The microwave assisted extraction sway on the features of antioxidant compounds and gelling biopolymers from Mastocarpus stellatus
2020
Ponthier, E. | Domínguez, H. | Torres, M.D.
Microwave assisted water extraction of hybrid carrageenan and antioxidant compounds from Mastocarpus stellatus red alga was first proposed to recover biopolymers with specific rheological properties, saving time, avoiding chemicals and enhancing extraction yields when compared with conventional treatments. The hybrid carrageenans, precipitated from the liquid fractions recovered after microwave assisted water extraction were analyzed by Fourier transform infrared attenuated total reflectance, high-performance size-exclusion chromatography and rheology. The corresponding soluble extracts were also characterized by total phenolic content, antioxidant capacity, proteins, sulfate and carbohydrate content. The highest phenolic, antioxidant capacity and sulfate content were observed at 190 °C, without notable effect of heating time between 3 and 6 min. In contrast, a clear impact of both microwave heating temperature and time on the molecular weight distribution of hybrid carrageenans as well as on the viscoelastic behavior of formulated hydrogels was identified, being the strongest hydrogels achieved at 170 °C for 6 min. It should be highlighted that all proposed hydrogels exhibited stable mechanical properties in the absence of syneresis for a month of cold storage, except those made with biopolymers obtained with the mildest extraction conditions (3 min at 70 °C).
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