SENSORY ANALYSIS OF A CHITOSAN GEL NANOFORMULATION 309 The incorporation of nanocapsules in the chitosan hydrogel only led to a higher percep- tion of fi lm formation on the skin, regarding the discriminative sensory analysis. This may be due to the nanocapsules skin adhesion and their high permanence time on the skin, or due to a higher consistence of this formulation. The increase on the fi lm forma- tion due to the nanocapsules is interesting for the cutaneous application because of the promotion of the interaction between skin and drug, and also the protection against drug degradation or drug washability. However, regarding the sensory, the volunteers probably considered the fi lm formation as a bad attribute. Considering the affective sensory analysis, the hydroxyethyl cellulose gels were preferred over the chitosan hydrogels, for the plain gels and gels containing nanocapsules. The presence of nanocapsules in the chitosan gel did not alter the acceptance of this formula- tion. The differences observed in the discriminative analysis (stickiness and fi lm forma- tion) probably infl uenced the result verifi ed in the affective analysis, indicating the attributes to be improved for the development of a new formulation of improved sensory properties. Phase II: Chitosan gels versus optimized chitosan gels. The phase II was devoted to the analysis of the improvements made on the chitosan hydrogel, after the results of phase I sensory analysis. The chitosan hydrogel was added of PCA-Na (carboxylic pirrolidon acid sodium salt) and volatile silicone fl uid (decamethylcyclopentasiloxane [DC 245]) to decrease the Figure 4. Attributes showing statistical differences in the phase I sensory study for the following sample comparisons: (A) CH vs. HEC, (B) CH-NC vs. HEC-NC, and (C) CH vs. CH-NC (CH: chitosan gel, HEC: hydroxyethyl cellulose gel, NC: nanocapsules).

JOURNAL OF COSMETIC SCIENCE 310 stickiness and perception of fi lm formation on the skin. So, the prior chitosan hydrogel was compared to the optimized chitosan hydrogel, both of them containing and not con- taining nanocapsules. Also, in this phase, the presence of nanocapsules was evaluated re- garding its infl uence on the sensory properties of the optimized chitosan hydrogel. Table V shows the answers of the volunteers, in percentage, when comparing the paired samples. As in phase I, the percentage of volunteers who saw differences among samples were al- ways higher than the percentage of volunteers who thought the samples were similar for the present attribute. Table VI shows the p value obtained comparing the percentage of Table V Responses from the Volunteers, in Percentage, When Comparing the Paired Samples in the Phase II Sensory Study Attribute Response from volunteers Paired analysis CH vs. CH-OPT CH-NC vs. CH-NC-OPT CH-OPT vs. CH-NC-OPT Spreadability Did not see differences 42 35 27 Saw differences 59 65 74 Chose the fi rst sample 32 30 52 Chose the second sample 27 35 22 Oiliness Did not see differences 45 53 32 Saw difference 55 47 68 Chose the fi rst sample 25 22 45 Chose the second sample 30 25 23 Imediate stickiness Did not see differences 37 45 23 Saw differences 64 55 77 Chose the fi rst sample 27 28 30 Chose the second sample 37 27 47 Residual stickiness Did not see differences 47 48 33 Saw differences 54 52 66 Chose the fi rst sample 17 22 23 Chose the second sample 37 30 43 Film formation Did not see differences 35 27 27 Saw differences 65 73 74 Chose the fi rst sample 47 50 37 Chose the second sample 18 23 37 Homogeneity of the fi lm Did not see differences 17 25 10 Saw differences 83 75 90 Chose the fi rst sample 28 32 30 Chose the second sample 55 43 60 Preference Did not see differences 10 7 7 Saw differences 90 94 93 Chose the fi rst sample 30 37 38 Chose the second sample 60 57 55 CH: chitosan gel, HEC: hydroxyethyl cellulose gel, NC: nanocapsules, OPT: optimized hydrogels.