A methodological investigation of the suitability of napping studies for characterizing sensory modalities

In recent years, an increasing practical and academic interest in the use of rapid sensory methods, such as napping, with untrained respondents (i.e., consumers) can be observed. The aim of napping is to compare several products regarding their relative sensory similarity to each other. Partial napping represents a variation in which different modalities are analyzed separately.
The present paper reports a partial napping study with 15 strawberry yogurt samples and n = 104 untrained participants combined with ultra-flash profiling, whereby the appearance, taste and texture of the products were subject to consumers’ evaluation.
Subsequent to data collection, the individual napping data for the three sensorys properties appearance, taste and texture were compared with each other by drawing sub-samples from the entire sample. The samples contained groups of 10, 15, 20 and 33 respondents and were analyzed using multiple factor analysis (MFA) and compared with the Generalized Procrust Analysis (GPA) in XLStat®.
The present findings highlight that it is far more challenging for consumers to characterize products’ texture and taste, than their appearance in napping studies, wherefore napping with consumers seems not equally recommendable for all sensory modalities. While napping turned out to be unproblematic when evaluating appearance, difficulties might arise when it comes to texture and taste evaluation. The results of the GPA show that with the attribute appearance the virtual identity of the data is already achieved from 20 test persons with the attribute texture and taste one needs 33 for this. These findings are in line with extant literature, according to which - although texture is regarded as a key determinant of food acceptance or rejection - human texture awareness is low.