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A Technical Guide for Wine Producers
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VIN 2000 A New Yeast For The 2008 Crush
Karien Lourens, Anchor Yeast (karien@anchor.co.za)
Anchor Yeast is proud to present a new yeast for the production of high quality, full-bodied white wines for the 2008 harvest season. VIN 2000, which was selected by the Institute for Wine Biotechnology, Stellenbosch University, is provisionally recommended for Chardonnay and Chenin Blanc.
Origin and evaluation
VIN 2000 was cultivated in 1998 and selected for further research by Prof. Sakkie Pretorius1 (Institute for Wine Biotechnology, Stellenbosch University) based on the combination of its fermentation abilities and aromatic potential. It was further evaluated by a team led by Dr. Pierre van Rensburg2, as part of the yeast hybridisation programme at the Institute for Wine Biotechnology. In 2004 Anchor Yeast produced and dried VIN 2000 experimentally and in 2005 and 2006 it was evaluated at the university for small-scale vinification. In January 2007 Anchor Yeast produced VIN 2000 on a large scale and it was tested in the South African wine industry. The conditions under which vinification takes place in the South African wine industry present a very good testing ground for potential new yeasts. High sugars and cold fermentation temperatures usually separate the men from the boys when it comes to yeasts. VIN 2000 passed the test with flying colours and an agreement was reached between the Institute for Wine Biotechnology and Anchor Yeast. As a result it will be available for the southern hemisphere harvest in 2008.
VIN 2000 aroma and flavour
The aroma and flavour of fresh and fruity (new world) wines depend largely on a combination of volatile thiols and esters. Typical esters in wines that were cold fermented (13 - 15°C) with VIN 13 and NT 116, can have banana, pineapple and floral aromas; depending on the yeast used and the grape variety fermented. In Australia and New Zealand the banana-like character, if it occurs in high concentrations, is sometimes referred to as 'confectionary aromas'. The floral esters complement (Weisser) Riesling and Viognier for example. Banana and pineapple esters are suitable for unwooded Chardonnay, but less so for Sauvignon blanc. This type of esters is therefore very desirable for certain wine styles and less so for others. VIN 2000 forms lower concentrations of the 'sweet' kind of esters, but higher concentrations of other aromatic esters, and can therefore be used in instances where the 'sweet' type of esters do not suit the wine style or the personal taste of the winemaker (Figure 1). The effect of VIN 2000 on volatile thiols has not been measured, but the wines fermented with it this past season displayed obvious guava, grapefruit and mango aromas and flavours.
VIN 2000 positioning
At present Anchor Yeast has three aromatic white wine yeasts that ferment strongly at cold temperatures, namely VIN 7, VIN 13 and NT 116. Consequently these three yeasts are used mostly for the production of fresh and fruity, tank fermented white wines. However, there is a demand among winemakers for yeasts that complement more full-bodied wines and that ferment more slowly so that they may be used in barrels, for example. The yeasts should therefore ferment more slowly than the three mentioned above, but should be as reliable as VIN 13 and NT 116. Results of the large-scale vinification in 2007 indicate that VIN 2000 complies with these requirements (Table 1).
VIN 2000 is consequently positioned for high quality, full-bodied wines. The vinification techniques accompanying the production of this type of wine are usually slightly higher fermentation temperatures (15-16°C) and oak barrels or oak alternatives. VIN 2000 is provisionally recommended for Chardonnay and Chenin blanc. Results of the trials involving the 2007 northern hemisphere crop in France, Spain, Italy and Germany will determine its suitability for other grape varieties.
1 Sakkie Pretorius is Managing Director at the Australian Wine Research Institute (AWRI).
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