The Importance of the Gluconic Acid Measurement During the Grape Harvest
Grape Quality
It is particularly important to control certain parameters in the vineyard:
- Potential alcohol: related to the amount of sugars in your grapes
- L-malic, total acidity and pH: an indication of the state of the ripeness
- Acetic and Gluconic acid: an indication of the health of the grapes
What is Gluconic Acid?
- Botrytis cinerea oxidates the glucose to transform it into gluconic acid
- Gluconic acid is an indicator of grape deterioration and sanitary condition
- Gluconic acid is the official OIV analysis to quantify Botrytis
Why is Gluconic Acid Checked?
- It is a metabolite of Botrytis and can be a useful marker for Botrytis activity in the vineyard
- It is associated with a sour taste and has an overall negative effect on quality
- Ii is used globally as a rapid screening tool for assessing fruit quality on incoming fruit, even as far as influencing the price and rejection criteria in vineyard contracts
- It can provide information of the grape’s health in the field and the level of disease pressure or spoilage microbes it may contain
What are the Benefits of Measuring Gluconic Acid?
Measuring gluconic acid allows you to separate the grapes by quality, so you can obtain higher quality wines with added value. High values of gluconic acid imake winemaking difficult even with good practices of vinification. Knowing the values of gluconic acid in can help make some decisions such as:
- Adding SO2 to avoid oxidation produced by the laccase generated by botrytis
- Separating grape batches by quality
- Pressure, temperature and enzymes when extracting the juice
- Use of fining pre-fermentation agents such as Chitosan, gelatine, bentonite etc.
- Increasing the acidity with the desired adjustments
- Choosing the optimal yeast or yeast strain
- Coupage
- Avoiding bad clarifications due to glucans coming from the fungus cell wall
- Quick starting of the alcoholic fermentation
- Avoiding long macerations and fermentations
Gluconic acid can be measured using the CDR WineLab analyser or the BioSystems Y15 automated analyser.
15/7/26