3-Isobutyl-2-methoxypyrazine is neutrally perceived by consumers at usual concentrations in French Sauvignon and Fer wines from the Gaillac area

Abstract

3-isobutyl-2-methoxypyrazine (IBMP) is a grape-derived aroma compound responsible for the bell pepper character of wine. It is still unclear whether this molecule is always negatively perceived by consumers. The objective of this study was to establish a consumer rejection threshold (CRT) for IBMP in French white and red wines from the Gaillac area made from Sauvignon and Fer respectively.The best estimate thresholds (BET) were determined by carrying out three-alternative forced choice (3-AFC) tests: 5.5 ng/L for Sauvignon and 16.8 ng/L for Fer. For the estimation of the CRT, consumers (n = 48) received pairs of samples consisting of a base wine and a base wine spiked with an ascending concentration of IBMP. They were asked to indicate which sample they preferred, and the CRT was calculated as the concentration for which the spiked sample was significantly rejected. CRTs were determined at 50 ng/L and 30 ng/L for Sauvignon and Fer respectively.Our findings indicate that IBMP is more acceptable in white wine than in red wine. As IBMP concentrations reported in the literature for Sauvignon and Fer are generally below CRT concentrations, IBMP appears to be neutrally perceived by consumers at usual concentrations in wines from Gaillac made from these two cultivars.Our findings tend to contradict the belief in the wine industry that consumers systematically reject ‘vegetative’ styles of wines, and do not encourage local winegrowers and winemakers to necessarily implement viticultural or enological practices to minimise IBMP concentrations in wine.

Grape Berry Secondary Metabolites and Their Modulation by Abiotic Factors in a Climate Change Scenario–A Review

“…Among the various methoxypyrazines, some alkylated methoxypyrazines, such as 2-methoxy-3isobutylpyrazine (IBMP), 3-sec-butyl-2-l methoxypyrazine (SBMP), and 2-methoxy-3-isopropylpyrazine (IPMP) ( Figure 5) are extremely odorous, with very low odor thresholds (nanogram per liter range in water) (Sidhu et al, 2015). In cultivars of the Carmenet family, such as Sauvignon blanc, Cabernet Sauvignon, Cabernet Franc, Merlot, and Fer, the vegetable-like aromas are reminiscent of pea pods and green peppers, and depending on the concentration they can contribute to earthy nuances (Geffroy et al, 2020). In the grape cluster, the stems contain the largest proportion of IBMP (79.2%), and in the berries, most of the IBMP is located in the skin (72%), followed by seeds (23.8%) and pulp (4.2%) (Roujou- de-Boubée and Botella, 2003).…”

Exploring the response to a new range of ethanol reductions in Chardonnay and Syrah wines using a Consumer Rejection Threshold approach

“…The aim of this research work was to explore a wider range of ethanol lowering and to formally evaluate consumer response to ethanol in white and red wines using the consumer rejection threshold (CRT) method (Prescott et al, 2005). The CRT approach, which is based on the repetition of paired preference tests, has been previously applied to compounds responsible for wine faults, such as cork taint (Prescott et al, 2005) or 3-isobutyl-2-methoxypyrazine (Geffroy et al, 2020), and more generally to determine a level of concentration beyond which a given molecule becomes undesirable (Francis and Williamson, 2015;Geffroy et al, 2018). In both base wines, difference thresholds for ethanol were also defined during a preliminary experiment to determine the difference in ethanol concentration that can be perceived by consumers.…”

Prevalence and Management of Alkyl-Methoxypyrazines in a Changing Climate: Viticultural and Oenological Considerations

“…MPs are extremely potent odorants, typically detected in grapes and wines at parts per trillion (ng/L; [12]). Specific human sensory thresholds in wine have been reported as IBMP, 5-16 ng/L [13,14]; SBMP, 1-2 ng/L (in water, [13]); IPMP, 0.3-2 ng/L [15,16]; DMMP, 31 ng/L [17]. Common with many odor molecules, individuals show a significant variation in their sensitivity to MPs, and detection thresholds vary with wine style [16].…”

“…Common with many odor molecules, individuals show a significant variation in their sensitivity to MPs, and detection thresholds vary with wine style [16]. Consumer rejection thresholds for IBMP have been reported for Sauvignon (50 ng/L) and Fer (30 ng/L) [14], suggesting that IBMP may be acceptable in some wine styles. Consumer rejection thresholds have not been reported for wine styles where MPs do not contribute to varietal typicity, nor for IPMP, SBMP, or DMMP in any wine style.…”