Green ultrasound-assisted extraction of pigments from Mexican Caribbean Sargassum

IntroductionThe increasing accumulation of Sargassum spp., primarily S. fluitans and S. natans, along Caribbean coastlines has become an environmental and economic challenge. These brown macroalgae are rich in high-value pigments with antioxidant, anti-inflammatory, and anticancer potential; however, conventional extraction methods rely on toxic organic solvents. This study evaluated ultrasound-assisted extraction (UAE) using hydroethanolic mixtures as a greener alternative for pigment recovery from Sargassum spp.MethodsSargassum spp. biomass was subjected to UAE under varying ethanol concentrations, temperatures, and solid-to-liquid ratios (SLR) to assess their effects on pigment extraction. Fucoxanthin was quantified using a rapid UHPLC method, while total chlorophyll and carotenoids were determined using adapted microplate-based spectrophotometric methods.ResultsThe highest pigment recovery with the lowest experimental variability was achieved using 70% (v/v) ethanol, 60 °C, and an SLR of 3 g:100 mL, yielding 26.64 ± 5.19 mg g-1 dw fucoxanthin, 163.11 ± 35.34 mg g-1 dw total chlorophyll, and 53.03 ± 14.43 mg g-1 dw carotenoids. Ethanol concentration was the primary factor influencing extraction efficiency, whereas temperature and SLR exerted secondary effects associated with mass transfer. Although pigment yields were lower than those reported for extractions using more hazardous organic solvents, the hydroethanolic UAE approach provided more consistent pigment recovery while reducing solvent toxicity and processing time.DiscussionThe combination of UAE with hydroethanolic solvents represents a sustainable and scalable strategy for pigment extraction from Sargassum spp. Furthermore, the rapid analytical methods developed for pigment quantification reduced analysis time and sample consumption, facilitating process monitoring and supporting the implementation of integrated marine biorefineries for Sargassum valorization.