SELECTION OF DESIRABLE STARCH PASTING PROPERTIES IN WHEAT FOR USE IN WHITE SALTED OR YELLOW ALKALINE NOODLES

Landraces of wheat may harbor wide diversity in quality-related traits , yet they have been little utilized to improve modern wheat varieties for major end uses such as noodles. Screening for starch physical pro perties in wheat breeding programs may provide valuable information on the suitability of genotypes for noodle manufacture. The pasting or v iscoamylograph characteristics, especially the peak viscosity and the rate of viscosity breakdown after gelatinization, have been widely use d to predict the eating quality of Japanese white salted noodles (WSN) and also applied to Chinese yellow alkaline noodles (YAN). We investi gated the pasting properties of purified wheat starch and wholemeal fr om 21 Iranian landrace accessions and five standard cultivars, in wate r and in salt and alkaline conditions. The peak viscosity of starch wi th added water or 2% salt and at as-is or alkaline pH (pH 11) were fou nd to be significantly correlated with each other. The results obtaine d were compared with the pasting profiles of wholemeal under the same treatment conditions. The peak viscosity of wholemeal was significantl y correlated with that of starch, especially when 0.5 mM sliver nitrat e was used to suppress the effect of alpha-amylase. It was confirmed t hat wholemeal may be used instead of starch during rapid screening of wheat genotypes when sample availability is limited, but wide differen ces in starch content in unadapted material, such as landraces, will r educe the accuracy of the results. When wholemeal is to be used for sc reening wheat for desirable end use quality, it is preferable to alway s use an amylase inhibitor like silver nitrate to eliminate the effect of endogenous amylases, even in nonsprouted material. The differences in pasting profiles resulting from alkaline versus nonalkaline condit ions indicate that whenever YAN quality is of particular importance, s creening under high pH should also be conducted.