Effects of different milling processes on whole wheat flour quality and performance in steamed bread making

Physical properties and sensory evaluation of bread containing micronized whole wheat flour

The aim of this study was to evaluate the potential use of micronized whole wheat flours in breadmaking. The micronization process was achieved by a jet mill and flours (JF) of particle size, ranged from 17 to 84 μm, were used. According to the particle size of the JF, the amount of water added to dough changed and ranged from 77 to 84% as it was calculated in farinograph experiments. JF breads had higher bread yield, firmer crumb, higher elasticity, lower porosity and darker bread color compared to control whole wheat bread. Overall a lower particle size of JF resulted in a close structure of bread. According to sensory evaluation, difference among samples was difficult to perceive. During storage JF bread presented lower limiting firmness potential. After all, there is evidence that jet milled flour determined bread physical characteristics and further storage stability.

Effects of Millet Bran Dietary Fiber and Millet Flour on Dough Development, Steamed Bread Quality, and Digestion In Vitro

Twenty-five percent of steamed millet flour (MF) and different contents of dietary fiber (DF) were added to wheat flour (WF). The results showed that 25% of steamed MF and DF had significant effects (p < 0.05) on dough farinographical and tensile properties. With the increase of DF content, the hardness of the steamed bread increased, the elasticity decreased significantly, and the sensory acceptability decreased. The results of digestion showed that the content of rapidly digested starch (RDS) and slowly digested starch (SDS) in MF steamed bread decreased with the increase of DF, while resistant starch (RS) increased. Meanwhile, the starch hydrolysis rate, hydrolysis index (HI), and glycemic index (GI) decreased significantly (p < 0.05), and protein digestibility decreased gradually. Comprehensive evaluation showed that the 2% DF sample had good sensory performance and medium GI, which is beneficial to the control of blood sugar levels. These good functional properties could meet the requirements of a healthy diet.

Small and large strain rheology of gluten and gluten-starch doughs containing wheat bran dietary fiber

BACKGROUND

The small and large strain rheology of gluten (G) and gluten-starch (G + S) doughs containing wheat bran dietary fiber (WBDF) were investigated.

RESULTS

At the small strain stage, i.e. frequency and strain sweep tests, the doughs containing high WBDF concentration are more vulnerable and unstable, as indicated by the lower dough linear viscoelastic strain limit as well as the higher slope of elastic modulus. However, the elastic nature of doughs remarkably increased upon WBDF addition, indicating the reinforcement of the dough mechanical strength, which is also confirmed by the large strain test wherein the maximum strain significantly decreased from 4.37 to 1.82 for the G system and from 12.09 to 2.72 for the G + S system. The creep recovery test showed that WBDF induced the reduction in the strain of the doughs at a fixed stress, which may be related to the enhanced strain hardening capacity.

CONCLUSION

The addition of WBDF resulted in more brittle and unstable doughs with undesirable higher mechanical strength. The presence of starch greatly weakened the dough strength and led to inferior resistance to both small and large deformations. These findings confirmed the impairment of dough viscoelasticity upon addition of WBDF. © 2019 Society of Chemical Industry.

Whole-wheat flour particle size influences dough properties, bread structure and in vitro starch digestibility

Whole-wheat flour (WWF) particle size is critical to dough properties, bread quality, and in vitro starch digestibility of bread.

Comparative Study on the Bread Making Quality of Normoxia- and Hypoxia-Germinated Wheat: Evolution of γ-Aminobutyric Acid, Starch Gelatinization, and Gluten Polymerization during Steamed Bread Making

To explore the bread making characteristics of germinated wheat flour, the current study focused on the componential evolution throughout the steamed bread making process. Hypoxia-germinated wheat (HGW) dough produced the maximum γ-aminobutyric acid as a result of high glutamic acid decarboxylase activity during fermentation compared to normoxia-germinated wheat (NGW) and sound wheat (SW). HGW was superior to NGW in terms of rheological properties and restored the organoleptic characteristics as SW bread. Blocking of α-amylase activity and protein polymerization demonstrated that the decline in pasting and gelation properties was not caused by changes in intrinsic starch and protein properties. Polymerization of α- and γ-gliadin to glutenin was facilitated in germinated wheat bread, while the cross-linking degree of glutenin-gliadin was suppressed. In comparison to NGW bread, more high-molecular-weight glutenin subunits but less α-gliadin fractions polymerized upon steaming of HGW dough. Results demonstrate that HGW has great potential to be exploited as a nutritious functional ingredient for wheat-based food.

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.

Effects of Fermented Wheat Bran on Flour, Dough, and Steamed Bread Characteristics

Wheat bran is rich in dietary fiber, which improves the flour nutritional content and also endows the flour with a richer flavor. However, a high content of insoluble dietary bran fiber can easily and significantly reduce the processing and edible quality of flour products. This study was conducted to explore ways to decrease the negative effects of adding bran to dough. Basidiomycete strain BS-01 was used to ferment the wheat bran. The surface structure of the bran was examined by scanning electron microscopy, and the fermented bran was incorporated into the wheat flour at various concentrations. The mixed flour farinographic and extensographic characteristics, dough rheological properties, and the specific volume, color, and textural properties of the steamed bread were determined and analyzed. The results suggested that adding an appropriate quantity of fermented bran improves the characteristics of the dough and the quality of the steamed bread compared to those with unfermented bran. The fermented bran effectively decreased the negative impacts exerted on the farinographic and extensographic characteristics of the mixed flour and exerted a positive influence on the dough viscoelasticity and bread specific volume.

Effects of microwave heating of wheat on its functional properties and accelerated storage

The effect of microwave heating wheat grains (700 W for 0-60 s) on gluten, farinograph, pasting properties and baking (steamed bread and biscuit) of flour was studied. The lipase (LA) and lipoxygenase (LOX) activities of the microwave-treated wheat were monitored, and the accelerated storage at 35 °C of whole wheat flour was also investigated. The results showed that the gluten, farinograph properties and viscosity were influenced to a small extent when microwave treatment time was less than or equal to 20 s and the temperature of the grains was less than or equal to 56 °C. Texture profile analysis indicated that steamed bread made from wheat treated by microwave for 20 s was softer and of better quality. Microwave treatment for longer periods (≥30 s) increased the temperature ≥68 °C, that damaged the gluten and made wheat unsuitable for making steamed bread; however, suitable for making food with lower gluten requirements, such as biscuits. The results obtained from enzyme activity and accelerated storage experiments demonstrated that microwave treatment could inactivate LA and LOX and extend the shelf-life.