Impact of the Closure Oxygen Transfer Rate on Volatile Compound Composition and Oxidation Aroma Intensity of Merlot and Cabernet Sauvignon Blend: A 10 Year Study

Abstract

This study evaluated the impact of closure type on unoaked 100 %-Merlot, oak-aged 70%-Merlot/30%-Cabernet Sauvignon, and 30%-Merlot/70%-Cabernet Sauvignon during a 10 year period. Closures were microagglomerate corks, screw caps, and synthetics with the known oxygen transfer rate (OTR), ranging from 0.1 to 4.6 mg/y, including natural corks. Oxidation intensity perception, dissolved oxygen, sulfite, and 3-methyl-2,4-nonanedione (MND) were monitored on a regular basis. After 10 years of aging, additional aroma impact markers were evaluated (3-sulfanylhexan-1-ol, H 2 S, DMS, methional, and phenylacetaldehyde). Low OTR levels (≤0.3 mg/y) delayed the oxidation of red wines in this long-term experiment. In addition, our results led us to hypothesize that the MND concentration in young wines might be linked with their ability to produce it during bottle aging that is with their aging potential. Finally, we found that the kinetic accumulation of MND in wines was first strongly impacted by its intrinsic composition and thereafter by the OTR T0 of the stopper.

Characterization of Key Aging Aroma Compounds in Aged Jiangxiangxing Baijiu and Their Formation Influencing Factors during the Storge Process

“…The 3-methyl-2,4nonandione was found earlier in wine as an impact odorant that might contribute to the early evolution of aroma during aging, characterized by the loss of fresh fruit and development of dried fruit aromas. 22 Ketol is considered an important precursor of 3-methyl-2,4-nonandione in the oxidation of red wines. 23 In the J3 Baijiu sample, ethyl acetate, 3-methylbutanal, ethyl propanoate, 2,3-butanedione, isoamyl acetate, 2-methyl-3-furanthiol, acetic acid, geosmin, and 2-methoxy-4-methylphenol were present in a higher value (≥256).…”

“…More substances with typical aroma characteristics were detected in JXX Baijiu for the first time, including 3-methyl-2,4-nonandione (anise, fruit pit), piperitone (pepper), HDMF (caramel, spice), and HEMF (caramel, spice), benefiting from the long-term aging of the Baijiu samples. The 3-methyl-2,4-nonandione was found earlier in wine as an impact odorant that might contribute to the early evolution of aroma during aging, characterized by the loss of fresh fruit and development of dried fruit aromas . Ketol is considered an important precursor of 3-methyl-2,4-nonandione in the oxidation of red wines .…”