Insight into the mechanism of digestibility inhibition by interaction between corn starch with different gelatinization degree and water extractable arabinoxylan.

On the basis of revealing the interaction mechanism between corn starch (CS) and water-extractable arabinoxylan (WEAX) with high/low molecular weight (H-WEAX, L-WEAX), the degree of gelatinization (DG) on structural behaviors and in vitro digestibility of CS-WEAX complexes (CS/H, CS/L) was evaluated. With the increased DG from 50 % to 95 %, the water adsorption capacity of CS/L was increased 64 %, 58 %, 47 %, which were higher than that of CS/H (39 %, 54 %, 33 %). The gelatinization of starch was inhibited by WEAX, resulting in the enhancement of crystallinity, short-range ordered structure and molecular size of CS-WEAX complexes. Stronger interaction was detected in CS/L than with CS/H as proved by the increased hydrogen bonds and electrostatic force. Complexes exhibited higher resistant starch content (RS) at diverse DG, especially for CS/L. Notability, RS content of samples with 50 % DG were increased from 27.72 % to 32.89 % (CS/H), 36.96 % (CS/L). Except for the reduction of gelatinization degree by adding WEAX, the other possible mechanisms of retarding digestibility were explained as the small steric hindrance of L-WEAX promoted encapsulation of starch granules, limiting enzyme accessibility. Additionally, the fragmentation of CS granules with high DG promoted the movement of H-WEAX, reducing the difference in digestibility compared to CS/L.

Impact of pre-meal immersion on multi-scale structural changes and starch digestibility of cooked dried noodles.

Pre-meal immersion is a common process for both the consumption of dried noodles and development of takeaway noodles, but its impact on the structure and digestibility of dried noodles is still unclear. In this study, dried noodles cooked for the optimal time were immersed at 80 °C for different time durations. Multi-scale structural changes, including texture, molecular structure, microstructure, and in vitro starch digestibility were studied using a combination of kinetic (first-order exponential decay function, the Peleg model, and LOS plots), physicochemical, and microscopic analysis. The relationship between multi-scale structural changes and starch digestibility was derived. As the immersion progressed, the hardness first rapidly decayed and then reached equilibrium. The decay rate in the initial stage depended on the gluten content. In most cases, the immersion process caused depolymerization of gluten proteins and further gelatinization of starch granules, which was observed from an increase in the free -SH content and decrease in the short-range ordered structure, although there were fluctuations over immersion time. Structural changes resulted in the corresponding changes in substance migration. However, a high gluten content (∼15% w/w) imparted a denser microstructure to the noodles, weakening the deterioration effects compared with a low gluten content (∼10% w/w). In vitro digestion experiments proved that samples with higher gluten content had higher starch digestion rates and lower starch digestion extent during immersion. Correlation analysis revealed that there was a negative correlation between k1 and the tightness of the gel. This study helps to reveal the structural mechanisms of starch digestibility in cooked noodles during immersion.

Interactions among the composition changes in fungal communities and the main mycotoxins in simulated stored wheat grains.

BACKGROUND: There are significant food safety risks associated with wheat spoilage due to fungal growth and mycotoxin contamination. Nevertheless, a few studies have examined how stored wheat grain microbial communities and mycotoxins vary in different storage conditions. In this study, changes in deoxynivalenol (DON) and deoxynivalenol-3-glucoside (D3G) content were measured with ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS), and an amplicon sequence analysis of fungi was performed on stored wheat grains from different storage conditions using high-throughput sequencing. The detailed interactions among the composition changes in the fungal community and the DON content of simulated stored wheat grains were also analyzed. RESULTS: Alternaria, Fusarium, Mrakia, and Aspergillus were the core fungal taxa, and the fungal communities of samples stored under different conditions were observed to be different. Aspergillus relative abundances increased, whereas Fusarium decreased. This led to an increase in the content of DON. The content of DON increased about 67% with 12% moisture and at 25 °C after 2 months of storage, which was influenced by the stress response of Fusarium. Correlations in fungal and mycotoxins changes were observed. There may be potential value in these findings for developing control strategies to prevent mildew infestations and mycotoxins contamination during grain storage. CONCLUSION: In storage, the more the fungal community composition and the relative abundance of Fusarium change, the more mycotoxins will be produced. We should therefore reduce competition between fungal communities through pre-storage treatment and through measures during storage. © 2023 Society of Chemical Industry.

