Abstract 068
Evaluation of a model of organic acid flavor thresholds in beer
J. Amer. Soc. Brew. Chem. 58 (3): 94-96, 2000
K.J. Siebert
A formula that successfully models the flavor thresholds in beer of organic acids as a function of their molecular properties (R2 = 0.905) was previously developed. The predictive ability of the model was evaluated by internal and external validation. Cross-validation of the original data set produced an R2 of 0.842, which represents a more conservative estimate of the model’s predictive ability. Flavor threshold determinations were attempted with four acids whose thresholds in beer were not available in the literature. In three of the four cases (benzoic, fumaric, and sorbic acids) the solubility limit of the acid in beer was exceeded before the threshold was encountered. The observed threshold for heptanoic acid (2.3 mg/L) was reasonably close to the model prediction (18 mg/L). The model was also used to make predictions for acids other than those used to construct the model. The two acids that had similar structures to those in the original data set, isobutyric and isovaleric, showed reasonably close agreement between observation and prediction. For two acids unlike any in the original data set, phenylacetic and gallic, predictions were wildly inaccurate.
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