Microstructure Of Dough Research Articles

Enhanced Stability, Quality and Flavor of Bread through Sourdough Fermentation with Nisin-Secreting Lactococcus lactis NZ9700

Sourdough bread is traditionally made fermenting a starter with high-gluten flour and water among other ingredients. However, the stability and safety of naturally fermented sourdough cannot always be fully guaranteed. In this study, Lactococcus lactis NZ9700, which actively secretes the bacteriocin nisin, was employed for sourdough fermentation and bread production. Three control groups were established to explore the complex and diverse changes occurring during sourdough fermentation, including a non-acidified dough group, a chemically acidified dough group, and a sourdough group fermented with L. lactis NZ9000 (which does not secrete nisin). The results demonstrate that fermentation with L. lactis leads to a rapid increase in colony-forming units (CFU) , stabilizing the pH of the sourdough at approximately 4.2 within 12 h. The in situ production of acids, sugars, and other metabolites during sourdough fermentation has a significant impact on the dough's microstructure. Microstructural analysis reveals that sourdough fermentation results in a more organized gluten network, with the L. lactis NZ9700 group exhibiting a more refined microstructure and fewer prominent starch granules. Furthermore, L. lactis NZ9700 produces stable nisin during fermentation, which persists even after baking, providing continuous antimicrobial protection to the final product. This reduced fungal contamination and extended the shelf life of the bread. Last, the growth of L. lactis NZ9700 during the early stages of fermentation provides more alcohols and ketones to the breads, endowing the sourdough breads with richer and more complex flavor profiles.

Isolation of ice structuring proteins from winter wheat in frigid region (Dongnongdongmai1) and the effect on freeze–thaw stability of dough

In this study, ice structuring proteins (WISPs) extracted from winter wheat in a frigid region were prepared and added to frozen-thawed dough. The WISPs were characterized, revealing that they contained a higher proportion of hydrophilic amino acids and had a molecular weight of approximately 15 kDa. The highest thermal hysteresis activity (THA) observed was 0.62 °C. The secondary structure of WISPs was determined to be as follows: β-sheet: 49.33 %, random coil: 13.87 %, α-helix: 16.35 %, β-turn: 20.45 %. The study investigated the effects of different additions of WISPs on the water mobility, glass transition temperature, microstructure, rheological properties, and texture analysis of frozen-thawed dough. The results demonstrated that the inclusion of WISPs reduced the fluidity of water and water migration in the dough during the frozen-thawed cycle. This protective effect preserved the internal structure and gluten network of the dough, leading to increased viscosity, elasticity, and improved texture properties of the frozen-thawed dough. Furthermore, the addition of WISPs at concentrations ranging from 0 % to 0.7 % resulted in a 1.8 °C increase in the glass transition temperature (Tg). Overall, these findings suggest that WISPs can serve as a beneficial additive for enhancing the freeze–thaw stability of dough.

Effects of heterotrophic Euglena gracilis powder on dough microstructure, rheological properties, texture, and nutritional composition of steamed bread

This study investigated the effects of incorporating different levels of Euglena gracilis microalgae powder (MP) on the dough properties, rheology, and quality attributes of Chinese steamed bread (CSB) for the first time. Moderate levels of MP (2%) reinforced the gluten network and improved protein structure, while higher levels (4–8%) adversely affected the gluten network and rheological properties. The addition of MP decreased the specific volume, pore number, and pore density of CSB, but increased pore size, hardness, and chewiness. It also imparted a yellow color to the CSB and slowed down moisture loss during storage. Notably, MP effectively increased the protein and lipid content of CSB, enhancing its nutritional value. The results suggest that optimizing the MP level is crucial to achieve nutritional enhancement while maintaining desirable texture and sensory attributes. An addition of 2% MP can strike a balance between nutrition and the overall quality of the final product.

Peptide incorporation in frozen dough and steamed bread: Characteristics and structure-function relationship

Antarctic krill peptide (AKP), a bioactive compound, has garnered significant attention in recent years. This study aimed to explore the effects of varying levels of AKP addition (ranging from 0% to 2.0%, based on the flour, w/w) and different freezing time (0, 1, 2, 4, and 6 weeks) on the rheological properties, rheo-fermentation properties, water distribution, and microstructure of dough. The results revealed that the addition of AKP led to a reduction in the freezable water content, T2 relaxation time, and free sulfhydryl content of frozen dough. After 6 weeks of freezing, the viscoelastic properties of the dough with AKP were higher than those of the control. Additionally, the fermentation height of dough containing 1.5% AKP increased by 25.85% compared with the control, resulting in increased springiness and specific volume, and decreased hardness in the resulting steamed bread. Pearson correlation analysis showed a positive correlation between freezable water content and free sulfhydryl groups, while a negative correlation was observed with springiness. Furthermore, springiness showed a positive correlation with the DPPH free radical scavenging rate. These findings highlight the potential of AKP as a novel food cryoprotectant capable of significantly enhancing the quality and nutritional value of frozen wheat products.

