Starch characteristics of waxy and nonwaxy tetraploid (Triticum turgidum L. var. durum) wheats

Manufacture of pasta products is paramount for durum wheat (Triticum turgid um L. var. durum). The recent development of waxy durum wheat containing st arch with essentially 100% amylopectin may provide new food processing appl ications and present opportunities for value-added crop production. This in vestigation was conducted to determine differences in some chemical and fun ctional properties of waxy durum starch. Starch was isolated from two waxy endosperm lines and four nonwaxy cultivars of durum wheat. One of the waxy lines (WX-1) was a full waxy durum wheat whereas the other line (WX-0) was heterogeneous, producing both waxy and nonwaxy seed. Effects on starch swel ling, solubility, pasting, gelatinization, and retrogradation were examined . The full waxy starch had four times more swelling power than the nonwaxy durum starches at 95 degreesC, and was also more soluble at three of the fo ur temperatures used. Starch pasting occurred earlier and peak viscosities were greater for starches from both waxy lines than for the nonwaxy starche s, but their slurries were less stable with continued stirring and heating. Greater energy was required to melt gelatinized waxy starch gels, but no d ifferences were found in either refrigerated storage or freeze-thaw retrogr adation, as determined by differential scanning calorimetry. The results of this investigation showed some significant differences in the starch prope rties of the waxy durum wheat lines compared to the nonwaxy durum wheats.