SENSORY CHARACTERIZATION OF COSMETIC EMULSIONS 97 CONCLUSIONS A CATA survey provided useful information about consumers’ perception of the skin feel and sensory characteristics of six cosmetic emulsions. Emulsions represented three main types of emulsions, differing in the amount and type of emulsifi ers. Emulsions of the Tabl e VI Comparison of Pairs of Emulsions for Statistical Differences Attributes Emulsion pairs 1–2 1–3 1–4 1–5 1–6 2–3 2–4 2–5 2–6 3–4 3–5 3–6 4–5 4–6 5–6 Appearance Glossy/shiny Dull/fl at * Thick/creamy *** *** *** *** *** *** *** *** * *** * *** *** * Thin/milky *** *** *** *** *** *** *** *** ** *** ** *** *** * Bright white Off-white * Cooling * Rub-out and pick-up Warming Easy to spread/slippery *** *** * ** *** ** *** Hard to spread/dragging ** ** ** ** * *** * *** * Thick/creamy/fi rm *** *** *** *** *** *** *** *** ** * Thin/milky *** *** *** *** *** *** *** *** * Hard to rub in ** * * Easy to rub in * Highly absorbent * Slightly absorbent Watery/wet *** *** *** ** *** *** *** *** ** *** * Oily/greasy *** ** ** *** ** ** * ** Silky/smooth ** ** Gluey/sticky ** *** * * *** * Light *** *** *** ** *** *** *** * * *** Heavy *** *** *** ** *** ** *** * *** * Afterfeel after 3 min Glossy/shiny Dull Oily/greasy ** *** * Smooth/soft * *** ** *** ** Wet/not fully dry * * Dry Sticky/tacky * * * White Total (stars) 0 35 28 25 18 41 29 24 16 9 17 28 7 13 9 ***Indicates signifi cant differences ( p 0.001) **Indicates signifi cant differences ( p  0.01) *Indicates sig- nifi cant differences ( p  0.05), according to two-sample ANOVA test.

JOURNAL OF COSMETIC SCIENCE 98 same type differed in the emollients, but all other ingredients were the same. We inves- tigated the effect of emulsifi er versus emollient on the skin feel and esthetic of emulsions. The identifi ed sensory differences between the emulsions can be explained by differences in ingredients, suggesting that the method was valid. Our fi ndings suggest that emulsi- fi ers, not emollients, have the dominant role in determining the esthetics of a skin care emulsion, which is in line with previous fi ndings (21,22). The fact that this study, using untrained consumers, resulted in similar fi ndings as studies using trained panelists suggests the validity of the CATA survey, and its reliability as a screening tool in the product de- velopment process. It is recommended that formulators evaluate a wide range of emulsifi ers and emulsifi er combinations at the beginning of the formulating process to fi nd the proper esthetic properties for a particular application. This is a more direct approach to engineer- ing formulations that pleases the target audience and meets their needs and preferences. Among the advantages of CATA surveys are that they provide a fast and convenient method for participants and no training is necessary after recruiting consumers. They can be recruited from the target group, which can add much value to the results, and recruit- ment can happen at any time. In this study, the 50 consumers were able to discriminate between the emulsions without any training. Another advantage of the CATA surveys is that consumers do not have to describe the products themselves they simply have to se- lect terms from a predetermined list, which is very helpful for those consumers who fi nd it diffi cult to verbalize their perceptions. A study (29) investigated whether the number of words had a signifi cant positive or detrimental effect on the outcome of CATA surveys. Findings showed that using more terms rather than less (10–17 vs. 20–28) did not appear to be detrimental. However, authors concluded that including more terms can make it more diffi cult and more tedious for consumers to fi ll out the survey and can compromise their attention to the task. Long lists of words can lead consumers to select the terms that easily catch their attention without thoroughly analyzing the sample and considering its characteristics. We believe that the number of terms used in this study (i.e., 30) was ap- propriate and necessary to well describe the emulsions and the similarities/differences between them. We also believe that grouping the synonym terms and listing them to- gether was advantageous for the following reasons: it made it easier for participants to select the appropriate terms for each product, it made characterization of products more consistent, and it made statistical analysis simpler. In CATA questions/surveys, participants are not told how many terms they should select they are usually advised to select as many terms as they feel appropriate to describe the given product. This leads to a disadvantage of this technique. We experienced that some consumers only selected 5–6 words from our 30-word list, whereas others selected 10–15 terms. Another limitation of CATA questions/surveys is that technical terms can only be used with careful consideration. Untrained consumers may not know the exact meaning of technical terms and might select them for the wrong reason or not select them at all, which takes away from the value of the results. If technical terms have to be used, defi ni- tions for each term should be given to consumers. However, if many terms are used, reading through the defi nitions and understanding the differences between terms may exhaust participants before even starting the study. Another approach that we used in this study was to provide each consumer with time to review the terms before the study and the op- portunity to ask questions. Previous studies (18,32) suggested that to produce reliable results, the number of un- trained consumers used for CATA surveys should be higher than the number of trained