DisplayTitle

An elevated amylopectin (AP) proportion of starch as observed in waxy and partial waxy wheat is known to have a substantial influence on the textural properties and shelf-life of many wheat-based products. Quality attributes of Chinese steamed bread (CSB) are presumed to be heavily affected by starch amylose (AM)/AP ratio, but much is yet to be verified. Two soft red winter wheat flours of normal starch endosperm were blended with 0-30% waxy wheat flour (WWF) of 5.1% starch AM content and tested for quality attributes of CSB, and moisture content, firmness, soluble starch content and thermal properties of CSB crumb, to determine the effects of starch AM content. The increased proportion of WWF in blends raised the mixograph absorption, probably due to the higher water affinity of AP as compared to AM. The incorporation of WWF increased the specific volume score of CSB from 15.7-16.1 to 18.4-18.4, and decreased crumb firmness from 22.0-21.7 to 11.2-13.3 N. Flour blends with 5-10% WWF, of which starch AM content is 22.4-24.7%, produced CSB of superior crumb structure (CS) without affecting surface smoothness (SS), stress relaxation (SR) and total score (TS). With more than 25% WWF in blends, negative changes in SR, CS, SS and TS of CSB were observed. The analysis of covariance indicated that CSB quality was little affected by protein content and dough strength parameters, indicating that starch AM/AP ratio was mainly responsible for the changes in CSB quality with the incorporation of WWF. Flour blends containing 15-20% WWF to produce a starch AM content of 20.5-22.7% exhibited reduced CSB staling (shown by decreased crumb firmness) and comparable TS to the control wheat flours. CSB prepared with more than 10% WWF exhibited a higher soluble starch content, indicative of reduced starch retrogradation, than that prepared with control flours during storage for 3 days.