Wine Chemistry and Biochemistry

(Steven Felgate) #1

214 E.J. Waters and C.B. Colby


taste of wines (Jones et al. 2008; Peng et al. 1997), on bubble persistence and bead


in sparkling wines (Girbau-Sola et al. 2002; Liger-Belair 2005; Senee et al. 1999),


on lacquer-like bottle deposit in red wines (Peng et al. 1996a, b; Waters et al. 1994)


and as allergens in rare cases of grape and wine allergy (Pastorello et al. 2003;


Sbornik et al. 2007; Schad et al. 2005; Vassilopoulou et al. 2007). This chapter will


focus on the role of endogenous wine proteins in white wine haze formation. It will


not cover the other roles of protein listed above nor will it describe the roles and


consequences of food proteins such as casein, egg white and isinglass, used in wine


processing.


Published scientific studies of these proteins and of protein haze in wine began


in earnest in the late 1950s and early 1960s with work by J. Koch in Geisenheim


(Koch and Sajak 1959), H.W Berg, at the University of California, Davis (Bayly and


Berg 1967; Berg and Akiyoshi 1961; Moretti and Berg 1965) and B. Rankine at the


Australian Wine Research Institute in Adelaide (Rankine 1962).


6C.2 The Origin of Wine Proteins


Where do the proteins come from that subsequently form hazes and deposits in


wine? Are they grape derived or do they come from the yeast? This is question


that has occupied researchers since the 1950s. Bayly and Berg (1967) fermented a


model juice solution and noted that protein levels contributed by the yeast were very


low and probably negligible in most cases. Twenty years later, Hsu and Heather-


bell (1987a) concluded the same using polyacrylamide gel electrophoresis. More


recently, Ferreira et al. (2000) and Dambrouck et al. (2003) used modern immuno-
logical techniques to confirm that wine proteins originate predominantly from the


grape. A contrasting possibility was raised by Yokotsuka et al. (1991), who anal-


ysed the protein profile ofVitis viniferacv. Koshu grapes as well as the resulting


wine made from the same grapes. In conflict with other authors, they found eight


wine protein fractions not present in the juice and suggested they had come from


yeast. Kwon ( 2004) demonstrated that there are multiple biological sources of wine


proteins using nano-high-performance liquid chromatography/tandem mass spec-


trometry, although the relative levels of proteins from microbiological sources was


not established by this methodology.


Waters et al. (1991, 1992) described two major wine protein fractions inV.


viniferacv. Muscat Gordo Blanc wine. By SDS PAGE, these proteins had molec-


ular masses of 24 and 32kDa. By analysing the amino acid sequence of the pro-


teins, Waters et al. (1996) showed that these 24-kDa and 32-kDa proteins shared


homology with thaumatin and chitinases respectively and were highly similar to


other plant pathogenesis-related (PR) proteins. Tattersall et al. (1997) further char-


acterised the 24-kDa protein,Vitis viniferathaumatin-like protein 1 (VvTL1). This


protein is highly expressed in conjunction with the onset of sugar accumulation and


softening in the grape berry. It has also been observed that there is relatively high


expression after v ́eraison of chitinase encoding genes inV. viniferacv. Shiraz grape


berries (Robinson et al. 1997).

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