Yeast Cell Wall Chitin Reduces Wine Haze Formation

Area of Science:

• Enology
• Microbiology
• Biochemistry

Background:

• Protein haze in bottled wine is a costly issue for the wine industry.
• Existing clarification methods are expensive.
• Yeast mannoproteins and chitin addition are known to reduce haze, with grape chitinases implicated as haze contributors.

Purpose of the Study:

• Investigate yeast strains' haze-protective capacities.
• Determine the role of yeast cell wall chitin in haze reduction.
• Propose a novel strategy for wine clarification using yeast strain selection.

Main Methods:

• Fermenting Chardonnay grape must with different yeast strains.
• Quantifying yeast cell wall chitin levels.
• Assessing protein haze formation in resulting wines.
• Using GFP-tagged grape chitinase to study binding to yeast cell walls.

Main Results:

• Significant variation in haze levels among wines fermented by different yeast strains.
• Strong positive correlation between yeast cell wall chitin content and haze protection.
• Demonstrated concentration-dependent binding of grape chitinase to yeast cell walls.
• Observed removal of commercial chitinase from synthetic wine, correlating with yeast chitin levels.

Conclusions:

• Yeast cell wall chitin plays a crucial role in reducing wine protein haze by binding grape chitinases.
• Selecting wine yeast strains with high cell wall chitin offers a cost-effective clarification strategy.
• Further research into environmental factors affecting yeast chitin levels is warranted.