly produced


during glycerol-pyruvic fermentation at the beginning of alcoholic fermentation. It


contributes directly to wine flavour giving sweetness (Noble and Bursick 1984) and


imparts some viscosity (Nurgel and Pickering 2005). Thus glycerol could directly


affect flavour perception.


The effect of glycerol-flavour interactions in white wine has been studied by


Lubbers et al. (2001). They found that glycerol at concentrations ranging from


5 to 50 mg/L did not modify the relative volatility of methyl-3-butanol, methyl-3-


propanol, ethyl hexanoate, or methyl-3-butyl acetate. They also carried out sensory


analysis, showing that the overall flavour of a model wine and white wine was not


changed by the addition of glycerol, suggesting that the concentrations in wine are


too low to have a significant effect on flavour perception.


In wines, De La Ossa and Gal ́an (1986) studied the effect of adding different


salts, such as CaCl 2 in a concentration range between 0 and 9.2 mol/L on aroma

Free download pdf