Modification of Soft Wheat Protein for Improving Cake Quality by Superheated Steam Treatment of Wheat Grain.

Many varieties of soft wheat in China cannot fully satisfy the requirements of making high-quality cakes due to their undesirable protein properties, which leads to shortages of high-quality soft wheat flour. Therefore, a modification of soft wheat protein is essential for improving the quality of soft wheat and thus improving cake quality. In order to modify the protein properties of soft wheat used for cake production, superheated steam (SS) was used to treat soft wheat grains at 165 °C and 190 °C for 1, 2, 3, 4, and 5 min, respectively, followed by the milling of wheat grains to obtain refined wheat flour. The properties of proteins and cakes were analyzed using refined wheat flour as materials. First, changes in the structures of wheat proteins were analyzed by determining the solubility, molecular weight distribution and secondary structure of proteins in wheat flour. Secondly, changes in the functional properties of proteins were analyzed by determining the foaming properties and emulsifying properties of proteins in wheat flour. Finally, the specific volume and texture of cakes with wheat flour milled from SS-treated wheat were analyzed. At the initial stage of SS treatment, some of the gliadin and glutenin aggregated, and the gluten macro-polymer (GMP) contents increased. This allowed a more stable gluten network to form during dough kneading, leading to an improvement in dough elasticity. In addition, a short time period (1-3 min) of SS treatment improved the emulsifying properties and foaming ability of wheat protein, which helped to improve the specific volume and texture of cakes. Increasing the SS temperature from 165 °C to 190 °C reduced the optimal treatment time needed to improve cake quality from 3 min to 1 min. SS treatment for longer time (>3 min) periods led to severe protein aggregation and a decrease in the foaming ability and emulsifying properties of protein, which led to a deterioration in the cake quality. Thus, SS treatment at 165 °C for 1-3 min and 190 °C for 1 min could be a suitable method of improving the physicochemical properties of soft wheat used to make cakes with high specific volumes and good texture.

Structure-activity relationship between gluten and dough quality of sprouted wheat flour based on air classification-induced component recombination.

BACKGROUND: Air classification can separate sprouted wheat flour (SWF) into three types: coarse wheat flour (F1), medium wheat flour (F2) and fine wheat flour (F3). The gluten quality of SWF can be indirectly improved by removing inferior parts (F3). In order to reveal the underlying mechanism of this phenomenon, the composition and structural changes of gluten, as well as the rheological properties and fermentation characteristics of gluten in recombinant dough in the process of air classification of all three SWF types, were analyzed in this study. RESULTS: Overall, sprouting significantly reduced the content of high-molecular-weight subunits, such as glutenin subunit and ω-gliadin. It also destroyed the structural content, such as disulfide bonds, α-helix and ß-turn contents, which maintained the stability of gluten gel. Air classification made the above changes in F3 more severe but reversed them in F1. Moreover, rheological properties were more affected by gluten composition, whereas fermentation characteristics were more affected by gluten structure. CONCLUSION: After air classification, particles rich in high molecular weight subunits from SWF are enriched in F1, and the gluten of F1 has more secondary structure that maintain gel stability, which ultimately lead to improved rheology properties and fermentation characteristics. F3 relatively exhibits the opppsite phenomenon. These results further reveal the potential mechanism of improvement of SWF gluten by air classification. Moreover, Thus, this study provides new perspectives for the utilization of SWF. © 2023 Society of Chemical Industry.

Superheated steam processing of cereals and cereal products: A review.

The concept of superheated steam (SS) was proposed over a century ago and has been widely studied as a drying method. SS processing of cereals and cereal products has been extensively studied in recent years for its advantages of higher drying rates above the inversion temperature, oxygen-free environment, energy conservation, and environmental protection. This review provides a brief introduction to the history, principles, and classification of SS. The applications of SS processing in the drying, enzymatic inactivation, sterilization, mycotoxin degradation, roasting, and cooking of cereals and cereal products are summarized and discussed. Moreover, the effects of SS processing on the physicochemical properties of cereals and the qualities of cereal foods are reviewed and discussed. The applications of SS for cereal processing and its effects on cereal properties have been extensively studied; however, issues such as the browning of cereal foods, thermal damage of starch, protein denaturation, and nutrition loss have not been comprehensively studied. Therefore, further studies are required to better understand the mechanism of the quality changes caused by SS processing and to expand the fields of application of SS in the cereal processing industry. This review enhances the understanding of SS processing and presents theoretical suggestions for promoting SS processing to improve the safety and quality of cereals and cereal products.

