The effect of sulfur dioxide and alternative fermentation techniques on the microbial communities and sensory profiles of wine
department or school: Arts and Sciences, Irving K. Barber School of (Okanagan)
department or school: Biology, Department of (Okanagan)
data provider: DSpace
degree campus: UBCO
creator: Morgan, Sydney Christian
issued: 2019-08-15T15:50:22Z
issued: 2019
related degree: Doctor of Philosophy - PhD
degree grantor: University of British Columbia
description: Modern winemaking often involves the addition of sulfur dioxide (SO₂), to remove potential spoilage microbes from the grape juice, and the addition of commercial wine yeasts, to ensure a successful and timely completion of alcoholic fermentation. However, consumer demand is shifting towards low-SO₂ wines, and wines fermented by a collection of indigenous yeasts and bacteria. Many winemakers wish to produce these wines for their customers, but there is a current lack of research into the relative risks and rewards of these winemaking strategies. We investigated these topics, and found that both SO₂ addition and inoculation technique can significantly influence the fungal and bacterial communities and the sensory profiles of commercially-produced wines. Fermentations conducted without SO₂ were found to contain more vineyard-derived microorganisms and produced more fruity characters, while the fermentations conducted with SO₂ produced wines with less-desirable characteristics. Pied de cuve inoculation had a limited effect on the wine microbial communities and was inhibited by the addition of SO₂; when it persisted, it resulted in slower fermentations, and produced wines with more sweetness and body as compared to wines that did not receive the pied de cuve inoculum. At one commercial winery, we identified a highly diverse indigenous population of Saccharomyces uvarum, a yeast that is related to the main winemaking yeast, Saccharomyces cerevisiae. S. uvarum was able to compete with a commercial S. cerevisiae strain in controlled fermentations, and produced wines with a unique composition of aroma-active volatile compounds, showing its potential to be used as an indigenous yeast inoculum for locally-made wines. In summary, we showed that both SO₂ addition and fermentation technique (uninoculated or pied de cuve inoculation) can alter the microbial communities and sensory profiles of commercial and laboratory-made wines, and reported an indigenous yeast population in the …
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/71293
note: THE EFFECT OF SULFUR DIOXIDE ADDITION AND ALTERNATIVE FERMENTATION TECHNIQUES ON THE MICROBIAL COMMUNITIES AND SENSORY PROFILES OF WINE By Sydney Christian Morgan A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in THE COLLEGE OF GRADUATE STUDIES (Biology) THE UNIVERSITY OF BRITISH COLUMBIA (Okanagan) August 2019 © Sydney Christian Morgan, 2019 ii The following individuals certify that they have read, and recommend to the College of Graduate Studies for acceptance, a dissertation entitled: THE EFFECT OF SULFUR DIOXIDE ADDITION AND ALTERNATIVE FERMENTATION TECHNIQUES ON THE MICROBIAL COMMUNITIES AND SENSORY PROFILES OF WINE submitted by Sydney Christian Morgan in partial fulfillment of the requirements of the degree of Doctor of Philosophy. Dr. Daniel Durall, Department of Biology, University of British Columbia, Okanagan Supervisor Dr. Michael Deyholos, Department of Biology, University of British Columbia, Okanagan Supervisory Committee Member Dr. John Klironomos, Department of Biology, University of British Columbia, Okanagan Supervisory Committee Member Dr. Richard Plunkett, Department of Biology, University of British Columbia, Okanagan Supervisory Committee Member Dr. David Scott, Department of Earth and Environmental Sciences, University of British Columbia, Okanagan University Examiner Dr. Thomas Henick-Kling, School of Food Science, Washington State University External Examiner iii Abstract Modern winemaking often involves the addition of sulfur dioxide (SO2), to remove potential spoilage microbes from the grape juice, and the addition of commercial wine yeasts, to ensure a successful and timely completion of alcoholic fermentation. However, consumer demand is shifting towards low-SO2 wines, and wines fermented by a collection of indigenous yeasts and bacteria. Many winemakers wish to produce these wines for their customers, but there is a current lack of research into the relative risks and rewards of thes…
has type: Thesis/Dissertation
date issued: 2019-09
is shown at: 10.14288/1.0380443
language: eng
degree discipline: Biology
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: Attribution-NonCommercial-NoDerivatives 4.0 International
rights URI: http://creativecommons.org/licenses/by-nc-nd/4.0/
scholar level: Graduate
type: Text
identifier URI: http://hdl.handle.net/2429/71293