Serving Duplicates in a Single Session Can Selectively Improve Sensitivity of Duplicated Intensity Ranking Tests

Duplicating ranking tests can improve the power of preference and sensory intensity tests, and reduce the number of panelists required. With multiple‐samples rankings, duplications could be served using different protocols: in two serving sessions (two sample sets, that is, 2SS) to allow a break period or jointly in one serving session (one sample set, that is, 1SS). Evaluating the duplicates in a single session improves statistical data analysis but increases concerns of sensory fatigue, adaptation, memory, and possible irritation. The extent to which each serving protocol for duplicated ranking affects detection of differences has not been reported. This study used panelists (n= 75) who performed both ranking test protocols on two sets of orange juice samples (k= 3). One set was designed to obtain higher similarity than the other set to investigate the effects of degree of difference. Sweetness and yellow color intensity rankings were performed separately for each set to compare the protocols between attributes. The magnitude of the differences was evaluated using Mack–Skillings (M–S) statistics, and the total and individual rank sum differences at varied n(10 to 75) values. With similar set samples, the 2SS serving protocol improved differentiation for yellow color intensity. Although in sweetness, using the 1SS serving protocol showed higher M–S statistics and higher sum of total rank sum differences. Paired comparisons followed the same pattern. With very different samples, both protocols had comparable performance. This study showed that serving duplicates in the 1SS can improve duplicated ranking's power, depending on the task difficulty and attribute, and should be considered before splitting replications into two sessions. This study evaluated two alternative and not previously studied protocols for conducting a duplicated ranking test. One protocol required that each panelist received duplicates in the same single serving session (1SS), against the alternative of serving duplicates separately in two sessions to allow a break period (2SS). Two attributes: yellow color intensity and sweetness intensity of orange juice samples were studied. This study showed that serving duplicates in the same single session can improve duplicated ranking's power, depending on the task difficulty and attribute, and should be considered before splitting replications into two sessions.