Structure and functional properties of waxy starches

Abstract

A comprehensive study was conducted to elucidate structural and functional properties of waxy starches. The specific objectives were to examine the relationship between gelatinization/pasting properties and morphology of starch cooks, determine how the retrogradation properties are affected by chain-length distribution, and use a novel sensory approach to assess freeze-thaw stability of starch pastes. Waxy potato starch had a greater degree of granule swelling, higher paste viscosities, and better paste clarity than waxy starches from maize, wheat, rice, and tapioca. Waxy starches typically had greater paste viscosities than their normal counterparts, but the exception was potato starches. Waxy potato starch, which had no amylose, had lower paste viscosity than normal potato starch. Both waxy rice and waxy tapioca starches had less retrogradation tendency, which was closely related to the higher proportion of chains with DP 6–11 and the lower proportion of chains with DP 12–24. The sensory evaluation in this study allowed for an easier assessment of water separation as compared to the conventional centrifuge methods. Waxy maize and waxy potato starches had noticeable water separation from the paste after 1–2 freeze-thaw cycles, whereas both waxy rice and waxy tapioca starches could survive 6 freeze-thaw cycles without apparent syneresis. Waxy wheat, waxy rice and waxy tapioca starches are potential starting materials from which clean-label functional starches may be produced.