Methoxypyrazine Content of Japanese Red Wines

Modeling Impacts of Viticultural and Environmental Factors on 3-Isobutyl-2-Methoxypyrazine in Cabernet franc Grapes

“…At three of the four sites where measurements of crop to vine size (crop load, yield per shoot, clusters per shoot) negatively correlated with log-fold decrease in IBMP, fruit maturity was positively correlated with log-fold decrease in IBMP, indicating that vines with higher crop to vine size had less mature fruit. Several groups have reported correlations between IBMP concentrations and fruit maturity indices such as Brix and malic acid (Chapman et al 2004, Hashizume and Umeda 1996, Roujou de Boubée et al 2002. Although neither IBMP at harvest nor the IBMP decrease could be predicted by Brix, pH, and TA across multiple sites, similar to previous observations (Ryona et al 2008), within a site the log-fold decrease in IBMP positively correlated with these simple maturity indices in six of the single-site models (Figure 3), a significant result ( p < 0.05, chi-squared test).…”

Analysis of methoxypyrazines in wine using headspace solid phase microextraction with isotope dilution and comprehensive two‐dimensional gas chromatography

“…They have a vegetative, herbaceous odour [2], similar to bellpepper, and a very low sensory threshold of between 1 -10 ng/L in water [3]. Fruit produced under cooler climatic conditions generally has higher methoxyprazine levels than fruit produced in hot climates, and can therefore impart distinct regional characteristics to the same grape variety.…”

“…Prior to SPME, extraction of methoxypyrazines from wine (or grape seeds, bunch stems, and skins [2]) was arduous, generally requiring pH adjustment followed by distillation and extraction of the distillate with ion-exchange resin. The neutralized resin is then repeatedly extracted with dichloromethane, and the latter concentrated prior to GC analysis [2,5].…”

“…Prior to SPME, extraction of methoxypyrazines from wine (or grape seeds, bunch stems, and skins [2]) was arduous, generally requiring pH adjustment followed by distillation and extraction of the distillate with ion-exchange resin. The neutralized resin is then repeatedly extracted with dichloromethane, and the latter concentrated prior to GC analysis [2,5]. Using SPME, however, methoxypyrazines can be extracted from wine or grape juice headspaces (HS-SPME), and a wide range of SPME fibers and extraction conditions (e. g., time, temperature, sample pH, sample volume) have been investigated [3,4,6,7].…”

“…GC-NPD is selective for the detection of nitrogen and/or phosphorus containing compounds, and is aptly suited to the detection of methoxypyrazines [3,6,7]; however, GC-MS has found much greater implementation [1, 2, 4, 5, 8 -10]. Specifically, quadrapole MS [1,2,5,9,10] and ion trap MS [4] have been used, with selected ion monitoring; reported detection limits for IBMP in wine ranged from 0.7 ng/L with quadrupole MS [5] to 1 ng/L for ion trap MS [4]. Development of a definitive MS method is best achieved using a stable isotope-labeled analogue of the analyte as an internal standard (cited in [1]), and has been reported in other studies [4,5,9].…”