Selection, breeding, evaluation and characterisation of new wine yeasts

Project Number
WW 10-01

Project title
Selection, breeding, evaluation and characterisation of new wine yeasts

Project leader
Hart, R S

Team members
Bergstedt, J

Project description
From 1995 to 1998 naturally occurring yeast strains were isolated from vineyards in cooler and warmer regions of the Western Cape. In 1999 this strategy was changed and yeasts were isolated from spontaneously fermenting must. This method of isolation resulted in a broader strain diversity. As the current number of yeasts in the yeast collection is in excess of 660, further isolations were ceased in the 2000 season.

During the year, the yeasts in the collection were screened for:
(a) strains that can ferment at higher temperatures (up to 30°C)
(b) strains that can naturally form higher levels of glycerol during fermentation and
(c) strains that are genetically different to the current local wine yeasts.

Small-scale winemaking was conducted with strains with a lower sugar to ethanol conversion rate. In Chardonnay, less variation in alcohol concentration was observed between the different strains used for fermentation. In Pinotage, however, the levels of alcohol varied from 14.05% for strain WH 18 to 15.95% for NT 50. The control strain, WE 372, formed lower levels of alcohol than most strains examined. Seven yeast strains that produced considerable amounts of glycerol during fermentation and strains that differ genetically from current commercial strains were evaluated in bottle fermentations. The best yeast strains were selected and are in the process of being evaluated for wine production. Results will be available in the next project report (2001 – 2002). One yeast strain (WH 202) was presented to the industry as a strain with the potential to be commercialised. Although strain WH 14 (Pinotage) excelled during sensory evaluation, it appears that this strain may produce elevated levels of urea and further research is necessary before any recommendations regarding this strain can be made. A brandy base wine yeast was dried experimentally and evaluated during commercial trials in 2000. The distillates produced with this strain are currently being matured in oak barrels and results are pending. The sales of five hybrid yeasts (NT-range) previously developed in this project are showing favourable growth. A number of them are also being exported. The current focus of this project will remain the expansion of the local wine yeasts that are currently available commercially.

Poster(s)
Khan, W, Van der Westhuizen, T J and Pretorius, I S. 1997. Geographic distribution of indigenous Saccharomyces cerevisiae strains in the warmer inland region of the Western Cape, South Africa. Poster presented at the 22nd National Congress of the South African Society for Enology and Viticulture. 12-13 November, Somerset West, South Africa.

Van der Westhuizen, T J. 1997. Improving wine yeast through a dedicated breeding programme. Poster presented at the 22nd National Congress of the South African Society for Enology and Viticulture. 12-13 November, Cape Town, South Africa.

Khan, W, Kritzinger, H, Van der Westhuizen, T J and Pretorius, I S. 1998. The physiological and biochemical characterisation of naturally isolated strains of Saccharomyces cerevisiae from the Western Cape region of South Africa. Poster presented at the 23rd National Congress of the South African Society for Enology and Viticulture. 12-13 November, Somerset West, South Africa.

Khan, W, Augustyn, O P H, Van der Westhuizen, T J, Lambrechts, M G and Pretorius, I S. 1999. Geographical distribution, characterisation and evaluation of Saccharomyces cerevisiae strains isolated from South African vineyards in the warmer, inland regions of the Western Cape. Poster presented at the 24th National Congress of the South African Society for Enology and Viticulture. 18-19 November, Somerset West, South Africa.

Khan, W, Augustyn, O P H, Van der Westhuizen, T J, Lambrechts, M G and Pretorius, I S. 2000. Geographical distribution, characterization and evaluation of Saccharomyces cerevisiae strains isolated from South African vineyards in the warmer, inland regions of the Western Cape. Poster presented at the BioY2K Combined Millennium Meeting. 23-28 January, Grahamstown, South Africa.

Farmer, J M, Jolly, N P, Pretorius, I S and Lambrechts, M G. 2000. Optimising a model grape must and preliminary comments on the urea formation by wine yeasts. Poster presented at the BioY2K Combined Millennium Meeting. 23-28 January, Grahamstown, South Africa.

Jolly, N P and Hart, R S. 2006. Selection, breeding, evaluation and characterisation of new wine yeasts for wine production. Poster presented at the 29th National Congress of the South African Society for Enology and Viticulture. 14-17 November, Somerset West, South Africa.

Jolly, N P and Hart, R S. 2006. Selection, breeding, evaluation and characterisation of new wine yeasts for wine production. Poster presented at the 8th International Symposium on Innovations in Enology. 21-22 April, Stuttgart, Germany.

Jolly, N P and Hart, R S. 2007. Selection, breeding, evaluation and characterisation of new wine yeasts for wine production. Poster presented at the 8th International Symposium on Innovations in Enology. 21-22 April, Stuttgart, Germany.

Hart, R S and Jolly, N P. 2008. Wine yeasts for Paarl regional Shiraz production. Poster presented at the 31st National Congress of the South African Society for Enology and Viticulture. 11-14 November, Somerset West, South Africa.

Hart, R S and Jolly, N P. 2010. Wine yeasts to develop the full aroma potential of especially Sauvignon blanc. Poster presented at the 4th International Congress of the South African Society for Enology and Viticulture. 28-30 July, Cape Town, South Africa.

Hart, R S and Jolly, N P. 2010. Winemaking trials with natural isolated wine yeasts for Paarl regional Shiraz production. Poster presented at the 4th International Congress of the South African Society for Enology and Viticulture. 28-30 July, Cape Town, South Africa.

