Physical modification of potato starch using mild heating and freezing with minor addition of gums

Abstract

An aqueous dispersion of potato starch with or without gums (0.3%, based on starch, total solids was 40%) was subjected to mild heating and cooling (HC, 1 h at onset gelatinization temperature, and 12 h at 4 degrees C), freezing and thawing (FT, 12 h at -20 degrees C for 12 h, and 1 h at 25 degrees C), and a combination of both treatments (HCFT) for physical modification of the starch. Scanning electron microscopy revealed that the FT disrupted the structure of starch granules, whereas the HCFT left the granules intact. The HC caused leaching of soluble starch chains, which induced the formation of outer layers on the surface of starch granules. The minor addition of various gums (xanthan gum, carboxymethyl cellulose, gum arabic, and guar gum) facilitated the formation of the outer layers, possibly through the interaction with soluble starch. Such starch-gum composite layers remained tightly attached to the granule surface, increasing the shear stability of the starch during pasting and thereby the final viscosity (up to similar to 4500 mPa s form similar to 2900). Moreover, the HCFT treatment accelerated the gelling of starch, with improvements in gel texture and freeze-thaw stability.