The accuracy of using near‐infrared spectroscopy (NIRS) for predicting 186 grain, milling, flour, dough, and breadmaking quality parameters of 100 hard red winter (HRW) and 98 hard red spring (HRS) wheat and flour samples was evaluated. NIRS shows the potential for predicting protein content, moisture content, and flour color b* values with accuracies suitable for process control (R2 > 0.97). Many other parameters were predicted with accuracies suitable for rough screening including test weight, average single kernel diameter and moisture content, SDS sedimentation volume, color a* values, total gluten content, mixograph, farinograph, and alveograph parameters, loaf volume, specific loaf volume, baking water absorption and mix time, gliadin and glutenin content, flour particle size, and the percentage of dark hard and vitreous kernels. Similar results were seen when analyzing data from either HRW or HRS wheat, and when predicting quality using spectra from either grain or flour. However, many attributes were correlated to protein content and this relationship influenced classification accuracies. When the influence of protein content was removed from the analyses, the only factors that could be predicted by NIRS with R2 > 0.70 were moisture content, test weight, flour color, free lipids, flour particle size, and the percentage of dark hard and vitreous kernels. Thus, NIRS can be used to predict many grain quality and functionality traits, but mainly because of the high correlations of these traits to protein content.

Cereal Chem. 75(3):374-379The baking properties of several genotypes of U.S. hard wheats grown in state nurseries for the Wheat Quality Council (WQC) were analyzed by the Hard Winter Wheat Quality Laboratory. Flours (250 mg) from each individual line and location were extracted three times with 50% 1propanol (1 mL) for 5 min each. Samples were vortexed continually during extraction. This method was effective in removing most monomeric proteins. Negligible detectable protein was found in the third extract. Significant amounts of polymeric glutenin were also extracted. Pellets were oven-dried (130°C) for 1 hr and analyzed for protein content using nitrogen combustion analysis. Protein remaining in the pellet consisted mainly of polymeric protein. The amount of gliadin and soluble polymeric protein could also be measured by separating the supernatant by size-exclusion chromatography. Good correlations between dough strength parameters and amounts of pellet protein and the relative amount of pellet protein (pellet protein/flour protein) were found for all samples. This procedure was simple and rapid, with the potential of analyzing large numbers of samples per day with good reproducibility.

Cereal Chem. 80(1): [52][53][54][55] Enzymes are good tool to modify wheat proteins by creating new bonds between the protein chains. In this study, the effect of the addition of glucose oxidase (GO) and transglutaminase (TG) on the wheat flour proteins is presented. The modification of wheat proteins was determined by analyzing the changes in gluten quality, alveograph parameters, and protein modifications. The amount of wet gluten increased with the addition of GO and TG, but the gluten quality was not improved in any case. Regarding the alveograph parameters, the effect of GO was readily evident obtaining wheat dough with higher tenacity and lower extensibility than the control, while TG led to doughs with lower tenacity and that were also less extensible. The protein modifications were characterized by free-zone capillary electrophoresis (FZCE). FZCE data indicated that TG polymerizes mainly glutenins and, of those, the high molecular weight glutenin subunits were the most affected. 2 Corresponding

Various whole‐kernel, milling, flour, dough, and breadmaking quality parameters were compared between hard red winter (HRW) and hard red spring (HRS) wheat. From the 50 quality parameters evaluated, values of only nine quality characteristics were found to be similar for both classes. These were test weight, grain moisture content, kernel size, polyphenol oxidase content, average gluten index, insoluble polymeric protein (%), free nonpolar lipids, loaf volume potential, and mixograph tolerance. Some of the quality characteristics that had significantly higher levels in HRS than in HRW wheat samples included grain protein content, grain hardness, most milling and flour quality measurements, most dough physicochemical properties, and most baking characteristics. When HRW and HRS wheat samples were grouped to be within the same wheat protein content range (11.4–15.8%), the average value of many grain and breadmaking quality characteristics were similar for both wheat classes but significant differences still existed. Values that were higher for HRW wheat flour were color b*, free polar lipids content, falling number, and farinograph tolerance. Values that were higher for HRS wheat flour were geometric mean diameter, quantity of insoluble polymeric proteins and gliadins, mixograph mix time, alveograph configuration ratio, dough weight, crumb grain score, and SDS sedimentation volume. This research showed that the grain and flour quality of HRS wheat generally exceeds that of HRW wheat whether or not samples are grouped to include a similar protein content range.

