Open Collections

Castellanos López, Elia Cristina

University of British Columbia

The interactions between geographical and biotic factors and the winemaking process influences the composition and sensorial characteristics of wine. The yeast carrying out the fermentation play a key role in shaping the aroma profile of the resulting wine. Commercially available strains of Saccharomyces cerevisiae (S. cerevisiae) help improve reproducibility and predictability of wine by establishing well-controlled fermentations that maintain wine quality. However, indigenous S. cerevisiae strains may be better acclimated to the conditions of specific wine producing regions and may enhance their typical sensory properties and characteristic profiles. The objectives of my research were to assess the oenological characteristics of six indigenous S. cerevisiae strains in lab-scale fermentations and to carry out pilot-scale fermentations in a winery with two strains and evaluate the aromatic composition of the finished wines. Six indigenous S. cerevisiae strains isolated from spontaneous fermentations in Okanagan Crush Pad (OCP) winery were selected for this research. Sterile Pinot Noir and Pinot Gris grape juice was used to perform 250mL lab-scale fermentations carried out at 25°C and 20°C, respectively. Primary metabolites were quantified by high performance liquid chromatography coupled to a refractive index detector (HPLC-RID), and volatile compounds were quantified by solid phase microextraction coupled to gas chromatography and mass spectrometry (SPME-GC/MS). After evaluation of their metabolite production and fermentation performance, the OCP-125 and OCP-088 strains were selected for winery pilot scale fermentations. Fermentations were carried out in triplicate 250 L stainless steel barrels, at OCP winery in Pinot Gris and Pinot Noir juice during the 2022 grape harvest. After fermentation was complete, major metabolites (organic acids, sugars, and ethanol) were quantified using HPLC-RID. Residual sugars were identified in both wines - mainly fructose, ranging between 16 g/L and 20 g/L. The alcohol by volume of the finished wine ranged between 10.82 and 11.58 %. Volatile aroma compounds were quantified by SPME-GC/MS and wines produced with OCP indigenous strains had significantly higher concentrations of ethyl decanoate, a fatty acid ester with a fruity aroma, than commercial wines. Wines produced with OCP-125 and OCP-088 strains had a similar aroma composition, producing an off-dry wine with a desirable aroma bouquet.

Text

2025-04-30

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/87883

Food Science

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/