2001 AACC Annual Meeting Charlotte, North Carolina October 14-18, 2001 Charlotte Convention Center

Pasting curves of starches in gum (hydrocolloid) solutions at low concentrations (starch 3.6%, gum 0.4%) were produced with a Brookfield viscometer. Gums produced a variety of effects on viscosities of starches during their normal pasting process (increase or decrease greatly or slightly or no effect), phenomena hypothesized to be due to differences in interactions between different amylopectins and different gums. A viscosity increase before the normal starch pasting temperature was detected for common corn starch in the presence of CMC, xanthan, guar gum, and alginate. No such event was observed with waxy corn starch, waxy rice starch, or tapioca starch. Regular rice, potato, and wheat starches gave mixed results. It appeared that interactions between certain amyloses and certain gums were responsible for the viscosity increase occurring before starch pasting. The pasting peak viscosity of potato starch was greatly decreased by negatively charged gums (CMC, carageenans, alginate, xanthan). The repelling forces between the phosphate groups on potato starch and the negative charges on the gum molecules were considered to be the main cause. This hypothesis was supported by results from similar systems (potato starch plus salt solution and phosphorylated common corn starch plus anionic gums), both of which systems also produced lower peak viscosities. It was found by microscopic examination of potato starch heated to 95 C in a solution of CMC without shear that the gum altered the granule pasting process.