Sensory evaluation of wine aromas and faults by casual wine consumers
Creators: name: Dectis, Katherine Constance
Publisher: name: No Publisher Supplied
Year: 2024

description: Wine aromas are important chemical compounds impacting wine quality and can originate from varietal differences, viticulture, vinification, bottling, and aging. Wine faults can inadvertently occur at some step in the process, which can be detrimental to wine quality. Wine professionals are traditionally used to assess wine and are highly trained to recognize quality indictors including faults or defects, however consumers make the majority of wine purchasing decisions and their perceptions of these wine aromas and faults are less understood. Sensory evaluation of wine aromas and faults using casual wine consumers could help benefit the wine industry to better understand this target market. Other personal factors have also been shown to play a role in wine perception including age, gender, wine involvement, and wine adventurousness. Taste sensitivity to the bitter compounds 6-n-propylthiouracil (PROP), a genetic indicator for taste perception, has been well studied in relation to differences in oral sensations and food perception and liking. However, PROP status has rarely been examined in wines, and is worth further examination. The aims of this thesis were: 1) to investigate consumer detection thresholds for 8 aroma compounds and wine faults presented in aqueous solutions; 2) study the impact of wine spiked with these compounds on sensory perception and liking; and 3), determine if other individual and genetic factors could play a role in compound sensitivity and wine perception. A total of 68 casual wine consumers were recruited from the Rutgers-New Brunswick area. Taste sensitivity to PROP was examined and participants were divided into three groups: supertasters, medium tasters, and non-tasters. The following 8 compounds were evaluated: 2,4,6-trichloroanisole (TCA) “Cork Taint”, 4-ethylphenol:4-Ethylguaiacol (4EP/4EG) “Brett Taint,” Acetic Acid, an indicator of volatile acidity, Diacetyl “Butter”, ß-ionone “fruity/floral”, 1-octen-3-one “mushroom”, 2,5-dimethyl-3-methoxypyrazine (DMMP) ‘green”, and (E)-2-decenal “vegetal”. Consumer detection thresholds were obtained using Best-Estimate Threshold (BET) methodology, which is the geometric mean of the concentration at which they perceive the compound and the next lowest concentration in the series. Individual thresholds were visualized via histograms and Gaussian Mixture Modeling. Group thresholds were established using regression analysis with Abbott’s formula. For the wine tasting portion, 4 compounds were spiked in neutral white wine (Acetic Acid, Diacetyl, ß-ionone, and (E)-2-decenal) and 4 compounds were spiked in neutral red wine (TCA, Brett Taint, 1-octen-3-one, and DMMP): control neutral red and neutral white wines were also evaluated. Spiked wine samples were evaluated using check-all-that-apply (CATA) for 30 attributes which were analyzed by Cochrane’s Q; liking ratings for 4 attributes were collected and analyzed by ANOVA and ANCOVA followed by Tukey’s HSD, controlling for age and analyzing other factors such as gender, PROP status, wine preferences, and wine adventurousness.Reliable detection thresholds were determined for 5 compounds (ß-ionone, Diacetyl, Brett taint, Acetic Acid and DMMP). These thresholds were considerably higher for consumers than previously reported for experts with the exception of Brett Taint which was similar across subject groups. Acetic acid has not been studied in experts. Our subjects were insensitive to 1-octene-3-one and TCA, such that thresholds could not be determined for these compounds. Inspection of individual Best-Estimate Thresholds (BETs) showed a wide range of sensitivities to these compounds amongst consumers.For the wine tasting portion, the results showed that only a few compounds had major impacts on perception and liking of spiked wines. The white wine results showed Acetic acid increased vinegar flavor (p&lt;0.0001) and reduced liking for flavor, mouthfeel, and overall. The red wine results showed that 1-octen-3-one increased garlic flavor (p&lt;0.05), while TCA increased musty/moldy (p&lt;0.01) and green flavor (p&lt;0.001), both compounds decreased nutty flavor (p&lt;0.01). Both 1-octen-3-one and TCA reduced aroma liking (p&lt;0.0001).With regard to individual factors, PROP status did not impact consumer liking of specific wine samples, but super-tasters gave higher liking ratings to white wines (pooled across samples) compared to non-tasters (p&lt;0.05). Other individual factors such as age, gender, wine adventurousness, and wine preferences also impacted wine liking ratings.These results support our hypothesis that consumers are less sensitive to most wine aromas and faults than experts, with a few notable exceptions. When wines are spiked with these aromas and faults, some of them are noticeable to consumers, but they had minimal impact on liking. Only acetic acid reduced flavor, mouthfeel, and overall liking of white wine and TCA and 1-octen-3-one reduced aroma liking of red wine. These findings can be utilized by winemakers to better tailor their wines to the preferences of casual wine consumers who make up a major portion of the U.S. wine market.