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The contribution of starch granules to the baking properties of frozen dough bread has been investigated using reconstituted dough method. The baking and aging characteristics of frozen dough bread were studied by texture analyzer, colorimeter, DSC, FTIR and LF-NMR. Results showed that starch had more impact on bread than gluten in specific volume of frozen dough bread, while gluten contributed more in color and cell density of frozen dough bread crumb during 8-weeks frozen storage. The changes of hardness mainly contributed to starch deterioration in first 4 weeks, then it was dominated by gluten in the later 4–8 weeks. A-Type granules have more effect on texture properties, number of cells and enthalpy of frozen dough bread during storage. B-Type granules contributed more on the size of cells in bread. The main aging change of wheat starch in profiles of bread was provided by A-Type granules during frozen storage. [Display omitted] • Wheat starch affect more on specific volume while gluten controls cell density of bread. • The hardness of frozen dough bread is determined by starch in early stage then by gluten. • A-Type granules affect the number of cells in bread, B-Type granule affect the size in them. • ●The main staling change of wheat starch in bread was provided by A-Type granules. [ABSTRACT FROM AUTHOR]

Effects of kneading time (3–11 min) on properties of dough and quality and volatile compounds of Chinese steamed bread (CSB) were investigated. Rheological analysis showed that increasing kneading time induced less elastic and more viscous dough. CSB-7 min (dough kneaded for 7 min) exhibited the largest specific volume and cell porosity. Kneading induced the development of aroma-active compounds i.e. 2-pentylfuran and short-chain aldehydes. These aroma-active compounds were probably arisen from lipid oxidation with a combination of the hydroperoxides decomposition and the degradation of long-chain aldehydes (octanal, nonanal, decanal and (E)-2-nonenal). Sensory analysis indicted that CSB-9 min got the highest score for its aroma. Results indicated that the optimal kneading time to obtain CSB with highest texture quality was inconsistent to that with best aroma. Further efforts should be paid to deal with the problem. The current study was beneficial for understanding the critical role of dough kneading on CSB quality and volatile compounds. • Effects of kneading time on dough and CSB aroma and quality were investigated. • Long chain aldehydes rapidly decreased with the increasing kneading time. • Short chain aldehydes increased during dough kneading. • High lipoxygenase activity caused lipid oxidation. • Nonanal, (E)-2-nonenal and decanal were related with the raw-flour aroma. [ABSTRACT FROM AUTHOR]

Depolymerization of glutenin macropolymers (GMP) widely exists in the frozen dough with little effort in elucidating its effects on steamed bread quality. To clarify this, GMP was fractionated from wheat flour and reconstituted to yeast and chemical leavened dough (YLD/CLD). Results showed that with supplementary GMP fraction, depolymerization degree was alleviated in frozen dough. The bread quality loss from freezing was partially counteracted along with better preserved GMP content. Both of dough elasticity and gas retention capability were enhanced in GMP-enriched frozen dough. Gassing power in frozen YLD decreased while remained constant in CLD. Addition of GMP did not affect the gassing power, which allowed interpreting the improved bread qualities from the enhanced dough elasticity and gas retention capability. Based on the improved facts of frozen steamed bread dough quality with additional GMP fractions, this study revealed the pivotal role of GMP depolymerization on the frozen steamed bread dough quality. [ABSTRACT FROM AUTHOR]

