Ultrasonic-assisted green extraction and incorporation of Spirulina platensis bioactive components into turmeric essential oil-in-water nanoemulsion for enhanced antioxidant and antimicrobial activities

The utilization of essential oils as natural antioxidants and preservatives is limited by high volatility, poor water solubility, and long-term instability. To address this, a novel ultrasonic-assisted method was used to prepare and stabilize a nanoemulsion of turmeric essential oil-in-water, incorporating bioactive components extracted from Spirulina platensis. Ultrasonic treatment enhanced the extraction efficacy and nanoemulsion stability. Algal biomass subjected to ultrasonic treatment (30 min at 80% amplitude) yielded a dry extract of 73.66 ± 3.05%, with the highest protein, phenolic, phycocyanin, and allophycocyanin content, as well as maximum emulsifying activity. The resulting nanoemulsion (5% oil, 0.3% extract, 10 min ultrasonic treatment) showed reduced particle size (173.31 ± 2.24 nm), zeta potential (−36.33 ± 1.10 mV), low polydispersity index, and enhanced antioxidant and antibacterial properties. Rheology analysis indicated shear-thinning behavior, while microscopy and spectroscopy confirmed structural changes induced by ultrasonic treatment and extract concentration. This initiative developed a novel ultrasonic-assisted algal-based nanoemulsion with antioxidant and antibacterial properties.