Feruloylation and Hydrolysis of Arabinoxylan Extracted from Wheat Bran: Effect on Dough Rheology and Microstructure.

Feruloylated arabinoxylan (AX) is a potential health-promoting fiber ingredient that can enhance nutritional properties of bread but is also known to affect dough rheology. To determine the role of feruloylation and hydrolysis of wheat bran AX on dough quality and microstructure, hydrolyzed and unhydrolyzed AX fractions with low and high ferulic acid content were produced, and their chemical composition and properties were evaluated. These fractions were then incorporated into wheat dough, and farinograph measurements, large and small deformation measurements and dough microstructure were assessed. AX was found to greatly affect both fraction properties and dough quality, and this effect was modulated by hydrolysis of AX. These results demonstrated how especially unhydrolyzed fiber fractions produced stiff doughs with poor extensibility due to weak gluten network, while hydrolyzed fractions maintained a dough quality closer to control. This suggests that hydrolysis can further improve the baking properties of feruloylated wheat bran AX. However, no clear effects from AX feruloylation on dough properties or microstructure could be detected. Based on this study, feruloylation does not appear to affect dough rheology or microstructure, and feruloylated wheat bran arabinoxylan can be used as a bakery ingredient to potentially enhance the nutritional quality of bread.

Effect of camellia oil gel on rheology, water distribution and microstructure of flour dough for crispy biscuits

This study investigated the effect of camellia oil gel on rheology, water distribution and microstructure of flour dough for crispy biscuits. Camellia oil gels, numbered 6#, 8#, and 10#, were formed by mixed plant-based wax and camellia oil (6 g/100 g, 8 g/100 g, 10 g/100 g). The results indicated that with the increase of mixed plant-based wax, the fat distribution in the dough changed from an unevenly dispersed droplet to a uniformly distributed film, and the gluten network structure changed from dense to sparse (P < 0.05). The adsorbed bound water coalesced in the multimolecular water layer of oil gel dough was reduced, but the free water was significantly higher than that of the lard added dough. The gluten matrix surface of the dough was partially exposed, the continuity between gluten protein and starch granules was broken, the gluten network structure was weakened, and the protein secondary structure composition and relative content were better than other oil samples (P < 0.05). As a result, 10# gel could be considered to replace or partially replace lard in baked goods to reduce the intake of saturated fatty acids, providing some theoretical support for the development of new plastic fats.

Atomic force microscopy, deformation-recovery and numerical study of wheat dough

Experimental and numerical modelling work related to microstructure and deformation of starch, gluten and wheat dough was presented. Atomic force microscopy analyses through force spectroscopy on starch samples showed elastic behaviour of both dried and reconstituted wet starch granules, where wet starch was shown to be more cohesive than dried starch. Deformation-recovery test over time under compression mode showed almost complete recovery to original sample height of gluten, whereas only a slight recovery was observed for dough. Finite element modelling was then commenced to simulate gluten deformation-recovery and starch-gluten dough deformation. The gluten geometry used for the starch-gluten dough model was obtained from cryo-SEM image from the previous work before the starch geometry was then included. The interface between the starch and gluten model was defined using viscoelastic cohesive zone elements. The modelling results suggested significant influence of gluten cellular structure towards starch-gluten dough integrity. In addition, the results from the current work further supported the previous report of the starch-gluten interfacial behaviour using viscoelastic cohesive zone model.

Effect of high-molecular-weight glutenin subunits silencing on dough aggregation characteristics

The qualities of wheat dough are influenced by the high-molecular-weight glutenin subunits (HMW-GS), a critical component of wheat gluten protein. However, it is still unknown how HMW-GS silencing affects the aggregation characteristics of dough. Two groups of near-isogenic wheat were used to study the effects of HMW-GS silencing on dough aggregation characteristics, dough texture characteristics, and dough microstructure. It was observed that the content of gliadin in LH-11 strain significantly increased compared to the wild-type (WT). Additionally, the amount of glutenin macropolymer and the glutenin/gliadin both decreased. The aggregation characteristics and rheological characteristics of the dough in LH-11 strain were significantly reduced, and the content of β-sheet in the dough was significantly reduced. The HMW-GS silencing resulted in a reduction in the aggregation of the gluten network in the dough, which related to the alteration of the secondary and microstructure of the gluten.

