Decoding Polysaccharides from Two Pichia Yeasts and Their Molecular Interaction with Wine Fruity Esters

Area of Science:

• Enology and Wine Chemistry
• Microbiology
• Biochemistry

Background:

• Yeast polysaccharides (YPs) play a role in wine's sensory properties.
• Understanding YP structure and interactions with flavor compounds is crucial for wine quality.

Purpose of the Study:

• To characterize yeast polysaccharides from Pichia fermentans and Pichia kluyveri.
• To investigate the structural attributes of YPs.
• To analyze the interaction between YPs and wine fruity esters.

Main Methods:

• Enzymatic extraction of YPs with optimized conditions (temperature, pH, enzyme ratio).
• Isolation and characterization of YP fractions using monosaccharide analysis, FTIR, and methylation analysis.
• Isothermal titration calorimetry (ITC) to study YP-ester interactions.

Main Results:

• Optimal YP yield achieved through enzymatic reactions.
• Four YP fractions isolated; two identified as glucans and two as mannoproteins (YPPF-W and YPPK-W).
• Mannoproteins (YPPK-W/YPPF-W) exhibited spontaneous interactions with fruity esters, varying with ester properties and temperature (optimal at 30°C).

Conclusions:

• Yeast polysaccharides, particularly mannoproteins, interact with fruity esters in wine.
• These interactions are influenced by ester molecular weight and hydrophobicity.
• Further research is needed to fully elucidate the impact of YPs on wine's sensory profile.