Issue link: http://winesandvines.uberflip.com/i/450857
72 practical winery & vineyard February 2015 w i n e m a k i n g gallons of wines with diverse instability have been successfully treated. A collaborative study between UC Davis and Laffort USA on tartrate stabil- ity was conducted at the UC Davis teach- ing and research winery. Traditional cold stabilization was compared to the addi- tion of carboxymethyl cellulose (CMC at 100 ppm, Celstab) to obtain tartrate sta- bility. Two different white wines, a Sau- vignon Blanc (pH 3.31, TA 7.9 g/L, 12.4% ethanol) and a Chardonnay (pH 3.71, TA 6.1 g/L, 14.2% ethanol) were included in the bench trial study. Both the Chardonnay and Sauvignon Blanc wines were determined to be tar- trate-unstable using the standard UC Davis conductivity test. The wines were protein- stabilized to a heat-test turbidity reading of less than 2 NTU before undergoing respec- tive tartrate-stabilization treatments. Quadruplicate samples of each wine were treated with 100 ppm of CMC (1,000 ppm of Celstab) or cold stabilized at a constant temperature of 25º F. Both the Sauvignon Blanc and the Chardon- nay achieved immediate tartrate stabil- ity when treated with CMC, where as the wines that were cold stabilized at 25º F took between eight and 10 weeks to achieve tartrate stability as determined by ISTC-50 testing. All wine samples for both the CMC and cold stabilization were still tartrate- stable after 22 months of bottle aging as determined by ISTC-50 testing. In a specific commercial winery trial application, tartrate-stabilization treat- ments including traditional cold sta- bilization, electrodialysis and CMC addition were compared relative to chemical alteration of the wine for pa- rameters including alcohol, pH, TA, free and total SO 2 and sensory evaluation preference testing. Results showed that CMC had the lowest impact on chemical parameters of the wine and was signifi- cantly preferred in tasting evaluations (Figure 7a and 7b). In a scientific study of an analyti- cal method to detect CMC in finished wine, sensory evaluation by a 20-mem- ber expert panel detected no signifi- cant effect on wine perception at the legal dose of 100 ppm. Further sensory experiments showed that at up to 15 times the maximum dose of a particu- lar CMC there was no significant impact on taste or aroma perception of the treated wine. 9 Figure 5. molecular structure of sodium carboxymethyl cellulose. Carboxymethyl group pKa of 4.0 indicates that the groups will be negatively charged at wine ph. (modified from london south bank university web page: lsbu.ac.uk/water/hycmc.html.)