LAUSR

BACKGROUND Separation and purification of Porphyra haitanensis polysaccharide (PHP), and determination of changes in Mw and antioxidant capacity after in vitro digestion were undertaken. RESULTS Analysis of two polysaccharide fractions (PHP0.5-1-UF and PHP1.0-1-UF) by various techniques showed that they were sulfated polysaccharides and had high purity without pigment or protein. PHP0.5-1-UF was filamentous or "tape-like" sheets, whereas PHP1.0-1-UF had some filaments and large numbers of rounded aggregates. The Mw of PHP, PHP0.5-1-UF and PHP1.0-1-UF were 2.06×106 (±2.02%), 6.68×106 (±3.17%), and 1.14×106 (±3.44%) (g/mol), respectively. After in vitro digestion, Mws of PHP, PHP0.5-1-UF, and PHP1.0-1-UF decreased. Their antioxidant capacities were markedly higher than before digestion, especially PHP0.5-1-UF and its digestion products, which might be related to the reductions in Mw. CONCLUSION These findings provide a greater understanding of separation and purification of sulfated polysaccharides, the influence of digestion on biological activities, as well as contributing to practical application of sulfated polysaccharides in functional foods. This article is protected by copyright. All rights reserved.