Antioxidant and Antimicrobial Activity of Citrus sinensis and Citrus aurantium Essential Oil Against Foodborne Bacterial Pathogens

Orange peel is a citrus-processing by-product and a promising source of volatile compounds for value-added applications. This study compared essential oils obtained by steam distillation from Valencia orange (Citrus sinensis) and sour orange (Citrus aurantium) peel under a common experimental framework. Antioxidant capacity was assessed independently by ABTS and FRAP, whereas antimicrobial activity was screened by disk diffusion against Escherichia coli, Shigella spp., Staphylococcus aureus, and Bacillus cereus. Both citrus materials yielded 1.25 mL essential oil/100 g peel. In the prepared oil batches, Valencia orange essential oil showed the higher antioxidant response in both assays, reaching 438.08 ± 6.50 µmol TE/L under ABTS and 187.21 ± 13.11 µmol TE/L under FRAP, approximately 2.80- and 2.62-fold the corresponding sour orange values. Sour orange essential oil produced inhibition zones against all four bacteria (16.0–29.5 mm), whereas no inhibition zone was detected for Valencia orange oil under the same screening conditions. Under this defined workflow, the two prepared oils showed contrasting functional response profiles, providing a quantitative basis for targeted compositional and application-oriented follow-up.