Impact of flash release treatment of lees on mannoprotein content during white wine ageing

This study investigates the impact of adding treated wine lees processed by flash release (FD), with or without enzymatic treatment, on the polysaccharide composition, molecular weight distribution, and sensory properties of Chardonnay wines aged on lees for six months. Standard oenological parameters (pH, total and volatile acidity, SO2 content, and alcohol) remained largely unaffected by lees addition, except for a slight pH and acidity increase in wines with 5 % untreated lees. Polysaccharide and oligosaccharide analyses revealed a significant increase in mannoproteins (MPs) content, especially in wines supplemented with FD-treated lees and FD-treated lees with enzymes, reaching concentrations up to 600 mg/L. FD treatment enhanced the extraction of high-molecular-weight polysaccharides, whereas enzymatic treatment by β-glucanase promoted their depolymerisation into mid-sized molecular fractions. High-performance size exclusion chromatography with a multi-angle laser light scattering (HPSEC-MALLS) analysis identified five major molar mass populations, with distribution patterns varying according to lees treatment. Sensory evaluation showed that wines aged with untreated lees exhibited more pronounced yeast and reductive aromas, whereas those aged with FD + enzyme-treated lees were perceived as more fruity, more acidic, and with greater aromatic persistence. Overall, the data demonstrate that flash release and enzymatic pre-treatment of lees significantly modify the colloidal composition of wine, with implications for both wine stability and sensory profile.