Enhanced extraction of Myristica fragrans houtt seed essential oil via microwave air-hydrodistillation: Parametric study, optimization, and antibacterial evaluation

• MAHD boosted nutmeg oil yield and efficiency under optimized conditions. • Max yield 6.53% at 600 W, 100 mesh, 0.30 g/mL ratio, 180 min. • GC–MS (28 volatiles) and FTIR confirmed key bioactive compounds. • Oil showed strong antibacterial activity, sustained for 192 hours. • MAHD saved ∼40% energy, aligning with green chemistry and SDGs. Nutmeg ( Myristica fragrans Houtt.) seed essential oil is valued for its potent antimicrobial, antioxidant, and aromatic properties, positioning it as a valuable natural additive for the food, cosmetic, and pharmaceutical industries. However, conventional extraction methods often lead to suboptimal yield and phytochemical degradation due to prolonged heating and energy inefficiency. This study investigates the application of Microwave Air-Hydrodistillation (MAHD) as a green alternative to enhance oil recovery and preserve bioactive compounds. Key parameters—microwave power (300–600 W), particle size (20–100 mesh), and solvent-to-solid ratio (0.20–0.30 g/mL)—were optimized using Response Surface Methodology (Box-Behnken Design). The optimal conditions (600 W, 0.30 g/mL, 180 min) yielded 6.53 % essential oil. GC-MS analysis identified 28 volatile compounds, with 4-terpinenol (29.45 %), myristicin (15.64 %), eugenol (7.76 %), and (–)-terpineol (7.18 %) as the predominant bioactives. FT-IR spectroscopy confirmed the presence of key functional groups (O–H, C=O, C–O–C), verifying the oil's chemical integrity. The oil exhibited significant antibacterial activity against Escherichia coli (11.25 mm) and Staphylococcus aureus (16.25 mm) in disk diffusion assays, with sustained efficacy over 192 hours. Compared to conventional methods, MAHD achieved up to 40 % energy savings, eliminated solvent use, and reduced processing time, aligning with green chemistry principles and supporting Sustainable Development Goals (SDGs). These results establish MAHD as an efficient and sustainable extraction technology for nutmeg essential oil, though future studies should address scale-up validation, expanded antibacterial screening, and in vivo toxicity assessment.