Tests de différenciation

Are replicate evaluations of triangle tests during a session good practice?

Results from four experiments in which replicated triangle tests were performed are reported. Two experiments were carried out with non experienced assessors and the two other ones with experienced assessors. Results from the non experienced assessors showed a slight performance increase from the beginning to the end of the session whereas results from the experienced assessors did not. This is explained by an attentional process allowing non experienced assessors to gradually focus their attention on the difference between the two tested products. In some specific occasions, replicate triangle tests might be a good methodological practice when the purpose of the test is to study the effect…

A matching task as a potential technique for descriptive profile validation

If panellists can successfully match products to the corresponding descriptive profiles, then the profiles can be regarded as product-relevant and valid. This work examined the ability of a trained panel to perform a matching task between products and their descriptive profiles. A 13-member panel, trained to assess eight cheeses in terms of 19 flavour attributes, performed the task based on their individually developed profiles. The panel's ability to match products to profiles was well above that expected by chance, and chi-square statistics for each of the products were significant (P<0.05). A correspondence analysis based on the group results indicated that all the products were relative…

Sensory analysis of Burgundy Pinot noir wines: A comparison of orthonasal and retronasal profiling

Thirty Burgundy Pinot noir wines were evaluated by quantitative descriptive profile by nose (BN) and by mouth (BM) separately, by a trained panel composed of 12 judges. A specific vocabulary of 20 terms was developed. Sensory results were analyzed and compared by univariate and multivariate statistical techniques. Principal component analyses of the mean ratings BN and BM were fairly comparable regarding correlation among variables and the position of the wines. However, five sensory characteristics seem to be more intensely perceived BM, against 6 BN. Panel discrimination of the wines and panel repeatability in the measure were found to be slightly better BN than BM. A further canonical di…

Within and between variations of texts elicited from nine wine experts

Nine wine experts tasted in replicate six Chardonnay wines that had been aged in oak barrels from different forests and/or species. They freely gave their descriptions in writing; the only instruction given was to underline three words or expressions that best characterized each tasted wine. The texts were submitted to an objective lexical analysis that quantified the important variation among the experts. In addition a matching task was performed by 117 assessors in which each assessor received from each expert six white cards and six yellow cards representing the descriptions of the six white wines and six red wines. The assessors were incapable of matching the descriptions for the same e…

REPLICATED TRIANGLE TESTS: EFFECT OF FEED-BACK AND PRODUCT COMPARISON ON PERFORMANCE

The feed-back procedure consists of informing assessors of the quality of their response (correct or incorrect) after each triangle test. This procedure showed a contrasted effect according to assessors' detection abilities. A decrease in performance was observed for assessors who had low detection abilities whereas a slight increase was observed for assessors who had higher detection abilities. When the feed-back procedure is followed by a comparison by tasting of the two products, the increase in performance from the beginning to the end of the session is larger than that of both feed-back and control (no information) groups. We suggest that information inference from previous tests, whic…

EFFECT OF ASSESSORS EXPERTISE LEVEL ON EFFICIENCY OF WARM-UP FOR TRIANGLE TESTS

The effect of warm-up on performance for repeated triangle tests is studied according to assessors' expertise level for both triangle test strategy and the pair of products to compare. Three experiments performed with orange flavored soft drinks show that the effect of warm-up depends on the assessors' expertise: (1) naive assessors do not increase their performance with warm-up; (2) assessors with a moderate practice of both triangle tests and the pair of products improve their performance with warm-up; (3) assessors with a moderate practice of triangle tests, but not familiar with the pair of products, improve their performance with warm-up too; and (4) assessors highly experienced for bo…

EFFECT OF WATER ACTIVITY ON CRISPNESS OF BREAKFAST CEREALS

Three breakfast cereals (two commercial products and one experimental product made by extrusion cooking) were placed over 10 saturated salt solutions in desiccators for 3 weeks and then studied by sensory and mechanical analysis. A slight decrease of sensory crispness intensity occurs between 0 and 0.50 (aw) or 7% (water content), after which there is a very rapid decrease. The value of critical water activity given by the intersection between the two straight lines which can be adjusted seems not to depend on the product. Moreover this value is confirmed by the mechanical analysis and, partially, by a Differential Scanning Calorimetry analysis. There is a good correlation between sensory c…

A comparison between nine laboratories performing triangle tests

WOS: 000299451400001; International audience; Fifteen groups of participants in nine laboratories performed triangle tests with two pairs of soft drinks. Groups differed in practice level with triangle tests: eight groups of 60 consumers who were not used to triangle test, three groups of qualified assessors who have already performed a few triangle tests, and four groups of trained assessors with a more extensive practice of triangle tests; qualified and trained groups included 9 or 18 assessors. The soft drinks were made from syrups at two levels of dilution in order to achieve about 55% of correct responses to test for difference and about 40% of correct responses to test for similarity.…