When formulating skin care emulsions, ingredient suppliers and formulators often focus on the technical requirements for the shelf-life stability of the end product. However, consumers consider it a given that the product will remain stable for months, even under harsh conditions. The sensory perception of the product and belief that the product delivers on its promise are far more important. Even performance claims supported by objective clinical evidence are strongly influenced by the aesthetic properties of the product both on the shelf and especially during use. Thus, the tactile sensory properties of a cosmetic product intended for application to the skin—the largest and most sensitive organ—are crucial to the product’s commercial success.
It is not easy for formulators to get a product’s aesthetics right. Usually the relationship between sensory perception and formulation acceptance by consumers is far from straightforward and depends on many uncontrollable parameters. Detailed and systematic consumer research is necessary to understand the sensory preferences of target market segments. Further, in trying to express their preferences, consumers often use unclear definitions and product descriptors.
However, if the sample size is large enough, one can group these descriptors and look for a relationship with the chemistry and physics of the formulation. Many such attempts have been made in the past 40 or more years and can be found in literature, but there remains a need for a bridge between qualitative consumer language and clearly defined sensory attributes based on the chemistry and physics of a formulation. Understanding the quantitative or even qualitative impact of ingredients is a complex task, especially given the complexity of formulations and enormous choice of ingredients.
Navigating regulatory and brand-specific restrictions, formulators tend to choose emulsifiers conservatively because they are viewed mainly as technical ingredients to keep oils and aqueous solutions together for a given length of time. The amounts of other ingredients, especially emollient oils, are considered less risky to adjust in a formula when fine-tuning it for skin feel. Here, the authors describe an approach to investigate the intrinsic effects of emulsifiers and quantify them before attempting to translate them into regional consumer sensory preferences.