Work

Ethanol-based ultrasonic extraction of Vietnamese macroalgae bioactive compounds: a green approach with optimised conditions and antimicrobial effects

Year: 2025

Type: article

Abstract: Underexploited Vietnamese macroalgae could provide clean-label antioxidant and antimicrobial ingredients for food systems, yet selective and scalable extraction remains challenging. Here, probe ultrasonic-assisted extraction (UAE-H) using aqueous ethanol was benchmarked against soaking, Soxhlet, and ultrasonic bath extraction for Porphyra vietnamensis. UAE-H delivered the highest phenolic recovery and antioxidant responses and was subsequently optimised using response surface methodology. The optimal conditions (56% ethanol, 10 min, 1:30 g/ml) produced 11.96 mg gallic acid equivalent/g dry weight (DW) total phenolics while suppressing carbohydrate co-extraction, indicating improved operational selectivity towards phenolics. The optimised extract exhibited broad-spectrum antibacterial activity against common food-borne bacteria (Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, and Salmonella typhi) with minimum inhibitory concentration values of 0.197–0.395 mg/ml. High-performance liquid chromatography coupled with diode array detection and electrospray ionisation mass spectrometry profiling showed a dominant phenolic peak putatively annotated as a methylated A-type proanthocyanidin dimer (m/z 589.68) based on spectrophotometric ultraviolet (UV) characteristics and diagnostic fragmentation patterns. Overall, UAE-H with food-grade ethanol provides a rapid and reduced-solvent route to valorise P. vietnamensis into antioxidant/antimicrobial fractions with potential for clean-label food and nutraceutical applications.

Source: International Journal of Food Science & Technology

DOI: 10.1093/ijfood/vvag085