Descriptive analysis of complex odors: reality, model or illusion?

The primary sensory tool for specifying the characteristics of a complex ar oma, fragrance, flavor or other odorous mixture of volatiles is descriptive analysis. Descriptive analysis uses a trained panel to specify the intensi ties of specific attributes, based on a psychophysical model for intensity scaling. However, the use of descriptive techniques for complex and well-bl ended aromas gives rise to several problems. The psychophysical intensity m odel based upon independent odor notes may be a poor way to characterize od or experience, bringing into question whether descriptive analysis is an ad equate tool for sensory analysis of complex smells. These problems include the following: (1) disagreement among experts in the most prominent odor no tes of a single product and other individual differences problems, (2) a co rrespondence between similarity scaling and intensity scaling, (3) the subs titution of applicability measures for intensity, (4) the need to use mid-t ier, general odor terms for profiling complex fragrances, and (5) blending and integration effects. Data will be presented on citrus-woody mixtures sh owing that ratings of similarity and intensity are highly correlated, sugge sting a common underlying process for both ratings. A related issue concern s whether odors and their mixtures are perceived as unitary or analyzable p ercepts. With these same stimuli, the perception of singularity vs, mixed-n ess of stimuli is difficult to predict. Sensory scientists should question the validity of descriptive data for such stimuli and avoid the simplistic mistake of equating data with perception. The use of simple and apparently independent intensity scales may produce the illusion that the odor experie nce is a collection of independent analyzable "notes" when it is not. (C) 1 999 Elsevier Science Ltd. All rights reserved.