Impact of the Chemical Composition and Structure of Yeast Mannoproteins from Pichia Strains on Wine Fruity Ester Release

Extended wine storage often leads to a reduction in volatile compounds, diminishing the fruity aroma. Yeast mannoproteins (MPs) have been identified as a mitigating factor against this effect, although the mechanisms involved remain poorly understood. This study examines the impact of MPs from Pichia strains, noting differences in chemical composition and structure, on the volatility of wine fruity esters. Gas chromatography, high-performance liquid chromatography, and Fourier transform infrared spectroscopy were used to analyze MPs from Saccharomyces cerevisiae SC-19 (MP-SC), Pichia fermentans Z9Y-3 (MP-PF), and Pichia kluyveri MP-PK. The influence of MPs on wine ester volatility was further explored through headspace solid-phase microextraction and gas chromatographic-mass spectrometry, alongside thermodynamic assessments. The findings revealed that mannose predominates in the monosaccharide composition of MPs, with MP-SC presenting the highest mannose levels. MP-PF and MP-PK, however, exhibited higher protein concentrations and significantly more hydrophilic amino acids, contributing to a 3–6-fold reduction in ester volatility compared with MP-SC, likely due to enhanced van der Waals forces and hydrogen bonding.