Composition and properties of agar-type polysaccharides fromGracilaria sjoestedtii Kylin

A study was made on the composition and properties of agar-type polysaccharides ofGracilaria sjoestedtii from Qingdao, China. Fractional extraction was carried out and four fractions were obtained. The yields and chemical composition of these fractions were determined. Gel strength measurements of the agar-type polysaccharide fractions were made after alkli modification. The nature of the non-gelling, highly sulphated galactans (Fraction II) present in the thaw water after the initial extraction of Gracilaria in a freeze-thaw cycle was reported and discussed.