Maturation Studies

Touriga Nacional (L) and Touriga Francesa (R) from Quinta dos Lages

Since mid August Graham’s has been conducting maturation studies to monitor the final ripening of the grapes, and these studies continue throughout the harvest period.  Our decisions about what to pick and when to pick it are based on a combination of lab analysis of grape samples and the personal assessment of Charles Symington and our team of viticulturists and wine makers as they visit the vineyards and taste the grapes themselves.

In the lab, each 200 berry sample of grapes is first weighed, then the grapes are pressed, and the resulting must is centrifuged and the volume measured.  These steps help us anticipate yields for each variety.  The must is then poured into a glass to be assessed visually for colour, and we run some chemical analyses for baumé (the measure of sugars and alcohol) and acidity.  Then we simply taste it and record our impressions.

For more than ten years Steve Rogerson, our research oenologist, has been tracking the data collected by the maturation studies, and he updates it every day as we test the grapes from all our quintas.  We can quickly see a graph of how the measures are developing over the course of each week’s testing this season, and we can also compare against prior seasons and averages.

Last week when I visited Steve at the lab he could show me quite clearly how a few of our samples started the season with baumés higher than our previous highest ever starting baumé readings.  They then dipped after the rainfall at the end of August, as is normal, and had already shown some recovery the following week.

Samples from four different parcels at Malvedos, taken 7 September.

Even though the rainfall was fairly evenly distributed from Pinhão to Vilariça, we could see the effect on the grapes and statistics of significant differences within as well as between quintas.  We sample from specific parcels within each quinta, and samples from valleys, which effectively collect and channel the rain, showed greater effect of rainfall than parcels in more open positions.  Evidence once more of the intense microclimatisation in our Douro vineyards.

If you look at the photo of four samples from Quinta dos Malvedos, the far right glass is Tinta Amarela, but the other three are all Tinta Barroca.  The lightest one is from a vineyard half way down the hill on the western side of the quinta, the other two are from the top of the hill on the northeastern side, quite open and free draining parcels.

With the continuing sunny and hot weather here in the Douro, the grapes are again concentrating and continuing to ripen just as Charles hoped.  Malvedos wine maker Henry Shotton tells me Charles will be ready to discuss the Malvedos picking order tomorrow, after he has seen the latest results and visited the vineyards again himself.

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2 thoughts on “Maturation Studies

  1. Dear Cynthia,
    When you are writing about wine there, confuces me. Do you really mean wine or juice?
    I have been reading you with great intrest. Fine information with fine pictures. Thank you!
    Greetings from Finland,
    Ari-Heikki Vikman

  2. Hi Ari-Heikki, Good point, it isn’t fermented, it isn’t wine. I will change that to must. Thanks for helping me keep this clear!

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