Sauvignon blanc production – Flagstone winery

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June 17, 2011  posted by Bernard Mocke

Gerhard Swart, Flagstone’s winemaker, is no stranger to awards. His Free Run Sauvignon blanc has consistently received high accolades over the past years and this comes as no surprise considering the care that goes into his Sauvignon blanc.

Let’s take a closer look at how this wine is made. The Sauvignon blanc is harvested from vineyards that are 8 to 12 years old during February and March. Yield is 6 to 8 tonnes/ha. Upon arrival, the grapes are stored overnight in a cold room at 0 to 2°C. The cool grapes are then fed into the crusher under a carbon dioxide blanket. Rapidase Expression (Oenobrands), sulphur dioxide and ascorbic acid are added sequentially at the crusher. Tannin Galacool is added during crushing when Botrytis infection is evident.  The crushed grapes and juice is then pumped into a skin contact tank and kept at 2 to 4°C for 18 hours. Free run juice from the skin contact tank is pumped to another tank and skins are pumped to a Velo Evolution Press (the press was designed so that grapes can be pressed in a reductive environment of nitrogen gas). Viniclar (PVPP, Laffort) is added to the free run juice before settling. The press juice is then pumped to another tank. Fining agents such as Polylact (PVPP and casein) and gelatine are added to the press juice. Settling enzyme, Rapidase Vino Super (Oenobrands) is added at the settling tank and this lasts for 2 days at 12 to 13°C.

All Sauvignon blanc fluffy lees is combined and kept at 3 to 5°C. Total sulphur dioxide levels are kept at 35 to 40 ppm. After sheet filtration of the fluffy lees, fermentation is initiated and Turbicell is added to increase the NTU level (sheet filtration decreases this too much and can lead to nutrient deficiencies). A typical minimum NTU level of 80 to 100 is sufficient for Sauvignon blanc ferments.

Gerhard uses the following yeasts for his Sauvignon blanc ferments: Anchor Alchemy I and II (Oenobrands) contributes floral, gooseberry and tropical flavours; Anchor VIN 7 (Oenobrands) makes a big contribution towards tropical aromas; X5 (Laffort) adds boxwood, lychee and passion fruit aromas; QA 23 (Lallemand) makes a contribution similar to the Alchemy yeasts and VL 3 (Laffort) produces a waft of khaki bush. Different yeasts add complexity to the wine. Dynastart (Laffort) is added at yeast rehydration and Nutristart (Laffort) is added when needed. Thiazote (Laffort) is added in 3 stages: after 3°B has been fermented, at 16°B and at 12°B. Inoculation is done at 12 to 13°C and fermentation at 12 to 16°C. Fermentation lasts 2 to 3 weeks after which ageing on gross lees (2 weeks) and fine lees (3 to 4 months) follows. Evolution in wine aroma is monitored during fermentation and ageing by regular tasting and chemical analysis.

The Sauvignon blanc is stabilised at the end of June, bottled at the end of July and released in September. Protein stability is done after final blending, right before bottling. All Sauvignon blanc is treated with bentonite after blending.

The Free Run Sauvignon blanc sells for £10 in the UK.

Bernard Mocke is a Technical Consultant for Anchor Wine Yeast.


And now for something completely different – S. blanc part 4

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March 26, 2010  posted by Karien O'Kennedy
This blog entry concludes my feature on what yeasts are used for Sauvignon blanc fermentations. For the “grande finalé” I decided to move abroad and focus on the German Sauvignon blanc of all Sauvignon blancs. Why? Well the winemaker has a very interesting approach to the fermentation and the result is a spectacular wine.
 
Christoph Hammel, owner of Weingut Hammel in the Phalz, is quite an opinion leader in his area. He is very open to new ideas and experimentation and it is this very experimentation that has lead him to his winning recipe on Sauvignon blanc. Christoph has 53 ha of Sauvignon blanc that he harvests on average in mid October at a sugar level of about 21.5°Brix. He does not chaptilise, which is often the case in Germany, but rather concentrates the juice with a “concentration machine” – to use his words. He does 5 hours skin contact at 5 – 10°C with an   addfood enzyme in the presence of SO2, ascorbic acid, dry ice and un-toasted wood chips. He does not cold settle the juice but rather flotates it with Nitrogen gas. This practice is quite common in Germany . 
 
Christoph uses two yeasts for fermentation that he inoculates at the same time for a co-fermentation. They are Anchor VIN 7 and Laffort X5. The yeasts are re-hydrated in Lallemand Go-Ferm and receive three additions of DAP during fermentation. They are therefore quite well fed. The yeasts are inoculated at 15°C and fermentation temperatures are kept between 15 – 17°C.
 
Why does he use these specific two yeasts in a co-fermentation? Over the years Christoph tried various yeast blends – with varying levels of success. This blend proves optimum for his Sauvignon blanc. Both yeasts are very effective in expressing the volatile thiols associated with S. blanc varietal character. They have slightly different aromatic profiles and X5 also consumes some of the volatile acidity produced by VIN 7.
 
Towards the end of the fermentation Christoph also adds B-Glucosidase (monoterpene aroma release) and B-Glucanase (yeast autolysis) enzymes. Fermentation lasts between 11 – 14 days. The wine is kept on the gross lees for 3 – 4 months until bottling.
 
The concept of co-fermentation originated with the 2005 AWRI research on Sauvignon blanc. There are very specific guidelines one must follow before attempting a co-fermentation. A common combination for S. blanc in Australia is Anchor VIN 7 and Lalvin QA 23. Recent results from AWRI research proved Anchor VIN 13 and Lalvin QA 23 to be a good combination for Chardonnay – unpublished results. Co-fermented wines have different aromatic profiles to wines made from two tanks that were blended after fermentation with the same individual yeasts. This is due to the interaction between the two yeasts during fermentation. Co-fermentation does not always have a more positive outcome and I suggest winemakers to consult with yeast suppliers first before attempting a co-fermentation.
 
The title of this blog was used without permission from Monty Python.:)

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