The last Porphyra haitanensis was abandoned as it was ugly, rough texture and had low price. In this paper, the abandoned Porphyra haitanensis cultivated in Guangdong Province was studied for the first time. The main nutritional composition of abandoned P. haitanensis and shanshui P. haitanensis were analyzed and compared. The extraction technology of polysaccharide from abandoned P. haitanensis was optimized. The polysaccharide extracted by direct hot water and assisted by microwave were purified, and the ...