SENSORY ANALYSIS OF A CHITOSAN GEL NANOFORMULATION 311 volunteers who saw differences among samples with the percentage of volunteers who could not identify differences. For the attributes spreadability (comparisons CH-NC vs. CH-NC-OPT and CH-OPT vs. CH-NC-OPT), oiliness (comparison CH-OPT vs. CH- NC-OPT), immediate stickiness (comparisons CH vs. CH-OPT and CH-OPT vs. CH- NC-OPT), residual stickiness (comparison CH-OPT vs. CH-NC-OPT), fi lm formation (all comparisons), homogeneity of the fi lm (comparisons CH vs. CH-OPT and CH-OPT vs. CH-NC-OPT), and preference (all comparisons), the percentage of volunteers who choose one or another sample was signifi cantly higher than the volunteers who did not see differences. Table VII shows the p value obtained when comparing the percentage of vol- unteers who choose the fi rst or the second sample in the pair, for the attributes mentioned above. Analyzing those results, it is possible to see that, only for the attributes spread- ability (comparison CH-OPT vs. CH-NC-OPT), oiliness (comparison CH-OPT vs. Table VI p Values Obtained from χ2 Test for Phase II Sensory Study (Comparison between the Percentage of Volunteers Who Saw Differences with the Percentage of Volunteers Who Did Not See Differences) Attribute p Value CH vs. CH-OPT CH-NC vs. CH-NC-OPT CH-OPT vs. CH-NC-OPT Spreadability 0.197 0.020* 0.000* Oiliness 0.439 0.606 0.005* Immediate stickiness 0.039* 0.439 0.000* Residual stickiness 0.606 0.796 0.010* Film formation 0.020* 0.000* 0.000* Homogeneity of the fi lm 0.000* 0.000* 0.000* Preference 0.000* 0.000* 0.000* CH: chitosan gel, HEC: hydroxyethyl cellulose gel, NC: nanocapsules, OPT: optimized hydrogels. *Statistical difference (p 0.05). Table VII p Values Obtained from χ2 Test for Phase II Sensory Study (Comparison between the Percentage of Volunteers Who Chose One or Another Formulation from the Paired Analysis) Attribute p Value CH vs. CH-OPT CH-NC vs. CH-NC-OPT CH-OPT vs. CH-NC-OPT Spreadability —a 0.631 0.007* Oiliness —a —a 0.042* Immediate stickiness 0.330 0.862 0.140 Residual stickiness 0.340 0.369 0.058 Film formation 0.006* 0.016* 1.000 Homogeneity of the fi lm 0.024* 0.180 0.014* Preference 0.014* 0.109 0.181 CH: chitosan gel, HEC: hydroxyethyl cellulose gel, NC: nanocapsules, OPT: optimized hydrogels. a The test was not applicable since the number of volunteers who saw difference was not statistically higher than the number of volunteers who did not see differences. *Statistical difference (p 0.05).

JOURNAL OF COSMETIC SCIENCE 312 CH-NC-OPT), fi lm formation (comparisons CH vs. CH-OPT and CH-NC vs. CH-NC- OPT), homogeneity of the fi lm (comparisons CH vs. CH-OPT and CH-OPT vs.CH-NC- OPT), and preference (comparisons CH vs. CH-OPT), the percentage of volunteers who choose one sample in the pair was different from the percentage of volunteers who choose the other sample. These results, showing signifi cant difference, are shown in Figure 5. Regarding the attributes considered to be improved, from the results of phase I (sticki- ness and fi lm formation), it can be seen that the perception of residual fi lm on the skin was decreased when the chitosan gel was optimized, despite the presence of nanocapsules. It is worth mentioning that the fi lm is still formed on the skin since the chitosan is still present, but its perception has been reduced. Besides that, the homogeneity of the fi lm was increased when the adjuvants were added in the gels without nanocapsules, leading to a higher preference for the CH-OPT gel comparing with CH. Although similar results were not statistically found for the gels with nanocapsules, there was a tendency for in- creasing the fi lm homogeneity and the gel preference due to the modifi cations in the chitosan hydrogel containing nanocapsules (Table 5). The stickiness, which was the other attribute probably responsible for the low acceptance of chitosan gel in phase I, could not be decreased due to incorporation of PCA-Na and volatile silicone, for the gels with and without nanocapsules. Since the residual stickiness was not higher in the chitosan Figure 5. Attributes showing statistical differences in the phase II sensory study for the following sample comparisons: (A) CH vs. CH-OPT, (B) CH-NC vs. CH-NC-OPT, and (C) CH-OPT vs. CH-NC-OPT (CH: chitosan gel, HEC: hydroxyethyl cellulose gel, NC: nanocapsules, OPT: optimized gel).