Sunday, September 17, 2023

Whole-Bunch Fermentation---What & Why?

                                     Whole grape clusters are used, including all of the stems

This is the second in a trio of articles for the month of September exploring common terms used in the grape harvest.  Those of you who have visited wineries may have heard the term whole bunch fermentation, but do you really know what it means and more importantly, do you understand why it is used?  By the time you finish reading this article you will know what it is, as well as why some winemakers choose to use it.

Whole-bunch (or whole-cluster) fermentation involves the practice of not destemming the grapes.  In fact, the entire bunch (stems and all) goes directly into the fermentation vat.   Prior to World War II, this was generally the way wine was made, as destemming machines weren’t commonly used.   So why would a winemaker use the whole-bunch technique of fermentation rather than destemming the fruit before fermentation? 

            The de-stemming machine (separates the grapes from the stems) is NOT used in                                                                         whole-bunch fermentation

Below are some reasons winemakers may choose to utilize whole-bunch fermentation:

1.   Lower alcohol wines

Warmer weather is increasing the amount of alcohol in wines (riper grapes translate to higher alcohol levels during fermentation.)   High alcohol wines not only decrease the amount of wine that can be enjoyed safely, but are harder to pair with food.                                                                                                                                                                                                             

2.  Paler color wines

               For inky opaque wines such as Syrah or Mourvedre, lightening them up a bit                     could be desirable.  

          3.  Lower acid wines

     Acids play an important part in a wine’s structure, however, too much acidity is       a problem. 

The last blog in this three-part harvest series will discuss the flavors and aromas of wine that are a direct result of fermentation.  Look for it September 27.  


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