The degeneration of skin cosmetics and the structural changes of the chemical components as an indicator of product shelf life

Abstract

We observed the thermal behavior of four cosmetic reagents with different chemical structures using accelerated aging tests under severe conditions. When citronellyl nitrile and lemonile were exposed to thermal stress, the CN decomposed to form CN, whereas the decomposition of the CO in citral resulted in the formation of CH2OH. Dihydromyrcenol has the least change in thermal stress. Despite the similarities in the chemical structure of citronellyl nitrile and lemonile, both compounds exhibited different decomposition rates, limiting their possible use as indicators in long term stability tests. The carbonyl (CO) in citral was significantly influenced by thermal stress and exhibited the most notable changes in the sensory scent tests and the spectroscopic analyses. Additionally, it was confirmed that the carbonyl (CO) functionality in a body mist carrier solution was susceptible to decomposition when the formulation of the body mist contained citral (14.5%) and other cosmetic materials such as ethanol and propylene glycol. This study presents the first attempt at establishing the correlation between the structural changes in the component chemicals of cosmetics and the observed fragrance related changes. These findings provide evidence for the feasibility of using carbonyl functional groups as indicators of long term stability in cosmetic products and may lead to the development of new sensory test protocols.