Caracterização físico-química das argilas caulim (branca) e bentonita (verde) associadas à polpa de acerola (Malpighia emarginata dc) como ativos para o desenvolvimento de uma formulação cosmética facial

Abstract

There is a growing consumer preference for natural raw materials, such as clays and fruits, in the development of cosmetic products. Clays, composed of minerals, are widely used in cosmetics due to their high adsorption rate, abundance in nature, low environmental impact, low risk of toxicity, high surface area, and excellent ion exchange capacity. Among the most common clays in cosmetics are kaolin (white) and bentonite (green), which offer benefits such as cleansing, adsorption of impurities, toning of the epidermis, hydration, and treatment of dermatitis and acne. Acerola, a fruit rich in vitamin C, has also been widely used in the cosmetics sector for its effectiveness in combating free radicals, in addition to its properties in lightening blemishes, increasing skin elasticity, and photoprotection, due to its high antioxidant potential. The objective of this study was to characterize the physicochemical properties of kaolin (white) and bentonite (green) clays combined with acerola pulp, aiming at their use as active ingredients in a cosmetic facial cream formulation. The clays underwent purification and drying processes via spray dryer, and the acerola fruits underwent pulp removal. Subsequently, they underwent microbiological analysis and were characterized according to their physicochemical properties, revealing a clayey material with a pH above the skin pH, low unit content, fine particle size after purification and drying, and rich in minerals according to XRF analysis. Bentonite presented better results in terms of density, porosity, and flow angle. In the TG and DTA analyses, kaolin showed endothermic peaks, and bentonite showed endothermic and isothermal peaks. The acerola pulp had an acidic pH and high vitamin C content. The clays and acerola pulp showed good application properties in a facial cream formulation with 0.5%, 1.5%, and 3.0% of each active ingredient equally incorporated into the cosmetic. The formulation was subjected to microbiological testing and analyzed for organoleptic, physicochemical, and rheological properties. The cosmetic presented good stability and underwent sensory analysis and in vivo tests approved by the ethics committee. Rheological analysis indicated that the formulation exhibited non-Newtonian pseudoplastic behavior, and the 3% active ingredient concentration best fit the rheological model. In microbiological analyses, the active ingredients did not show bacterial or fungal colony growth. The facial cream, in turn, showed bacterial growth within the limits permitted by law. The facial cream containing clays and acerola pulp obtained promising results in terms of hydration, pores, and skin elasticity. In the sensory analysis, oiliness, firmness, and overall evaluation were the best-rated attributes. In terms of purchasing behavior, it was found that 50% of evaluators would buy the clay cream with acerola. Thus, this study provides relevant information on the use of clay and acerola pulp, demonstrating their benefits for the skin through facial creams containing these active ingredients. This suggests a potential product for application as a facial cream, a promising alternative for the development of innovative, effective, and sustainable cosmetic products.