Red pitaya peel as encapsulant for hybrid crude palm oil nanoparticles: Characterization and 60-day stability

The red pitaya peel (Hylocereus polyrhizus) is an underutilized agro-industrial by-product rich in functional compounds, while hybrid crude palm oil contains high levels of carotenoids and tocopherols but is prone to oxidation. This study developed and characterized hybrid crude palm oil nanoparticles using freeze-dried pitaya peel as an encapsulant. Eight formulations were tested using a 2³ factorial design, and the one with 150 mg of oil and 150 mg of peel was selected. The nanoparticles exhibited high encapsulation efficiency (95.6 ± 2.6%), full carotenoid retention (1386.8 ± 21.2 μg/g), and betalain content (2.40 ± 0.01 mg/g). They exhibited psizes of 331.5-351.8 nm, PDI 0.35-0.36, and zeta potential near ±30 mV, with good stability at 4 ± 1 °C over 60 days. Despite some pigment degradation, antioxidant activity remained more stable than in free constituents. These results highlight the feasibility of using pitaya peel as a sustainable encapsulating matrix for functional applications.