Effect of orange peel essential oil (Citrus sinensis l.) on the oxidative and qualitative stability of shea butter (Vitellaria paradoxa) produced in northern ivory coast during storage

Aims: The oxidation of fats is a cause for concern regarding the quality of most oils, particularly shea butter (Vitellaria paradoxa). The objective of this study is therefore to contribute to improving the oxidative stability of shea butter (Vitellaria paradoxa) produced in northern Côte d’Ivoire during storage at room temperature through the use of orange peel essential oil (Citrus sinensis L.).
Methodology: To achieve this, the essential oil was extracted from orange peels using steam distillation. The physical and chemical properties of this essential oil were then determined. The shea butter was then treated with the orange peel essential oil before being stored. Finally, the quality parameters of the treated shea butter and the control shea butter were monitored over a four-month storage period.
Results: The results obtained show relatively high extraction yield, density, and refractive index for orange peel essential oil, at 1.2%, 0.811 ± 0.02, and 1.481 ± 0.02, respectively. Furthermore, the DPPH radical scavenging assay yielded inhibition percentages for the essential oil ranging from 9.69% to 90.27%, corresponding to concentrations between 5 and 20 µg/mL. Furthermore, the EC50 value of the essential oil, determined by linear regression, was 10.23 µg/mL, associated with an antioxidant activity index of 2.15. As for the study of the oxidative stability of shea butter treated with orange peel essential oil, the acidity of the control sample ranged from 5.078% to 6.974%, corresponding to a change in acid value from 9.778 to 13.251 mg/g over four (4) months of storage. The treated butters showed a slight variation in acidity ranging from 4.769% to 5.299%, equivalent to acid values of 9.061 to 10.068 mg/g. The peroxide value of the control sample ranged from 10.254 to 12.322 meq/kg, compared to 10.076 to 11.081 meq/kg for the treated sample. The impurity indices ranged from 0.177 to 0.202% for the control sample, compared to 0.178 to 0.198% for the treated shea butter.
Conclusion: Ultimately, the essential oil significantly reduced the oxidation rate of the treated shea butter compared to the untreated control. The acidity, acid value, peroxide value, and levels of insoluble impurities in the shea butter treated with the essential oil remained relatively low throughout the shelf life, unlike the untreated butter.