Check-all-that-apply (CATA) questions for sensory product characterization by consumers: Investigations into the number of terms used in CATA questions

In recent years methodological research into application of CATA questions has gained momentum. Yet, key questions for this approach remain unaddressed – how to generate the sensory terms that populate CATA questions and how many terms should be used. The second of these questions was addressed in seven consumer studies, involving a total of 735 consumers and five product categories (crackers, cheese, fruit-flavored drinks, chocolate, milk desserts). Sensory product characterizations elicited with “short” and “long” CATA questions (10–17 terms vs. 20–28 terms) were compared on a number of criteria such as frequency of CATA term use, product differences, spatial configurations (samples and terms) and task perceptions. Two strategies for generating “long” lists of CATA terms were examined: adding synonym terms to those already featuring on the “short” list (e.g., ‘hard’ and ‘firm’), and adding antonym terms to those already featuring on the “short” list (e.g., ‘hard’ and ‘not hard’ or ‘natural’ and ‘artificial’). Between-subjects experimental designs were used to compare product characterizations from “short” and “long” CATA questions. Results revealed that “short” and “long” lists of CATA terms generated largely similar results. In general, sample configurations were very similar, as were task perceptions. However, there were, at times, differences in frequency of CATA term use and term configurations, as well as instances where conclusions about sample differences depended on whether “short” or “long” CATA lists were used. Additionally, here was some evidence that CATA questions with “long” lists of synonym or antonym terms may cause a “dilution” effect of the responses. This fits expectations of idiosyncrasy in consumer perception/expression of sensory stimuli, but may be associated with reduced discriminatory ability of the CATA question. How to best balance these opposing considerations is deserving of further investigation.     

Further investigations into the reproducibility of check-all-that-apply (CATA) questions for sensory product characterization elicited by consumers

The purpose of the present research was further investigate the reproducibility of check-all-that-apply (CATA) questions for sensory product characterization. Evaluations obtained when such questions are used by consumers are rarely replicated and therefore reproducibility of the data may be at risk. Results from the present work, which included five studies, each with 100–200 consumers across a range of product categories, revealed that sensory product characterizations obtained using CATA questions with consumers are highly reproducible. Hence, the research confirms previous research by Jaeger, Chheang, et al. (2013) and extends it to the use of CATA terms in randomised presentation order as has been recommended to avoid satisficing response behavior. In the future, if CATA studies are conducted without replication and researches seek to examine the reliability of CATA data, the use of a posterior bootstrapping re-sampling approach is suggested.     

Comparison of Correspondence Analysis based on Hellinger and chi-square distances to obtain sensory spaces from check-all-that-apply (CATA) questions

Sample configurations from check-all-that-apply (CATA) questions are obtained using Correspondence Analysis (CA). Classical CA is based on chi-square distance, which has been reported to be strongly affected by infrequently selected terms. The Hellinger distance has been proposed as an alternative distance metric, and the aim of the present work was to compare product spaces from CATA questions obtained using CA based on chi-square and Hellinger distances. Data sets from 71 studies (5121 consumers), differing by product category, number of consumers, number of samples and number of terms included in the CATA question, as well as frequency of infrequently used terms, were analyzed. For each of the studies, frequency tables were input to CA based on chi-square and Hellinger distances. Sample and term configurations in the first two dimensions were compared using the RV coefficient. Furthermore, the stability of sample and term configurations for each type of distance was evaluated by simulating repeated experiments using a bootstraping resampling approach. Sample and term configurations obtained using Hellinger and chi-square distances were similar (average RV coefficients for sample configurations = 0.99; average RV coefficients between term configurations = 0.89). The stability of sample and term configurations were not largely affected by the type of distance used to analyze frequency tables. Results from the present work suggest that CA based on chi-square and Hellinger distances provide similar results. Contributing to guidelines for practitioners, this research therefore supports classical CA analysis as an acceptable approach to the analysis of sensory-specific CATA data.     

Visual attention to rate-all-that-apply (RATA) questions: A case study with apple images as food stimuli

The check-all-that-apply (CATA) question format and variants hereof have become very popular in sensory and consumer research. In the present study, focus is directed to rate-all-that-apply (RATA) questions where participants in addition to selecting terms that are applicable for describing a focal stimulus must also indicate if this term has an intensity corresponding to ‘low’, ‘medium’ or ‘high’. Knowledge of how assessors approach the RATA task is lacking, and this study was dedicated to understanding consumers’ visual attention to RATA questions. This aim was achieved by tracking participants’ eye movements when using a 15-term question to evaluate images of apples with different degrees of internal defect (flesh browning). As expected, participants first looked at the terms, then checked the box corresponding to “applies” and finally selected intensity level, i.e. participants tended to rate attribute intensity immediately after indicating that a term was applicable to describing a focal sample. Commensurate with the two parts to the task, preliminary evidence of more visual attention was suggestive of larger cognitive effort in RATA than CATA questions. Potentially this could be associated with a more “analytical” frame of mind among participants. More visual attention to the RATA question was associated with higher ability to discriminate among samples, in agreement with previous results for CATA questions. Overall, the research supported consumers’ ability to use RATA questions as intended, and indirectly to continued methodological uptake.     

Flavouring of imitation cheese with enzyme-modified cheeses (EMCs): Sensory impact and measurement of aroma active short chain fatty acids (SCFAs)

Enzyme-modified cheeses (EMCs) are used to impart flavour to imitation cheese products. Cheeses (pH 6 or 5.5) were formulated with 5% w/w EMC, having low, medium or high levels of lipolysis and were examined by a sensory panel. Free fatty acid analyses were performed using SPME/GC. The flavour profile of the flavoured cheeses was affected by EMC composition and pH of the cheese base. Cheeses at a pH of 6.0, flavoured with low lipolysis EMCs, were described as ‘bland’. Lowering the pH of the cheese matrix to 5.5 appeared to increase the flavour intensity of the cheese flavoured with low lipolysis EMC and panellists ranked this cheese the highest, describing its flavour as ‘well-balanced and ‘cheesy’. This study shows that the flavours of imitation cheeses are influenced by the level of lipolysis of the EMCs used to flavour them and also by the pH of the cheese base.