A Study on the Oxidative Stability of Coconut Oil and Shea Butter as Ingredients in a Lip Balm Formulation.

Oxidation, characterized by the production of reactive oxygen species, is a major factor in skin damage. Coconut oil and shea butter are two natural ingredients that are frequently employed in lip balm formulations due to their moisturizing qualities. These lipids are, nonetheless, prone to oxidation which may cause unfavourable changes to the skin or decrease efficacy. The physicochemical properties of lip balm formulations are also crucial to their efficacy. This study aimed to assess the oxidative effect and stability of coconut oil and shea butter as ingredients in lip balm formulations and evaluate the physicochemical properties (spreadability and antimicrobial properties) of the formulated lip balms. The oxidative stability of the coconut oil and shea butter as well as the effect of antioxidants in protecting the oil and butter from oxidation were determined using the peroxide value method and the active-oxygen method (AOM). The oxidative stability of coconut oil and shea butter were also determined in the presence of antioxidants at varying concentrations. Lip balms were formulated using ingredients (including coconut oil and shea butter) of varying quantities (%w/w). The physicochemical properties of the formulated lip balms were evaluated using a research questionnaire and tested for spreadability and antimicrobial activity. The effect of the oxidation of coconut oil and shea butter on the skin was evaluated through patch testing. The results revealed an increased peroxide values and decreased active-oxygen method (AOM) value of the oxidized coconut oil and shea butter compared to the unoxidized samples. The use of antioxidants at different concentrations prolonged the oxidative stability of the coconut oil and shea butter samples by decreasing the peroxide values and increasing the AOM values. The single plate spreadability test results revealed that all samples formulated were semi-stiff. The multiple xiii plate results showed that the spreading index of the formulated samples increased with increasing quantities (%w/w) of oil and butter used and with increasing cumulative weights of the plates. The spread factor was inversely proportional to the cumulative weights of the plates. The formulated lip balm samples showed antimicrobial activity to microorganisms due to the addition of phenoxyethanol as preservative for the formulations. The oxidized coconut oil and shea butter produced more untoward effect on the skin compared to unoxidized samples. The study concluded that the oxidative stability of coconut oil and shea butter can be maintained and prolonged with the use of antioxidants and that the formulated lip balms possessed the physicochemical properties of ideal ointments. Further studies are recommended to get a better understanding of the oxidative stability of coconut oil and shea butter.