UBC Theses and Dissertations
Yeast population and community dynamics : their effect on the chemical and sensory profiles of inoculated and spontaneous Pinot noir and Chardonnay fermentations at a Canadian winery Neuner, Marissa
The Okanagan Valley of British Columbia, Canada, has grown to include over 130 wineries, spanning 8,060 acres. As a result, competition within the local industry and has caused Okanagan winemakers to seek the production of a more sensorially unique product. Traditionally, inoculated fermentations are most commonly conducted by adding an abundance of a Saccharomyces cerevisiae yeast strain to produce consistent and specific chemical and sensory attributes in the wines; however, winemakers are choosing to showcase their unique winery yeast flora by conducting spontaneous fermentations. Spontaneous fermentations are conducted under the assumption that the fermentative yeast populations come from diverse winery resident organisms which, therefore, create different chemical and sensory profiles. Specifically, spontaneous and inoculated fermentations of Pinot noir and Chardonnay during the 2013 vintage at Quails’ Gate Estate Winery were assessed. Throughout fermentation these wines were subjected to both culture-dependent microsatellite analysis and isolate sequencing, as well as culture-independent Illumina MiSeq analysis. This determined the yeast populations conducting alcoholic fermentation and compared the capabilities of each method when studying yeast communities. Uniquely diverse yeast populations were found between spontaneous and inoculated fermentations of Pinot noir; however, yeast populations within inoculated and spontaneous Chardonnay treatments showed no differentiation. Unexpectedly, Pinot noir and Chardonnay fermentations were found to include non-Saccharomyces yeasts, specifically Hanseniaspora sp., throughout the entirety of fermentation in large relative abundance. Gas chromatography flame ionization detection (GC-FID) was conducted to determine the concentration differences of fermentation-derived chemicals associated with the identified yeast species fermenting both varietals; however, only isoamyl acetate, was found to differ between Pinot noir treatments. Sensory analysis revealed unique attributes were associated with the sensory profiles of inoculated or spontaneously fermented Pinot noir wines. The unique yeast communities found between inoculated and spontaneous fermentations of Pinot noir were responsible for slight chemical variation and unique sensory profiles between treatments. The similarity in yeast communities between inoculated and spontaneous fermentations of Chardonnay precluded chemical and sensory differences from occurring. Thus, to increase the chemical and sensory variation within wines and differentiate varietals from those fermented by competitors, wineries should consider producing both inoculated and spontaneous fermentations.
Item Citations and Data
Attribution-NonCommercial-NoDerivatives 4.0 International