The Effects of Transglutaminase and Refrigerated Storage on the Physicochemical Properties of Whole Wheat Dough and Noodles

This study investigated the effects of transglutaminase (TG) concentrations (0, 0.1% and 1%) on the physicochemical properties of whole wheat dough (WWD) and noodles (WWN) during refrigerated storage (0, 1, 2, and 3 days). The yield, ferulic acid (FA) content, molecular weight (Mw), and apparent viscosity (AV) of water extractable arabinoxylan (WEAX) from refrigerated WWDs were analysed. The WEAX yield and FA tended to increase with refrigerated storage, while the Mw decreased. WEAX FA of from WWD with TG tended to be smaller than the control during refrigeration. The AV for all WEAXs gradually decreased during refrigeration. The TG concentration effects on WWD resistance to extension and extensibility and the WWN cooking properties and texture profile analysis (TPA) were studied. The water absorption and swelling index tended to decrease in WWNs with TG depending on refrigeration time compared to the control samples. The TPA results showed that WWNs with TG were significantly harder than the control after two days of refrigeration. This study demonstrated that TG affected not only WWD composition but also WWN physical properties during refrigerated storage.

A Cross between Bread Wheat and a 2D(2R) Disomic Substitution Triticale Line Leads to the Formation of a Novel Disomic Addition Line and Provides Information of the Role of Rye Secalins on Breadmaking Characteristics

A bread wheat line (N11) and a disomic 2D(2R) substitution triticale line were crossed and backrossed four times. At each step electrophoretic selection for the seeds that possessed, simultaneously, the complete set of high molecular weight glutenin subunits of N11 and the two high molecular weight secalins of rye, present in the 2D(2R) line, was carried out. Molecular cytogenetic analyses of the BC₄F₈ generation revealed that the selection carried out produced a disomic addition line (2n = 44). The pair of additional chromosomes consisted of the long arm of chromosome 1R (1RL) from rye fused with the satellite body of the wheat chromosome 6B. Rheological analyses revealed that the dough obtained by the new addition line had higher quality characteristics when compared with the two parents. The role of the two additional high molecular weight secalins, present in the disomic addition line, in influencing improved dough characteristics is discussed.

Effects of Milling Methods and Cultivars on Physicochemical Properties of Whole-Wheat Flour

The aim of the present study was to investigate the influence of milling methods (jet mill (JM) and hammer mill (HM)) and wheat cultivars (Keumkang (K), Jokyung (J), and Anzunbaengi (A)) on physicochemical and dough properties of whole-wheat flour (WWF). The color, particle size, starch damage (SD), falling number (FN), water absorption index (WAI), water solubility index (WSI), pasting and Mixolab® properties, and dough extensibility of WWF were measured. Significant differences were observed in proximate compositions as well as in color, particle size, FN, and WAI between the distinct milling methods and cultivars (p<0.001). The particle sizes of each cultivar milled with a HM (K: 188.5 µm; J: 115.7 µm; A: 40.34 µm) were larger than those milled with a JM (K: 41.8 µm; J: 50.7 µm; A: 20.8 µm). The final viscosity of WWF milled with a HM (K: 1304 cP; J: 1249 cP; A: 1548 cP) was higher than that of cultivars milled with a JM (K: 1092 cP; J: 1062 cP; A: 994 cP). Dough extensibility and resistance to extension also differed among the cultivars, and the C2 Mixolab® parameter (an indicator of protein weakening) was influenced by the milling method. Overall, results from principal component analysis showed that, among the three cultivars, Keumkang WWF was the most affected by the milling method.

The impact of yeast fermentation on dough matrix properties

BACKGROUND

Most studies on dough properties are performed on yeastless dough to exclude the complicating, time-dependent effect of yeast. Baker's yeast, however, impacts dough matrix properties during fermentation, probably through the production of primary (CO2 and ethanol) and secondary (glycerol, acetic acid and succinic acid) metabolites. The aim of this study is to obtain a better understanding of the changes in yeasted dough behavior introduced by fermentation, by investigating the impact of yeast fermentation on Farinograph dough consistency, dough spread, Kieffer rig dough extensibility and gluten agglomeration behavior in a fermented dough-batter gluten starch separation system.

RESULTS

Results show that fermentation leads to a dough with less flow and lower extensibility that breaks more easily under stress and strain. The dough showed less elastic and more plastic deformation behavior. Gluten agglomerates were smaller for yeasted dough than for the unyeasted control.

CONCLUSION

These changes probably have to be attributed to metabolites generated during fermentation. Indeed, organic acids and also ethanol in concentrations produced by yeast were previously shown to have similar effects in yeastless dough. These findings imply the high importance of yeast fermentation metabolites on dough matrix properties in industrial bread production. © 2015 Society of Chemical Industry.

