Impact of protein fining agents and bentonite on rotundone concentration in red wine made from <i>Vitis vinifera</i> L. cv. Tardif

Rotundone, the main aroma compound responsible for peppery notes in red wine, has a strong affinity with solids and may be affected by wine fining. This work aimed to study the impact of several fining agents on this compound using a red wine made from Tardif. Egg albumin, gelatine, vegetable protein (pea protein) and sodium bentonite were investigated at the same dosage (D1, 20 g/hL) to compare their effect under similar conditions and at a second dosage, which corresponds, depending on the agents, either to half of D1 or twice D1 to reflect more common winemaking practices. Overall, the fining agents had a minor, although significant effect on rotundone, with the greatest impact, which might not be detectable sensorily speaking, observed for vegetable protein (pea protein) used at 40 g/hL (–12.1 %). At D1, although not statistically different from gelatine and vegetable protein (pea protein), egg albumin induced the largest decrease in rotundone, which could be attributable to its higher surface charge density. A correlation (R2 = 0.85) was noticed between mean values of rotundone concentrations (3 replicates) and A620, suggesting that this proxy can be used to predict the impact of fining on rotundone in Tardif red wines. Though further work is necessary to investigate the impact of additional fining agents and to better understand the mechanisms involved, notably using computational chemistry, our results encourage winemakers to use fining agents in their wine if required, without having to fear excessive rotundone losses.