Lipid oxidation induced egg white protein foaming properties enhancement: The mechanism study revealed by high resolution mass spectrometry

Effect of protein oxidation on the structural characteristics and emulsification properties of rice bran protein fibril: Assessing the role of peroxyl radicals

The effect of peroxyl radical-induced oxidation by thermolysis of 2,2'-azino-bis(2-amidinopropane) (AAPH) on the structural characteristics of rice bran protein fibril (RBPF) and the stability of high internal phase Pickering emulsion (HIPPE) was investigated. The results indicated that the thioflavin T intensity (1306.67 a.u.), average particle size (1208 nm), ζ-potential value (26.31 mV), surface hydrophobicity (1105.81 a.u.), and contact angle (80.7°) of RBPF reached the maximum value when the AAPH concentration was 3 mmol/L, while the α-helix to β-sheet ratio (0.32) of RBPF reached the minimum value. Furthermore, moderate oxidation induced by peroxyl radicals (derived from AAPH concentration ≤ 3 mmol/L) improved the viscoelasticity of RBPF-HIPPE. Correspondingly, RBPF-HIPPE remained stable after 70 days of storage at 25 °C, 1 h of heating at 100 °C, and 4 freeze-thaw cycles. Overall, peroxyl radicals-induced protein oxidation could enhance the stability of RBPF-HIPPE by modulating structural characteristics of RBPF and the rheological properties of RBPF-HIPPE.

Cysteine and dialysis mediated inhibition of dynamic changes in glycosylated egg white protein during storage

Glycosylation is commonly used to improve the solubility and functionality of egg white protein (EWP), but glycosylated EWP is prone to quality deterioration during storage. To enhance its storage stability, cysteine (Cys) addition and dialysis-based desugar treatment were applied to xylo-oligosaccharide (XOS) glycosylated EWP (GEW) in accelerated storage examinations. Both Cys addition and dialysis minimized changes in soluble protein content, color difference, and particle size during storage. Further, they inhibited the Maillard reaction and the accumulation of its intermediate products. Cys addition effectively maintained protein structures and prevented protein crosslinking. However, dialysis lost the filling and protective effect of free sugars, lowering the denaturation temperature of ovalbumin. Cys and dialysis effectively maintained the stability of emulsifying properties, while Cys better preserved gelation. Overall, both Cys addition and dialysis markedly enhanced the storage stability of GEW, with Cys proving to be more effective.

Effect of oxidation on finely segmented products of snakehead: Digestibility and microstructure

The present study was performed to investigate the digestive profiles of snakeheads' belly muscles (BM), tail muscles (TM) dorsal muscles (DM), and eye muscles (EM), with further explorations of relevant factors. Kinetic models were adopted to describe the digestion process with crucial parameters. BM showed the highest digestibility and digestive rate, followed by DM, TM, and EM. Meanwhile, the BM showed the lowest hardness and springiness among the four muscles observed by texture Profile Analysis. The oxidation during storage promoted the digestion of muscles as well. The deformation due to oxidation caused a growth in cooking loss, TVB-N values, and gap rates of muscles, making the muscles more sensitive to digestive enzymes. The varying conformations of myofibrillar proteins (MP) led to the devious digestibility: MP obtained from BM held the highest release level of free amino groups because of a loosened and disordered structure with the lowest denaturation temperature.

Egg white protein‑sodium alginate smart labels based on pH-driven method and nonphase change 3D printing in mackerel freshness response

The smart labels prepared via the casting method and molten 3D printing method have a long heating time at high temperature and a dense network structure, resulting in a decrease in the color response ability of the labels. Therefore, this study uses a nonphase change foam 3D printing method with a shorter heating time to improve the color sensitivity of smart labels. By the pH driving method, the blending and pregelation of sodium alginate (Alg) can extend the drainage time of the interfacial film to the maximum extent, thus further improving the foam stability of egg white protein (EWP) and endowing the interfacial adsorption layer with better flexibility and fluidity. The pregelled Alg-EWP foam has good 3D printing adaptability, shows obvious shear thinning behavior, and has excellent shear recovery and creep recovery properties. The 3D-printed smart label has significantly higher swelling rate (275 % → 400 %), porosity (19.86 % → 42.86 %) and phenolic retention rate (55.51 % → 97.26 %). In addition, the sensitivity of the smart labels prepared via foam 3D printing significantly increased, indicating mackerel freshness. Therefore, the method of nonphase-change foam 3D printing provides a new strategy for preparing smart labels with increased porosity and color sensitivity.

