Cereal Chem. 77(1):39-43Development of a small-scale method to measure dough extensibility, using a 2-g mixograph and the TA.XT2 texture analyzer (TA) equipped with Kieffer rig, suitable for early-generation wheat quality screening is presented. Three hook speeds 3.3, 7.0, and 10.0 mm/sec were tested on the TA. Only at the lower hook speed of 3.3 mm/sec were wheats, varying in quality, clearly differentiated. The ability to differentiate between wheats using the TA was compared with the Brabender Extensigraph. The sample ranking based on the resistance to extension (R max ) from the TA at a hook speed of 10.0 mm/sec correlated highly (r = 0.99) to the ranking obtained on the extensigraph. Dough extensibility data from the extensigraph and the TA, using hook speed 10.0 mm/sec, was correlated (r = 0.90) to loaf volume. Similarly, dough extensibility on the TA, using hook speed 3.3 mm/sec, was correlated to loaf volume (r = 0.96). The effect of three dough water contents (farinograph absorption, farinograph absorption + 6%, and 2-g mixograph water absorption) on physical properties of dough were evaluated by mixing the dough in a 2-g mixograph and testing the extensibility on the TA. Dough prepared at farinograph absorption + 6% and at mixograph absorption allowed differentiation between wheats based on the resistance to extension (R max ).

Traditional breeding of common wheat (Triticum aestivum L.) concentrates largely on the improvement of protein quality because of the importance of protein in end‐product functionality, nutritional value, and economic impact. New, rapid, and inexpensive protein quality tests are required to identify premium quality families from large and diverse early‐generation breeding populations. In this study, a simple method was designed using organic solvents to divide wheat proteins into monomeric‐rich (single‐chain, mostly gliadin), polymeric‐rich (multichain, mostly low‐ and high‐molecular weight glutenin), and total soluble protein (monomeric and polymeric protein). Monomeric‐rich and total soluble protein fractions were quantified at 280 nm with an ultraviolet (UV) spectrophotometer. Protein fractions were expressed in terms of absolute concentration and as a proportion of total soluble protein. A strong linear relationship between the protein concentration in the fractions and the absorbance reading indicated that the method could accommodate a large range of protein fraction concentrations. The specific relationships between quantity and proportion of monomeric/polymeric protein fractions and dough quality tests allowed for the design of an algorithm eliminating poor quality lines from further breeding assessment. Simplicity, reliability, low cost, and a potential for automation could make this UV‐spectrophotometric method suitable for routine use in wheat breeding programs.

Wheat protein composition is important for understanding the biochemical basis of wheat quality. The objective of this study was to design a simple protein fractionation protocol with low crosscontamination and to show that these protein fractions were associated with wheat quality. The protocol consists of three sequential extractions from 100 mg of flour with 7.5% propan-1-ol and 0.3 M sodium iodide (monomeric-rich protein), 50% propan-1-ol (soluble glutenin-rich protein) and 40% propan-1-ol and 0.2% dithiothreitol (insoluble glutenin-rich protein). Nitrogen content of protein solubility groups was determined from dry residues using an automated combustion nitrogen analyser. About 90% of the total protein in the flour was solubilised. Cross-contamination of protein fractions was evaluated by SDS-PAGE, SE-HPLC and RP-HPLC. Variation in nitrogen content of the protein solubility fractions was lowest for monomeric-rich protein (<2%) and insoluble glutenin-rich protein (<4%). Three wheats with similar high-molecular-weight (HMW) glutenin subunit composition, Alpha 16, Glenlea and Roblin, varied significantly (P ≤ 0.05) in the proportion of monomeric-rich and insoluble glutenin-rich protein in the flour. Dough rheological properties were directly related to the proportion of insoluble glutenin-rich protein and inversely related to the proportion of monomeric-rich protein. The protocol was validated using an expanded set of 11 wheats which also showed that inter-cultivar differences in the proportion of monomeric-rich, insoluble glutenin-rich protein and glutenin-to-gliadin ratio in the flour governed dough rheological properties such as mixograph, farinograph and microextension tests. The protocol has merit for quality screening in wheat-breeding programmes when the sample size is too small or when time constraints limit the ability to perform traditional rheological tests. For the Department of Agriculture and Agri-Food, Government of Canada,  Minister of Public Works and Government Services Canada

Cereal Chem. 76(1): [164][165][166][167][168][169][170][171][172] Flour dispersed in aqueous solutions of sodium dodecyl sulfate (SDS) forms a proteinaceous gel when centrifuged at high speed. The conventional methodology for SDS gel testing was modified to develop a smallscale (<1 g of flour or wheat meal) screening test for evaluation of the protein quality of wheat for breadmaking. The principal modification involved centrifugation with a swinging-bucket rotor to facilitate direct measurement of gel height, which is the primary test parameter. The effects of suspension temperature and time, centrifugation speed, sample size, and sieving of ground wheat or flour on the efficacy of the test were examined. Gel height, wet weight, and protein content were assessed as test parameters. In the standard test procedure that was developed, 0.67 g of flour or ground whole wheat was dispersed in 13.5 mL of 1.5% SDS solution for 15 min at 20°C, followed by centrifugation at 80,000 × g for 30 min. The test was evaluated using seven Canadian commercial wheat flours with diverse breadmaking quality. For the samples, gel height was strongly related to loaf volume (R 2 = 0.89 and 0.95 for flour and ground wheat, respectively). Sieving flour through a 75-µm sieve slightly increased the predictive power of the test (R 2 = 0.94). SDS gel height gave better discrimination of samples for prediction of loaf volume than did the traditional SDS sedimentation test. The performance of the sedimentation test improved when sieved ground wheat was used. The relationship between gel height or protein content and flour protein content was comparatively poor (R 2 = 0.25). The SDS gel test appears to primarily measure the effects of flour protein quality.

This study was conducted to evaluate the influence of kernel size and its potential interaction with genotype on durum wheat quality with emphases on kernel physical characteristics, milling performance, and color-related quality parameters. Wheat samples of seven genotypes, selected from the 2018 Canadian durum variety registration trial, were segregated into large (LK), medium (MK), and small-sized kernels (SK). In general, the kernel size greatly affected the durum wheat milling performance. Within a given size fraction, a strong impact of genotype was shown on the test weight of SK and the milling yields of MK and LK. Particularly, the MK fraction, segregated from the genotypes with superior milling quality, had a higher semolina yield than LK from the genotypes of inferior milling quality, inferring the importance of intrinsic physicochemical properties of durum kernels in affecting milling quality. SK exhibited inferior milling quality regardless of the genotypes selected. A strong impact of genotype was shown for the total yellow pigment (TYP) content and yellowness of semolina, while the kernel size had a significant impact on the brightness and redness of the semolina and pasta. Despite SK possessing much higher TYP, the semolina and pasta prepared from SK were lower in brightness and yellowness but with elevated redness.