Changes in M:G ratios of extracted and residual alginate fractions on boiling with water the dried brown alga Kjellmaniella crassifolia (Laminariales, Phaeophyta)

Kjellmaniella crassifolia, the edible macro-brown alga in Japan contained nearly 27% of alginates of which nearly 7% was extractable from the fronds with boiling water for 6 h and the residual alginates in the frond were almost exhaustively extracted with a dilute alkali at 60 degree C for 6 h. The alginates dissolved in all these extracts with both boiling water and dilute alkali were purified by fractionation with MgCl sub(2) and alcohol. The content of MM blocks in the boiling water-soluble alginate sample increased remarkably during heating for 6 h while that of GG blocks from the same sample decreased. In contrast, MM blocks in the alkali-soluble alginate sample decreased during 6 h heating while GG blocks continued to increase. Since the amounts of MG blocks showed slight fluctation, the M:G ratio of alginates extracted with boiling water increased towards the end of extraction whereas the reverse is true for the alkali-soluble alginates.