Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
Ester production by yeast in wine and brandy
Thesis (M.Sc.Agric.) -- University of Stellenbosch, 1998.
Saved in:
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Thesis |
| Language: | English |
| Published: |
Stellenbosch : Stellenbosch University
2012
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867613921052983296 |
|---|---|
| access_status_str | Open Access |
| author | De Villiers, Mariska |
| author2 | Pretorius, I. S. |
| author_browse | De Villiers, Mariska Pretorius, I. S. |
| author_facet | Pretorius, I. S. De Villiers, Mariska |
| author_sort | De Villiers, Mariska |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (M.Sc.Agric.) -- University of Stellenbosch, 1998. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/50956 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:43:49.382Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2012 |
| publishDateRange | 2012 |
| publishDateSort | 2012 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/50956 Ester production by yeast in wine and brandy De Villiers, Mariska Pretorius, I. S. Lambrechts, M. G. Stellenbosch University. Faculty of AgriSciences. Dept. of Viticulture & Oenology & Institute for Wine Biotechnology. Fermentation Wine and wine making -- Chemistry Alcoholic beverages -- Flavor and odor Brandy Agricultural biotechnology Dissertations -- Agriculture Thesis (M.Sc.Agric.) -- University of Stellenbosch, 1998. Wine flavour is the result of the interaction of chemical constituents with the consumer's senses of taste and smell. It is important to note that although we speak of flavour we include aroma, since flavour is composed of both volatile compounds, which are responsible for the smell of wine, and non-volatiles which cause taste sensations, such as sweetness, sourness etc. The aroma of wine is due to several hundred volatile compounds, and, since any one compound does not normally dominate, the balance between them is important. When dealing with wine aroma we make four distinctions: (i) the aroma which originates with the grapes, (ii) precursors from the grapes that are transformed during fermentation to aroma compounds (iii) the aroma produced by the primary fermentation, and (iv) the bouquet arising from the transformations during maturation and bottling. Esters are important contributors to the fermentation bouquet by imparting fruity aromas to wine. Most esters, especially isoamyl acetate (banana-like aroma) and ethyl acetate (light-fruity, solvent-like aroma), are the most important flavour compounds in wine, beer and other alcoholic beverages. In fact, isoamyl acetate is essential for the characteristic character of Pinotage wines. Esters are secondary products produced by yeasts during sugar metabolism. During the fermentation process, not only does the yeast strain contribute and affect the ester concentration in the final wine, but also technological factors such as fermentation temperature. During brandy distillation the amount of yeast lees present during the distillation process also influences the final ester concentration present in the final distillate. Therefore, all of these factors should be kept in mind to control ester formation. The acetate esters are synthesized by the enzymatic condensation of acetyl coenzyme A (acetyl-CoA) and the corresponding alcohol in yeast cells during fermentation. The ATF1 gene from Saccharomyces cerevisiae encodes the alcohol acetyltransferase enzyme (AAT/Atf1p) that has been shown to be involved in the formation of isoamyl- and ethyl acetate. The objectives of this study were two-fold: (1) to overexpress the ATF1 gene in several wine yeasts used to ferment Pinotage, Chenin blanc and rebate wines thereby increasing the levels of acetate esters produced by these wine yeasts; and (ii) to evaluate the effect of these increased acetate esters on the aroma profiles of the resulting wines and brandies. Masters 2012-08-27T11:34:15Z 2012-08-27T11:34:15Z 1998 Thesis http://hdl.handle.net/10019.1/50956 en Stellenbosch University 109 pages : ill. application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Fermentation Wine and wine making -- Chemistry Alcoholic beverages -- Flavor and odor Brandy Agricultural biotechnology Dissertations -- Agriculture De Villiers, Mariska Ester production by yeast in wine and brandy |
| title | Ester production by yeast in wine and brandy |
| title_full | Ester production by yeast in wine and brandy |
| title_fullStr | Ester production by yeast in wine and brandy |
| title_full_unstemmed | Ester production by yeast in wine and brandy |
| title_short | Ester production by yeast in wine and brandy |
| title_sort | ester production by yeast in wine and brandy |
| topic | Fermentation Wine and wine making -- Chemistry Alcoholic beverages -- Flavor and odor Brandy Agricultural biotechnology Dissertations -- Agriculture |
| url | http://hdl.handle.net/10019.1/50956 |
| work_keys_str_mv | AT devilliersmariska esterproductionbyyeastinwineandbrandy |