A comparison of the interaction of water with refined kappa-carrageenean (INS 407) and processed Eucheuma seaweed (INS 407A)

Abstract

1 Introduction Previously identified as either semi-refined or Philippines Natural Grade(PNG) carrageenan, this food additive is now regulatory termed Processed Eucheuma Seaweed (PES). It is defined for regulatory purposes in the Compendium of Food Additive Specifications (FAO, 1998a) as “A substance with hydrocolloid properties obtained from either Eucheuma cottonii or E. spinosum from the Rhodophyceae class of red seaweeds. The functional component of the product obtained from E. cottonii is kappa-carrageenan.” It is this material (INS No 707a) we compare here with conventional kappa-carrageenan, (INS No 407) which is defined in the Compendium (FAO, 1998b) simply as “A substance with hydrocolloid properties obtained from certain members of the class Rhodphyceae (red seaweeds).” The chemical composition, structure and functionality has been described (Gunning et al., 1998; Phillips, 1996). The water-soluble component in PES, is kappa-carrageenan, and as such is indistinguishable from the conventional kappa-carrageenan. Nevertheless, based on overall composition, using chemometric methods, these two forms of carrageenan can be readily distinguished, and they form quite distinct clusters if the individual analytical parameters are subjected to multivariate analysis (Jurasek & Phillips, 1998). There is as an insoluble component of cellulose I, normally present in algae cell walls, and this component has been identified by solid state NMR, X-ray diffraction and atomic force microscopy (Gunning et al., 1998; Phillips, 1996). The effects of this insoluble component on the gelation mechanism has been studied (Tanaka, Hatakeyama, Hatakeyama, & Phillips, 1996). Here the effect of the insoluble component on the interaction with water is investigated using differential scanning calorimetry (DSC).