Impact of swelling power and granule size on pasting of blends of potato, waxy rice and maize starches

Abstract

This study investigated the impact of swelling power and granule size on pasting of blends of potato starch (PS) and maize (MS) or waxy rice (WRS) starch. First, viscosity development of one starch in the blend was reduced by cross-linking it to such extent that no viscosity development was recorded with Rapid Visco Analyser at the used concentrations. This way the difference in swelling power between the starches in a blend was changed. Comparison of the pasting profiles of blends of cross-linked PS and WRS or MS with those of blends of only native starch, showed that cross-linked PS contributes to viscosity development when another starch is present by increasing the total solid content and binding some of the available water. This was also observed for blends of PS and cross-linked WRS and MS. In a second approach, the impact of granule size was investigated by size fractionation of PS into PSsmall, PSmedium and PSlarge and by blending these fractions with WRS. PSsmall had lower amylose and higher phosphorus contents, a higher swelling power and lower carbohydrate leaching than PSmedium and PSlarge. All fractions had similar pasting properties. Peak, minimum and end viscosities were higher for blends of WRS with PSsmall than for those with PSmedium or PSlarge. This is probably due to the higher swelling power and higher rigidity (due to its lower granule size) of PSsmall.