Acidity Modification in Wine Fermentations from Arkansas-Grown Chambourcin Grapes using Lachancea thermotolerans Yeast
Amanda Fleming and Renee Threlfall*
*University of Arkansas-Department of Food Science, 2650 N Young
Ave, Fayetteville, AR, 72704 (rthrelf@uark.edu)
The interest in using non-Saccharomyces yeast, such as Lachancea thermotolerans, to modify acidity and other wine attributes has increased. Chambourcin (Vitis hybrid) red wine grapes were harvested in 2020 from a commercial vineyard in Arkansas, randomized into eight 17.5 kg batches, crushed, and destemmed. Four fermentation treatments in duplicate were done using S. cerevisiae (SC) with and without malolactic fermentation (MLF) and L. thermotolerans with a sequential inoculation after 48 hrs with S. cerevisiae (LT-SC) with and without MLF. Basic composition, sugars, and organic acids of the must/wine were evaluated daily during fermentation for seven days at 21°C. Prior to inoculation, must had 21.34% soluble solids, 3.43 pH, 0.78% titratable acidity, 19.51% total sugars, and 0.90% total organic acids (primarily 0.35% tartaric, 0.33% malic, and 0.18% lactic). Regardless of MLF, SC wines completed fermentation (<0.3% sugar and 10% ethanol) at five days, while LT-SC wines completed fermentation at seven days. At five days, there was no difference in tartaric acid and, regardless of MLF, LT-SC wines were lower in pH (3.26 to 3.33) and higher in lactic (0.65 to 0.66%) and total organic acids (1.25 to 1.27%) than SC wines (3.46 to 3.49 pH, 0.24 to 0.29% lactic, and 0.84 to 0.91% total organic acids). Titratable acidity was greater in LT-SC wines, regardless of MLF (1.21 to 1.22%), than in SC-MLF wines (0.82%), but was not greater than SC wines (0.90%). From 0 to five days, LT-SC-MLF had a greater reduction (12%) in malic acid than SC-MLF wines (9%). At day five, lactic acid production for SC-MLF was 12%, while production for LT-SC and LT-SC-MLF was tripled (46% and 47% increase, respectively). Increases in lactic acid using L. thermotolerans, with or without malolactic co-inoculation, broadens options for achieving smoother, more complex wines due to higher lactic acid production while achieving greater stability due to lower pH values.
Funding Support: Lallemand Inc, Danstar Ferments AG