Behavior of wheat flour dough at different pretreated temperatures through rheological characteristics and molecular interactions of proteins.

Rheological properties and chemical interactions of doughs prepared at different temperatures were evaluated. The results showed that the rigidity of pretreated doughs was enhanced, and the processing performance of doughs was weakened. Preheating resulted in the polymerization of gluten through the conversion of sulfhydryl groups to disulfide bonds. The noncovalent interaction of dough played a dominant role and further led to the production of glutenin macropolymers (55.77 mg/g). CLSM images verified that preheating promoted the formation of the coarse and scattered gluten network, while preheating at 80 °C led to a higher gluten area percentage (40.27 %) and lower lacunarity (6.74 × 10-2) structure. The migration of water promoted changes in hydrogen bond and hydrophobic interaction in doughs, which directly affect the processability of doughs. The study provides information for predicting the rheological behavior of dough in actual production and makes it possible to modify gluten by preheating treatment without complicating existing operations.

Comparison and mechanism analysis of the changes in viscoelasticity and texture of fresh noodles induced by wheat flour lipids.

To understand the functionality of wheat flour starch lipids (SLs), non-starch lipids (NSLs), glycolipids (GLs), phospholipids (PLs), and neutral lipids (NLs) in non-leavened wheat-based products, their independent influence on noodle dough viscoelasticity and noodle texture were compared and the underlying mechanism was elucidated. Defatting caused slightly improved hydration, marginally promoting dough viscoelasticity and noodle springiness and adhesiveness but the resulting absence of starch-lipid complexes and few B-starch granules signally reduced the noodle hardness. Independently adding 2.50 g of these five lipids back into 100 g of defatted flour, GLs showed the most improved effects, followed by PLs, SLs, NSLs, and NLs. These lipids associated with gluten proteins and enhanced water-solids interplay, resulting in a significantly decreased SDS-soluble gluten proteins and further producing dough with increased ß-turn, moderate protein aggregation, and properly intensive microstructures. Consequently, the resultant noodle dough exhibited an optimal viscoelasticity and the cooked noodle had a desirable texture.

Mechanical action on the development of dough andits influence on rheological properties and protein network structure.

Four simple dough preparation methods were proposed to imitate the rheological behaviors of traditional hand-made doughs and the underlying mechanism was concomitantly elucidated. It indicated the hand-made doughs, including the conventional hand-made dough (CHD), bidirectional pressed dough (BPD), bidirectional rolled dough (BRD), unidirectional pressed dough (UPD), and unidirectional rolled dough (URD), showed weaker mechanical resistance than the mixer-made dough did. Compared with UPD and BRD, BPD and URD had better tensile resistance and deformation recovery. CLSM analysis showed that these two doughs also possessed smaller lacunarity (7.22-7.24 × 10-2) and larger branching rate (0.23 × 10-2), suggesting bidirectionally pressing and unidirectionally rolling could produce a dough with better gluten network connectivity. Analysis of gluten protein solubility showed that the stronger hydrogen bonds and hydrophobic interactions of gluten protein were derived in rolled doughs (URD and BRD), and the stronger slip caused by intermediate water in pressed doughs (UPD and BPD) may lead to the high gluten extractability. In addition, more disulfide bonds were formed in BPD (3.37 µmol/g) and URD (3.62 µmol/g), promoting the stronger mechanical resistance in BPD and URD. Nevertheless, pressing or rolling promoted no statistically significant increase in the content of glutenin macropolymers. Physical entanglement caused by the recombination of noncovalent interactions may be the main cause. In conclusion, theeffect ofmanual external forces ondough qualitywasverified theoretically, and gluten network analysis can quantitatively evaluate dough microstructural changes.

Interactions between wheat globulin and gluten under alkali or salt condition and its effects on noodle dough rheology and end quality.

