Studies on by-products from the industrial extraction of alginate

The content, the chemical composition and some physical-chemical properties of soluble and insoluble dietary fibres from an industrial alginate extraction by-product, flotation cellulose, were measured by two enzymatic gravimetric methods: an adaptation of the AOAC method (standard method) and a physiological method which used conditions closer to those prevailing in the digestive tract (pH, temperature, ionic strength and ionic composition). Total dietary fibres content obtained with the two methods were close (48.4–52.7; 56.3–59.8%) and about 68–95% of them were insoluble. Soluble fibre were essentially composed of uronic acids and were extracted under the simulated gastric conditions.Swelling in water and water absorption in NaCl (154 mM) of insoluble fibres with particle size between 250–500 µm were 21.9 g g^-1 and 3.6 gg^-1, respectively. The content and physical-chemical characteristics of fibres from flotation cellulose are close to those obtained from other plant and algal industrial by-products. Soluble fibre presented low intrinsic viscosity (152 ml g^-1).