EFFECT OF ACID-HYDROLYSIS ON THE MOLECULAR-WEIGHT OF KAPPA-CARRAGEENAN BY GPC-LS

Kappa carrageenan was subjected to acid-catalyzed hydrolysis under clo sely controlled pH and temperature conditions. The effect of acid hydr olysis was followed by measuring the change in molecular weight by gel permeation chromatography (GPC) coupled to a triple detector system c onsisting of a single (90 degrees) angle laser light scattering (RALLS ) detector, a viscometer and a refractometer. The changes in the weigh t average (M(w)) molecular weight of kappa carrageenan can be describe d by a first-order random hydrolysis process involving selective attac k at carrageenan glycosidic linkages. Kinetic parameters are also calc ulated and a general mathematical model is presented relating hydrolys is rate to pH and temperature. The model was used to compare carrageen an molecular weight change to published data on gel strength variation . Copyright (C) 1996 Elsevier Science Ltd