Submitted to: Starch
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/20/2004
Publication Date: 11/12/2004
Citation: Chakraborty, M., Matkovic, K., Berzonsky, W.A., Mcmullen, M.S., Doehlert, D.C. 2004. Physicochemical and functional properties of tetraploid and hezaploid waxy wheat starch. Starch. Vol. 56:339-347. Interpretive Summary: The waxy mutation in grains results in the accumulation of starch with different properties than normal starch. Normal starch contains about 75% of a branched form of starch called amylopectin and 25% of a straight chain form of starch, called amylose. The waxy mutation causes the elimination of all amylose in the grain. In this study, we have compared physical and chemical properties of waxy starch from bread wheat and compared these with those of waxy durum wheat. Significant differences in thermal properties of waxy starches between bread wheat and durum wheat were observed, as measured by differential scanning calorimetry. Texture analysis of these starches by the Rapid Visco Analyzer also indicated differences between waxy starches from bread wheat and durum wheat. These results indicate that these starches will behave differently in food systems, and that applications will need to be tailored according to the specific properties of each.
Technical Abstract: Waxy wheats possess unique starch functional properties that may be useful in specific end-uses. To assess the physicochemical, thermal, and pasting properties, starches from seven waxy genotypes originating from two wheat classes, durum and hard red spring (HRS), were evaluated and compared with their counterpart non-waxy wild types. The amylose content ranged from 2.3% to 2.6% in waxy durum lines, compared to 29.2% in normal durum control, and 2.1% to 2.4% in waxy HRS, compared with 26.0% in normal HRS control. Significant differences in the degree of crystallinity were observed between the waxy and control starches, despite similar A-type X-ray patterns, although differences between the two wheat classes were non-significant. Both, control and waxy starches displayed an X-ray peak corresponding to the amylose-lipid complex, but the intensity of the peak was markedly lower in the waxy starches. The waxy durum starches exhibited the highest DSC transition temperatures compared to all genotypes, whereas, the enthalpy of gelatinization of most waxy genotypes was statistically higher than the controls. RVA analysis displayed the characteristic high peak, high breakdown, and low setback profile for all waxy starches. Texture analysis of RVA gels revealed significant differences between waxy and non-waxy wheats, as well as between waxy tetraploid and hexaploid wheats, confirming that the nature and class of wheat starch would play a significant role when using waxy wheat blends in different wheat-based products.