A series of water-soluble and water-insoluble heteroxylans, citrus pectin, and both starch components, amylose and amylopectin, were hydrophobically modified by introducing low amounts of p-carboxybenzyl groups at constant reaction conditions. The achieved degree of substitution ranged from 0.03 to 0.22. The derivatives were characterized by chemical and spectral analyses. They exhibited tensioactive properties evaluated by various surface-activity tests. The results indicate a weak surface tension-lowering effect and low foamability of all derivatives. However, significant emulsifying and protein foam-stabilizing effects were found for most of the studied derivatives, the most pronounced for the modified pectin and acidic xylans. The rheological behavior of the derivatives was investigated by rotational and oscillation rheometry. The results indicated that the hydrophobic interactions lowered significantly the apparent viscosity of the xylan dispersions and introduced changes, particularly in their flow properties.