Hedonic scale with reference: performance in obtaining predictive models

Although the hedonic scale can be used to optimise product acceptability, an alternative procedure allowing for direct comparison between the target product and the prototypes may be advantageous. The use of the magnitude estimation scale for hedonic responses has been exhaustively studied, but the use of the hedonic scale, adjusted to allow for the comparison between various samples and a reference, has not been reported. The objective of this research was to evaluate the performance of a hedonic scale with a reference to generate predictive models for product acceptability. Eleven formulations of reconstituted orange juice were prepared using a 2² central composite design. The independent variables studied were °Brix and acidity. Overall acceptability was evaluated using both the 9-point hedonic scale and a hedonic scale with reference. The data were analysed using Response Surface Methodology, residual analysis and Dunnett's test. The models generated by the two scales were similar with respect to: the adjusted R² (P<0.001), the non-significance of the lack of fit (P⩽0.05), the appropriateness of residuals to the statistical assumptions inherent in the regression analysis and, the optimised regions. However, it should be noted that the optimised region obtained by utilizing the hedonic scale with reference refer to samples whose acceptability are likely to be greater than that of the reference sample, as by using this scale consumers are forced to evaluate each sample in relation to the reference. For researchers working in product development this type of information can be a valuable tool.