Effect of hydrocolloids on normal and waxy maize starches cross-linked with epichlorohydrin

Abstract

Research was conducted to test the hypothesis that the surface charge on maize starch granules cross-linked with POCl3 affects how hydrocolloids (HC) interact with them. Normal (NMS) and waxy maize (WMS) starches were cross-linked with epichlorohydrin (ECH) to 2 extents. The products were heated in water or one of 9 HC solutions, and the pasting and paste properties and the rheological attributes of the produced gels were determined and compared to those of POCl3 cross-linked NMS and WMS. Results confirm the hypothesis that the ability of HC to alter early events in the pasting process is an important factor in their effects in altering the properties of starch pastes, as all HC used appeared to have an effect on granule swelling of heated slurries of both native and cross-linked starches. Differences in the effect produced by the different HC on the pasting and paste properties of POCl3 and ECH cross-linked products of both NMS and WMS appeared primarily to be in degree and unrelated to whether the cross-linked starch had a negative surface charge. Two mechanisms are proposed for the influence of HC on granule swelling: 1) strengthening of granules via interactions with HC molecules, and 2) inhibition of water penetration and, therefore, granule swelling by plugging of granule micro- and mesopores by those hydrated HC molecules that are too large to enter them. Rheological properties of the produced gels determined before and after cold storage also had both similarities and differences in effects produced by addition of a HC.