Valorization of Citrus sinensis (L.) Osbeck Peel Waste: Extraction, Antibacterial Activity, GC–MS Characterization and Development of a Natural Perfume Formulation

Abstract

The increasing global demand for natural and sustainable products has prompted the exploration of agro-industrial by-products as sources of high-value bioactive compounds. This study investigated the extraction of essential oil from Citrus sinensis (sweet orange) peels using hydrodistillation and its subsequent application to the formulation of a natural perfume. The hydrodistillation process yielded 2.9% (w/w) essential oil, which was characterised by its distinctive citrus aroma and light yellow appearance. Antibacterial evaluation using the agar well diffusion method revealed significant antimicrobial activity against both Staphylococcus aureus (zone of inhibition: 12 mm) and Escherichia coli (zone of inhibition: 14 mm) at a concentration of 60 mg/mL, demonstrating differential sensitivity between Gram-positive and Gram-negative bacteria. The formulated perfume, comprising 10–15% essential oil, 70–80% ethanol, 1–3% glycerol as a fixative, and 5–10% distilled water, exhibited favourable physicochemical properties, including a pH of 6.58, excellent stability under various storage conditions (25°C, 40°C, and 4°C) for 30 days and desirable volatility characteristics. Sensory evaluation using a hedonic scale confirmed high acceptability, with scores of 4.5 for intensity, 4.8 for pleasantness, and 4.7 for overall acceptability. Finally, GC–MS analysis of the essential oil revealed a complex volatile profile, with a predominant peak at a retention time of 13.88 min, accounting for 66.21% of the total peak area, which was tentatively identified as limonene based on mass spectral library matching. Other compounds, including α-pinene and p-cymene, were also tentatively identified. Overall, this research demonstrates the technical feasibility of valorising orange peel waste for natural perfume production, contributing to circular economy principles and sustainable development in the fragrance industry.