Wine Chemistry and Biochemistry

(Steven Felgate) #1

9A Anthocyanins and Anthocyanin-Derived Compounds 455


identified in Port wine fractions (Mateus et al. 2005). Similarly, the pigment phenyl-


vinylpyranomalvidin-3-glucoside hasbeen recently detected in aged red wine


(Mateus et al. 2006).


Factors affecting the reaction.Factors affecting the formation vinylpyranoantho-


cyanins must comprised those previously described for their precursor compounds.


9A.3 Enzymatic Deglycosilation of Anthocyanins During


Winemaking


Theβ-glucosidase activity of certain strains ofSaccharomyces cerevisiaewine


yeast, which has a positive effect in wine aroma releasing the volatile aglycone


of terpenol glycosides (Palmeri and Spagna 2007 and references therein), is also


responsible for breakdown of the glucosidic bond of the anthocyanidin-3-glucosides


(anthocyanin-β-glucosidase or anthocyanase activity). The released anthocyanidin


is very unstable and is rapidly degraded leading to losses in wine color (Mazza and


Miniati 1993).


There is very little information in relation to the effects of yeastβ-glucosidase


activity on grape and wine anthocyanins. AlthoughS. cerevisiae, the main wine


yeast, is not a good producer ofβ-glucosidase, other non-Saccharomyceswine


yeasts (Brettanomyces, Candida, Debaromyces, Dekkera, Hanseniaspora, Hanse-
nula, Kloeckera, Pichia, Rhodotorula, Saccharomycodes, Schizosaccharomyces,


Torulaspora,among others) are considered potential sources of this enzyme.


S ́anchez-Torres et al. (1998) reported that the action of aCandida molischianaβ-


glucosidase activity resulted in a 50% color loss during the fermentation time. More


recently, Manzanares et al. (2000) studied the glucosidase activity in 53 yeast strains


belonging to the generaCandida, Dekkera, Hanseniaspora, Metschnikowia, Pichia,


Rhodotorula, SchizosaccharomycesandZygosaccharomyces, mainly isolated from


grape and wine. Yeast strains showing the largestβ-glucosidase activity belonged to


the generaCandida, HanseniasporaandPichiaand exhibited cell wall bond activity.


The anthocyanin-β-glucosidase activity resulted in 30–70% color loss among yeast


strains considered as best producers of the enzyme. To date, no structural dependent


effect on anthocyanin-β-glucosidase activity has been reported.


9A.4 Adsorption of Anthocyanins on Yeast Cell Walls


The main structural constituents ofSaccharomyces cerevisiaeyeast cell wall are


glucans and mannans with a minor proportion of chitin (Walker 1998). Manno-


proteins are located in the outer layer of the yeast cell wall and determine most


of the surface properties of the wall. Vasserot et al. (1997) studied the capacity of


yeast lees to adsorb anthocyanins in an attempt to reduce the detrimental effects of


charcoal on the color of red musts and wines. Experiments based on model wine


solutions revealed that yeast lees possessa greater affinity for anthocyanins than

Free download pdf