Uniaxial compression test for dough and several commercial products like jello, mozzarella cheese, cheddar cheese, tofu and sausage (cooked and uncooked) was performed using a texture analyzer (TA). Percent stress relaxation (%SR ), k1 (initial rate of relaxation), k2 (extent of relaxation) and relaxation time (RT) were calculated and compared for different products. The TA software was used to convert the raw SR data into a linear form. Constants k1 and k2 were determined from the intercept and slope of the linear data. Higher values of %SR and k2 (90 and 9, respectively) indicated higher elasticity for jello, whereas wheat flour dough samples showed the lowest values (20–30) for %SR and 1 to 2 for k2. The RT and k1 values were not good indicators for differentiating different products based on their viscoelastic behavior. Measurement of RT was limited by the maximum time for which the data were collected, whereas k1, because of its mathematical form, needed careful interpretation. In this study, %SR was found to be a good measure to interpret viscoelasticity of different food samples.

Free zone capillary electrophoresis conditions have been improved to allow rapid (2-8 min) separations of grain proteins from several cereals (wheat, oats, rice, barley, and rye) with high resolution and reproducibility. This new method utilized the isoelectric compound iminodiacetic acid (IDA) in conjunction with 20% acetonitrile and 0.05% hydroxypropylmethylcellulose. Cultivars of all cereals tested could be differentiated in 3 min, including wheat, using either prolamin or glutelin protein patterns. Resolution was similar to or higher than that of separations in other acidic buffers. Migration time repeatability was excellent with run-to-run variability <1% RSD, day-to-day <1.4% RSD, and capillary-to-capillary <3.3% RSD. Because larger inner diameter capillaries (50 microm) could be used with this buffer, sensitivity was improved and capillary rinse times could be reduced when compared to smaller capillaries (25 microm i.d.). This also served to reduce total separation time so that the majority of cereal storage protein from several types of cereals could be analyzed with total analysis times of 2-8 min with extremely high resolution and repeatability. This method would allow unattended, high-throughput ( approximately 180-400 samples/24 h) analysis of cereal proteins without the generation of much organic solvent waste as well as automated data analysis and storage.

Studies were conducted to produce faster, simpler, more rugged protocols for separating wheat proteins by high performance capillary electrophoresis (HPCE). Three areas were targeted for improvement: initial capillary equilibration procedures, buffer composition, and post-separation rinsing procedures. For the initial equilibration of capillaries, a brief rinse with a hydroxypropylmethylcellulose (HPMC) solution was the most critical factor for successful separation of wheat proteins. To reduce separation time and maintain resolution, beta-alanine and glycine were each used in place of sodium phosphate as buffer ions. Two isoelectric buffers, aspartic acid and iminodiacetic acid (IDA) were also tested. Each of these four buffer systems generated substantially lower currents, and provided faster separations, than sodium phosphate-based buffers. Finally, post-separation rinsing procedures were re-examined with the goal of reducing the time necessary to rinse the capillary after each separation. A critical factor in achieving this goal was removal of albumins and globulins prior to separation. These proteins bind to the capillary wall and cause rising baselines and excessive peak tailing. Once these proteins were removed, capillaries could be rinsed with buffer for only 2 min between separations. Capillary equilibration procedures were shortened from 90 min to 30 min. Likewise, separation times were reduced by approximately 40% (25 min to 15 min) by using glycine in place of sodium phosphate in the separation buffer. Finally, post-separation times were reduced by 80% (10 min to 2 min). Overall, these factors resulted in a reduction in total separation time of 50% (35 to 17 min) and maintained high resolution separations and good run-to-run repeatability.

No abstract