The influences of wheat globulin on dough and noodle quality under alkali or salt conditionwere investigated, and the protein interactions were revealed. Results indicated that dough viscoelasticity, noodle hardness, springiness and extensibility of samples with globulin added were remarkably increased under alkali condition. However, the corresponding enhancement was less significant under salt condition. In dough system, added globulin decreased the protein surface hydrophobicity by 38.71%, implying the enhancement of hydrophobic interactions. Under salt and alkali conditions, added globulin further increased the ß-sheets structure by 1.68% and 3.17%, respectively, indicating the enhancement of hydrogen bonds interaction. In addition, disulfide bonds interactions between globulin and gluten have also been demonstrated induced by alkali. The results were accountable for protein network polymerization observed in micro-structures. This paper provides new insights into the structural properties of wheat globulin, and demonstrates the excellent potential to improve noodle processing quality under alkali condition significantly.

Effects of wheat flour particle size on flour physicochemical properties and steamed bread quality.

In this study, differently sized particles of wheat flour (from 52.36 µm to 108.89 µm) were obtained by adjusting the distance between the rolls (0.02, 0.04, 0.06, 0.08, and 0.1 mm) of a heart mill. Results showed that reducing the particle size significantly increased the damaged starch (DS) content. Uniaxial tensile measurement of dough showed that reducing the particle size of wheat flour can effectively increase the maximum tensile resistance, but the extensibility reaches the maximum in samples at medium particle diameter (78 and 66 µm). Additionally, the ratio of dynamic moduli (G″/G') decreased with a reducing particle size. The results of disulfide bond content, gluten microstructure, showed that finer flour granulation can strengthen the gluten network. The steamed bread (SB) making test showed that SB made from wheat flour of a smaller particle size had a significantly smaller specific volume than that made from a larger particle size. The texture profile analysis showed that with a decrease of wheat flour particle size, the hardness, chewiness of SB increased, the resilience decreased, and there was no significant difference in adhesiveness. Overall, the quality of SB made flour of medium particles (78 µm) is better.

Impact of wheat globulin addition on dough rheological properties and quality of cooked noodles.

Impact of globulin addition on the functional and protein structural properties of dough and cooked noodles were investigated. The underlying mechanism was explored through analyzing the interaction between globulin and gluten by using SDS-PAGE, size exclusion chromatography, free sulfhydryl/disulfide bond analysis, laser scanning confocal microscopy and Fourier transform infrared spectroscopy. Results showed that the stiffness/hardness and maximum resistance of dough and cooked noodles were both increased when globulin addition was 1.5% or higher. Besides, extensibility of cooked noodles was also improved when the addition up to 3.0%. The addition of globulin facilitated weakening the S-S bonds in the gluten network and cross-linked with SDS-soluble gluten mainly through non-covalent interactions, especially hydrophobic interactions. Meanwhile, a more rigid protein network structure was observed. Additionally, following cooking, globulin addition accelerated the aggregation of protein molecules. When the addition reached 3%, the protein conformation was transformed from ß-sheets and random coils to ß-turns.

Effects of vacuum degree, mixing speed, and water amount on the moisture distribution and rheological properties of wheat flour dough.

Effects of vacuum degrees (0.00, 0.02, 0.04, 0.06, 0.08 MPa) on water distribution state, tensile properties, stress relaxation properties, and viscoelasticity of dough, as well as the effects of mixing speed (50, 70, 90 rpm/min) and water content (40%, 45%, 50%) under optimum vacuum degree were studied. The results showed that the proper vacuum degree (0.06 MPa) could promote the full contact between flour and water and improved the water-holding capacity of the dough. Meanwhile, the dough had stronger tensile strength, the best viscoelasticity and the ability to recover from external deformation more quickly. Under the vacuum of 0.06 MPa, with the increasing of mixing speed, the response to the external force of dough increased first and then decreased. Adding more water reduced the strength of dough, weakened the response to external forces, and led to a significant decrease in tensile resistance and tensile area of the dough, as well as a decrease in viscoelasticity (p < 0.05). The proper vacuum mixing allowed the preparation of dough to require more water and less energy. PRACTICAL APPLICATION: In the processing of wheat flour products, vacuum mixing is considered to be beneficial to the quality of noodles and breads. As the intermediate of these products, the dough is of great significance for the monitoring of its rheological characteristics. In this study, a moderate vacuum degree led to a significant improvement in the rheological properties of the dough, and the processing performance was the best. Under the optimal vacuum degree, the influence of mixing speed and water amount cannot be ignored. Vacuum mixing is an efficient dough preparation method, which can produce certain economic benefits.