Hart, R S and Jolly, N P. 2010. Semi-commercial winemaking trials with a hybrid yeast to promote varietal characteristics of white wine. Poster presented at the 4th International Congress of the South African Society for Enology and Viticulture. 28-30 July, Cape Town, South Africa.

Hart, R S and Jolly, N P. 2010. Expression of Paarl regional Shiraz characteristics with natural isolated wine yeasts. Poster presented at the presented at the 4th International Congress of the South African Society for Enology and Viticulture. 28-30 July, Cape Town, South Africa.

Presentation(s)
Jolly, N P, Hart, R S and Du Plessis, H W. 2008. The new generation of wine yeast and bacteria strains. Presentation at the Winetech and South African Society for Enology and Viticulture Information Day. 18 April, Stellenbosch, South Africa.

Article
Van der Westhuizen, T J. 1995. Rasegtheid van aktiewe droë wyngiste – ‘n kritiese parameter, Wynboer, Mnth Oct (p. T8)

Van der Westhuizen, T J, Augustyn, O P H, Pretorius, I S. 1999. The value of long-chain fatty acid analysis, randomly amplified polymorphic DNA and electrophoretic karyotyping for the characterisation of wine yeast strains, South African Journal of Enology and Viticulture, v. 20 (1) (p. 3-10)

Khan, W, Augustyn, O P H, Van der Westhuizen, T J, Lambrechts, M G, Pretorius, I S. 2000. Geographic distribution and evaluation of Saccharomyces cerevisiae strains isolated from vineyards in the warmer, inland regions of the Western Cape in South Africa, South African Journal of Enology and Viticulture, v. 21 (1) (p. 17-31)

Pretorius, I S, Van der Westhuizen, T J, Augustyn, O P H. 2000. Yeast biodiversity in vineyards and wineries and its importance to the South African wine industry: a review, South African Journal of Enology and Viticulture, v. 20 (2) (p. 61-74)

Van der Westhuizen, T J, Augustyn, O P H, Khan, W, Pretorius, I S. 2000. Geographical distribution of indigenous Saccharomyces cerevisiae strains isolated from vineyards in the coastal regions of the Western Cape in South Africa, South African Journal of Enology and Viticulture, v. 21 (1) (p. 3-9)

Van der Westhuizen, T J, Augustyn, O P H, Khan, W, Pretorius, I S. 2000. Seasonal variation of indigenous Saccharomyces cerevisiae strains isolated from vineyards of the Western Cape in South Africa, South African Journal of Enology and Viticulture, v. 21 (1) (p. 10-16)

Nieuwoudt, H H, Prior, B A, Pretorius, I S, Bauer, F F. 2005. Glycerol in South African table wines: fact and fiction, WineLand, Mnth Nov (p. 96-101)

Swiegers, J H. 2005. The role of the wine yeast Saccharomyces cerevisiae in the amplification of Sauvignon varietal aroma, New World Winemaker,

Jolly, N P, Hart, R S. 2006. Wine yeasts developed by team of microbiologists, WineLand, Mnth Mar (199) (p. 60)

Swiegers, J H, Francis, I L, Herderich, M J, Pretorius, I S. 2006. The choice of yeast for fermentation offers great potential to adjust the aroma of Sauvignon blanc wines, Australian and New Zealand Wine Industry Journal, Mnth Jan v. 21 (1) (p. 34-42)

Swiegers, J H, Francis, I L, Herderich, M J, Pretorius, I S. 2006. The choice of yeast for fermentation offers great potential to adjust the aroma of Sauvignon blanc wine, New World Winemaker,
http://www.newworldwinemaker.com/articlecontent.asp?id=203

Walsh, T, Heinrich, A, Skurray, G. 2006. Yeast selection contributes to Shiraz aroma and flavour,
http://www.maurivinyeast.com/upload/yeastandshirazarticle.pdf

Walsh, T, Heinrich, A, Skurry, G. 2006. Yeast selection – yeast contributes to Shiraz aroma and flavour, WineLand, Mnth Oct (p. 89-91)

UCLM S377 Technical data sheet.
http://www.warenchem.co.za/images/products/wine/…/FT_UCLM_S377_EN.pdf

Swiegers, J H, King, E, Travis, B, Francis, L, Pretorius, I S. 2007. Enhancement of Sauvignon blanc wine aroma through yeast combinations, New World Winemaker,

Swiegers, J H, King, E, Travis, B, Francis, L, Pretorius, I S. 2007. Enhancement of Sauvignon blanc wine aroma through yeast combinations, WineLand, Mnth Dec

Hart, R S, Jolly, N P. 2008. New wine yeasts for the South African winemaker, Wynboer Technical Yearbook, (p. 97-101)

Jolly, N P, Hart, R S. 2008. New wine yeasts for South African winemakers, WineLand, Mnth Nov (p. 20-24)

Perdue, A. 2008. Alcohol a burning issue with wine,
http://www.winepressnw.com/summer08/story/2046.html

Hart, R S, Jolly, N P. 2011. Residual urea in wines following fermentation using experimental and commercial active dried wine yeasts, WineLand, Mnth Sep (p. 128-131)

Rayne, S, Forest, K, Friesen, K J. 2011. Projected climate change impacts on grape growing in the Okanagan Valley, British Columbia, Canada, Mnth Feb
http://www.precedings.nature.com/documents/3162/version./1/files/npre20093162-1.pdf

FinalReport.pdf

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