Duo-trio difference

Acid hydrolysates were added to a low aroma intensity white wine (ie the base wine), and the aroma properties of these samples were assessed by sensory descriptive analysis. In addition, the glycoside isolates from the Australian vineyards were subjected to glycoside hydrolase enzyme treatment, and duo-trio difference tests were performed on these hydrolysates added to a base wine. The volatile composition of each of the hydrolysates was investigated by GC/MS, and relationships between the two sets of data were determined. Finally, the glycoside concentration of each of the juices and skin extracts was determined by the glycosyl-glucose assay. 

In a separate part of this study, the aroma properties of glycoside enzyme hydrolysates added to a white base wine were assessed by duo-trio difference tests with 20 judges. The Australian samples only were evaluated. In tests comparing the... 

In the duo-trio test one presents to each panellist (or subject ) an identified reference sample, followed by two coded samples, one of which matches the reference sample (Fig. 38.2). The subjects are asked to indicate which of the two coded samples matches the reference. If enough correct replies are obtained the two coded samples are perceived as different. Table 38.2 gives the critical values... 

Fig. 38.2. Duo-trio test two different products are presented the assessor has to indicate which of these two is similar to a third product.

A third effect that has been encountered [185] is a structure that is made from a mixture of different kinds of clusters which are all finite stacks and vary by the number of their members. At the first glance such a material looks as if the zero-sum rule were violated - but for each individual cluster it is not. Figure 8.45 shows a sketch of the probability of different clusters in such a structure. In the study [ 185] the parallel fit using three finite stacks (solos, duos, trios of lamellae) yielded a peculiar coupling of cluster fractions according to the relation... 

Difference testing has not changed greatly over the years. The triangle test and duo-trio test remain popular and well-accepted, although much effort has been extended to prove one better than the other. The best advice is to use the one that fits your test situation. 

As the name suggests, this DUO-TRIO test (ISO Standard 10399 [8]) lies between the two types of test mentioned above. As a rule, it is a DUO test in which 2 samples are tested against a THIRD sample (standard, control, etc.) thus making it a TRIO. The difference to the triangle test, however, is that in principle only 2 samples are being processed . As with the Duo test, the statistical probability that it will be done CORRECTLY is assumed to be 50% (p= 1/2), whereas with the triangle test it is only 33 1/3% (p = 1/3). 

Difference Testing at Different Stages of Cellar Storage. To determine whether any flavor change for the wines had occurred as a result of the juice treatments, duo-trio aroma difference tests were done between control replicates and treatment replicates after 6, 12, 20, and 27 months cellar storage. The first three series of comparisons were done between randomly selected pairs of control and treatment replicates. 

Difference testing can be useful tools for assessing panelist s skills. Methods such as the triangle and duo-trio tests are what are communally known as forced choice discrimination tests because panelists are presented with multiple samples and must decide which examples are the same and which are different. These tests can also be used in assessing the impact of changes in supply chain and production techniques. Succinct descriptions of these and other discrimination tests can be found in Bamforth (2014) and Simpson (2006). More in-depth discussions of these techniques are covered by Kilcast (2010), Meilgaard et al. (2007) and Stone et al. (2012). 

B Rousseau, A Meyer, M O Mahony. Power and sensitivity of the same-different test Comparison with triangle and duo-trio methods. J Sens Stud 13 149-173, 1998. 

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