The main goal of maturity monitoring is to determine accurately the time of harvest.  It helps the winemaker to organise his or her team and the harvest strategy which will depend also on the weather and health state of grapes and vines.

Sugar ripening and phenolic maturity are not always in synch.  The winemaker must make a decision when to harvest based on Brix measured by refractometry and also the ratio of tartaric to malic acid.  Wine style will also impact the decision.  Working with a professional oenologist will be a big help at this stage.  While Brix measurement will give an indication on the level of potential alcohol, acid levels will hint at the level of grape maturity.  In our northern climate, significant levels of L-malic acid occur in grapes especially in hybrid grapes.  During maturation, these levels will decrease as L-malic acid will become an energy substrate for the vine and total acidity will also decrease as a result.  When performing maturity monitoring, we look at: Brix, Sugars, Density, pH, Titrable Acidity, Potential Alcohol, Tartaric Acid and L-Malic Acid.

Ideally, sampling is done at the end of the veraison stage and twice after that.  This allows for efficient monitoring of sugars and acids.  A minimum of 200 individual berries are needed and are usually sampled over several rows.  A good sampling strategy is to collect berries on 50 grapes clusters, by taking 4 berries per cluster, on the top, at the bottom, at the front and at the back.

Download our sampling guide in the “Document” tab, then “Downloads” tab.

Maturity analyzes are fast and cheap.  They bring real value to the winemaker.  Organic acids are not usually measured at the winery as opposed to Brix, pH and total acidity.  Knowing the balance between tartaric acid and L-malic acid is important for upcoming winemaking steps because high L-malic acid levels may affect malolactic fermentation negatively.