Magnesium ions regulated ovalbumin-lysozyme heteroprotein complex: Aggregation kinetics, thermodynamics and morphologic structure.

This study aims to investigate the mechanism of magnesium ions regulated ovalbumin-lysozyme (OVA-LYS) heteroprotein aggregation behavior via aggregation kinetics model, exploring the relationship between differential aggregation behavior and protein molecular structure, intermolecular interactions and thermal stability. Results showed that the aggregation rate (kapp) and maximum absorbance (Amax) of the OVA-LYS heteroprotein complex were located between OVA and LYS. Meanwhile, the thermal denaturation temperature (Td) and denaturation enthalpy (ΔH) were between the values of OVA and LYS as well. Compared with OVA, the thermal stability of the OVA-LYS heteroprotein complex increased owing to the electrostatic interactions between OVA and LYS, resulting in slower aggregation rate and lower aggregation degree. Molecular dynamics simulations revealed the molecular conformational changes during OVA-LYS binary protein binding and the stability of the complex conformation. Moreover, MgCl2 weakened the OVA-LYS interactions through Debye shielding while increasing thermal stability, allowing the two proteins to aggregate into amorphous precipitates rather than spherical coacervates. Overall, this study provides information to further understand the regulation mechanism of proteins differential aggregation behavior by ions.

Substitution of sucrose by erythritol in angel cake: Effect on protein foaming, baking performance and digestion properties.

Sugars played an important role in the processing of products such as cakes, however, their high-calorie character often posed a health risk to consumers. Therefore, this paper aimed to better investigate the effect of sugar substitutes on the improvement of egg white foaming properties and angle cake digestibility characteristics. It was demonstrated that the addition of erythritol improved the surface properties of egg whites, thus enhancing their foaming properties. Particularly, when the erythritol substitution was 50 %, the sugar-egg white complex structure unfolded and had the best foaming capacity. On this basis, the baking performance of angel cakes with sucrose replaced by erythritol was analyzed. When the erythritol substitution was lower than 50 %, the specific volume and the baking loss rate of the cakes were basically unchanged, and the texture and sensory taste of the cakes were all excellent. Finally, the gastrointestinal digestive kinetic analysis suggested that erythritol substitution for sucrose was beneficial for reducing blood glucose levels in vivo. Furthermore, for the MgCl2-based samples, both the degree of protein destruction after digestion was weakened and the glucose-lowering effect was better exerted. Overall, this study provided a new theoretical basis for the low-calorie sugar-substituted health food products development in the future.

Colonization of Clostridium butyricum in Rats and Its Effect on Intestinal Microbial Composition.

Gut microorganisms participate in many physiological processes. In particular, Clostridium butyricum can modulate gut microorganisms and treat diseases. The colonization and persistence of strains in the gut contribute to beneficial effects, and the colonization by C. butyricum in the gut is currently unknown. We investigated the total intestinal contents of C. butyricum at 12 h, 24 h, 48 h, and four and six days using real-time reverse transcription-PCR, after oral administration of C. butyricum to rats for seven consecutive days. We assessed the bacterial community structure using Illumina MiSeq sequencing. The results showed that C. butyricum was mainly colonized in the colon. The total content of C. butyricum in the gut increased significantly at 12 h after administration. Exogenous C. butyricum could still be detected in the gut six days after administration. Administration of C. butyricum significantly enhanced gut microbial diversity. The relative abundance of short-chain fatty acid-producing bacterial genera was shown to be higher than that of the control group, and treatment with C. butyricum elevated Firmicutes and diminished Bacteroidetes phyla compared with to the control group. These findings laid the foundation for the study of probiotic colonization capacity and the improvement of microflora for the prevention of gut diseases.

Biotransformation of alkylamides and alkaloids by lactic acid bacteria strains isolated from Zanthoxylum bungeanum meal.

Zanthoxylum bungeanum meal (ZBM) is the by-product of Z. bungeanum seeds after pressing. It is restricted as a feed additive because it contains stimulating and potentially harmful substances, which are alkylamides and alkaloids. This study described the use of Lactobacillus paracasei and L. acidipiscis isolated from ZBM in solid-state fermentation of ZBM to reduce the concentration of undesirable alkylamides and alkaloids. By optimizing the substrate and fermentation conditions, the minimum contents of alkylamide and alkaloid were 2.96 and 3.20 mg/g, and the degradation rates reached 51.86% and 39.59%, respectively. Moreover, the biotransformation pathways of hydroxyl-α-sanshool and chelerythrine were established by identifying the metabolites. Bacterial diversity was shift significantly, and the relative abundance of Lactobacillus increased from 0.10% to 99.0% after fermentation. In conclusion, this study introduced a reliable strategy for processing ZBM as a feed additive.