EVALUATION OF BITTERNESS OF CAFFEINE IN HOT CHOCOLATE DRINK BY CATEGORY, GRAPHIC, AND RATIO SCALING

Perceived intensity of bitterness of caffeine (0.5 - 1.6 g/100 mL) and of quinine HCI (0.5 - 1.6 g/L) added to hot cocoa gave similar response distributions with concentration by category scales (CS) and magnitude estimation (ME). Using caffeine additives, CS and graphic analogue scales (GS) gave similar bitterness response functions. Parabolic functions provided the best fit between concentration and ratings for CS, GS and ME. The data demonstrated no difference for ME of bitterness intensity between free or fixed moduli. Hedonic responses also were not modified by whether the modulus was free or fixed, however, greater ME values were ascribed to lower concentrations in the series when the reference was 4 g/L than when it was 2 g/L caffeine. CS intensity response distributions were similar between a series with a larger number of low levels versus a series with a larger number of high levels across the same concentration range. The results indicate that ME may be inappropriate for scaling of degree of liking, independent of type of modulus.