Impact of enrichment with egg constituents on water status in gluten-free rice pasta - nuclear magnetic resonance and thermogravimetric approach

Physicochemical properties and structure of rice dough and protein based on TGase combined with sodium metabisulfite modification

To improve the toughness of the rice dough, protein transglutaminase (TGase) combined with sodium metabisulfite (SMB) modification was used. The influences of modification on rice dough and protein were investigated, and their physicochemical and structural characteristics were analyzed. Mechanical analysis results indicated that the tanδ and texture characteristics of the modified rice dough were close to those of the wheat dough. The content of weakly bound water increased after rice dough modification. The average particle size of the modified rice protein (MRP) increased. The α-helix and β-turn increased, the β-sheet of MRP was reduced. The hydrogen, ionic, and hydrophobic bond contents of the MRP were significantly higher than those of the unmodified rice protein (URP). The results showed that TGase combined with SMB changed the URP network structure, thereby effectively regulating the viscoelastic balance of the unmodified rice dough.

Exploring novel antioxidant cyclic peptides in corn protein hydrolysate: Preparation, identification and molecular docking analysis

Antioxidant cyclic peptides were successfully identified from a corn protein hydrolysate. Hydrolysate by Alcalase + Flavourzyme showed the highest cyclic peptide purity (48.36 ± 1.81 %) and higher antioxidant activities compared with other hydrolysate. The success of peptide cyclization in hydrolysate was demonstrated by thermogravimetric analysis and thin-layer chromatography (TLC) analysis. Thermogravimetric analysis showed that the thermal stability of hydrolysate after cyclization was significantly increased, which was related to the formation of cyclic peptides. Peptides with molecular weight less than 1000 Da accounted for more than 80 % in hydrolysate after cyclization. After separation using gel silica chromatography and semi-preparative reverse phase high performance liquid chromatography (RP-HPLC), 22 novel antioxidant cyclic peptides were identified by ultra performance liquid chromatography-quadrupole-time of flight mass spectrometry (UPLC-Q-TOF-MS) and orbitrap-tandem mass spectrometry (Orbitrap-MS/MS). Synthetic cyclic peptides with the same sequence were synthesized and characterized for their antioxidant activity. Molecular docking suggested that the free radical molecules could bind with the cyclic backbone and side chain of cyclic peptides through hydrogen bonding, hydrophobic interaction as well as electrostatic interaction. This study has important implications for the high-value utilization of corn protein and new cyclic peptides drugs or functional food development.

Effect of egg white protein on the protein structure of highland barley noodles during processing

The effect of egg white protein on the protein structure of highland barely noodles during processing was investigated, and the underlying mechanism was examined. Egg white protein significantly influenced the stress relaxation of highland barley dough. 1% and 2% egg white protein improved the cooking and textural properties of highland barely noodles. During mixing and sheeting, it improved the structure of the protein network by promoting protein aggregation and cross-linking, whereas its effect on non-covalent interactions was quite different. During cooking, egg white protein promoted protein aggregation and cross-linking via heat-induced polymerization, and the distribution regularity of the protein network was improved as its flexibility diminished. The protein structure of highland barely noodles during processing was closely related to the addition amount of egg white protein, and the cooking, textural, and chemical interactions of highland barely noodles during processing changed considerably when more than 3% egg white protein was added.

Effects of sodium carboxymethyl cellulose on storage stability and qualities of different frozen dough

Hydrocolloids as Additives have been used for improving the quality of frozen dough for a long time. In this work, the effects of sodium carboxymethyl cellulose (CMC) on quality changes of frozen dough in storage were studied. The water loss rate of the dough and water holding capacity were measured. Rheological and texture properties of the frozen dough were measured by a rheometer and a texture analyzer, respectively. Scanning electron microscopy (SEM) was used to characterize surface network structure and protein structure changes of the frozen dough. Our results reveal that the addition of CMC can inhibit the formation of ice crystals and recrystallization, thus effectively stabilizing the molecular structure of starch, and resulting in more uniform moisture distribution in the frozen dough. When 3% addition of CMC, the water holding capacity of the two kinds of dough reached the best, and the water loss rate of corn dough reached the lowest. The cohesion of the two kinds of dough reaches the maximum with 3 wt% addition of CMC, while the hardness and chewiness of wheat and corn multigrain dough reaches the maximum with 3 wt% and 4 wt% addition of CMC, respectively. The results show proper CMC addition (3 wt% and 4 wt%) finally improves the stability and qualities of the frozen dough. The research concerning the effects of CMC on quality of frozen dough provides better understanding for the frozen food industry.

The use of time domain 1 H NMR to study proton dynamics in starch-rich foods: A review

Starch is a major contributor to the carbohydrate portion of our diet. When it is present with water, it undergoes several transformations during heating and/or cooling making it an essential structure-forming component in starch-rich food systems (e.g., bread and cake). Time domain proton nuclear magnetic resonance (TD ¹ H NMR) is a useful technique to study starch-water interactions by evaluation of molecular mobility and water distribution. The data obtained correspond to changes in starch structure and the state of water during or resulting from processing. When this technique was first applied to starch(-rich) foods, significant challenges were encountered during data interpretation of complex food systems (e.g., cake or biscuit) due to the presence of multiple constituents (proteins, carbohydrates, lipids, etc.). This article discusses the principles of TD ¹ H NMR and the tools applied that improved characterization and interpretation of TD NMR data. More in particular, the major differences in proton distribution of various dough and cooked/baked food systems are examined. The application of variable-temperature TD ¹ H NMR is also discussed as it demonstrates exceptional ability to elucidate the molecular dynamics of starch transitions (e.g., gelatinization, gelation) in dough/batter systems during heating/cooling. In conclusion, TD NMR is considered a valuable tool to understand the behavior of starch and water that relate to the characteristics and/or quality of starchy food products. Such insights are crucial for food product optimization and development in response to the needs of the food industry.

