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.:)