Sunscreen sensory attribute prediction via textural, rheological and tribological tests

This study aims to find the quick ways to predict sensorial attributes of sunscreens using instrumental measurements. We specifically focus on the attributes most relevant to consumer 'liking' and the easiest measurements to implement in industrial labs for product development. Of the latter, we consider three types of measurements: emulative 'textural' tests typically performed with a texture analyser as well as rheological and tribological measurements. Textural tests are generally preferred but may be paralleled by rheological measurements provided they are implementable on simple viscometers used in industry (albeit with additional data processing). We found that both textural and simple rheological/viscometrical tests work well for predicting sensorial attributes about flow before (thickness) and during (spreadability) application of the products. Tribology provides useful additional information for the latter but is primarily useful for after-feel or residue attributes (absorption and skin stickiness). These findings show that simple lab tests relying on these techniques can predict human sensory attributes, thus efficiently guide product developers while reducing the need for costly and time-consuming panel studies.