Effect of pigskin-originated gelatin on dough properties and bread characteristics, especially on bread staling was investigated in terms of starch retrogradation and water migration in the present study. Results showed that gelatin significantly improved bread qualities during storage. Compared with the control, 7-day staling rate of bread containing 0.5% and 1.0% gelatin decreased by 6.56% and 20.83% respectively, indicating gelatin retarded the staling process of bread. This retardation effect was related to starch retrogradation and water migration. The relative crystallinity decreased from 15.12%, 11.60% to 10.75%, which demonstrated the alleviation effect of amylopectin crystallization. Bread samples containing 1.0% gelatin had the lowest retrogradation enthalpy of 2.93 ± 0.24 J/g followed by 0.5% gelatin bread and the control group, further indicating that gelatin may induce less water available to form crystal lattice and restrict the migration of starch molecules. The 5-day moisture loss rate for the control group was highest with the values of 12.39%, which was 1.43% and 1.83% higher than that of bread with 0.5% gelatin and 1.0% gelatin, respectively. Water activity and T 2 relaxation results provided the information that gelatin inhibited water migration upon storage and gelatin interacted with bread components. However, the effect of gelatin on improving bread quality and retarding staling could not be reflected by the dough properties measured through farinograph, extensograph and rheometer. This study suggested gelatin from pigskin had great potential to be served as an effective bread improver. Image 1 • Gelatin enhanced the bread qualities significantly, especially retarding the staling process. • Gelatin hindered the chain reassociation of starch molecules during storage. • Gelatin interacted with bread components and restricted water transfer. • Dough properties showed gelatin might to some extent weaken the gluten network. [ABSTRACT FROM AUTHOR]

Highlights • The acidified bread showed higher volume, lower moisture content and lower hardness. • Gluten network weakened and yeast activity enhanced in chemical acidified doughs. • Proteins and starches in acidified doughs showed varying degrees of hydrolysis. • Hydrolysis of proteins and starches mainly occurred after dough mixing. • Proteolysis and amylolysis basically depended on types of organic acids. Abstract This study aimed to improve the bread quality by adding acetic acid, lactic acid, malic acid, fumaric acid and citric acid to its ingredients. The underlying mechanism was explored through the changes in the yeast activity, proteolysis and amylolysis. All organic acids gave bread a higher specific volume, a lower moisture content, a lower pH value and a decreased hardness. Moreover, the yeast activity was enhanced, whereas the gas retention capability decreased in acidified doughs. Organic acids also reduced the molecular weight of proteins and starches, which led to the increase of NH 2 , free SH and reducing sugar contents. These changes were the most significant in the dough with 0.3% fumaric acid. Proteolysis and amylolysis mainly occurred after dough mixing and depended on the types of acids present in the mixture. Nevertheless, the cleavage of disulfide bonds in gluten might rest with the H+ concentration in the dough system. [ABSTRACT FROM AUTHOR]

Abstract The aim of this study was to compare effects of linear dextrans (backbones of α-(1 → 6) linkages) varying with weight-average molecular weights (Mw: T10, T70, T250, T750, T2000) on the quality of wheat breads. The firmness of fresh bread crumb was decreased with increasing dextran Mw and the highest Mw dextran (T2000) lowered the staling rate of stored breads. Dough rheology clarified that only the specific dextran (T70) apparently changed dough viscoelastic, strengthening the viscous behavior. Significant decreases in breakdown and setback viscosity of starch slurry were observed by addition of dextrans, especially dextran T2000. Analyses in the long-term retrogradation of starch and starch-gluten systems indicated that the promising antistaling influence of dextran T2000 was caused by either inhibitions of amylopectin retrogradation or beneficial variations induced by gluten. Positive effects of starch-gluten and dextran-gluten associations on amylopectin retrogradation were revealed. These results suggested that the highest Mw dextran (T2000) possessed the potential for increasing consumer acceptance of bread products. Highlights • Dextran T2000 decreased the formation of amylose crystallites. • Dextran T2000 inhibited amylopectin recrystallization. • Retardation of dextrans on the long-term retrogradation of amylopectin was highlighted by gluten. • Starch-gluten and dextran-gluten associations played a powerful role in amylopectin reordering. [ABSTRACT FROM AUTHOR]

