Effects of Frozen Materials Other Than Grapes on Red Wine Aroma Compounds. Impacts of Harvest Technologies

An undesirable sensory attribute (“floral taint”) has been detected in red wines North America, caused by leaves and petioles (materials other than grapes [MOG]) introduced during mechanical harvest after killing frosts. From 2017 to 2019, several strategies were evaluated on Ontario Cabernet franc: hand (HH), conventional machine harvesting (MECH), Braud-New Holland Opti (OPTI), Gregoire GL8, MECH + optical sorting (MECH+OS), with preharvest leaf removal (MECH+BLR). Concentrations of 41 odor-active compounds quantified gas chromatography-mass spectrometry. Harvest treatment effects varied season. In 2017, HH resulted lowest ethyl isobutyrate (MECH+BLR), nonoate, cis-linalool oxide (plus OPTI), trans-linalool MECH+OS), β-citral, cis- trans-rose OPTI). Ethyl hexanoate was MECH, MECH+BLR, isoamyl all treatments except HH, α-ionone MECH+BLR. 2018, the β-damascenone, salicylate OPTI Gregoire), citronellol eugenol Gregoire). Isobutyl acetate, hexanoate, nerol additionally reduced Gregoire, isopropylmethoxypyrazine HH. strategy affected 27 compounds, including 11 esters 12 terpenes. Treatments leading concentrations (nine compounds), (eight MECH+BLR (10 (21 MECH+OS (22 compounds). Wines from fruit that had undergone a frost contained different 14 eight (2018), 17 13 (2019) for franc Sauvignon, respectively. Results suggest specific technologies can reduce MOG associated increases aroma although seasonal differences may occur.