Debranning of wheat: Quality of flour and thermomechanical, microstructural, and extensional properties of dough

This study investigated the impact of debranning degrees (0, 3, 6, 9 and 12% by weight) on the qualities of wheat flour and dough. The physicochemical and pasting properties of wheat flour and thermomechanical, microstructural, extensional and rheological properties of wheat dough with different debranning degrees were assessed. The insoluble dietary fiber, soluble dietary fiber, protein, and ash contents for debranned wheat flour were significantly higher than that of refined flour. The content of protein was the highest when the debranning degree of wheat was 6%. Debranning degree of 6% significantly increased the gluten index for wheat flour and showed better pasting and mixing properties than untreated samples. Debranning treatment increased the L* value and decreased the a* and b* values of the wheat flour. Furthermore, when the debranning degree increased, the protein matrixes were more continuous and compact, and the starch granules were better entrapped in the gluten network. Debranning treatment caused significant increases in the dough's resistance to extension, extensibility, extensibility area, and extensibility rate, and a decrease in the dough's viscoelasticity. The debranning degree of 6% could effectively improve the parameters such as mixing properties, microstructure, and extensional properties of wheat dough.

Multiphoton microscopy is a nondestructive label-free approach to investigate the 3D structure of gas cell walls in bread dough

During the different steps of bread-making, changes in the microstructure of the dough, particularly in the gas cell walls (GCW), have a major influence on the final bread crumb texture. Investigation of the spatial conformation of GCWs is still a challenge because it requires both high resolutions and 3D depth imaging. The originality of the present work lies in the use of label-free non-destructive multiphoton microscopy (NLOM) to image the 3D structure of GCWs, shedding light on their behavior and organization in wheat bread dough. We demonstrated that second and third harmonic generation (SHG, THG) allow imaging, respectively, of starch granules and interfaces in bread dough, while the gluten matrix was detected via two-photon excitation fluorescence (TPEF). Last, a distinction between the gluten network and starch granules was achieved using gluten endogenous fluorescence (EF) imaging, while the position, size, and 3D orientation of starch granules in GCWs were determined from harmonic imaging, made possible by the acquisition of backward and forward SHG with linear polarization. These innovative experiments highlight the strengths of NLOM for a label-free characterization of bread dough microstructure for the first time, in order to understand the role of starch granules in dough stabilization.

Effects of garlic peptides on rheology, moisture, microstructure, gluten distribution, and baking properties of dough

The effects of different proportions of Garlic Peptides (GPs) on wheat dough were investigated to improve the dough quality. The pasting, rheological properties, water migration and distribution, microstructure, protein polymerization, and baking behaviors of GPs on the dough were determined. Pasting results showed that GPs inhibited starch swelling and gelatinization, improved the gas production capacity of yeast, and promoted dough fermentation. Rheological properties showed that GPs had a moderate weakening effect on dough, thus reducing the viscoelasticity of dough. Meanwhile, GPs could effectively bind water molecules and inhibit the water migration. Moreover, GPs could change the gluten distribution in the dough, facilitating the development of gluten networks. In addition, baking characteristics showed that GPs helped produce bread with uniform internal structure and soft texture. Therefore, this study emphasized the potential role of GPs and showed the theoretical basis of interactions in peptides-dough systems.

Application of magnetic field for improving the frozen deterioration of wheat dough

This study was to investigate the protective effect of magnetic field (MF) on frozen dough processing quality. The texture, microstructure, rheological and physicochemical properties of wheat dough treated by freezing-thawing cycles under different magnetic flux densities (0, 2, 4, 6, 8, and 10 mT) were analyzed. Compared with conventional frozen dough, MF-treated frozen dough had lower hardness and higher elasticity. Scanning electron microscope exhibited that MF treatment minimized the freezing-induced damages on morphology of starch and gluten, which was consistent with the decreased tan δ in rheological analysis. Application of MF facilitated high relative crystallinity and gelatinization enthalpy in starch granules while the depolymerization of gluten macropolymer was inhibited as manifest with more ordered secondary structure and decreased free sulfhydryl groups. The integrated structure in MF-treated frozen dough resulted in lower free water content as shown by low field nuclear magnetic resonance. The results provided valuable knowledge for the MF-assisted freezing technology and made it possible to improve the freezing-induced deteriorations on wheat-based food.

