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Thanhaeuser S.M.,Hans Dieter Belitz Institute For Mehl Und Eiweissforschung | Wieser H.,Leibniz Institute | Koehler P.,Leibniz Institute
Journal of Cereal Science | Year: 2015

Spectrophotometric and fluorimetric methods for quantitating quality-related parameters of wheat flour such as the gliadin (GLIA), glutenin (GLUT), and glutenin macropolymer (GMP) contents were adapted. The bicinchoninic acid (BCA) assay, the Bradford assay, the fluorescamine assay, the Naphthol Blue Black (NBB) assay, and the acid orange 12 assay were studied. Calibration functions were generated by using protein references isolated from a mixture of flours of 10 wheat cultivars. Among the assays studied, only the Bradford, the fluorescamine and the NBB assays provided useful results. The Bradford assay succeeded in quantitating the GLIA and GLUT fractions, but it was unsuitable for the GMP fraction because of the presence of SDS. All relevant protein fractions could be quantitated with the fluorescamine and the NBB assays. While the former showed higher coefficients of variation, the NBB assay was more reliable. NBB and HPLC data as well as NBB and micro-scale baking test data were strongly correlated. The NBB assay is a good alternative to chromatographic methods, which require time and sophisticated equipment. It can be adapted as easy-to-use, high throughput method that enables screening of a large number of flour samples for quality parameters in a short time per sample. © 2015 Elsevier Ltd. Source


Scherf K.A.,TU Munich | Pflaum T.,Leibniz Institute | Pflaum T.,Hans Dieter Belitz Institute For Mehl Und Eiweissforschung | Koehler P.,Leibniz Institute | And 2 more authors.
Food Hydrocolloids | Year: 2015

The perceived salt taste intensity of viscous solutions and gels of agar-agar and starches varying in their amylose/amylopectin ratio, as well as cellulose suspensions with fine, compact particles up to coarse, fibrous particles was systematically investigated. Saltiness intensity was correlated with instrumental-analytical data on viscosity, gel firmness, and sodium ion availability upon chewing. Salt taste perception was demonstrated to be dependent on the type and concentration of the polysaccharide. It was directly affected by viscosity, gel firmness, the mechanosensory perception of solid particles, and the rate of sodium release. On the one hand, sodium ion availability seemed to be a limiting factor determining salt taste perception in highly viscous and firm gel systems. On the other hand, texture-induced cross-modal interactions between taste and mechanosensory cues seem to play the key role impairing perceived taste impact at lower polysaccharide concentrations and, in particular, in the presence of solid particles. Intriguingly, solid particles that only minimally increased the viscosity drastically reduced perceived taste intensity, not only for saltiness, but also for sour, umami, and sweet tastes, with the exception of bitterness. These findings provide new knowledge on the impact of mechanosensation on taste perception. © 2015 Elsevier Ltd. Source


Thanhaeuser S.M.,Hans Dieter Belitz Institute For Mehl Und Eiweissforschung | Wieser H.,Leibniz Institute | Koehler P.,Hans Dieter Belitz Institute For Mehl Und Eiweissforschung | Koehler P.,Leibniz Institute
Cereal Chemistry | Year: 2014

The baking performance of a set of flours from 13 wheat cultivars was determined by means of two different microscale baking tests (10 g of flour each). In the micro-rapid-mix test the dough was mixed for a fixed time at a high speed, whereas the microbaking test used mixing to optimum dough consistency in a microfarinograph. Quality parameters such as sedimentation value, crude protein content, dough and gluten extension data, and microfarinograph data were also determined. Finally, quality-related protein fractions (gliadins, glutenins, SDS-soluble proteins, and glutenin macropolymer) were quantitated by extraction/HPLC methods with reversed-phase and gel-permeation columns. All quality parameters were correlated with the bread volumes of both baking tests. The results demonstrated that the microbaking test (adapted mixing time) was much more closely related to the quality parameters than the micro-rapid-mix test (fixed mixing time), which hardly showed any correlation. Among the standard quality parameters, only the crude protein content showed a medium correlation with the bread volume of the microbaking test (r = 0.71), whereas the contents of gliadins (r = 0.80), glutenins (r = 0.76), and glutenin macropolymer (r = 0.80) appeared to be suitable parameters to predict the baking performance of wheat flour. All other quality parameters were not or were only weakly correlated and unsuitable for predicting baking performance. © 2014 AACC International, Inc. Source


Koenig A.,Hans Dieter Belitz Institute For Mehl Und Eiweissforschung | Konitzer K.,Leibniz Institute | Wieser H.,Leibniz Institute | Koehler P.,Hans Dieter Belitz Institute For Mehl Und Eiweissforschung | Koehler P.,Leibniz Institute
Food Chemistry | Year: 2015

Wholemeal flours from 62 spelt and 13 wheat cultivars were studied. The quantitative protein compositions of the Osborne fractions determined by reversed-phase high-performance liquid chromatography, showed that the chromatograms of the reduced gliadin fractions were most suitable for the distinction of spelt from wheat and for the classification of spelt. The patterns of the reduced spelt gliadins showed one to three markers that were not present in wheat. Based on these markers, spelt cultivars were classified into three groups ranging from 'typical spelt' to 'similar to common wheat'. Marker 1 was identified as ω1,2-gliadin and markers 2, 3a and 3b were identified as γ-gliadins by means of N-terminal sequence analysis and determination of the relative molecular mass by mass spectrometry. As glutenin-bound ω-gliadins were present in wheat and absent in spelt, this protein type may be used to detect and quantitate small amounts of wheat in spelt products. © 2014 Elsevier Ltd. All rights reserved. Source

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