The present study comparatively evaluated the evolution of yeast and chemical leavened steamed bread dough (YLD/CLD) quality during freeze/thaw (FT) cycles. The steamed bread quality of CLD was more freeze-stable than that of the YLD after 3 FT cycles. Decreased yeast viability contributed to the loss of gassing power in YLD while no significant differences were observed for CLD during FT cycles. However, faster gas release rate in frozen CLD indicated gas retention loss due to the distortion of gluten network. Glutenin macropolymers (GMP) depolymerization via breakage of inter-chain disulfide (SS) bonds and conversions of α-helix and β-turn to β-sheet structures were the main indicators of gluten deterioration. Gluten network was more vulnerable in frozen YLD, resulting in detectable loss of viscoelasticity. The results suggested that supplement of chemical leavener contributed to a more freeze-tolerant gluten network besides its stable gassing power. [ABSTRACT FROM AUTHOR]

Flavourzyme is a commercial peptidase, mainly with exopeptidase activity. In this study, effects of Flavourzyme addition (0–0.16 g/100 g) on properties of wheat dough and bread were systematically studied. Bread with a low concentration (0.01–0.08 g/100 g) of Flavourzyme addition had a large specific volume and soft texture with a uniform cell structure. The optimal Flavourzyme content was 0.04 g/100 g and the specific volume increased from 3.9 mL/g to 4.4 mL/g, the hardness decreased from 21.7 N to 13.3 N. The gas production capacity of yeast increased with low concentrations of Flavourzyme addition, promoting dough expansion. Flavourzyme had a clear hydrolysis effect on wheat gluten in dough and caused the depolymerization and unfolding of gluten structure, thus decreasing the strength and viscoelasticity of dough. Confocal laser scanning microscopy and scanning electron microscopy results further revealed that a low concentration of Flavourzyme had a slight effect on gluten. However, the gluten structure became discontinuous and open, which made the dough easily collapsed during fermentation, resulting in poor bread quality with high Flavourzyme content. The positive effects of appropriate amount of Flavourzyme addition on dough and bread properties indicated the potential of Flavourzyme as a bread improver by substituting chemical additives. • Moderate amount of Flavourzyme addition improved the quality of bread significantly. • The optimal addition of Flavourzyme is 0.04 g/100 g (based on wheat flour). • Dough expansion was enhanced with moderate Flavourzyme addition. • Moderate Flavourzyme addition did not cause obvious damage to gluten network. [ABSTRACT FROM AUTHOR]

Abstract: In this study, a glucose oxidase (GOX), papain and xylanase combination was developed for fresh whole wheat dough for both browning inhibition and rheological improvement. Measurements of carotenoids extracted from enzyme-treated doughs showed that 0.001% (w/w) GOX could catalyze the oxidization of 40.0% carotenoids and thus cause a decrease of browning index (BI) by 5.20 during dough preparation. For 24 h browning inhibition, 0.010% (w/w) xylanase and papain individuals were able to separately act on the phenolic compounds and polyphenol oxidase, leading to lower BI rises (5.36 and 7.04, respectively) of doughs as compared to the BI rise (13.53) of the control dough; however, 0.020% GOX caused a higher BI rise (16.60) than control although it made BI decrease by 6.34 at 0 h. Rheological investigations on enzyme-treated doughs revealed that both xylanase and papain led to decreases of elastic (G′) and viscous modulus (G″) of doughs while GOX caused increases of G′ and G″. Therefore, an optimal combination composed of 0.010% (w/w) xylanase, 0.005% (w/w) papain and 0.002% (w/w) GOX was carried out using orthogonal experimental design by comparing BI rises in 24 h, which was also proved as a rheological improver for fresh whole wheat dough. [Copyright &y& Elsevier]

