Effects of Maceration and Fermentation on Aromatic Profile of Zelen Wines

Abstract

Introduction: Maceration and fermentation strongly influence the chemical and sensory composition of white wines. In Vitis vinifera L. ‘Zelen’, an autochthonous variety of the Vipava Valley, volatile phenols like 4-vinylguaiacol (4-VG) and methyl salicylate (MeSA) are key markers of varietal typicity, affected by maceration and microbial metabolism.

Aim: The study evaluated the effects of maceration and spontaneous fermentation on volatile phenols in Zelen wines.

Materials and Methods: Microfermentations were performed in triplicate. In the preliminary trial, 250 g of juice or pomace (both obtained from the producer) were fermented without maceration or with 1, 3, or 5 days of maceration using Saccharomyces cerevisiae Fermol Premier Cru (FPC). In the second entirely lab-controlled trial, the scale was increased to 1 L of juice and 2 kg of pomace with 3-day maceration, inoculated either with FPC or a pied de cuve prepared by spontaneous pomace fermentation. Volatile phenols were measured using HS-SPME-GC-MS.

Results: In the preliminary trial, maceration influenced volatile phenols, particularly 4-VG. Both 4-VG and MeSA decreased with maceration, likely due to uncontrolled microbial activity and matrix effects. In the scale-up trial, maceration increased MeSA (up to 17.5 µg/L) and guaiacol. Although MeSA remained below its olfactory threshold (OT; 38 µg/L), literature indicates perceptibility at lower concentrations via interactions with other compounds, suggesting a contribution to Zelen’s herbal–spicy profile. 4-VG consistently exceeded its OT (931–1301 µg/L), confirming its role as a defining varietal marker. 4-vinylphenol (4-VP) exceeded OT only in macerated FPC fermentations, consistent with its reported hydroxycinnamate decarboxylase activity.

Conclusion: Maceration and spontaneous fermentation significantly modulated volatile phenols in Zelen wines. While MeSA remained sub-threshold, it may still influence aroma. 4-VG consistently exceeded OT and was confirmed as the main varietal marker. Maceration also promoted 4-VP above OT in FPC fermentations, underlining the impact of yeast enzymatic activity and matrix effects on varietal typicity