Effects of salt and kansui on rheological, chemical and structural properties of noodle dough during repeated sheeting process.

Effects of different levels of salt (1-2%, fwb) and kansui (0.5-1%) on the rheological, chemical and structural characteristics of noodle dough developed by repeated sheeting were studied. The rupture stress was increased by salt and kansui. The rupture elongation was increased by salt while reduced by kansui. The rupture stress and elongation increased to a maximum at 3 or 4 sheeting passes then decreased. The larger polymeric glutenin (LPP) increased while glutenin macropolymer (GMP) and free SH contents declined with the increased sheeting passes except for the dough contained 1% kansui at which these indicators remained constant. The ß-sheet was increased while the ß-turn was decreased by salt and kansui. The results showed the LPP disaggregated from GMP through physical disentanglement and experienced a reaggregation process with the SS bonds participate in, but the addition of kansui especially at 1% concentration could inhibit the disaggregation of GMP through protein cross-linking.

Effects of wheat flour particle size on physicochemical properties and quality of noodles.

The effect of particle size on the physicochemical and noodle quality of wheat flours was investigated. Granular wheat flour was ground by adjusting the distance between the rolls (0.02, 0.04, 0.06, 0.08, and 0.1 mm) of the flour mill to obtain wheat flour in five different particle sizes. The results showed that milling intensity significantly reduced the particle size and increased the damaged starch content and sedimentation value, but there were no significant differences in protein or ash contents. The reduction of wheat flour particle size significantly decreased the peak viscosity, trough viscosity, final viscosity, breakdown, and setback of the blends, while there were no significant differences in pasting temperature. Stress relaxation characteristics indicated that as the particle size of wheat flour decreased, dough hardness increased. The noodles made from wheat flour with a smaller particle size had a higher water absorption rate and cooking loss rate. Textural profile analysis parameters showed that as the particle size of wheat flour decreased, the hardness, chewiness, recovery, and adhesiveness of noodles showed increasing trends, and there was no significant difference in elasticity. In summary, it is found that the quality of the noodles made by sample C (D50 : 78.47 µm) is better.

Reduction of Aflatoxin B1 in Corn by Water-Assisted Microwaves Treatment and Its Effects on Corn Quality.

Aflatoxin B1 (AFB1) is one of the most commonly found mycotoxin in corn, which is highly toxic, carcinogenic, teratogenic, and mutagenic for the health of humans and animals. In order to reduce the AFB1 in corn, corn kernels were processed with Water-assisted Microwaves Treatment (WMT) and the feasibility of WMT processing on AFB1 reduction and its effects on corn quality were analyzed. Increasing the treatment time and microwave power could increase the reduction of AFB1, and the maximum reduction rate could reach 58.6% and 56.8%, respectively. There was no significant correlation between the initial concentration of AFB1 and the reduction rate of AFB1. During WMT, the main toxigenic molds were sterilized completely, and the moisture content of corn climbed up and then declined to the initial level. WMT could obviously increase the fatty acid value and pasting temperature of corn and reduce the all paste viscosity of corn. However, it had little effect on the color of corn. The results indicated that WMT could reduce AFB1 effectively and avoid the vast appearance of heat-damaged kernels simultaneously. Undoubtedly, water played an important role in WMT. This result provides a new idea for the reduction of AFB1 by microwave.

Ultrafine grinding of wheat flour: Effect of flour/starch granule profiles and particle size distribution on falling number and pasting properties.

In the present paper, the properties of different ultrafine flour samples, including particle size distribution, damaged starch content, falling number, and pasting properties, were examined. The results indicated that the particle size decreased significantly after jet milling, as the rotation speed and grinding time increased, and the damaged starch content significantly increased as the size of the flour/starch decreased; this is in contrast to the significant decrease in falling number. Significant differences in pasting temperature were observed between straight-grade flour (68.6°C) and five ultrafine flour samples (from 86.3 to 87.9°C). We also observed significant increases in peak viscosity, trough, breakdown viscosity, final viscosity, and setback as the flour particle size decreased from 43.07 µm to 25.81 µm (D50). The same parameters significantly decreased as the flour particle size decreased from 25.81 µm to 10.15 µm (D50). Correlation analysis identified a significant negative correlation between flour particle size (D50) and damaged starch content and pasting temperature, while a significant positive correlation was found with the falling number values. The results of this work may have an important impact on the quality of processed foods.

