The chemical and sensorial effects of plant-based fining agents on Washington State Riesling and Gewürztraminer wines

Laura Ellen Hill

The objective of this study was to determine the chemical and sensory impact of plantbased fining agents on WA State Riesling and Gewürztraminer wines. Riesling and Gewürztraminer wines were made in from WA State (Paterson, WA) grapes. Following alcoholic fermentation, five fining agents were applied to the wines: bentonite (Gewürztraminer: 150 mg/100 mL; Riesling: 100 mg/100 mL), soy milk powder (Gewürztraminer: 2.16 mg/100 mL; Riesling: 3.24 mg/100 mL), Plantis Fine (Gewürztraminer: 15 mg/100 mL; Riesling: 25 mg/100 mL), Plantis AF (Gewürztraminer: 30 mg/100 mL) and Blankasit (30 ul/100 mL) and an unfined control. The resulting wines were evaluated for sensory attributes using a trained panel and for acceptability using a consumer panel. Solid-phase microextraction (SPME) was coupled with gas chromatography/mass spectrometry (GC/MS) to quantify selected the volatile compounds in both wines. For Gewürztraminer, the trained sensory panel found a difference in floral flavor, with the unfined control and Blankasit having the highest concentration and the remaining fining agents having lower concentrations (p< 0.05). No differences in acceptance were found between the Gewürztraminer wines (p>0.05). For Riesling, no significant differences in sensory attributes were found by the trained panelists. However, the consumer panel showed a significant difference in appearance acceptance of the wines, with the unfined control Riesling being less acceptable than the fined Riesling wines (p<0.05). In Gewürztraminer wine, the volatile compound concentrations that significantly differed between treatments included 3-methyl-1-butanol (malt, burnt aroma) and 1-hexanol (green aroma) which were both highest in the Blankasit-fined wine (p<0.05). Ethyl hexanoate (apple, fruit aroma) was highest in the soy milk powder-fined wine and ethyl dodecanoate (leaf aroma) was highest in the unfined wine. In Riesling, ethyl decanoate (grape aroma) and ethyl dodecanoate (leaf aroma) were significantly higher in the unfined wine compared to the fined wines. Many of the volatile compounds quantified were present at concentrations below odor threshold detection values, and therefore did not translate into sensorial differences in wine aroma or flavor. The fining agents applied in this study impacted the chemical properties of wines, specifically volatile composition, color parameters and protein stability; however these differences were not as apparent using sensory methods.

The chemical and sensorial effects of plant-based fining agents on Washington State Riesling and Gewürztraminer wines

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