The effect of Uncinula necator (powdery mildew) and Botrytis cinerea infection of grapes on the levels of haze-forming pathogenesis-related proteins in grape juice and wine

Abstract

Powdery mildew on Chardonnay grapes resulted in increased levels of a grape thaumatin‐like protein, VvTL2, in the free run juice compared to that from uninfected grapes. These increased levels persisted through winemaking and at the highest level of infection (> 30% of bunches infected) had a significant impact on the haziness in the wine following a heat test. Infection of Cabernet Sauvignon grapes (1–20% of bunches infected) did not affect the protein concentration of free run juice, and only traces of pathogenesis‐related (PR) proteins remained detectable in the Cabernet Sauvignon wines from either infected or healthy grapes. In contrast, infection of Chardonnay or Semillon grapes by Botrytis cinerea in the vineyard resulted in decreased levels of all PR proteins in the free run juice and in a total protein extract from infected berries compared to that from uninfected grapes. Similar trends were observed when B. cinerea was grown in the laboratory on surface‐sterilised berries or in filter‐sterilised juice.

Degradation of white wine haze proteins by Aspergillopepsin I and II during juice flash pasteurization

“…Several authors have investigated the effects of microbial proteases such as those from Aspergillus niger (Bakalinsky & Boulton, 1985), Saccharomyces cerevisiae (Dizy & Bisson, 2000;Feuillat, Brillant, & Rochard, 1980;Lagace & Bisson, 1990;Younes et al, 2011), and Botrytis cinerea (Cilindre, Castro, Clément, Jeandet, & Marchal, 2007;Girbau et al, 2004;Marchal et al, 1998). However, in each study, the enzymes were not able to effectively degrade grape PR proteins because of their high proteolysis resistance and because winemaking temperature conditions are unfavourable for enzyme activity (Waters, Peng, Pocock, & Williams, 1995;Waters et al, 1992).…”

New directions in stabilization, clarification and fining of white wines

“…Secretion of proteases by B. cinerea has been observed in culture media and on fruits such as apple (Zalewska-Sobczak et al, 1981) and tomato (Brown and Adikaram, 1983). Girbau et al (2004) also examined the impact of infection of grapes with B. cinerea in the vineyard and showed that infection resulted in marked decreases in the levels of PR proteins in the berries. Similar although less dramatic trends of reductions in protein levels were seen in laboratory experiments in which otherwise healthy berries were inoculated with B. cinerea (Girbau et al, 2004).…”

“…Of these three putative gene products, only VvTL2 has been detected as a soluble protein in grape juices and wines (Waters et al, 1996). Girbau et al (2004) demonstrated that powdery mildew infection of V. vinifera cv. Chardonnay grape bunches resulted in increased levels of a grape minor thaumatin-like protein, VvTL2, in wine.…”

“…Girbau et al (2004) also examined the impact of infection of grapes with B. cinerea in the vineyard and showed that infection resulted in marked decreases in the levels of PR proteins in the berries. Similar although less dramatic trends of reductions in protein levels were seen in laboratory experiments in which otherwise healthy berries were inoculated with B. cinerea (Girbau et al, 2004). Protein levels were also reduced in juice when B. cinerea was grown in this medium (Girbau et al, 2004).…”

Vineyard Practice

“…Cladosporium bunch rot also reduces the quality (color and flavor) of wines produced from affected red grapes (Briceño et al, 2009). Botrytis infection can also increase problems associated with protein haze (Girbau et al, 2004). This appears to result from the enhanced production of thaumatin-like (PR) proteins.…”