Abstract: The starting product is rich in broken-down plant cell walls. Water is added, if necessary, to obtain a mixture suitable for the subsequent shearing treatment. The product is subjected to a shearing stress before extrusion, to obtain product containing a water-soluble polysaccharide fraction greater than that which exists in nature, without changing the overall chemical composition. The modified product is obtained in the form of crushable aggregates. If the starting product is derived from higher plants naturally rich in pectins, the latter (which have a dry matter content of at least 70%) are extracted from the water-soluble fraction by precipitation by an alcohol or by its multivalent salts. The extraction residue consists of edible fibres.

Abstract: Plant wall-rich products originating, for example, from higher plants naturally rich in pectins, algae, or from by-products, such as wheat bran, potato pulp, shells or oil works residues, and the like, are modified to contain a fraction of water-soluble polysaccharides which is higher than, in particular equal to at least twice that existing naturally, without modification of their overall chemical composition. To obtain them, water is added, if necessary to the natural product in the divided state, to form a mixture capable of undergoing a shearing treatment, and the resulting product is subjected to a shearing force before extrusion, resulting in modified products as aggregates which can be converted into powder. By means of aqueous extraction, performed directly on the extruded product, a water-soluble fraction is obtained, from which there are isolated, for example, pectins, with a degree of methylation .gtoreq.