Mango (Mangifera indica L.) byproducts, which represent 35-60 % of the processed fruit, are a potential source of dietary fiber. After ethanolic purification, we found that peels and fibrous waste pulp had a high dietary fiber content (74% of the dry matter) with a soluble/insoluble ratio close to 1 and a 15-20 % uronic acid content. The fiber water-soluble fraction showed shear-thinning behavior. In vitro studies indicate that these fibers decreased total starch digestibility and slowed the final rate of amylolysis of mashed potatoes as the starch source. Glucose diffusion was also retarded in the presence of mango fiber. These results suggest that mango byproducts are a good source of dietary fiber which could be of potential benefit in controlling plasma glucose.

Orange and lemon peels were extruded under controlled conditions of varying severity, and their physico-chemical characteristics and effect on the enzymatic hydrolysis of starch and glucose diffusion were studied. Extrusioncooking treatment increased the soluble fraction of dietary fibre as well as solubilised pectic substances and arabino-galactomannan chains. The apparent viscosities of aqueous extracts of extruded fibre were increased slightly for orange and more markedly for lemon fibre. With both fibre sources, viscosities values were higher in Tris-maleate buffer (0.1 M) than in NaCl(l54 mM). However, these modifications had no effect on starch hydrolysis and glucose diffusion in oitro.

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