Development via quantitative sensorial evaluation

Some others are sensorial (appearance, flow, spreading over the skin). While the first group of evaluations has technological relevance (in other words, necessary to understand the average physico-chemical, microbial or functional behaviour of products) the other is related to perceptive characteristics, that cannot be measured with standard devices or easily expressed with numbers. The way of providing this type of evaluation with the characteristics of scientific measurements (i.e. reproducibility and repeatability, possibility of comparison with previous values, statistical significance and reliability) is the task of sensorial analysis. Its applications in the development of a successful cosmetic product are many but, until now, only very few big industries are using this tool in a systematic way. Some examples in which sensorial analysis demonstrates its usefulness can be taken from everyday problems of the cosmetic industry: how to select among a set of formulations, having the same stability (and costs) the one having quicker superficial absorption? Which amount of perfume gives the best performances at low costs? How to control if the industrial production run has the same perceived characteristics as the laboratory sample? How to qualify the supplier of an ingredient in a successful product, without changing its perceived characteristics? How to formulate a product sensorially very similar to the main competitor on the market? Which controls are more suitable during the product stability evaluations? Finally, is moisturising power increasing by 10% (instrumentally measured) the hydration level of our epidermis perceivable by consumers? This paper will try to give answers to some of these questions.

Clues in sensorial analysis

 We use sensorial evaluations throughout our life: we smell, touch, look, listen, taste; our senses are essential for the control of (and survival in) our environment, the maintenance of our life and social behaviour. The external perceptions reaching our brain are decoded into three main components. Firstly comes the type of perception. Our brain identifies the key structure of the stimulus: thermal, pressure, evenness, friction, noise, odour, visual impact. This is the qualitative variable. The second is the intensive one, related to the amount of stimulus we perceive: how intense is a yellow shade, how soft is a cream, how black is Vegemite, how much time a perfume requires to fade are typical examples. The last one is the hedonic one, or in other words the pleasure or disgust that these sensations can induce, because of our personal history, attitudes, culture, experience, taste, mood. In normal life we do not make a clear separation between these variables, but we use verbal or mental expressions for their combination, as they are decoded by our brain.