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The impact of adding zein on the gluten network during extruded noodle processing and the quality of the noodles by extrusion-cooking were investigated. These changes were studied by size exclusion-high performance liquid chromatography (SE-HPLC), free sulfhydryl (SH) measurement, non-covalent interactions, Fourier-transform infrared spectroscopy (FTIR), particle size analysis, confocal laser scanning microscopy (CLSM), and scanning electron microscopy (SEM). Zein reduced the protein aggregation, resulting in a higher free sulfhydryl content and increased hydrogen bonds and hydrophobic interactions during noodle processing. Moreover, Zein reduced the relative content of β-sheets by 4.54% and 7.48% at the extrusion and cooking stages, respectively. Zein decreased the particle size during extrusion but increased it during cooking. Zein improved the compactness and strength of noodle microstructure during cooking, exhibited higher hardness and impeded water mobility compared to extruded noodles made only with wheat flour (WF). The extruded noodles containing zein showed a significant increase of 26.10% and 61.11% in tensile strength and distance, respectively. Zein did not cause significant changes in the cooking loss and water absorption in the extruded noodles. Research on the impact of zein on protein during the processing of extruded noodles could provide a dependable approach and valuable mechanistic insights for improving the quality of extruded noodles. [Display omitted] • The inclusion of zein in the extruded noodle processing resulted in reduced protein aggregation. • Zein increased hydrogen bonds and hydrophobic interactions during extruded noodle processing. • Zein reduced the relative content of β-sheets in extruded noodles. • Zein improved the quality of extruded noodles to have higher hardness, and tensile force and distance. [ABSTRACT FROM AUTHOR]

Surfactin could improve the quality of fresh noodles (FNs) during storage. The impacts of different levels of surfactin (0.0%, 0.2%, 0.3%, and 0.4%) on the quality and gluten network structure of FNs after storage (0d, 1d, 2d, and 3d) at 25 °C were investigated. The results showed that the addition of surfactin inhibited the tendency of hardness and tensile strength to decrease in FNs and improved their cooking properties. Size exclusion (SE-HPLC) and electrophoresis were employed to evaluate the strength of the gluten network, which indicated that surfactin increased the cross-linking of the gluten network during storage by promoting more disulfide bonds (SS). Surfactin increased the total contents of SDS-soluble polymers (SDS-P) and SDS-insoluble polymers (SDS-I) from 24.66% (control samples) to 33.32% (FNs with 0.4% surfactin) after 3 days of storage. The secondary structure of gluten network was determined using Fourier transform infrared (FTIR) spectroscopy, suggesting that surfactin increased α-helices and decreased random coil during storage. Moreover, confocal laser scanning microscopy (CLSM) showed that surfactin additions delayed the depolymerization of the gluten network in FNs during storage. This research could provide a theoretical basis for using surfactin as improver for FNs. [Display omitted] • The gluten network of fresh noodles (FNs) collapsed during storage. • Surfactin addition improved cooking properties, textural, and water transfer. • Surfactin improved the gluten network and inhibited its depolymerization. • CLSM analysis showed a compact gluten network in FNs with added surfactin. [ABSTRACT FROM AUTHOR]

Abstract: In this study, the effect of frozen storage on chemical and physical properties of wheat gluten-, glutenin- and gliadin-rich fractions was evaluated. Chemical changes were studied by size-exclusion (SE) and reversed-phase (RP) high-performance liquid chromatography (HPLC), thiol (SH) measurement, sodium dodecyl sulphate poly-acrylamide gel electrophoresis (SDS-PAGE), circular dichroism (CD) spectroscopy and Fourier transform infrared (FTIR) spectroscopy. Physical properties were determined by dynamic rheological measurements. During the frozen storage, depolymerization of glutenin macropolymer (GMP) was observed by SE-HPLC in gluten- and glutenin-rich fractions with a higher depolymerization rate of GMP in gluten-rich fraction, this further suggested that gliadin might have the potential to disaggregate the GMP. The depolymerization effects led to the major variation of thiol content. The results of SE-HPLC were also in accordance with that of the SDS-PAGE profiles of gluten and glutenin-rich fractions. No aggregation behavior was observed for α-gliadin and γ-gliadin containing cysteine in gluten- and gliadin-rich fractions, leading to the constant content of thiol content of gliadin during the frozen storage. The results of combined CD spectroscopy and FTIR spectroscopy indicated non-covalent interactions were also affected. Significant loss of elastic modulus (G′) and viscous modulus (G″) to gluten- and glutenin-rich fractions were detected with the increasing storage except that no apparent changes occurred in gliadin-rich fractions, suggesting that variation of glutenin functionality was quite important for that of gluten. Moreover, highly significant negative correlations between the content of SDS-soluble glutenin and data of G′ were found in gluten- and glutenin-rich fractions suggested depolymerization of GMP was the main indicator of deterioration of gluten and glutenin during the frozen storage. [Copyright &y& Elsevier]

Abstract: The effect of frozen storage on the water sorption capability, water mobility, secondary structure, thermal and microscopic properties of gluten-, glutenin- and gliadin-rich fractions were investigated. Lower water sorption capability was observed for samples after frozen storage, suggesting that more hydrophobic moieties were exposed. Conversions of α-helix structure to β-turn structures and specific β-sheet structures were observed in the secondary structure analysis of gluten- and gliadin-rich fractions. Frozen storage induced higher water mobility in hydrated gluten proteins. Similar changes were observed in gluten-water and gliadin-water systems, implying that the changes were primarily attributed to subdued gliadin-water interactions and gliadin can stabilize glutenin network to confine the water mobility. Meanwhile, thermo gravimetric analysis (TGA) and differential scanning calorimetry (DSC) showed that thermal degradation temperature decreased while thermal denaturation stability increased in gluten- and glutenin-rich fractions with the increasing time of frozen storage. However, the enthalpies of all the gluten proteins decreased, indicating more disordered structures in the aged gluten proteins. The micrographs of scanning electron microscopy (SEM) also confirmed more disordered and weak structures in gluten- and glutenin-rich fractions induced by frozen storage. Furthermore, consistent changes in gluten-, glutenin- and gliadin-rich fractions indicated that the variations in conformational, thermal and microscopic properties of gluten might originate from glutenin and gliadin upon frozen storage. [Copyright &y& Elsevier]

Wheat flour superheated steam treatment can improve the baking food quality by modifying the functionality of wheat flour. To reveal the underlying mechanism of improving wheat flour quality by superheated steam treatment, the gluten molecular rearrangement and polymerization behavior of wheat flour upon superheated steam were studied. Molecular size distributions of samples were analyzed using size exclusion (SE-HPLC) and electrophoresis, which illustrated that superheated steam treatment promoted the aggregation of gluten due to cross-links of disulfide (SS) bonds. Superheated steam treatment increased the SDS-insoluble proteins content from 63.07% (native wheat flour) to 93.32% (treated at 150 °C for 1 min). Infrared spectroscopy (FTIR) was used to calculate the different secondary structures percentages of gluten, suggesting that superheated steam treatment increased intermolecular β-sheet and α-helix while it decreased anti-parallel β-sheet, β-turn and β-sheet. Furthermore, thermo gravimetric analysis (TGA) and rheology suggested that superheated steam treatment enhanced gluten mass but weakened gel system due to molecular rearrangements of SS bonds and hydrogen bonds. [Display omitted] • Gluten polymerization behavior of wheat flour upon superheated steam were studied. • Superheated steam treatment induced gluten aggregation and SS bonds cross-links. • Superheated steam treatment weakened the wheat flour gel system. [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]