Physicochemical characteristics of air classification products of sprouted wheat (Zhoumai 27) flour

SummarySprouting negatively impacts wheat processing and edibility. Sprouted wheat flour (SWF) was air‐classified into three categories based on particle sizes, F1 (&gt;45 μm), F2 (20–45 μm), and F3 (&lt;20 μm). The sizes were examined using a laser particle size analyser and scanning electron microscopy. Their components, such as starch, protein properties, rheology, and dough microstructure, were also examined. After air classification, reducing sugar, damaged starch, amylase, protease, and inferior gluten components were primarily concentrated in F3. Decreasing particle size considerably impaired gelation strength, gluten quality, rheology properties, and dough microstructure. Compared with SWF, these characteristics significantly improved in F1. The results suggested that air classification could induce SWF component fractionation. The inferior components that reduce the quality of SWF were enriched in fine flour. Thus, removing these inferior components can considerably improve SWF rheological quality and dough structure. These results can provide useful information on the important effect of air classification on the quality of SWF products. Moreover, the study findings provide a reference for future application of air classification of SWF.

Effects of transglutaminase and glucose oxidase on the properties of frozen dough: Water distribution, rheological properties, and microstructure

The effects of transglutaminase (TG) and glucose oxidase (GOX) on the water distribution, rheological properties, and microstructure of dough after freeze-thaw cycles were studied. The results showed that, when TG (1%, w/w) and GOX (0.006%, w/w) were added to the dough simultaneously, the syneresis rate of the dough after 8 freeze-thaw cycles reduced by 12.9%, and the extensibility and maximum resistance of the frozen dough increased by 9.6 mm and 14.7 g, respectively. Moreover, the G′ and G″ values of the frozen dough were significantly increased, and the hardness and freezable water content were reduced by 60.1% and 2.9%, respectively. The LF-NMR analysis showed that the tightly bound water content increased by 4.9%, and the semi-bound water content decreased by 4.0%. The number of free sulfhydryl groups in the dough treated with the two enzymes decreased by 16.3 μmol/g. Fourier IR revealed that the content of α-helix increased by 3.1%, β-sheet increased by 5.8%, and β-turn decreased by 4.8%. Scanning electron microscope images indicated that the gluten network of the two enzyme-treated dough remained uniform and dense after multiple freeze-thaw disruptions.

Kappaphycus alvarezii flours as an ingredient for seaweed‐enriched, rice‐based, snacks: raw algae pretreatment and physical properties of the dough and snacks

SummaryIn this work, the addition of pretreated Kappaphycus alvarezii flour to a rice‐based snack formulation was proposed as an alternative to producing algae‐enriched snacks adding value to this seaweed and improving the quality of the snacks. Dried algae were submitted to multiple washing cycles to allow the reduction of the natural salt concentration of the algae. After, algae were dried and milled to obtain flour. The flour was added in different concentrations (0%, 2%, 5%, and 10%) in the model formulation of rice‐based dough. Rice‐K. alvarezii snacks were produced by baking at 220 °C. The proximate composition of the raw and pretreated algae was determined, as well as the colour, texture, and microstructure of dough and snacks. The pretreatment efficiently allowed for a reduction of 78% of the initial content of sodium and an 85% reduction of potassium. The concentration of 5% and 10% of algae addition presented higher values of hardness and consistency of the dough and lower adhesiveness. At higher concentrations, the seaweed flour acts as a processing aid during the preparation steps of the snacks but does not influence the hardness of the final snacks. The pretreated K. alvarezii flour is an alternative for increasing the quality of rice‐based snacks while preserving the algae's potential health benefits.

Enrichment of Wheat Bread with Platycodon grandiflorus Root (PGR) Flour: Rheological Properties and Microstructure of Dough and Physicochemical Characterization of Bread.

Platycodon grandiflorus (Jacq.) A.DC. root (PGR) flour is well known for its medical and edible values. In order to develop nutritionally fortified products, breads were prepared using wheat flour, partially replaced with PGR flour. The rheological properties and microstructure of dough and the physicochemical characterization of bread were investigated. Results showed that lower level of PGR addition (3 and 6 g/100 g) would improve the baking performance of breads, while the higher level of PGR addition (9 g/100 g) led to smaller specific volume (3.78 mL/g), increased hardness (7.5 ± 1.35 N), and unpalatable mouthfeel (21.8% of resilience and 92.6% of springiness) since its negative effect on the viscoelasticity and microstructure of dough. Moreover, sensory evaluation analysis also showed that the PGR3 and PGR6 breads exhibited a similar flavor to the control bread, but the 9 g/100 g addition of PGR provided bread with an unpleasant odor through its richer volatile components. As expected, the phenolic content and antioxidant capacity of bread increased significantly (p < 0.05) as PGR flour was added to the bread formulation. The total phenolic content (TPC) ranged from 14.23 to 22.36 g GAE/g; thus, DPPH• and ABTS•+ scavenging capacity increased from 10.44 and 10.06 μg Trolox/g to 14.69 and 15.12 μg Trolox/g, respectively. Therefore, our findings emphasized the feasibility of PGR flour partially replacing wheat flour in bread-making systems.

