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T. H. Shellhammer1, A. I. Gitelman2, and M. R. MCDANIEL1. (1) Dept. of Food Science & Technology, Oregon State Univ., 232-A Wiegand Hall, Corvallis, OR 97331-6602, (2) Dept. of Statistics, Oregon State Univ., 48 Kidder Hall, Corvallis, OR 97331-3366 Making positive changes in the magnitude and quality of bitterness intensity in certain foods requires an understanding of how people respond to bitter stimuli. The objective of this study was to measure the bitterness perception of trained panelists by spiking an inherently low-bitterness commercial beer with each of eight compounds (caffeine, quinine hydrochloride, quinine sulfate, sucrose octaacetate, tetrahydroiso-alpha acids, dihydroiso-alpha acids, and high and low isocohumulone mixtures of iso-alpha acids). Temporal bitterness was measured using a time-intensity procedure with a computer data acquisition system (CompuSense). The panel consisted of 14 experienced tasters (8 male, 6 female). To eliminate olfactory influences, panelist wore nose clips throughout training and data collection. Panelists trained one month with the bitter compounds in water and two months with the same compounds in beer. Throughout the training process, concentrations of all compounds were adjusted until the panel’s mean peak intensity of each compound differed by less than 1 point on a 16-point scale. These “equi-bitter” levels were used for data collection in an effort to eliminate peak intensity effects on bitter perception comparisons. Using panelists as blocks in a randomized block design, data were collected from five independent replications. Although the panel as a whole found only small differences in the peak intensity of all eight compounds (means ranging from 58.9 – 48.6 on a 100 point scale), a significant panelist by compound interaction was present (p<0.001) for peak intensity as well as other temporal parameters such as duration, rate of stimuli onset, area under the curve, etc. Panelists differed significantly in their sensitivity to overall bitterness. Furthermore, variability in bitterness sensitivity was compound-specific. Closer examination of the panelist by compound interactions using hierarchical linear models revealed unexpected differences in responses to the different compounds, suggesting that bitterness is a very subject-dependent quality.
Session 97, Sensory Evaluation: Analytical testing
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