Disclosed is a polyuronic acid having an average degree of polymerization
less than 20. The method of the present invention comprises the steps: (a) providing
a solution containing 5 wt. % or more of a high molecular weight polyuronic acid
predominantly as its lithium salt; (b) adding hydrogen peroxide and a ferrous salt
to the solution prepared in step (a) to oxidatively degrade the high molecular
weight polyuronic acid; and (c) isolating a polyuronic acid having an average degree
of polymerization less than 20 obtained in step (b).