The effects of wheat cultivar, flour particle size and bran content on the rheology and microstructure of dough and the texture of whole wheat breads and noodles

The rheological properties and microstructure of doughs, and the texture properties of whole wheat breads and noodles were investigated. The gluten strength of doughs were discriminated due to wheat cultivar. Reduced flour particle size led to the doughs with a stronger gluten strength (i.e., smaller C2), lower degree of starch retrogradation (i.e., smaller C5), and longer relaxation time (i.e., larger n values). Firmer crumb of breads were prepared by flours with smaller particle size. With increased bran content, the gluten strength of dough weakened (i.e., increased C2), the development and relaxation time of dough and the degree of starch retrogradation decreased (i.e., decreased C1 time, n values and C5), the dough structure became more porous, and the product texture appeared to be firmer. As such, outcomes from this research will provide a practical guidance for the bakery industry to improve the consumer acceptability of whole wheat products.

Effect of sucrose, trehalose, maltose and xylose on rheology, water mobility and microstructure of gluten-free model dough based on high hydrostatic pressure treated starches

Due to functional and physicochemical properties, starch in its native state has limited range of applications. Simultaneously, information on effects of different sugars and their interactions with modified starch on gluten-free model dough is also limited. To better overcome these restrictions, the effects of sucrose, trehalose, maltose and xylose on rheology, water mobility and microstructure of gluten-free dough prepared with high hydrostatic pressure (HHP) treated maize (MS), potato (PS) and sweet potato starch (SS) were investigated. MS, PS and SS dough with trehalose exhibited a lower degree of dependence of G′ on frequency sweep (z'), higher strength (K) and relative elastic part of maximum creep compliance (Je/Jmax), suggesting stable network structure formation. Total gas production (VT) of MS dough with maltose, PS dough with sucrose and SS dough with trehalose was increased from 588 to 1454 mL, 537 to 1498 mL and 637 to 1455 mL respectively. Higher weakly bound water (T22) was found in the dough with trehalose at 60 min of fermentation, suggesting more hydrogen bonds and stable network. Thus, trehalose might be a potential improver in HHP treated starch-based gluten-free products.

Dough rheological properties, texture, and structure of high-moisture starch hydrogels with different potassium-, and calcium-based compounds

The effects of four kinds of potassium- (potassium alginate, PA; potassium dihydrogen phosphate, KDP) and calcium-based (calcium carbonate, CC; calcium silicate, CSi) compounds on the pasting behavior, rheological properties, microstructure, water mobility, and textural characteristics of pastes, dough, and high-moisture starch hydrogels from potato starch were evaluated. The results showed that the addition of 0.5% CSi, 0.5% CC, 0.4% PA and 0.4% KDP (w/w, total starch basis) significantly improved the tensile strength of high-moisture starch hydrogels compared to that of pure potato starch. Further discussion about the mechanism revealed that the addition of these components could reduce the swelling capacity and peak viscosity of potato starch during heating, further enhance the network structure of the starch dough, and reduce the water mobility thereof, thus contributing to a compact stacking of starch and smaller and denser pore structure of the high-moisture starch hydrogels. This study provides a theoretical basis for the formulation design of alum-free hydrogel derived products.

Mechanistic study of the impact of germinated brown rice flour on gluten network formation, dough properties and bread quality

The objective of the study was to investigate the impact of germinated brown rice flour (GBRF) on the mechanism of high gluten wheat flour (HGWF) network formation and dough properties. Therefore, dough properties, microstructures, stability mechanism and bread quality were evaluated. Results showed that HGWF+10%GBRF exhibited a higher dough stability time (DST), pasting temperature, storage modulus (G′) and loss modulus (G′′), as well as a lower compliance value. The microstructure of dough showed that GBRF interfered with the self-organization of gluten protein molecules and affected the formation of gluten network structure. The disulfide bonds and β-sheet structure were proved to play an important role in facilitating the formation of a stable three-dimensional network structure, which revealed the regulatory mechanism of GBRF in maintaining the dough stability and strength. Furthermore, the dough mixing properties and texture parameters (i.e., hardness and fracturability) of breads were significantly correlated. Overall, GBRF can be used as a potential ingredient for whole grain products and its realistic role in bread-making has been demonstrated.