Impact of Extraction Methods of Wine Lees β-Glucan on the Rheological Properties of Low-Fat Yogurt

Wine lees, a byproduct of winemaking, represent an underutilized source of β-glucans with potential functional applications in food. This study aimed to extract β-glucans using two methods—acid–alkaline treatment and autolysis assisted by ultrasound—and evaluate their effects when incorporated into low-fat stirred yogurt. The extracted β-glucans were added at a concentration of 0.3% (w/w), and rheological measurements were conducted over 20 days of storage. All yogurt samples showed shear-thinning behavior, with apparent viscosity decreasing from 10⁵ mPa·s at low shear rates (0.1 s⁻¹) to 10³ mPa·s at 100 s⁻¹. Yogurt with β-glucans from autolysis retained higher viscosity and viscoelastic moduli (G′ and G″), indicating better structural integrity. Time-dependent tests showed up to 45% decrease in shear stress over 10 min of continuous shearing in the sample with chemically extracted β-glucans, compared to only 28% for autolysis-derived ones. Oscillatory tests confirmed that all samples behaved as weak gels (G′ > G″). These findings suggest that β-glucans obtained via autolysis can improve the textural stability of yogurt, offering potential for functional dairy development and valorization of wine industry byproducts.