Abstract
An undesirable sensory attribute (“floral taint”) has been detected in red wines in North America, caused by leaves and petioles [materials-other-than-grapes (MOG)] introduced during mechanical harvest subsequent to killing frosts. In 2017-2019, several harvest strategies were evaluated on Ontario Cabernet franc: Hand harvest (HH), conventional machine harvesting (MECH), Braud-New Holland Opti (Opti), Gregoire GL8, MECH + optical sorting (MECH+OS), MECH with pre-harvest leaf removal (MECH+BLR). Concentrations of 41 odor-active compounds were quantified by GC-MS. Harvest treatment impacts varied by season. In 2017, HH resulted in lowest ethyl isobutyrate (MECH+BLR); ethyl nonoate; cis-linalool oxide (plus MECH and Opti); trans-linalool oxide (plus MECH+OS); β-citral; cis- and trans-rose oxide (plus MECH and Opti). Ethyl hexanoate was lowest in MECH, and MECH+BLR, isoamyl hexanoate was lowest in all treatments except HH, and α-ionone was lowest in MECH and MECH+BLR. In 2018, HH resulted in lowest β-damascenone; ethyl salicylate (plus Opti and Gregoire; citronellol (plus Gregoire); cis- and trans-rose oxide (plus Gregoire); and eugenol (plus Gregoire). Isobutyl acetate, isoamyl hexanoate, and nerol were additionally reduced by Gregoire, and isopropylmethoxypyrazine was reduced by all treatments except HH. In 2019, harvest strategy impacted 27/41 compounds, including 11 esters and 12 terpenes. Treatments leading to lowest concentrations were: HH (nine compounds), MECH (eight compounds), MECH+BLR (10 compounds), Opti (21 compounds), Gregoire (10 compounds), MECH+OS (22 compounds). Wines from fruit that had undergone a killing frost contained different concentrations of 14 and eight compounds (2018), and 17 and 13 compounds (2019) for Cabernet franc and Cabernet Sauvignon, respectively. Results suggest that specific harvest technologies can reduce MOG and associated increases in aroma compounds, although seasonal differences may occur.
- Received October 2021.
- Revision received December 2021.
- Revision received January 2022.
- Accepted January 2022.
- Published online March 2022
- Copyright © 2022 by the American Society for Enology and Viticulture. All rights reserved.
This is an open access article distributed under the CC BY license (https://creativecommons.org/licenses/by/4.0/).