• Gracilaria lemaneiformis, rich in polysaccharide, is a kind of economic red algae. • The extraction, purification, structure and bioactivities of GLP were provided. • The mechanisms of bioactivities of GLP were described. • The urgent problems to be solved are raised in this paper.

• The effect of magnetic field freezing (MF) on white shrimp quality was studied. • 60 mT MF (MF-60) shortened the freezing time, reduced thawing/cooking loss. • MF-60 helped to maintain the water holding capacity and texture properties. • MF-60 reduced the mobility and loss of immobilized water and free water. • The microstructure of MF-60 was less damaged by ice crystals.