Citric Acid Improves Egg White Protein Foaming Characteristics and Meringue 3D Printing Performance

Meringue has limited the use of meringue for personalization because of its thermally unstable system. Citric acid (CA) enhancement of egg white protein (EWP) foaming properties is proposed for the preparation of 3D-printed meringues. The results showed that CA increased the viscosity, exposure of hydrophobic groups (79.8% increase), and free sulfhydryl content (from 5 µmol/g to 34.8 µmol/g) of the EWP, thereby increasing the foaminess (from 50% to 178.2%). CA treatment increased the rates of adsorption, stretching, and orientation of EWP at the air-water interface to form multiple layers, resulting in a delay in foam thinning. The secondary structure of CA-treated EWP remained intact, and the exposure of amino acid residues in the tertiary structure increased with the expansion of the hydrophobic region. CA-treated EWP-prepared protein creams had a suitable viscosity (from 233.4 Pa·s to 1007 Pa·s at 0.1 s-1), shear thinning, structural restorability, and elasticity, which ensured good fidelity of their printed samples. Experiments involving 3D printing of CA-treated EWP showed that CA could significantly enhance the 3D printing fidelity of EWP. Our study could provide new ideas for the development of customizable 3D-printed foam food products.

In vitro digestion and functional properties of bovine β-casein: A comparison between adults and infants

Gastrointestinal digestibility behavior, structural and functional characteristics of bovine β-casein (β-CN) were studied in vitro under infant and adult conditions. This direct comparison helps reveal the effects of different physiological stages on the digestive behavior of β-CN. Not only was the degree of hydrolysis (DH) of β-CN analyzed, but also the changes in its digestive morphology, microstructure, and secondary structure during digestion were explored in depth. Meanwhile, we focused on the physicochemical properties of β-CN digesta, including solubility, emulsifying and foaming properties, as well as their functional properties, such as antimicrobial and antioxidant activities. Key results showed that β-CN underwent more extensive hydrolysis in the adult digestion model, with approximately twice the DH compared to the infant model. The adult model exhibited faster digestion kinetics, less protein flocculation, and a more loosened secondary structure, indicating a more efficient digestion process. Notably, the digesta from the adult model displayed significantly improved solubility and emulsifying properties, and also enhanced antioxidant capacities, with significantly better inhibition of two common pathogenic bacteria than the infant model, and an average increase in the diameter of the inhibition zone of approximately 2 mm. These findings underscore the differential digestive behavior and functional potential of β-CN across physiological stages. This comprehensive assessment approach contributes to a more comprehensive insight into the digestive behavior of β-CN. Therefore, we conclude that producing products from unmodified β-CN may be more suitable for the adult population, and that the digesta in the adult model exhibit higher functional properties.

Storage impact on egg white powder's physical and functional properties

BACKGROUND

Changes in storage temperature and time alter the functional properties of egg white powder (EWP) and determine its quality and shelf-life, finally affecting the consumer acceptance of the products made from EWP. In the present study, the EWP samples were stored at four different temperatures (-20, 4, 25 and 37 °C) for 60 days, and then the protein structural, physical and functional properties of EWP were measured and assessed further for correlation with storage conditions using heatmap.

RESULTS

The viscosity of the EWP solution increased after 30 days. Foaming ability and rheological properties increased first and then decreased compared to untreated samples with the prolonged storage time. Correlation analysis results indicated that the gel hardness, water holding capacity, foaming ability, emulsifying ability, particle size, dispersibility and viscosity of EWP were significantly related to storage time (P < 0.05). Only the gelation properties of EWP stored at 37 °C for 60 days changed significantly and were negatively related to its moisture content (P < 0.05). Additionally, the random coil content of EWP was positively correlated with particle size, moisture content, solubility and gel properties, whereas β-sheet was negatively correlated with them.

CONCLUSION

Compared to other temperatures, the functional properties of EWP were relatively stable under 4 °C. Therefore, the low temperature (4 °C) was selected as the most suitable storage temperature for EWP. The results of the present study could provide a theoretical basis for the shelf-life extension of EWP. © 2022 Society of Chemical Industry.

Effects of spray drying, freeze drying, and vacuum drying on physicochemical and nutritional properties of protein peptide powder from salted duck egg white

Salted duck egg white contains many kinds of high quality protein, but it is often discarded as food factory waste because of high salinity and other reasons. The discarded salted duck egg white not only causes a waste of resources, but also causes environmental pollution. Using salted duck egg white as raw material, this study was completed to investigate the effects of three drying methods including freeze drying, vacuum drying, and spray drying on physicochemical and nutritional properties of protein powder from salted duck egg white. The results showed that the solubility, foaming and foaming stability, emulsification and emulsification stability of the protein peptide of salted duck egg white decreased to different degrees after drying. The scavenging rates of freeze-dried samples for superoxide anion, hydroxyl radical, and 1,1-Diphenyl-2-picrylhydrazyl (DPPH·) reached 48.76, 85.03, and 80.17%, respectively. Freeze drying had higher scavenging rates than vacuum drying and spray drying. The results of electron microscopy showed that freeze-drying had the least effect on the structure of protein peptide powder of salted duck egg white. The purpose of this experiment was to provide theoretical guidance and technical support for industrial drying of salted duck egg white protein solution.