Observation and Nursing of Adverse Reactions in Severe Patients with Enhanced MRI

In order to explore the observation and nursing of adverse reactions in severe patients with enhanced magnetic resonance imaging, a family nursing service model was proposed in patients with enhanced magnetic resonance imaging. 150 patients who underwent enhanced magnetic resonance imaging in a hospital were selected as the research objects. The patients were divided into two groups by random number table method. 75 patients in the control group received routine nursing intervention and 75 patients in the observation group received family nursing service intervention. The anxiety score, depression score, examination time, one-time success rate, comfort score, incidence of adverse reactions, excellent image quality rate and nursing satisfaction were compared between the two groups. The results showed that the anxiety score and depression score of the observation group were lower than those of the control group (P < 0.05), the examination time of the observation group was significantly shorter than that of the control group (P < 0.05), and the comfort score and one-time success rate of the observation group were significantly higher than those of the control group (P < 0.05). The incidence of adverse reactions was significantly lower than that in the control group (P < 0.05), the excellent and good image quality rate (95.00%) and nursing satisfaction (97.22%) were significantly higher than those in the control group (83.00%, 86.56%). This shows that the application effect of family nursing service mode in magnetic resonance enhanced scanning is remarkable. Therefore, the use of family care mode in MRI patient examination can effectively reduce patients' anxiety and depression scores, shorten examination time, reduce adverse reactions, improve the success rate of one-time examination, improve patients' comfort during examination and patients' evaluation of nursing services. The effect is ideal and worthy of clinical research and promotion.

Modification methods and applications of egg protein gel properties: A review

Egg protein (EP) has a variety of functional properties, such as gelling, foaming, and emulsifying. The gel characteristics provide a foundation for applications in the food industry and research on EP. The proteins denature and aggregate to form a dense three-dimensional gel network structure, with a process influenced by protein concentration, pH, ion type, and strength. In addition, the gelation properties of EP can be altered to varying degrees by applying different treatment conditions to EP. Currently, modification methods for proteins include physical modification (heat-induced denaturation, freeze-thaw modification, high-pressure modification, and ultrasonic modification), chemical modification (glycosylation modification, phosphorylation modification, acylation modification, ethanol modification, polyphenol modification), and biological modification (enzyme modification). Pidan, salted eggs, egg tofu, and other egg products have unique sensory properties, due to the gel properties of EP. In accessions, EP has also been used as a new ingredient in food packaging and biopharmaceuticals due to its gel properties. This review will further promote EP gel research and provide guidance for its full application in many fields.

Near-infrared spectroscopy coupled with chemometrics algorithms for the quantitative determination of the germinability of Clostridium perfringens in four different matrices

Clostridium perfringens (C. perfringens) has the ability to form metabolically-dormant spores that can survive food preservation processes and cause food spoilage and foodborne safety risks upon germination outgrowth. This study was conducted to investigate the effects of different AGFK concentrations (0, 50, 100, 200 mM/mL) on the spore germination of C. perfringens in four matrices, including Tris-HCl, FTG, milk, and chicken soup. C. perfringens spore germinability was investigated using near infrared spectroscopy (NIRS) combined with chemometrics. The spore germination rate (S), the OD₆₀₀%, and the Ca²⁺-DPA% were measured using traditional spore germination methods. The results of spore germination assays showed that the optimum germination rate was obtained using 100 mM/L concentrations of AGFK in the FTG medium, and the S, OD₆₀₀% and Ca²⁺-DPA% were 98.6%, 59.3% and 95%, respectively. The best prediction models for the S, OD₆₀₀% and Ca²⁺-DPA% were obtained using SNV as the preprocessing method for the original spectra, with the competitive adaptive weighted resampling method (CARS) as the characteristic variables related to the selected spore germination methods from NIRS data. The results of the S showed that the optimum model was built by CARS-PLSR (RMSEV = 0.745, R_c = 0.897, RMSEP = 0.769, R_p = 0.883). For the OD₆₀₀%, interval partial least squares regression (CARS-siPLS) was performed to optimize the models. The calibration yielded acceptable results (RMSEV = 0.218, R_c = 0.879, RMSEP = 0.257, R_p = 0.845). For the Ca²⁺-DPA%, the optimum model with CARS-siPLS yielded acceptable results (RMSEV = 44.7, R_c = 0.883, RMSEP = 50.2, R_p = 0.872). This indicated that quantitative determinations of the germinability of C. perfringens spores using NIR technology is feasible. A new method based on NIR was provided for rapid, automatic, and non-destructive determination of the germinability of C. perfringens spores.

NMR Relaxation Measurements on Complex Samples Based on Real-Time Pure Shift Techniques

Longitudinal spin-lattice relaxation (T₁) and transverse spin-spin relaxation (T₂) reveal valuable information for studying molecular dynamics in NMR applications. Accurate relaxation measurements from conventional 1D proton spectra are generally subject to challenges of spectral congestion caused by J coupling splittings and spectral line broadenings due to magnetic field inhomogeneity. Here, we present an NMR relaxation method based on real-time pure shift techniques to overcome these two challenges and achieve accurate measurements of T₁ and T₂ relaxation times from complex samples that contain crowded NMR resonances even under inhomogeneous magnetic fields. Both theoretical analyses and detailed experiments are performed to demonstrate the effectiveness and ability of the proposed method for accurate relaxation measurements on complex samples and its practicability to non-ideal magnetic field conditions.