Effect of heat-moisture treatment on the structure and physicochemical properties of ball mill damaged starches from different botanical sources.

The morphology, structure and physicochemical properties of ball milling (BM) damaged starches from mung bean, potato, corn and waxy corn were investigated before and after heat-moisture treatment (HMT) (100 °C, for 12 h at a moisture content of 25%). The results showed that the damaged starch (DS) content of BM modified starches was decreased by 4.49%, 10.68%, 17.11% and 22.98% after HMT for mung bean, potato, corn and waxy corn starch, respectively. The solubility and swelling power were significantly decreased, and the modified effect was depended on the type of starch, among which waxy corn starch exhibited the maximum reduction. Different degrees of aggregation and fusion of granules were found in starches modified with BM-HMT, and the extent of fusion was related to amylose content and crystalline pattern. The crystallinity of BM modified starches was increased by 6.3%, 5.9%, 17.9% and 22.4% after HMT for mung bean, potato, corn and waxy corn starch, respectively. The dual physical modification had various effects on the starches from different botanical sources, the increase in crystallinity and peak temperature (Tp) were related to the DS and amylose content, and the changes in gelatinization temperature range (Tc-To) were related to the crystalline pattern of starches.

Comparison of rheological behavior, microstructure of wheat flour doughs, and cooking performance of noodles prepared by different mixers.

Large deformation characteristics in biaxial tensile and stress relaxation, and small deformation properties in frequency sweeping and microstructure of dough produced by three kinds of mixers were assessed in this study. Differences in noodle quality were also compared. Results indicated that dough made by vacuum or spiral mixer had good resistance to external force and good resilience. But the dough and noodles made by vacuum mixer showed the best tensile and cooking properties respectively, and had overall the best performance. Confocal microscopy revealed that the protein matrix of the three doughs formed along the direction of shear flow, whereas the starch granules of dough made by the vacuum mixer were tightly wrapped in gluten, resulting in a compact and sequential gluten network. Other samples showed signs of minor structural damage (pin mixer) or the presence of holes (spiral mixer). Assessment using Pearson correlation analysis identified a number of significant correlation coefficients between the dough rheological characteristics and noodle quality. Characterization of biaxial tensile and stress relaxation was advantageous for noodle assessment prediction. The index of flow and degree of deformation were negatively correlated with tensile properties. Frequency scanning is superior in predicting cooking and stretching characteristics of noodles. PRACTICAL APPLICATION: The research provides technical guidance for obtaining better dough in noodle processing.

Detoxification of Deoxynivalenol by 60Co γ-ray Irradiation and Toxicity Analyses of Radiolysis Products.

Background: Deoxynivalenol (DON) is a type B trichothecene that occurs predominantly in grains such as wheat, maize, and barley and has been implicated in incidents of mycotoxicoses in both humans and farm animals. Objective: In the present study, we chose 60Co γ-ray irradiation to degrade DON. Methods: First, the degradation effect of irradiation on DON was analyzed. Second, the toxicity analyses of radiolysis products were studied by oral gavage. Results: The results indicated that 60Co γ-ray irradiation had significant degradation effect on pure DON: when 20 kGy γ-ray irradiation was used for 2 µg/mL DON in acetonitrile-water, the degradation efficiency of DON was 83%, and 2 µg/mL DON in ultra-pure water was completely degraded after 5 kGy γ-ray irradiation. The concentration of 200 µg/mL DON in ultra-pure water had significant toxicity to mice: decreased body weight gain and feed consumption as well as pathological changes in liver and kidney were observed compared with the control group. Conclusions: No significant toxicity was observed in mice that were given these degraded solutions treated by γ-ray irradiation, which indicated that the toxicity of radiolysis products in ultra-pure water had significantly decreased after treatment by γ-ray irradiation. Highlights: This research offered some reference to detoxify DON in cereal grains.