# SPME Method Optimized by Box-Behnken Design for Impact Odorants in Reduced Alcohol Wines
## 3 Results and Discussion
### Volatile Changes after RO-EP Treatment  
Tables 3 and 4 report the results of the GC-MS analysis of all analytes determined in the natural and reduced alcohol wines for Shiraz and Chardonnay, respectively. A total of 23 compounds were identified and quantified in the different headspace extracts, namely, esters (13), alcohols (3), acids (3), terpenes (2), sulfur compounds (1), and phenols (1). Analysis of variance (ANOVA) showed that the concentration of most analytes clearly decreased with dealcohlization by up to 82% from their natural concentration. As reported in Tables 3 and 4, most esters decreased in both wine varieties by 20-81% from their natural concentration, except for methyl octanoate and methyl decanoate in both wine varieties at all dealcohlized levels, and isoamyl octanoate and ethyl-s-lactate in the Shiraz and Chardonnay wines, respectively. The percentage losses of esters increased with the increased extent of dealcohlization (from 8 to 5% \(v/v\)). For example, ethyl-3-methyl butyrate and isoamyl acetate were not appreciably  
Figure 3: The \(b\)-coefficients (absolute units) for SPME optimization parameters for 23 compounds with an ethanol concentration of 13% \(v/v\). Significant coefficients for specific compounds are indicated with an asterisk (*). Compound identification is cross-referenced to the numbered compounds in Table 1.  
diminished in the 8% \(v/v\) Shiraz and Chardonnay treatments in comparison to the natural wines, but they decreased in the 5% \(v/v\) samples. Three alcohols (other than ethanol) have been identified and quantified in the wines, originating from grape-derived precursors, such as (z)-3-hexenol, or yeast's metabolism, such as 3-methyl-1-butanol and \(\beta\)-phenyl ethanol. It is noteworthy that these alcohols followed a similar trend for both wine varieties. Whereas 3-methyl-1-butanol and (z)-3-hexenol decreased with dealcoholization by 32-41% and 13-21% for Shiraz and Chardonnay respectively; no differences were found between 5 and 8% \(v/v\) ethanol wines. Another additional piece of information is that \(\beta\)-phenyl ethanol, which has a characteristic odor of rose-honey-like at a high concentration of \(\geq\)14,000 \(\upmu\)g/L [31], significantly increased with dealcoholization by up to 25% and 44% in the Shiraz and Chardonnay wines, respectively. The greatest increase for \(\beta\)-phenyl ethanol in the Shiraz and Chardonnay wines was observed in the 8% \(v/v\) treatment compared to the standard wines. For this compound, a retention effect exerted by the wine non-volatile matrix, possibly due to the \(\uppi\)-\(\uppi\) stacking interactions with wine polyphenols, was previously suggested [14; 25]. For both wine varieties, propanoic acid did not decrease at any dealcoholization level. On the other hand, octanoic acid decreased by up to 21% and 14% in the Shiraz and Chardonnay wines, respectively. These results are in general agreement with the previous studies for similar membrane Contactors, in which losses of up to 17% and 68% for octanoic acid and decanoic acid were respectively reported [32]. Of all quantified acids, decanoic acid was the most decreased. It decreased by up to 58% and 77% in the Shiraz and Chardonnay wines, respectively. Nevertheless, no differences were observed between the 8 and 5% \(v/v\) treatments for both wine varieties. Two monoterenes were identified and quantified in the Shiraz and Chardonnay wines, namely linalool and geraniol. Intriguingly, the concentration of linalool, which has been reported to have a characteristic lavender flower aroma [31], increased by up to 58% in the Shiraz dealcoholized wines. This was in contrast to the Chardonnay samples where the concentration of linalool decreased with dealcoholization by up to 78% from its natural concentration, possibly due to the different non-volatile matrix composition between these wines [33].