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).