CORRELATION BETWEEN RHEOLOGICAL AND SENSORY PROPERTIES IN COMMERCIAL SUNSCREENS: A MULTIVARIATE APPROACH

Inadequate exposure to ultraviolet (UV) radiation is associated with skin damage such as photoaging, hyperpigmentation, and skin cancer. Although broad-spectrum sunscreens are essential for prevention, low adherence to their use is often related to unfavorable sensory attributes. In this context, the objective of this study was to evaluate the correlation between rheological parameters, photoprotective efficacy, and sensory attributes of commercial sunscreens using a multivariate approach. Ten commercial formulations were evaluated for in vitro photoprotective efficacy, rheological behavior, and sensory attributes through descriptive analysis conducted by a trained panel. The data obtained were subjected to analysis of variance (ANOVA), Pearson’s correlation, and principal component analysis (PCA). The formulations exhibited predominantly pseudoplastic behavior and adequate UVA protection, with variability among the samples. The correlation analysis revealed significant associations between rheological parameters and sensory attributes. Viscosity at high shear rates (η∞ and η1000 s⁻¹) and yield stress (τ₀) showed a strong correlation with each other (r > 0.89). Spreadability correlated negatively with stickiness (r ≈ -0.70) and positively with softness (r ≈ 0.70), while absorption showed a strong negative correlation with visual residue (r = -0.86), indicating that formulations more resistant to flow tend to exhibit greater stickiness and lower spreadability. In turn, PCA explained more than 70% of the total variance, with axis F1 (49.38%) associated with attributes such as oiliness, shine, and visual residue, and axis F2 (22.77%) related to stickiness and absorption. These findings reinforce the notion that rheological properties can serve as predictors of the sensory perception of sunscreens. It is concluded that the integration of instrumental and sensory analyses, combined with multivariate tools, represents a promising strategy for the rational development of formulations that balance photoprotective efficacy and consumer acceptance.