Determination of the optimum mixture of transglutaminase, l-ascorbic acid and xylanase for the quality and consumer acceptability of bread using response surface methodology

The optimum levels of transglutaminase (TGase), l-ascorbic acid (l-AA), and xylanase (Xyl) were determined using response surface methodology to improve quality and consumer acceptability of bread made with wheat flour. A Box-Behnken design with three independent variables (TGase, l-AA, and Xyl) and three levels was used to develop models for the different responses (peak time, mixing tolerance, extensibility, resistance, specific volume, hardness, and consumer acceptability). Overall, l-AA and Xyl improved dough and bread properties, whereas the addition of TGase positively affected to texture and overall acceptability by consumer test. The optimal formulation for dough and bread properties and consumer acceptability were identified and the optimal value was 0.36 g/100 g TGase, 0.026 g/100 g Xyl, and 0.005 g/100 g l-AA. The results demonstrate that the addition of optimum amounts of TGase, Xyl, and l-AA improves the baking quality of the flour by enhancing dough properties and increase the consumer acceptability of the bread.

Glycerol production by fermenting yeast cells is essential for optimal bread dough fermentation

Glycerol is the main compatible solute in yeast Saccharomyces cerevisiae. When faced with osmotic stress, for example during semi-solid state bread dough fermentation, yeast cells produce and accumulate glycerol in order to prevent dehydration by balancing the intracellular osmolarity with that of the environment. However, increased glycerol production also results in decreased CO2 production, which may reduce dough leavening. We investigated the effect of yeast glycerol production level on bread dough fermentation capacity of a commercial bakery strain and a laboratory strain. We find that Δgpd1 mutants that show decreased glycerol production show impaired dough fermentation. In contrast, overexpression of GPD1 in the laboratory strain results in increased fermentation rates in high-sugar dough and improved gas retention in the fermenting bread dough. Together, our results reveal the crucial role of glycerol production level by fermenting yeast cells in dough fermentation efficiency as well as gas retention in dough, thereby opening up new routes for the selection of improved commercial bakery yeasts.

Effect of high molecular weight glutenin subunit composition in common wheat on dough properties and steamed bread quality

BACKGROUND

Steamed bread is a popular staple food in Asia with different flour quality requirements from pan bread. Little is known about how glutenin characteristics affect steamed bread quality. This work investigated how deletions of high-molecular-weight glutenin subunits (HMW-GS) influence gluten properties and Chinese steamed bread quality using 16 wheat lines grown in Texas.

RESULTS

Although similar in protein content (134-140 mg g⁻¹), gluten composition and dough properties differed widely among the lines. Compared with non-deletion lines, deletion lines had lower (P < 0.05) unextractable polymeric protein (294 vs 470 mg g⁻¹), HMW-GS/low-molecular-weight glutenin subunit ratio (0.25 vs 0.41), dough force to extend (0.16 vs 0.44 N) and mixing peak time (2.03 vs 4.52 min). Deletion lines with HMW-GS composition of 2*/17+_/5+_ and 2*/17+_/2+12 showed moderate gluten strength (mixing peak time, 1.96-2.94 min; force to extend, 0.18-0.23 N) and high dough extensibility (106-129 mm). These lines also produced good steamed bread quality (score, 60.8-65.0) with good elasticity and crumb structure.

CONCLUSION

Deletion at Glu-B1y and/or Glu-D1y loci in high-strength hard wheat produced good dough properties for steamed bread. This suggests that wheat functionality for steamed bread can be improved by manipulating HMW-GS composition.

Ethanol at levels produced by Saccharomyces cerevisiae during wheat dough fermentation has a strong impact on dough properties

Yeast's role in bread making is primarily the fermentative production of carbon dioxide to leaven the dough. Fermentation also impacts dough matrix rheology, thereby affecting the quality of the end product. Surprisingly, the role of ethanol, the other yeast primary metabolite, has been ill studied in this context. Therefore, this study aims to assess the potential impact of ethanol on yeastless dough extensibility and spread and gluten agglomeration at concentrations at which it is produced in fermenting dough, i.e., up to 60 mmol per 100 g of flour. Reduced dough extensibility and dough spread were observed upon incorporation of ethanol in the dough formula, and were more pronounced for a weak than for a strong flour. Uniaxial and biaxial extension tests showed up to 50% decrease in dough extensibility and a dough strength increase of up to 18% for 60 mmol of ethanol/100 g of flour. Ethanol enhanced gluten agglomeration of a weak flour. Sequential extraction of flour in increasing ethanol concentrations showed that better gluten-solvent interaction is a possible explanation for the changed dough behavior.