The sensory properties of cosmetic products, such as appearance, smell, texture, and feel on the skin, play a key role in consumer acceptance and satisfaction, in addition to safety and efficacy. Sensory evaluation, in which cosmetic products are assessed using the senses such as sight, smell, and touch, as opposed to instrumental measurements, is an important tool in the process of developing and optimizing cosmetic product formulations. It can be divided into hedonic and analytical tests. Hedonic tests involve a more subjective evaluation by volunteers who are not trained performing sensory analyses, while analytical tests are characterized by an objective evaluation performed by trained personnel. The properties described by sensory analysis can also be analyzed to a certain extent by instrumental measurements. By combining both methods, we can take advantage of the benefits of both approaches, obtaining complementary data while reducing the costs and time of analysis.
As part of the thesis, we investigated the effect of Dunaliella microalgae extract on the sensory and textural properties of cosmetic products, comparing two types of formulations, a hydrophilic cream and a product based on lyotropic liquid crystals. For this purpose, we prepared four samples, each of the formulations with and without the extract, and evaluated them in sensory testing involving 16 volunteers. We also supplemented the results with an instrumental evaluation of the spreadability of the formulations. The results of the sensory analysis showed that the microstructure of the formulations significantly influenced the perception of the product properties. The hydrophilic cream was rated as more spreadable, moisturizing and pleasant to use, while the subjects percieved the lyotropic liquid crystals-based samples as having that was more difficult to absorb into the skin. The results of the texture analysis showed a better spreadability of the lyotropic liquid crystal-based samples, which did not correspond to the volunteers' perception. The incorporation of the extract did not have a significant effect on the sensory and textural properties, the volunteers only noticed a difference in color and absorbency. Based on the results obtained, we can conclude that the microstructure of the different formulations has a greater influence on the sensory and textural properties than the addition of Dunaliella species extract. The composition and technological manufacturing process, as well as the microstructure of cosmetic products play a key role in shaping the sensory and textural properties of the product.
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