The magnetic field is an emerging physical method used for food preservation, characterized by its high penetrability in food materials. The effect of a static magnetic field (MF, 2 mT) on frozen dough upon freeze-thaw treatments (3, 7, and 10 cycles) was investigated, with conventional freeze-thaw (CF) treatments being used as control. Results showed that the magnetic field ensured the baked bread made from dough a 17.59% larger specific volume and a 30.87% smaller crumb hardness. It accelerated the time for the dough to pass through the maximum ice crystal formation zone by 7 min and reduced the ice melting enthalpy from 63.55 J/g to 56.67 J/g after 10 freeze-thaw cycles. Nuclear magnetic resonance analysis suggested that the conversion of bound water to immobilized water and free water was inhibited. The yeast viability and activity were also better maintained, precisely as the observed increase of 18.18% and 42.23% in its survival and gassing power. After 10 freeze-thaw cycles, the free disulfide (SH) content was determined to be 1.642 μmol/g for CF doughs and 1.624 μmol/g for MF ones, respectively. A reduction of 24.26% in glutenin macropolymer depolymerization was achieved, indicated a more stable gluten structure under the magnetic field. [Display omitted] • Magnetic field improved the quality of frozen dough bread. • Lower depolymerization degree was detected in gluten using magnetic field. • Yeast survival and gassing power were better preserved under magnetic field. • Magnetic field inhibited water migrations and status change. [ABSTRACT FROM AUTHOR]

Reduced glutathione (GSH), released from lysed yeast cells, is well-known for weakening dough structure. However, its influence on bread texture and staling has not yet been completely elucidated. Herein, this study aims at assessing the effects of GSH on dough properties and bread quality, especially bread staling, using Rheofermentometer analysis, texture profile analysis (TPA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and low-field nuclear magnetic resonance (LF-NMR). The results revealed that GSH substantially decreased the dough height and gas-retention capacity during fermentation. The weakened dough structure was attributed to GSH-induced disulfide bond cleavage in gluten proteins and the depolymerization of glutenin polymers. The addition of 0.005%–0.01% GSH resulted in acceptable bread quality. However, bread supplemented with 0.015%–0.03% of GSH exhibited a coarser and more open crumb microstructure, as well as high level of hardness and low resilience during aging. GSH promoted crumb water loss and drove the water shift from the immobilized to the bound state. The DSC and XRD analyses further confirmed that GSH promoted starch retrogradation and recrystallization. These results suggest that apart from the gluten structure, GSH also altered gluten−starch interactions and water redistribution, ultimately decreasing bread quality and accelerating bread staling. Image 1 • Glutathione depolymerized protein and weakened gas retention capacity. • Glutathione decreased loaf volume and bread resilience, and increased hardness. • Moisture content decreased and water became less mobile with glutathione. • A coarser porous bread crumb was obtained in the presence of glutathione. • Bread staling rate was significantly increased in the presence of glutathione. [ABSTRACT FROM AUTHOR]

Effect of pigskin gelatin and its hydrolysates on overall changes that frozen dough underwent during storage was investigated. The results showed that gelatin from pigskin could fortified the frozen dough bread quality, embodying in larger bread volume, softer and more uniform bread crumb. Impact of pigskin gelatin on changes in the structure of gluten network in frozen dough was evaluated by different techniques. SDS-polyacrylamide gel electrophoresis (SDS-PAGE) showed gelatin may inhibit the crosslinking of HMW macromolecules and entangle with SDS-soluble LMW proteins. The increased SDS-soluble proteins suggested a lower aggregation extent of glutenin macropolymer (GMP) caused by pigskin gelatin. However, the significant reduction in GMP depolymerization degree and thiol groups (-SH) content after 60-day frozen storage in presence of gelatin indicated the formation of a more resistant gluten structure against the distortion of ice crystals. There were no significant differences in the alteration of secondary structure and high-temperature stability between gelatin-depleted and gelatin-fortified groups. Nevertheless, the effect of pigskin gelatin on qualities of frozen dough was independent on its hydrolysis degree. Image 1 • Gelatin from pigskin fortified the frozen dough bread quality. • Effect of pigskin gelatin on qualities of frozen dough was independent on its hydrolysis degree. • Pigskin gelatin resulted in a lower aggregation extent of glutenin macropolymer. • Gelatin inhibited the crosslinking of HMW macromolecules and entangle with SDS-soluble LMW proteins. [ABSTRACT FROM AUTHOR]