Research Articles (Institute for Wine Biotechnology)
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Browsing Research Articles (Institute for Wine Biotechnology) by Subject "Alcoholic fermentation"
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- ItemIdentifying genes that impact on aroma profiles produced by Saccharomyces cerevisiae and the production of higher alcohols(Springer-Verslag, 2011-05) Styger, Gustav; Jacobson, Dan; Bauer, FlorianDuring alcoholic fermentation, many volatile aroma compounds are formed by Saccharomyces cerevisiae, including esters, fatty acids, and higher alcohols. While the metabolic network that leads to the formation of these compounds is reasonably well mapped, surprisingly little is known about specific enzymes involved in specific reactions, the regulation of the network, and the physiological roles of individual pathways within the network. Furthermore, different yeast strains tend to produce significantly different aroma profiles. These differences are of tremendous biotechnological interest, since producers of alcoholic beverages such as wine and beer are searching for means to diversify and improve their product range. Various factors such as the redox, energy, and nutritional balance of a cell have previously been suggested to directly or indirectly affect and regulate the network. To gain a better understanding of the regulations and physiological role of this network, we screened a subset of the EUROSCARF strain deletion library for genes that, when deleted, would impact most significantly on the aroma profile produced under fermentative conditions. The 10 genes whose deletion impacted most significantly on higher alcohol production were selected and further characterized to assess their mode of action within or on this metabolic network. This is the first description of a large-scale screening approach using aroma production as the primary selection criteria, and the data suggest that many of the identified genes indeed play central and direct roles within the aroma production network of S. cerevisiae.
- ItemUnderstanding problem fermentations – a review(South African Society for Enology and Viticulture, 2007) Malherbe, S.; Bauer, Florian; Du Toit, M.Despite advances in winemaking technology and improvements in fermentation control, problem alcoholic and malolactic fermentations remain a major oenological concern worldwide. This is due to possible depreciation of product quality and its consequent negative economic impact. Various factors have been identified and studied overv the years, yet the occurrence of fermentation problems persists. The synergistic effect of the various factors amongst each other provides additional challenges for the study of such fermentations. This literature review summarises the most frequently studied causes of problematic alcoholic and malolactic fermentations and in addition provides a summary of established and some potential new analytical technologies to monitor and investigate the phenomenon of stuck and sluggish fermentations.