Characterization, functional properties and antioxidant activities of macromolecular extracts isolated from Porphyra yezoensis

Porphyra yezoensis is one of the most economical seaweed species
in China. Determining how to make full use of mature P.
yezoensis and exploring new ways to increase the value of its
resources are important subjects of research for the development of the
laver breeding industry. In this study, we provide a simple method to
comprehensively extract the bioactive substances from P. yezoensis. The
characteristics, functional properties and antioxidant activities of two
types of biopolymer extract from P. yezoensis were studied and
analyzed relatively. Based on the characterization of water-soluble
concentrate (WPC) and alkali-soluble concentrate (APC), obtained via
chemical analysis, FT-IR, TGA and differential scanning calorimetry (DSC),
they both had typical polysaccharide and protein characteristics and
steady composition. APC showed higher nitrogen solubility, water holding
capacity and foaming ability. APC could not only be used as a protein
supplement; it also performs well in improving the properties of foods in
terms of water-holding and fat-absorption. The emulsifying activity and
oil-holding capacity of WPC were observed to be higher than those of APC;
thus, WPC has the potential to be used as an emulsifier. Surprisingly, WPC
and APC have radical scavenging capacity in vitro, which broadens the
direction of their application.