Volatile profile of two monovarietal white wines under different antioxidant environments during storage in bottle

Abstract

The volatile organic compounds (VOCs) formed during winemaking can be modulated by several additives, namely by the use of sulphur dioxide (SO2) which has been well-accepted on winemaking as a preservative agent. However, some drawbacks associated with SO2 wine application led to the need to reduce or replace its use. In this work, VOCs profile after storage in bottle under different antioxidant conditions of two Portuguese monovarietal wines (‘Arinto’ and ‘Síria’) was studied. Wines were obtained by different winemaking environments (0, 50, 100 mg/L of SO2 and 100 mg/L ascorbic acid for ‘Síria’ and 15, 30, 45 mg/L of SO2 and 100 mg/L of ascorbic acid for ‘Arinto’ both with and without bentonite). After alcoholic fermentation, a second SO2 treatment was applied: 0 and 60 mg/L of SO2 to ‘Arinto’ wines and 30 and 60 mg/L of SO2 to ‘Síria’ wines. Wines were kept over lees for three months, bottled and analysed after three months in bottle. The VOCs present were analysed by HS-SPME-GC/MS six months after fermentation. The maturation conditions did not influence the evolution of free and total SO2. Regarding the VOCs profile evolution, the ANOVA analysis showed that esters are the most important group, presenting significant differences among samples. Through the PCA analysis, using wines after fermentation as reference, 74.13 % and 54.92 % of the variation were explained by the first two principal components for ‘Arinto’ and ‘Síria’, respectively. VOCs profile evolution of wines seems to be mainly influenced by the fermentation conditions.

Different SO2 Doses and the Impact on Amino Acid and Volatile Profiles of White Wines

“…VOCs were tentatively identified by matching mass spectra with spectra of reference compounds in the NIST library. LRIs were also calculated using a commercial hydrocarbon mixture (C8-C20) and compared with LRIs described in the literature [15,[34][35][36][37][38][39]. Table 1 shows the information regarding VOCs, by compound number, tentatively identified in the analyzed samples of AV and BL if they have appeared, at least, in one sample under study.…”

“…In order to build the PCA for each wine group (AV and BL) illustrated in Figures 2 and 3, the relative areas of the tentatively identified VOCs (Table 1) were used. These relative areas were normalized against the relative areas of the initial wine, according to Santos et al, 2022 [34]. Hence, the wine after fermentation (t = 0) is placed in PC1 = 0 and PC2 = 0.…”

“…a Linear retention indices calculated from C8-C20 n-linear alkanes; b Identification by NIST comparison; c Compound observed only on AV wines; d Compound observed only on BL wines; LRIlit-Linear Retention indices reported in the literature for WAX capillary column; NC: not calculated since LRI were calculated in the range from C8 to C20 n-linear alkanes[6,15,31,34,37,38,[40][41][42][43][44][45][46][47][48][49][50][51].…”