Abstract
The growing demand for sustainable and nutrient-rich food sources has positioned macroalgae as a promising alternative for food product development. This study investigates the extraction and characterization of hydrocolloids from three red macroalgae species (Chondrus crispus, Gracilaria gracilis, and Gelidium corneum) using water bath (WB), ultrasound (US), and hybrid ultrasound-water bath (USWB) treatments for 45 and 60 min. The physicochemical properties of the extracts, including rheological behavior, particle size distribution, antioxidant activity, and texture, were assessed. The results show that C. crispus produced the firmest gels due to its high carrageenan content, with WB and USWB treatments yielding the most stable gel structures. In contrast, G. gracilis and G. corneum exhibited lower gel strength, consistent with their agar composition. WB-treated samples demonstrated superior antioxidant retention, while US treatment was more effective in preserving color stability. The findings highlight macroalgae as a viable and sustainable alternative to conventional hydrocolloids, reinforcing their potential as natural gelling agents, thickeners, and stabilizers for the food and pharmaceutical industries. This study provides a comparative evaluation of WB, US, and USWB extraction methods, offering insights into optimizing hydrocolloid extraction for enhanced functionality and sustainability.