CHEMICAL AND PHYSICAL-CHEMICAL CHARACTERISTICS OF DIETARY-FIBERS FROMULVA-LACTUCA (L) THURET AND ENTERMORPHA-COMPRESSA (L) GREV

Dietary fibres from Ulva lactuca (L.) Thuret (sea lettuce) and Enterom orpha compressa (L.) Grev. (A.O. nori) were measured according to a 's tandard' method and a 'physiological' protocol simulating the gastric and intestinal environments. U. lactuca contained 15.8-8.0% soluble an d 24.2-32.6% insoluble fibres according to the 'standard' and 'physiol ogical' methods, respectively. For E. compressa, these values were 14. 9-15.9 and 21.6-28.7 %, respectively. For both algae, the composition suggests that the soluble fibres were xylorhamnoglycuronans sulphates and insoluble fibres were essentially composed of glucans. No marked c hemical compositional variation was observed between soluble fractions extracted under the simulated gastric and intestinal conditions. Fibr es in both algae are hydrophilic but the water holding capacities were higher after extraction of soluble fibres (5.5-9.5 g g-1 for the dry algae; 14.0-16.0 g g-1 for the standard insoluble fibres). Water solub le fibres demonstrated low intrinsic viscosities at 37-degrees-C in bu ffers, particularly those from E. compressa (36.0-36.5 ml g- 1), and w as affected by pH for those of U. lactuca (147.5 ml g-1 at pH 3.0 and 175.0 ml g-1 at pH 7.3).