Exploring the Use of Pineapple Peel Extract for Underarm Care: Antioxidant and Anti-ageing Properties for Serum Formulation and Stability Testing

Pineapple peel (PP), a significant waste product from the agricultural industry, presents both environmental challenges and potential for value-added applications. This study aimed to upcycle PP into a valuable skincare ingredient, particularly for developing an underarm care product. We prepared the PP extract by maceration and then evaluated its total phenolic content, antioxidant activity, and inhibitory effects on skin-related enzymes. The PP extract had a total phenolic content of 14.76 ± 0.67 mg gallic acid equivalent/g. It demonstrated potent antioxidant activity, capable of scavenging free2,2-diphenyl-1-picrylhydrazyl radicals with a half-maximal inhibitory concentration (IC50) of 340.03 ± 2.80 µg/mL, and it had a Trolox equivalent antioxidant capacity of 0.35 ± 0.04 mM Trolox/g. The extract exhibited moderate anti-tyrosinase activity with an IC50 of 1.03 ± 0.08 mg/mL, as determined by the dopachrome method but showed limited inhibition of elastase and collagenase, as determined by the spectrophotometric method. We developed eight underarm skincare serum formulations to demonstrate practical applications and assessed their properties. Formulation F8 emerged as the optimal choice based on physical, chemical, and microbiological stability tests when stored at 2-8 °C. These findings suggest that PP extract offers promising properties for skin health applications while providing a sustainable solution for agricultural waste management. Future research should explore long-term stability and involve clinical trials to develop a more comprehensive and safer product.