The expectation of consumer and its influence on sensory perception and acceptance of coffee / A expectativa do consumidor e sua influencia na aceitação e percepção sensorial de cafe soluvel

AUTOR(ES)
DATA DE PUBLICAÇÃO

2003

RESUMO

In products such as instant coffee, which require preparation before consumption, the expectations of the consumer may be influenced by the sensory stimuli emanating from the product during the manipulation and gradual contact occurring during the preparation process. On the other hand, sensory analysis still lacks research studying the validation of statistical analyses of the data produced in consumer studies in which the consumers are segmented as a function of their individual perceptions and not as a function of the arithmetic mean obtained with the group of individuals who participated in the test. Thus the objectives of this study were: i) verify, specifically with instant coffee, how the sensory stimuli observed during preparation influenced liking and the perception of the attributes bitterness and richness in the final beverage and; ii) compare the traditional statistical methodologies of ANOVA and Tukey with Preference Mapping, in order to explore sensory data generated by consumers. Two experiments were carried out to achieve these objectives. In the first experiment, the performance of Internal Preference Mapping (IPM) was studied and compared with that of ANOVA followed by Tukey s test, in the analysis of the data generated by 178 English consumers for liking and the intensity of bitterness and richness, in 9 commercial instant coffee samples acquired on the English market. The consumers used a 9 point structured hedonic scale and category scales to evaluate the samples. The coffee samples were prepared with a concentration of 17% plus 17% pasteurized semi-skimmed milk. The order of presentation was according to a balanced complete block design. The scores attributed by the consumers were submitted to ANOVA, Tukey s test and the vector model of Internal Preference Mapping (IPM). IPM was shown to be a useful technique in the data analysis, showing the segmentation of the consumers according to their preferences and providing information not available from the traditional statistical analyses, that of identifying two groups of consumers: i) a smaller group (23%), which strongly discriminated the samples with respect to their liking and, ii) a larger group constituted by the majority of the participants (77%), which, despite showing similar preferences to the first group, used a smaller portion of the hedonic scale, discriminating the samples less with respect to their liking as compared to the first group. In the second experiment the effect of contact with the sensory stimulus of the instant coffee was evaluated, with respect to consumer expectation, liking and bitterness perception. Thus initially three different sets of package + coffee sample were prepared, so as to confirm, positively disconfirm and negatively disconfirm consumer expectation. The evaluations occurred in three steps: i) blind evaluation, in which the consumers evaluated the samples from codified containers; ii) expectation evaluation in which the consumers evaluated their expectation from the package and/or sensory product stimulus and iii) informed evaluation, where the consumers evaluated the coffee samples in the presence of their respective packages. In the expectation evaluation, the consumers were divided into three groups, and each group evaluated the expectation after adopting one of three different procedures: 1) manipulate the package; 2) manipulate the package, open it and evaluate product aroma and 3) manipulate the package, open it, evaluate the aroma and dose the product for preparation. The samples and packages used were acquired from English supermarkets. Ninety-six consumers took part in this study, each with a similar preference profile for instant coffee. To evaluate the samples they used a nine point structured hedonic scale and a category scale. In all three evaluations, the samples were presented according to a balanced complete block design. Individual effects of expectation were identified: i) by way of an analysis of the graphs (EX - SE) x (IN - SE), plotted for each sample for each group of consumers, where EX represents the scores generated in the expectation evaluation, SE in the blind evaluation and IN in the informed evaluation and ii) by way of the linear regressions calculated for each graph. To evaluate the effects of expectation on liking and bitterness perception in each consumer group, the scores for SE, EX and IN obtained for each group were expressed as mean values and submitted to ANOVA followed by Tukey s test. In addition, the data obtained for each group in the blind (SE) and informed (IN) evaluations, were submitted to ANOV A, considering the following sources of variation: type of evaluation (blind or informed), consumer and sample. The t test was applied to compare the means for SE and IN, obtained for each set in the 3 different procedures. The results obtained in the present study suggest that different forms of consumer contact with the sensory stimuli of instant coffee before tasting, strongly influence consumer liking, each in a distinct way. The effect assimilation was predominantly identified, its occurrence being significant (p?0,05) after both negative disconfirmation (product worse than expected) and positive disconfirmation (product better than expected). These results reinforce the importance of the package in the acceptance and decision to buy of the product by the consumers

ASSUNTO(S)

expectativa (psicologia) coffee expectation (psychology) avaliação sensorial cafe soluvel consumidores sensory evaluation consumers

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