Comparison of Reverse Osmosis to Chaptalization in Free Run Chardonnay (2017)

The purpose of this study is to compare reverse osmosis treatments of juice to reverse osmosis treatments on wine, traditional chaptalization techniques, and no treatments at all. These techniques are commonly used in the wake of heavy rainfall events forcing winemakers to pick early. Chardonnay grapes were harvested and pressed into tank. This free run juice was allowed to settle overnight, and then was split into three separate lots: 1) Control, 2) Chaptalized, and 3) Reverse Osmosis Before (ROB) Fermentation. The ROB juice was concentrated 15%. After fermentation and malolactic conversion, the control lot was split into two separate barrels, and one of these received another treatment: 4) Reverse Osmosis After (ROA) Fermentation and malolactic conversion, to concentrate 15%. The juice chaptalization treatment was increased by 0.5 Brix in order to produce a potential alcohol which would mimic the ROA alcohol concentration, as opposed to the ROB alcohol concentration. Wines were bottled for the WRE right after the ROA treatment in early January. All other treatments between lots were equal. The ROB wine had higher alcohol content than the other wines. Lactic acid was slightly higher in the ROA wine, which also had a higher TA. The sensory results suggest that reverse osmosis can increase the perception of alcohol in wine, as well as increase acidity and other descriptive parameters. Reverse osmosis wines were generally preferred over the chaptalized wine, but this may have been due to reduction being present in the chaptalized treatment. More studies are needed to better elucidate the impact of RO on the aromatic and mouthfeel qualities of wine.  This study should be read in comparison to its sister study on press fraction Chardonnay.

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