maximumresistance of a slab reinforced with new system is determined as: (4) V R d , max , PLUS = V R d , max , ETA + ∑ V R d , dow 2 . The punching resistance V Rd, max, ETA is calculated from Eq. (3) . The V Rd, dow is the shear
The rheological properties of seven winter wheat cultivars from two harvest years were studied. Rheological testing included two empirical rheological methods, alveograph and extensograph. Principal component analysis on the studied rheological parameters showed that the alveograph and extensograph parameters are influenced by entirely different factors. The first component was responsible solely for the extensograph parameters, primarily for the resistance properties of dough samples. The second component affected the extensograph extensibility (E) and alveograph tenacity (P) parameters as well, in spite of the fact that these parameters refer to different properties of dough. The third component explained only alveograph parameters, such as P, L and G values. The Pearson’s correlation coefficients showed that the extensograph area parameter primarily depends on the maximum resistance to extension of dough (r=0.91). The extensibility and resistance at a constant extension of 5 cm properties did not show such strong relationship with the area parameter (r=0.56 and 0.65, respectively). The relationship between the extensograph maximum resistance and extensibility parameters was positive (r=0.20), while the correlation coefficient between alveograph P and L value was negative (r=0.34).
Authors:D. Horvat, V. Spanic, K. Dvojkovic, G. Simic, D. Magdic, and A. Nevistic
Under artificial Fusarium infection the total glutenin content determined by chromatographic (RP-HPLC) method was significantly reduced in comparison to gliadins which were increased. Among protein types, α-GLI and HMW-GS were the highest affected. Artificial Fusarium infection significantly increased GLI/GLU ratio when compared with the natural infected samples. Artificial Fusarium infection dramatically decreased the dough mixing tolerance and had a considerable negative effect on dough energy, maximum resistance, and resistance/extensibility ratio. Disturbed GLI/GLU ratio and an increased amount of mycotoxin DON under artificial Fusarium infection showed a strong negative impact on affected functional properties of dough and bread. Total and γ-GLI as well as GLI/GLU ratio were significantly positively affected by mycotoxin DON in contrast to total GLU, HMW-GS and LMW-GS which were negatively affected. Results indicated that the stability of baking quality parameters of cultivars more tolerance to the Fusarium infection can be well define by lower accumulation of mycotoxin DON.
Two lines, L-19-613 and L-19-626, were produced from the common wheat cultivar Longmai 19 (L-19) by six consecutive backcrosses using biochemical marker-assisted selection. L-19 (Glu-D1a, Glu-A3c/Gli-A1?; Gli-A1? is a gene coding for unnamed gliadin) and L-19-613 (Glu-D1d, Glu-A3c/Gli-A1?) formed a set of near-isogenic lines (NILs) for HMW-GS, while L-19-613 and L-19-626 (Glu-D1d, Glu-A3e/Gli-A1m) constituted another set of NILs for the LMW-GS/gliadins. The three L-19 NILs were grown in the wheat breeding nursery in 2007 and 2008. The field experiments were designed using the three-column contrast arrangement method with four replicates. The three lines were ranked as follows for measurements of gluten strength, which was determined by the gluten index, Zeleny sedimentation, the stability and breakdown time of the farinogram, the maximum resistance and area of the extensogram, and the P andWvalues of the alveogram: L-19-613 > L-19-626 > L-19. The parameters listed above were significantly different between lines at the 0.05 or 0.01 level. The Glu-D1 and Glu-A3/Gli-A1 loci had additive effects on the gluten index, Zeleny sedimentation, stability, breakdown time, maximum resistance, area, P and W values. Although genetic variation at the Glu-A3/Gli-A1 locus had a great influence on wheat quality, the genetic difference between Glu-D1d and Glu-D1a at the Glu-D1 locus was much larger than that of Glu-A3c/Gli-A1? and Glu-A3e/Gli-A1m at the Glu-A3/Gli-A1 locus. Glu-D1d had negative effects on the extensibility and the L value compared with Glu-D1a. In contrast, Glu-A3c/Gli-A1? had a positive effect on these traits compared with Glu-A3e/Gli-A1m.
In bread making the wheat dough undergoes some degree of deformation in each step of the process. It is generally accepted that the baking properties of wheat flour dough are mainly due to the viscoelasticity of the gluten protein. Measurement of the rheological properties of dough gives valuable information concerning the quality of the wheat flour, the machining properties of the dough and the textural characteristics of the finished products. This technique uses a new apparatus (wheat gluten quality analyser&WGQA, C HANG, 1994) especially developed to evaluate the rheological properties of gluten by measuring the following parameters: resistance to extension (newton), extensibility (mm) and energy (joule). The test realized with the apparatus WGQA was carried out on wheat gluten isolated according to the A.A.C.C. (1995) method. Results obtained using the new technique showed high levels of correlation for maximum resistance to extension (R 2 =0.9018) and energy (R 2 =0.8824) between WGQA and standardized parameters obtained from Brabender Extensograph.
Authors:D. Horvat, Z. Jurković, G. Drezner, G. Šimić, D. Novoselović, and K. Dvojković
The gluten proteins of 15 winter wheat cultivars grown in eastern Croatia were studied for their contribution to the bread-making quality. Composition of high-molecular-weight glutenin subunits (HMW-GS) was analyzed by SDS-PAGE, while the quantity of gluten proteins was determined by combined extraction/RP-HPLC procedure. The results of the linear correlation analysis carried out on the particular gluten proteins and technological properties showed that the amount of total gluten content highly correlates with protein content. Among gluten proteins, the glutenins showed higher correlation with protein content, with pronounced influence of HMW-GS, than gliadins. Wet gluten content was significantly correlated to total gliadin quantity. Gluten index as gluten quality parameter was positively influenced by total glutenins and low-molecular-weight glutenin subunits (LMW-GS), and negatively, by the ratios of gliadin to glutenin (Gli/Glu), whereas the amount of gliadins was not important. Dough development time was strongly correlated with total gluten content, total glutenins and the Gli/Glu ratio. Dough mixing resistance was strongly affected by total glutenin content with pronounced influence of HMW-GS. Degree of dough softening is mainly negative influenced by total glutenins and ratio of Gli/Glu. Farinograph quality number as flour quality index was highly positively correlated with total glutenins, with emphasized influence of HMW-GS. The Gli/Glu ratio had the highest influence on dough maximum resistance. Dough extensibility showed moderate correlation with total gliadins. The results of the linear correlation indicated that loaves volumes were significantly influenced by total gluten proteins, HMW-GS and LMW-GS.
concrete is shown in Fig. 7 . The maximumresistance to penetration of acids was observed at 15% replacement of SF for both M25 and M40 grades of concrete. Upon increase in the percentage of the SF, the rate of resistance to acid penetration was reduced