Ageing & Yeast Autolysis
Autolysis refers to the enzymatic self-destruction of yeast cells. The most important aspect of autolysis for sparkling wine is the release of flavour components: e.g. benzaldehyde (nutty, toasty), cis- & trans-farnesol (sunflower) & amino acids, proteins and lipids that act as surfactants.
Autolysis is affected by:
- Percentage alcohol: increases speed of autolysis
- pH: higher pH favours quicker autolysis
- Temperature: higher temps cause increased speed, but interfere with natural ageing, so optimum is 10 - 15°C
- Time: there is very little autolysis for first few months after alcholic fermentation, with the most significant increase in next six months. e.g., wine is 24 % higher in amino acids after 1 year & 26 % after 4 years. After 6 years, there is no further autolytic activity.