June 2017 - The creation of a vintage involves innumerable steps, actions, and manoeuvres. It’s a work of nature shaped by the hands of men and women, both in the vineyard and in the cellar. Some of these operations are less well known, yet play roles every bit as crucial in the elaboration of a vintage. Notably those which take place in the laboratory, next to the winery. It’s a place like no other – white, immaculate, and dedicated to chemistry.
The chemistry of wine: polyphenols, density, extractability, alcohol potential, available nitrogen, malic acid, anthocyanins… it’s the science of all that unfolds from the moment a vintage first blooms to life in the vineyard. And it’s the science which comes sharply into focus in the days just before the harvest, when the berries have nearly fully ripened, and the harvest team is at the ready.
To determine the exact moment of perfect grape maturity, and thus launch the harvest, a series of berry analyses are conducted. Sylvain Fries, head of vine research and development, diligently scours the vineyards. He observes. Pauses. Tastes. Picks. He chooses 200 berries for each analysis, which he brings back to the laboratory. Tommaso Nicolato, who manages the laboratory, then performs two common maturity tests, one for technological maturity, and another for phenolic maturity.
The technological maturity test consists of measuring the sugar and acid levels in the grapes. As the grapes mature, malic acids levels diminish and the sugar concentration increases. At Château Palmer, the sugar concentration is closely monitored via densimetry (the measurement of density). Measuring the density of grape must allows us to estimate its potential alcohol, as it’s the sugar which will become alcohol during fermentation. The acid levels are measured with a simple pH test.
To test phenolic maturity, we will measure polyphenols, specifically anthocyanins and tannins. With this analysis, we monitor the accumulation of anthocyanins and the transformation of the tannins, which in maturing will develop a velvety character, veritable signature of the wines of Château Palmer. The most commonly used method was developed by one Professor Glories; it provides a clear picture of the quantity and quality of these polyphenols, and their extractability.
These analyses help reinforce the conclusions drawn in tasting the berries. They are additional tools in our arsenal as we gauge the precise moment to start the harvest. But the ultimate diagnosis is always that of our taste buds, for in the end, aromatic complexity cannot be measured, it can only be tasted. Come September, the time for tasting will be upon us once again, as we prepare to harvest the 2017 vintage!