VINES AND WINES: NEWS YOU CAN USE

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By Donn Rutkoff

August 4, 2014( San Diego’s East County)--If you are a grower or winemaker, or serious wine drinker, this report covers three recent news items of research going on in the wine world.

1.  Research on tannins, which we feel as coarse roughness in the mouth, but we can't taste.

2.  Is Saccaromyces the best yeast?

3.  Conserving water.

What are tannins?  They are the molecules in the skin that make skin waterproof.  Why are tannins important?  Because they are a preservative that are part of the ageing process, and some are necessary for the right texture in wine. Erika Syzmanski, writing a blog called Wine-o-Scope, looks into the research on the texture and feel of wine, a subject that is very subjective to say the least, and the words we use to describe tannin are not part of our regular vocabulary.  What exactly are tannins and what behavior and life cycle do they have?  Her article reports on research by scientists at the Aussie wine institute (AWRI), and Dr. Kennedy's group at Fresno State. Kennedy is the enology chairman at Fresno State and he spoke at CSU San Marcos recently about growing high quality grapes.

The AWRI has a software package called The Wine Cloud,.  "is a web-based application that allows users to store, analyse and benchmark grape and wine-related analytical data on-line. The WineCloud also provides an option to calculate tannin, colour and phenolics attributes in red grape, ferment and wine samples based on UV/Visible spectral readings." It has 2 portals, one for grapes and the 2nd for wine.

"The WineCloudTM provides the ability to measure tannins, phenolics and colour attributes in grapes, as well as wines."  For wine, it  gives you 5 measures:  1.  total phenolics;  2.  total tannin; 3.  total pigment; 4.  free anthocyanins, and;  5. pigmented tannins. Their new cloud software measures these 5 molecules using standards set around 30 years ago, called the Adams-Harbertson assay.

But the next question and a bigger question, without a lot of answers, is the behavior of these molecules over time as the wine ages.  Dr. Kennedy and his team have just published an article on the stickiness of tannins.  (Journal of Agricultural and Food Chemistry , June 2014.  The article is titled "High-Performance Liquid Chromatography Determination of Red Wine Tannin Stickiness"

Their research studies how much tannin exists, and how sticky it is, that is to say how much it adheres to other molecules without the tannin itself breaking down into lesser, non-binding, molecules.  Or, in other words, how long it protects wine from bacteria, and how long your teeth will stay purple after a glass of  high tannin Cabernet vs. a glass of low tannin Pinot noir. 

Whew.  Heavy duty science.

2. From July 8 news link in winebusiness.com, an article in the July 2014 issue of Wine & Vines, about native yeast and inoculating with the standard Saccharomyces yeast.

"Role of non-Saccharomyces yeasts in wine production"  by Neil P. Jolly, Cristian Varela, Glen Osmond, and Isak S. Pretorius    

This story is about whether the standard yeast, Saccharomyces cerevisiae, is truly the dominant yeast that exists naturally in the air and on the skins of grapes, and the different flavors and results if you allow some of the other natural yeasts to get a start in your fermentation.  Most decisions you have as a new winemaker are about different strains within the Saccharo c. family, whereas this article is about those yeasts that are not in the Saccharo c. family. Even if decide not to inoculate, and you let the fermentation start just from the native yeasts that are on the skins naturally, they are mostly Saccharo anyway, but there are these other yeasts out there.  

Read more at: http://www.winesandvines.com/template.cfm?section=features&content=135080&ftitle=Role%20of%20non-Saccharomyces%20yeasts%20in%20wine%20production

Copyright © Wines & Vines

3.  Article in Wines and Vines magazine, reporting on a water use seminar, at the annual meeting of the ASEV (American Society of Enology and Viticulture).

We all know that water is scarce. The ASEV seminar started with research from UC Riverside about watering during dormant season to lower the  salt level, and again, in Australia, research on using reclaimed water.  Australia has bigger and very permanent water shortages, worse than California, and they use a lot of reclaimed water.  You have to watch our for  high salt, high potassium, and high ph. And a Sonoma county consultant talked about waiting to irrigate as late as possible.

"When water of marginal quality is used for irrigation, the level of soil salinity can increase, according to Donald L. Suarez, laboratory director at the USDA Agriculture Research Service Salinity Lab in Riverside, Calif. It may be necessary to alter water-management practices, possibly include leaching to control the level of salinity. Suarez presented a study which found that there was a “winter irrigation window” when the plants were dormant and the soil was wet, and leaching at that time had a “major impact on spring salinity levels, even in years of average to low rainfall.” Drip irrigation was more effective on heavier soils and sprinklers on sandy soils." 

Read more at: http://www.winesandvines.com/template.cfm?section=news&content=134991

Copyright © Wines & Vines

Next time, news on the foul tasting Brettanomyces yeast, some debate about terroir, and other heavy reading.  Until then, DMRW.