Comparison between sensory and instrumental characterization of topical formulations: impact of thickening agents.

OBJECTIVE: Sensorial properties of cutaneous formulations are important in determining their acceptability by consumers. However, sensorial analysis is time-consuming and requires an available panel of trained assessors. Thus, this article aimed to study the impact of thickening agents on mechanical properties of creams and investigate how these measurements could correlate the sensory attributes using a combined instrumental-sensorial approach. METHODS: For this purpose, eight semisolid formulations were prepared, containing in their composition different thickening agents at different concentrations. These formulations were firstly microscopically observed and then assayed through textural, rheological and spreadability measurements. Textural characterization and rheological characterization were performed during six months to assess the physical stability of the studied formulations. Finally, six sensory attributes, namely firmness, adhesiveness, cohesiveness, spreadability, consistency and adhesiveness post-application, were tested by a trained panel. RESULTS: It was observed that thickening agents influence the microstructure of semisolid emulsions and also their mechanical properties. In general, an increase in the concentration of thickening agents improves the physical stability of formulations over time. Besides, textural parameters (firmness and adhesiveness), viscosity and difficulty to spread also increase. A good correlation between mechanical characterization and sensorial analysis was verified, mainly for spreadability properties. CONCLUSION: With the obtained results, it is possible to conclude that the proposed methods for mechanical characterization can be correlated with sensorial perception obtained from volunteers, representing a faster and less expensive alternative than sensory analysis.

Significância dos argilominerais em produtos cosméticos / Significance of clay minerals in cosmetic products

Os argilominerais apresentam estrutura cristalina em camadas, fazendo parte do grupo de minerais denominados filossilicatos. Possuem composição química e propriedades físicas e físico-químicas singulares, como tamanho coloidal inferior a 2?m, elevada área superficial específica, capacidade de sorção e de troca iônica, sensação agradável quando aplicado na pele e características plásticas e tixotrópicas. Devido a isso, tais minerais são adequados a serem usados em produtos de uso tópico. De fato, suas propriedades já eram conhecidas e exploradas desde a pré-história com relatos de seu uso no tratamento de feridas e para a limpeza da pele. Este artigo de revisão enfatiza a importância desses minerais no uso em cosméticos, onde podem exercer diversas funções, como excipiente ou como componente ativo, sendo incluídos em inúmeros produtos, tais como emulsões para o cuidado da pele, máscaras faciais, protetores solares, produtos para limpeza da pele, xampus e produtos de maquiagem. O aumento verificado nos últimos anos no uso de produtos naturais, associado a uma maior conscientização da necessidade de preservação do meio ambiente, tem despertado crescente interesse pelos argilominerais. O Brasil, como detentor de uma das maiores reservas mundiais de argila é o terceiro país maior depositário de patentes nessa área. Considerando o amplo potencial de utilização dos argilominerais, pode-se afirmar que eles constituem grandes oportunidades para a pesquisa e o desenvolvimento de novos produtos cosméticos.(AU)

The clay minerals have layered crystal structure, they are part of the mineral group called phyllosilicates. They have chemical composition and physical and physico- chemical properties different, such as colloidal size less than 2?m, high specific surface area, sorption and ion exchange capacities, pleasant sensation when applied to skin, and plastic and thixotropic characteristics. Because of this they are suitable to be used in topical products. In fact, their properties were already known and exploited since prehistoric times with reports of its use in the treatment of wounds and as for cleaning the skin. This review paper emphasizes the importance of these minerals in use in cosmetics, which can perform various functions, both as an excipient or as an active component, and have been included in numerous products, such as skin care emulsions, facial masks, sunscreens, cleansers skin, shampoos and makeup products. The increase over recent years in the use of natural products, associated with a greater awareness of the need to preserve the environment, it has attracted increasing interest in clay minerals. Brazil, as a holder of one of the world?s largest reserves from clay has the third biggest depository of patents in this area. Considering the wide potential use of clay minerals, it can be stated they are great opportunities for research and development of new cosmetic products.(AU)

Characterization, sensorial evaluation and moisturizing efficacy of nanolipidgel formulations.

BACKGROUND: Nanostructured lipid carriers (NLC) have been widely studied for cosmetic and dermatological applications due to their favourable properties that include the formation of an occlusive film on the skin surface that reduces the transepidermal water loss (TEWL) and increase in water content in the skin which improves the appearance on healthy human skin and reduces symptoms of some skin disorders like eczema. OBJECTIVE: The main objective of this study was the development of semisolid formulations based NLC with argan oil or jojoba oil as liquid lipids, by addition of Carbopol®934 or Carbopol®980 as gelling agents, followed by comparison between instrumental analysis and sensorial evaluation and in vivo efficacy evaluation. METHODS: Nanostructured lipid carriers dispersions were produced by the ultrasound technique, and to obtain a semisolid formulation, gelling agents were dispersed in the aqueous dispersion. Particle size, polydispersity index and zeta potential were determined. Instrumental characterization was performed by rheological and textural analysis; the sensorial evaluation was also performed. Finally, skin hydration and TEWL were studied by capacitance and evaporimetry evaluation, respectively. RESULTS: Particles showed a nanometric size in all the analysed formulations. All the gels present pseudoplastic behaviour. There is a correspondence between the properties firmness and adhesiveness as determined by textural analysis and the sensory evaluation. The formulations that showed a greater increase in skin hydration also presented appropriate technological and sensorial attributes for skin application. CONCLUSIONS: Nanolipidgel formulations with the addition of humectants are promising systems for cosmetic application with good sensory and instrumental attributes and moisturizing efficacy.