CEREAL CHEMISTRY 332 Mixing Properties, Baking Potential, and Functionality Changes in Storage Proteins During Dough Development of Triticale-Wheat Flour Blends Hamid A. Naeem, 1–3 Norman L. Darvey, 1 Peter W. Gras, 4 and Finlay MacRitchie, 3,4 ABSTRACT Cereal Chem. 79(3):332–339 Flours from advanced lines or cultivars of six triticales and two prime hard wheats, along with triticale-wheat blends, were investigated for mix- ing, extension (excluding blends), and baking properties using microscale testing. Percentage total polymeric protein (PPP) and percentage unex- tractable polymeric protein (UPP) of flours and doughs, including blends, mixed to optimal dough development were estimated using size-exclusion HPLC to determine the changes in protein solubility and association with blend composition (BC), mixing properties, and loaf height. Each triticale was blended with flours of each of the two wheat cultivars (Hartog and Sunco) at 0, 30, 40, 50, 60, 70, and 100% of wheat flour. Nonlinear rela- tionships between BC and mixograph parameters (mixing time [MT], band- width at peak resistance [BWPR], and resistance breakdown [RBD]) were observed. A linear relationship between BC and peak resistance (PR) was predominant. PPP of triticale flours was mostly higher than PPP of wheat cultivars. UPP of all triticales was significantly lower than wheat culti- vars. PPP of freeze-dried doughs was mostly nonsignificant across the blends and showed a curvilinear relationship with BC. The deviations from linearity of MT and PPP were higher in triticale-Sunco blends than in triticale-Hartog blends. UPP of blends was closer to or lower than the lower component in the blend. The deviations from linearity for MT and UPP were greater in triticale-Hartog blends than triticale-Sunco blends. A highly significant correlation (P < 0.001) was observed between BWPR and loaf height. This suggested that BWPR in triticale-wheat flour blends could be successfully used for the prediction of loaf height. Triticale flour could be substituted for wheat flour up to 50% in the blend without dras- tically affecting bread quality. Dough properties of triticale-wheat flour blends were highly cultivar specific and dependent on blend composition. This strongly suggested that any flour blend must be tested at the desired blend composition. Secondary hexaploid triticale (Χ Triticosecale Wittmack) is cur- rently a commercially successful triticale. It is high yielding and well adapted to extreme cold, drought, and acidic soils. It is grown in almost all geographic regions where the parental species are grown. The area under triticale cultivation is increasing steadily all over the world (Varughese et al 1996), which seems to indicate that triticale will join other cereals to provide food to the rapidly growing human population. In breadmaking, the physical properties of dough determine the quality of the finished product. The quantity and quality of gluten largely determine these physical properties. Triticale gluten is widely perceived to be weak, with consequent poor dough-handling proper- ties (Pena and Ballance 1987), such as high levels of dough stickiness and poor baking potential. Some of the present day triticales have good breadmaking potential that may be regarded as exceptions to this assumption (Amaya et al 1986). From a nutritional point of view, triticale has certain valuable dietary characteristics such as higher amounts of soluble dietary fiber (Villegas et al 1970) and better overall amino acid composition, in particular higher lysine, than wheat (Morey and Evans 1983). Given these advantages, as well as agronomic potential, it can be concluded that triticale has all the vital quality attributes of a food cereal and should become an important food cereal in the near future. One possible approach to improve bread quality could be blending triticale flour with wheat flour. Earlier studies showed that addition of up to 30% of triticale flour resulted in satisfactory bread. A more recent study (Pena and Amaya 1992) indicated that breads of accep- table quality, although significantly different from bread baked with wheat flour, could be produced with 1:1 blends of triticale-wheat flour. Reexamining the data of Pena and Amaya (1992) (Fig. 1) shows that bread volume is not proportional to the amount of triticale flour in the blend. The addition of even 50% triticale flour had a negligible effect on loaf volume. This implies that when triticale and wheat flour are blended together, the baking performance is a non- linear function of the blend composition (BC). While the data from these workers encompassed only two composite flours of triticale cultivars, it suggested that this type of nonlinearity was a widespread phenomenon. Dough development during mixing is the phase of the bread- making process where gluten functionality is critical. As mixing pro- ceeds, the initial incoherent dough mass develops viscoelastic prop- erties. Gluten proteins form a matrix defined both by chemical bonds and physical entanglements. Protein solubility and major changes in the gluten complex take place before the optimal dough develop- ment (Bushuk et al 1997). It seems likely that to understand the processes taking place during mixing and baking, it would be neces- sary to study the changes occurring in the polymeric protein of developing dough. Previous studies in this area focus on wheat (MacRitchie 1975; Danno and Hoseney 1982; Weegels et al 1996; Bushuk et al 1997), but there are no reports regarding mixing prop- erties and changes in polymeric protein of triticale and triticale-wheat flour blends. The flour quality parameters of cultivars or advanced lines of six triticales and two wheats were investigated. The triticale flours were each blended at several levels with each of the two prime hard Australian wheat cultivars. Wheat cultivars were current high-quality bread wheats that differed at Glu-1 loci. Mixing properties, changes in soluble and insoluble protein concentration of doughs, and loaf height were evaluated for each of the triticales, wheats, and triticale- wheat blends. 1 Department of Crop Science, The University of Sydney, Plant Breeding Institute, PMB 11, Camden NSW 2570, Australia. 2 Corresponding author. E-mail: hnaeem@wheat.ksu.edu Phone: 1-785-532-4813. Fax: 1-785-532-7010. 3 Present address: Department of Grain Science and Industry, Kansas State University, 205 Shellenberger Hall, Manhattan, KS 66506. 4 CSIRO Plant Industry, GQRL, North Ryde, NSW 2113, Australia. Publication no. C-2002-0401-02R. © 2002 American Association of Cereal Chemists, Inc. Fig. 1. Relationship between percentage of triticale flour in triticale-wheat flour blends and loaf volume.