Sustainable Processing Approaches in White Winemaking: Impact of Oak Aging and Ultrasound-Assisted Treatment on...

Sustainability challenges in the wine sector have intensified the need for alternatives to conventional oak barrel maturation, a practice associated with high wood consumption, long maturation periods, and considerable economic and environmental cost. This study evaluates a resource-efficient maturation strategy for white wine using an experimental design comparing conventional oak alternatives with ultrasound-assisted extraction. Experiments were conducted in triplicate (n = 3) considering oak type (French chips vs. granules), dosage, toasting level (fresh, light, medium), and contact time (10 vs. 20 days). To enhance mass transfer, a 15 min ultrasound treatment (35 kHz) was applied. Statistical analysis (ANOVA One Way) indicated that oak fragment type and contact time significantly governed phenolic extraction (p < 0.05). Gallic acid concentrations increased significantly from 1.54 ± 0.03 mg L^-1 in the control to 4.41 ± 0.12 mg L^-1 in the most intensive ultrasound-assisted extraction treatment (p < 0.05). Syringaldehyde concentrations also showed a significant rise (1.13 to 1.44 mg L^-1; p < 0.05). Ultrasound significantly accelerated extraction kinetics while mitigating the loss of flavan-3-ols (≤28%) compared to conventional oak treatments (up to 34%). Economic assessment demonstrated a substantial reduction in production costs, from 0.21-0.56 € L^-1 range for standard fragment treatments to 0.05-0.07 € L^-1 when ultrasound was applied. Cost-efficiency metrics (<0.03 € mg^-1 gallic acid) confirmed that the combination of ultrasound and alternative oak materials provides an optimal, statistically significant balance between phenolic yield and economic viability.