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Wednesday, August 30, 2017

Benefits of Low Temperature Fermentation

My husband has gone to some creative measures to ensure that the fermentation for our white varieties is at a constant low temperature. In 2015, when we had our first extremely modest harvest, he modified our 30 year old refrigerator to be at at constant 60 degrees with the use of a Johnsons temperature controller.
The benefits to keeping a constant low temperature during fermentation is to:
  • preserve the aroma and flavors that high temperatures might volatilize including esters from fatty acids, organic acids, and higher alcohols
  • prevent the development of off-flavors, specifically volatile sulfur-containing compounds like hydrogen sulfide, mercaptans (thiols) and disulfides which can lead to aromas or flavors reminiscent of rotten eggs, cooked cabbage and skunk
  • improve the clarity of wine, since yeast cells are less likely to give off colloids
  • better control of microbial growth to minimize potential spoilage
We are proponents of low temperature, long fermentations designed to preserve the aromatics and flavors that can be achieved by that process. This year was going to present somewhat of a challenge to keep our harvest at a low temperature, but I think that we will be able to use our basement for this one last time. Procurement (my husband) has ordered 2 more chest freezers and is in the process of ordering our half kegs that will fit in the chest freezer.
References:
1. Penn State Extensions, An Introduction on Low Temperature Fermentation in Wine Production
2. Antonio G. Cordente, Christopher D. Curtin, Cristian Varela, Isak S. Pretorius, Flavor-active Wine Yeast, Applied Microbiology and Biotechnology, November 2012, Volume 96, Issue 3, pp 601-618.
All structures were drawn by the freely available drawing program from ACD Labs called ACD/ChemSketch Freeware.

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