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