Belinda Kemp1, Andrew Wilson2, Hannah Charnock2
1 Cool Climate Oenology & Viticulture Institute (CCOVI), Brock University, St Catharines, L2S 3A1, Ontario, Canada
2 Department of Biological Sciences, Brock University, St Catharines, L2S 3A1, Ontario, Canada
Email contact: bkemp[@]brocku.ca
AIMS. The main objective of this study was to establish if beet sugar produces a different concentration of “fruity” volatile aroma compounds (VOCs), compared to cane sugar when used for second alcoholic fermentation of Auxerrois sparkling wines.
METHODS. Auxerrois base wine from the 2020 vintage was separated into two lots; half was fermented with cane sugar and half with beet sugar (both sucrose products and tested for sugar purity). These sugars were used in yeast acclimation (IOC 2007), and base wines for the second fermentation (12 bottles each). Base wines were manually bottled at the Cool Climate Oenology and Viticulture Institute (CCOVI) research winery. The standard chemical analysis took place at intervals of 0, 4 weeks, and 8 weeks post-bottling. Acidity and pH measurements were carried out by an auto-titrator. Residual Sugar (g/L) (glucose (g/L), fructose (g/L)), YAN (mg N/L), malic acid, and acetic acid (g/L) were analyzed by Megazyme assay kits. parameters were analyzed by Megazyme assay kits. Alcohol (% v/v) was assessed by GC-FID. VOC analysis of base wines, finished sparkling wines, as well as the two sugars in model sparkling wine solutions, was carried out by GC-MS. VOCs included ethyl octanoate, ethyl hexanoate, ethyl butanoate, ethyl decanoate, ethyl-2-methylbutyrate, ethyl-3-methylbutyrate, ethyl 2-methyl propanoate, ethyl 2- hydroxy propanoate, 1-hexanol, 2-phenylethan-1-ol, ethyl acetate, hexyl acetate, isoamyl acetate and 2-phenylethyl acetate.
RESULTS. Base wine chemical composition included TA 8.9 (g/L), pH 3.3, residual sugar 2g/L and 12 (mg N/L) YAN, so a YAN addition of 30ppm was made. There were no differences in the rate of yeast acclimation between cane and beet sugar wines, or between glucose and fructose concentrations during the second fermentation. GC-MS analysis is still being completed.
CONCLUSION. VOC differences are due to the raw material used (cane or Canadian-grown beet), and their respective processing methods. Winemakers can use this knowledge to adjust the flavor profile of sparkling wines, although further analysis during aging in contact with yeast lees is needed for the long-term effect of each sugar on the final wine.