Application of high-chitin yeast cell wall hulls to mitigate protein haze in white wine

Protein haze formation remains a challenge in white wine production due to its detrimental effect on visual clarity and consumer acceptance. Bentonite fining, the industry standard for protein stabilisation, is effective but has several limitations, including the non-selective removal of desirable aroma and flavour compounds, increased lees volume and associated wine yield losses. Bentonite use also raises sustainability concerns, as it is a non-renewable clay mineral and its mining is linked to land degradation and energy-intensive extraction. In white wine, protein haze is primarily induced by pathogenesis-related (PR) proteins, notably thaumatin-like proteins and chitinases, the latter of which is most prone to aggregation upon heat exposure. Recent studies have demonstrated that chitin-rich yeast cell walls can selectively bind grape-derived chitinases, facilitating their removal from wine. In this study, yeast hulls derived from Saccharomyces cerevisiae wine yeast mutant strains selected for increased cell wall chitin levels and enhanced chitinase-binding capacity were evaluated for their ability to reduce protein haze in Sauvignon blanc wines. The data show that such hulls can reduce chitinase levels in the wine matrix. However, the reduction in haze formation potential after cell wall treatment was not linearly correlated with cell wall chitin concentration, suggesting that other cell wall features contribute to haze protection. The data suggest that high-chitin yeast hulls represent a promising tool to reduce or, in some cases, eliminate the need for bentonite fining, with potential benefits for process efficiency, wine quality preservation and environmentally conscious production.