Analyses of yeast assimilable nitrogen (YAN) and gluconic acid for optimum management of alcoholic fermentation
Download the article: VINIFICATION IN THE ERA OF GLOBAL WARMING to better understand:
- the influence of difficult climatic conditions on wine-making
- how to establish a prudent wine-making protocol avoiding stuck fermentation and resulting in an improvement of the quality of wine
As is known, due to global warming, we are witnessing increasingly adverse and difficult weather conditions. The rise in average temperatures is in fact causing an increase in the frequency of hot and dry vintages alternating with rainy and cool years.
How do you avoid stuck fermentation in years with high temperatures and high water scarcity?
In years characterised by high temperatures and marked water shortage the vine will use nitrogen, almost exclusively, for its metabolism. The must produced from grapes under these conditions will suffer from a yeast assimilable nitrogen deficiency leading to fermentative difficulties which can irreversibly undermine the organoleptic characteristics of the “future wine”.
YAN analysis is therefore a fundamental tool for better management of the alcoholic fermentation, allowing for prudent planning of yeast nutrition and thus avoiding dangerous stucks fermentation.
How do you manage alcoholic fermentation in cool and rainy years?
In fresh and rainy years the appearance of grey mould is one of the main problems of the winegrower. This problem obviously has serious repercussions from an oenological perspective.
Grapes affected by grey mould can, in fact, present high concentrations of gluconic acid derived from the oxidation of glucose by mycelium.
This situation leads to deterioration of the health status of the must, in addition to difficulty in protecting against oxidation due to the high combined effect of gluconic acid with SO2. An additional effect of grey mould is the depletion of nutrient resources for yeasts.
This will result in a decrease in YAN in the must that will inevitably lead to fermentative problems.
Chemical analysis to better manage alcoholic fermentation and avoid stuck fermentation
In difficult climatic conditions, in addition to the usual analysis of sugar, total acidity, pH and acetic acid, yeast assimilable nitrogen and gluconic acid are the fundamental parameters available to the oenologist to better manage the fermentative process, an essential starting point to avoid stuck fermentation and to obtain a quality wine.
What are yeast assimilable nitrogen and gluconic acid? How can these analyses affect alcoholic fermentation?
For further information on these important themes you can download the article: VINIFICATION IN THE ERA OF GLOBAL WARMING