Water mobility and microstructure of gluten network during dough mixing using TD NMR

Protein aggregation behavior during highland barley dough formation induced by different hordein/glutelin ratio

To investigate why highland barley dough cannot form a gluten structure, the mechanism by which the ratio of hordein/glutelin affects protein aggregation behavior during the formation of barley dough was investigated. It was observed that the pasting properties of the reconstituted flour were markedly diminished (1154-1303 × 10-3 Pa•s). The 50Hordein-50Glutelin sample exhibited the highest farinograph quality number. The K, A22 (48.82-65.26 %), hardness, free -SH (0.76 %-0.95 %), random coil, and hydrogen bonding (0.091-0.179 g/100 g) exhibited a notable increase with a reduction in the hordein/glutelin ratio. Conversely, β-sheet (27.39 %-40.11 %) and fluorescence intensity declined pronouncedly. The 50H-50G facilitated the reinforcement of protein crosslinking and polymerization, enhanced the continuity and order of the protein network structure, and further augmented the dough's viscoelasticity. The results would regulate the macroscopic quality of barley and other miscellaneous grain products through endogenous components, establishing a foundation for enhancing their quality.

Behavior of endo-xylanases on wheat milling products in relation with variable solid loading conditions

To investigate the incubation conditions encountered by enzymes in cereal-based product transformation processes, this study aims to provide comprehensive information on the effect of low (18 %) to high (72 %) solid loading on the behavior of bacterial and fungal xylanases towards wheat grain fractions, i.e. white flour, ground whole grain and bran. Both enzymes are effective from 30 % water content. A water content of 50 % appears as the threshold for optimal arabinoxylan solubilisation. The specificity of enzymes was influenced by low hydration conditions, particularly in wheat bran, which contains arabinoxylan with diverse structures. Especially the bacterial xylanase became more tolerant to arabinose substitution as the water content decreased. Time Domain-NMR measurements revealed four water mobility domains in all the fractions. The water populations corresponding to 7.5 nm to 15 nm pores were found to be the most restrictive for enzyme activity. These results define the water content limits for the optimal xylanase action in cereal products.

Folding during sheeting improved qualities of dried noodles through gluten network proteins

The texture properties after cooking for 12 min were selected to optimize the sheeting parameters, and the results were verified using the comprehensive quality of dried noodles. The distribution of water, characteristics of gluten protein, and interaction between gluten network and starch were analyzed to clarify the mechanism of the quality of dried noodles. Results showed that the optimal folding angle was 45°, under this condition, the largest anti-extension displacement perpendicular to the rolling direction and the smallest cooking loss were obtained. The hardness and smoothness of cooked noodles increased by about 14% to 17%. Further, the transverse relaxation time of strongly bound water significantly decreased, while the relative content and binding strength increased. The hydrogen bonds and α-helix contents increased by about 68.8% and 53.1%, respectively. Folding and sheeting enhanced the combination of starch granules and gluten network causing, decreased in the average length and porosity of the gluten network. It is depicted from the results that the method of optimizing the sheeting process based on the texture of dried noodles cooked for 12 min was feasible. And the 45° folding and sheeting could help to improve the quality of dried noodles.

Dynamic Study on Water State and Water Migration during Gluten-Starch Model Dough Development under Different Gluten Protein Contents

Mixing is crucial for dough quality. The gluten content influences water migration in dough development and properties, leading to quality changes in dough-based products. Understanding how the gluten protein content influences water migration during dough development is necessary for dough processing. A compound flour with different gluten protein contents (GPCs, 10-26%, w/w) was used to study the dough farinograph parameters and water migration during dough development. According to the farinograph test of the gluten-starch model dough, the GPC increases the water absorption and the strength of the dough. Water migration was determined via low-field nuclear magnetic resonance (LF-NMR). With the increase in GPC, the gluten protein increases the binding ability of strongly bound water and promotes the transformation of weakly bound water. However, inappropriate GPC (10% and 26%, w/w) results in the release of free water, which is caused by damage to the gluten network according to the microstructure result. Moreover, the changes in proteins' secondary structures are related to the migration of weakly bound water. Therefore, weakly bound water plays an important role in dough development. Overall, these results provide a theoretical basis for the optimization of dough processing.