We’ve recently been bottling the 2019 vintage Rathfinny wines before putting them in the Cellar to age. Whilst each year I still get excited to see the wines go into bottle for their second fermentation, it also proves to be a bit stressful. I will pass on the fact that bottling didn’t start until the heatwave – always great when you’re running around all day…
However, we’re now more than half-way through and I’m pleased to say that the only slight problem has been due to a seized vacuum pump on the bottling machine. Since then, it’s been minor issues and bugs that have been easy to fix.
I used the word stressful because despite all the care and attention required, one crucial part of bottling, if not done properly, could be a disaster: the yeast cultures.
Yeast are funny: they metabolise sugars and generate alcohol, carbon dioxide and heat. Guess what is toxic to yeast? Yes, alcohol! You can’t just add sugar and yeast to the wine to be bottled and hope for the best. Instead, you need to work with the yeast and gradually adapt them so they can survive and do their job of the second fermentation.
Remember, for the second fermentation you add sugar and yeast to a still wine which already has an alcohol level of around 11%. I have to “cultivate” and grow the yeast between four to five days prior to bottling.
The first step is rehydration, since the yeast is initially dehydrated. It’s a fifteen-minute step, where yeast come out of their “sleep” in warm water. Then, rude awakening, you add a small amount of wine and some sugar. The day after, you have to add some sugar, and a lot of wine.
Finally for the next few days, you will mix and aerate the culture so the yeast population can grow and ultimately thrive once transferred into the wine and in the bottle. At this stage, oxygen is key for yeast to synthesise very important components of their membrane (sterols and some fatty acids), increasing their resistance to alcohol. In fact, twelve days of bottling means twelve cultures. Four days for each at two aerations a day, that is a total of thirty-two hours of work!
Taking those steps, the second fermentation will go smoothly and in a few weeks the yeast will have converted the base wine into a sparkling wine. Else, you could end up with a batch of wine not fermenting all the way: still sugary and not very fizzy. Yikes!
Now, after two to three years of ageing in the cellar on lees, you’ll be able to enjoy a glass of 2019 Sussex sparkling wine.