Structures and Pasting Properties of Potato Starches from Jaga Kids Purple '90 and Red '90

Abstract

Starches from two new potato varieties, Jaga Kids Purple '90 (Purple) and Jaga Kids Red '90 (Red), which were selected through the protoplast breeding method, had similar properties as follows. Purple and Red contained 21.7 and 21.0% amylose, 840 and 800 ppm phosphorus and showed high maximum and breakdown viscosities by a Rapid Visco Analyzer (RVA) . The amylose molecules of Purple and Red respectively had d.p.n 2190 and 2110, d.p.w 5400 and 5130, apparent d .p.-distribution range 590-12, 150 and 560-11, 750, and branch linkages for both was 3 .9 mol-1. The amylopectin molecules of both starches had an average chain length of 23, the iodine affinity was 0.06 and 0.08, and the chain-length distribution was similar. To clarify the effect of phosphate groups on the pasting properties of potato starch, nine potato starches with different phosphorus contents were examined. Regression analysis suggested that maximum, minimum, and breakdown viscosities and the pasting temperature by an RVA increased with the increase of linked phosphate groups. The potato starches showed a greater tendency of retrogradation than other non-cereal starches .