EFFECTS OF FORGETTING ON VARIOUS PROTOCOLS FOR CATEGORY AND LINE SCALES OF INTENSITY

Unstructured numerical intensity scales: Models, protocols and errors

A sample of 62 untrained subjects were assessed on their ability to use unstructured numerical 9-point and 30-point category scales along with an unstructured line scale, using both rank-rating and serial monadic protocols. Visual stimuli were used for convenience, the task being to rate the heights of 12 easily discriminable columns of mung beans held in transparent vertical cylinders. Such stimuli had no perceptual variance, which would otherwise have added uncontrolled variance to the subjects' performance. Two measures of performance were used for each of the 6 experimental conditions. First, mean number of 'scaling errors' made in each of the six experimental conditions was computed. In this experiment, a scaling error was defined as giving a taller column a score equal to or less than a shorter column. The lower the error count, the better the subjects' performance. The second measure was to match the subjects' rating scale pattern of scores to a 'true' pattern of scores, derived from the physical measurements of the 12 columns. For this, a 'dissimilarity score' was developed. This compared the sum of the Euclidean distances between standardized true scale ratings for each of the column's 12 true heights, with those obtained from each subject. This gave a measure of the mismatch between the subject's set of scores and the true set of scores. Both the scaling error counts and the dissimilarity measures, indicated that subjects performed significantly better using the rank-rating protocol than the serial monadic. This was because of the effects of forgetting the exact intensities of stimuli once they had been removed, removal of stimuli being a necessary part of the serial monadic protocol. Subjects were penalized when using the 9-point scales, because there were too few categories to represent the different heights of all 12 columns. This introduced the concept of 'sufficient space'. Using the rank-rating protocol, the 30-point and line scales, with no memory problems and sufficient space elicited the best performances; they were not significantly different.

Novel Modelling Approaches to Characterize and Quantify Carryover Effects on Sensory Acceptability

Sensory biases caused by the residual sensations of previously served samples are known as carryover effects (COE). Contrast and convergence effects are the two possible outcomes of carryover. COE can lead to misinterpretations of acceptability, due to the presence of intrinsic psychological/physiological biases. COE on sensory acceptability (hedonic liking) were characterized and quantified using mixed and nonlinear models. N = 540 subjects evaluated grape juice samples of different acceptability qualities (A = good, B = medium, C = poor) for the liking of color (C), taste (T), and overall (OL). Three models were used to quantify COE: (1) COE as an interaction effect; (2) COE as a residual effect; (3) COE proportional to the treatment effect. For (1), COE was stronger for C than T and OL, although COE was minimal. For (2), C showed higher estimates (−0.15 to +0.10) of COE than did T and OL (−0.09 to +0.07). COE mainly took the form of convergence. For (3), the absolute proportionality parameter estimate (λ) was higher for C than for T and OL (−0.155 vs. −0.004 to −0.039), which represented −15.46% of its direct treatment effect. Model (3) showed a significant COE for C. COE cannot be ignored as they may lead to the misinterpretation of sensory acceptability results.

The 9-point hedonic scale and hedonic ranking in food science: some reappraisals and alternatives

The 9-point hedonic scale has been used routinely in food science, the same way for 60 years. Now, with advances in technology, data from the scale are being used for more and more complex programs for statistical analysis and modeling. Accordingly, it is worth reconsidering the presentation protocols and the analyses associated with the scale, as well as some alternatives. How the brain generates numbers and the types of numbers it generates has relevance for the choice of measurement protocols. There are alternatives to the generally used serial monadic protocol, which can be more suitable. Traditionally, the 'words' on the 9-point hedonic scale are reassigned as 'numbers', while other '9-point hedonic scales' are purely numerical; the two are not interchangeable. Parametric statistical analysis of scaling data is examined critically and alternatives discussed. The potential of a promising alternative to scaling itself, simple ranking with a hedonic R-Index signal detection analysis, is explored in comparison with the 9-point hedonic scale.

Development and optimisation by means of sensory analysis of new beverages based on different fruit juices and sherry wine vinegar

BACKGROUND

Despite the long history of sherry wine vinegar, new alternatives of consumption are being developed, with the aim of diversifying its market. Several new acetic-based fruit juices have been developed by optimising the amount of sherry wine vinegar added to different fruit juices: apple, peach, orange and pineapple. Once the concentrations of wine vinegar were optimised by an expert panel, the aforementioned new acetic fruit juices were tasted by 86 consumers. Three different aspects were taken into account: habits of consumption of vinegar and fruit juices, gender and age.

RESULTS

Based on the sensory analysis, 50 g kg(-1) of wine vinegar was the optimal and preferred amount of wine vinegar added to the apple, orange and peach juices, whereas 10 g kg(-1) was the favourite for the pineapple fruit. Based on the olfactory and gustatory impression, and 'purchase intent', the acetic beverages made from peach and pineapple juices were the most appreciated, followed by apple juice, while those obtained from orange juice were the least preferred by consumers.

CONCLUSION

New opportunities for diversification of the oenological market could be possible as a result of the development of this type of new product which can be easily developed by any vinegar or fruit juice maker company.