Today’s Wine Word: Refractometer


photo courtesy of lyzadanger on Flickr

 Refractometer? Yup. It plays a very important role, now, as harvest approaches because it measures the sugar in the grapes.

The refractometer is a really nifty little instrument because it gives the winemaker an instant sugar reading. It’s kind of like a prism and measures the soluble solids in the grape juice. All you have to do is squeeze a little juice onto the lens of the refractometer. When you hold it up to the light it measures how much the light bends as it passes through the liquid. The denser the liquid, the more the light bends and the higher the reading will be (about 90% of the soluble solids is sugar). 

Why is the sugar so important? It determines the alcohol. The winemaker can assume that a little over half of the sugar measured at harvest will result in alcohol in the finished, dry wine. So, if the grape sample measures 25% sugar the wine will be in the ballpark of 13.5 – 14% alcohol.

Incidentally, the degrees Brix, another wine word, translates to the percentage of sugar. 25 degrees brix = 25% sugar. So, you got a two-fer! 

Other important components? 

  • Acid – it keeps the color bright, makes the wine refreshing and lively, balances sweetness and richness, makes it food friendly and helps it to age. 
  • pH – The pH is kind of a mirror image of the acidity. You might say it measures the strength of the acidity. It has a lot to do with the health and stability of the wine. Wine is high in acid. On a pH scale of 0 – 14, zero being acid and 14 being alkaline, wine falls between 3 and 4.

What important factor trumps all of these numbers? Flavor, of course! At least at the best wineries, flavor is it! 

The Napa Valley harvest of 2012 began very quietly last Friday, the 12th. So far, Mother Nature has been very kind to us – especially compared to the last few years. Let’s hope her generosity of spirit continues! 

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