Extraction Of A Water-Soluble Polysaccharide From Potato Starch Waste Residue And Its Application To Acidified Milk Beverages

Potato starch waste residue (PSR) is an unused agricultural resource that is rich in dietary fiber. We focused on a water-soluble polysaccharide contained in the fiber of PSR. We investigated the conditions for efficient extraction of a potato water-soluble polysaccharide (PP), the physical properties of the obtained PP, and its application as a stabilizer for acidic milk beverages. PP was obtained from PSR with a high extraction yield of 53 % by heating at 110 degrees C for 1.5 hours at pH 4.5. The obtained PP had an average molecular mass of 1.9 million (g/mole), and consisted of galacturonic acid, arabinose, rhamnose, galactose, and glucose. The aqueous solution showed intermediate viscosity characteristics between high-methoxyl-type citrus pectin and soybean polysaccharide. It rapidly thickened at a pH lower than pH 4, and showed properties similar to citrus pectin as it thickened and formed a gel when sucrose was added to the PP solution to make the concentration more than 30 %. The molecular image obtained by a scanning probe microscope showed a multi-branched structure similar to that of soybean polysaccharide. Furthermore, the PP appeared to function as a dispersion stabilizer as it suppressed the aggregation and precipitation of milk proteins under the weakly acidic condition of pH 4.2 to pH 5.0.