Study on process of Yak and Holstein casein‐glucose Maillard reaction and functional properties of their products

Magnetic field-driven biochemical landscape of browning abatement in goat milk using spatial-omics uncovers

Influence of magnetic field (MF) treatment on the glycation of goat milk proteins is yet to be elucidated. Proteomic and metabolomic analyses of brown goat milk samples with and without MF treatment were performed. Assessed glycation degree and structural modification of proteins explained that MF treatment dramatically down-regulated the glycation of brown goat milk protein, possibly due to the aggregation behavior induced by MF treatment, which consumed additional glycation sites as well as altered their accessibility and preference. Integrated datasets uncovered that the energy metabolism-related biological events including carbohydrate metabolism, glycerophospholipid metabolism, TCA cycle may mainly account for the browning abatement mechanism of MF. In addition, MF treatment enhanced both the quality and flavor of brown goat milk. This study suggests the feasibility of MF treatment to reduce glycation in brown goat milk for producing high-quality dairy ingredients and products.

Changes in partial properties of glycosylated egg white powder during storage

BACKGROUND

Glycosylation is an effective method to modify protein. However, there is a lack of research on the property changes of glycosylated protein during storage. In the present study, the changes in the physicochemical, functional, and structural properties of xylo-oligosaccharide (XOS) glycosylated egg white powder (EWP) (XOS-EWP conjugates) prepared with different glycosylation conditions (XOS/EWP ratio and reaction time) were investigated when stored at 25 °C and 60% relative humidity.

RESULTS

In the 12 weeks of storage, the degree of grafting, browning, and the formation of Maillard reaction products of XOS-EWP conjugates increased. The increase in XOS/EWP ratio and reaction time led to an increase in protein aggregation, though a decrease in solubility, due to increased degree of glycosylation and structural changes. Furthermore, improved gel hardness of XOS-EWP conjugates deteriorated, while improved emulsification ability was kept stable during storage. For the sample with a lower XOS/EWP ratio and reaction time, the gel hardness and emulsifying properties underwent little or no deterioration even improving during storage. The results could be attributed to the limited degree of glycosylation, further unfolding of the protein structure, increased surface hydrophobicity of protein, and improved thermal characteristics.

CONCLUSION

During storage, the Maillard reaction would continue to occur in the glycosylated EWP, further affecting the performance of modified EWP. Modified EWP prepared under different glycosylation conditions performed differently during storage. Modified EWP with a larger XOS/EWP ratio and reaction time meant it was harder to maintain good performance. Modified EWP with a smaller XOS/EWP ratio and reaction time changed significantly to better performances. © 2022 Society of Chemical Industry.

Structure, chemical stability and antioxidant activity of melanoidins extracted from dark beer by acetone precipitation and macroporous resin adsorption

Melanoidins contribute to the sensory and functional properties of dark beers. The structure, stability, and antioxidant activity of acetone precipitation extracted melanoidins (APE-M) and macroporous resin adsorption extracted melanoidins (MAE-M) from dark beer were investigated. The structural properties of melanoidins were characterized using Fourier transform infrared spectroscopy (FTIR), circular dichroism (CD), scanning electron microscopy (SEM), and the solution storage stability, thermal behavior and antioxidant activity of melanoidins in dark beers were evaluated. MAE-M revealed more sophisticated structures than APE-M, including more concrete characteristics of Maillard reaction (MR) products in FTIR (1550-1500 cm^-1), more ordered secondary structure in CD spectra, and thinner slices as well as more microspheres in SEM. The solution storage stability assay showed that certain factors, including 55 °C, 5 % v/v ethanol, UV light, and H₂O₂ solution, accelerated the degradation of melanoidins. The moderate extraction process of MAE-M performed a minor enthalpy change (-92.28 Jg^-1) in the DSC-TG test than that of APE-M (-319.41 Jg^-1). Furthermore, the ABTS and DPPH radical scavenging activities and the FRAP assay demonstrated that the antioxidant activity of MAE-M was almost twice that of APE-M. In general, MAE was more effective in extracting beer melanoidins while maintaining its accurate structure and profitable antioxidant activity than APE.