Physicochemical Properties and End-use Quality of Wheat Starch as a Function of Waxy Protein Alleles

Abstract

Soft wheat (Triticum aestivum L.) quality tests (milling and baking quality) and starch characteristics (amylose concentration, X-ray diffractograms, thermal properties and pasting properties) were determined for eight granule-bound starch synthase (GBSS: waxy protein) genotypes in a soft wheat background. Lines carrying two null alleles showed reduced amylose concentrations relative to those of single null and wild-type lines. Milling and baking quality traits were clearly different between waxy (triple null) and the other genotypes. Waxy lines showed the highest alkaline water retention (AWRC) capacity; even though, the protein concentration was not signi®cantly different from some double null and single null lines. The typical A-type patterns of X-ray diffractograms were observed for all starches. Waxy starch showed higher crystallinity than non-waxy starches. Analysis by Rapid Viscoanalyser (RVA) showed distinctive differences among the eight genotypes. Waxy starches showed higher peak viscosity, lower peak temperature and shorter peak time than those of all other genotypes. The results suggest that baking quality of waxy wheat can not be predicted by either AWRC or protein concentration. The interactions based on biochemical analysis between protein and other fractions (amylose and amylopectin, damaged starch) of partially and fully waxy wheat¯ours must be assessed before baking quality can be predicted. Furthermore, waxy wheat may not be suitable for current application of soft wheat products; however, distinct properties of waxy starch may open the possibility of commercial use in novel applications. Also, double null and single null genotypes may be a good source of variation for speci®c end-use products.

Factors Governing Pasting Properties of Waxy Wheat Flours

“…No significant differences were observed in the pasting temperatures among waxy wheat flours. The low pasting and peak temperatures for these waxy wheat flours agreed with previous findings on waxy wheat flours (Yasui et al 1999;Ishida et al 2003) and isolated waxy wheat starches (Hayakawa et al 1997;Sasaki et al 2000;Grant et al 2001;Kim et al 2003).…”

“…When waxy wheat flours are heated in excess water, they exhibit different properties compared with normal wheat flours (Graybosch et al 2000;Ishida et al 2003;Kim et al 2003;Graybosch 2005). Waxy wheat flours exhibit peak viscosity at a lower temperature than normal wheat flour (Kim et al 2003); this property can be used as an indicator to identify waxy wheat flours.…”

“…Waxy wheat flours exhibit peak viscosity at a lower temperature than normal wheat flour (Kim et al 2003); this property can be used as an indicator to identify waxy wheat flours. In addition, waxy wheat flours have lower final viscosity during pasting than normal wheat flours (Yasui et al 1999;Geera et al 2006).…”

Functionality of native tetraploid wheat starches: Effects of waxy loci alleles and amylose concentration in blends

“…The functional characters of waxy hexaploid wheat (T. aestivum L.) starches have been extensively investigated (Epstein et al, 2002;Kim et al, 2003;Yamamori and Quynh, 2000). Comparatively little is known of the effects of amylose variation in durum wheat starch.…”

Starch meets biotechnology : in planta modification of starch composition and functionalities

“…For instance, Waxy wheat is more suitable for different food applications. Pastas made with durum wheat containing lower amylose content are of better quality (Kim et al, 2003;Sharma et al, 2002).…”