TGase-7S gels prepared after different HIU pretreatment times were used to intervene in healthy mice to analyze their effects on growth characteristics and intestinal morphology, and 16S rRNA high-throughput sequencing was applied to fecal samples to investigate the effects of the gel on the structure and diversity of intestinal flora in mice. The results showed that the intestinal tissues of mice in different treatment groups showed better integrity, and the intake of gel increased the length of small intestinal villi in mice, among which the 30-gel group had the highest value of villi length (599.27 ± 44.28) μm (p < 0.05) and showed the neatest and tightest arrangement, indicating that the intake of gel did not have adverse effects on the intestinal tract. The effect of gel ingestion on the diversity of the intestinal microbial community structure was more significant, positively promoting the growth of beneficial bacteria such as Desferriobacterium, Synechococcus, and Bifidobacterium. In addition, the ingestion of the gel improved the intestinal health of mice by altering the physiological functions of the intestinal flora and modulating their participation in various metabolic pathways. The above findings provide some theoretical value for the safety of 7S gel in food applications.

In this study, we investigated the effects of different high-intensity ultrasound (HIU) pretreatment times (0–60 min) on the structure of β-conglycinin (7S) and the structural and functional properties of 7S gels induced by transglutaminase (TGase). Analysis of 7S conformation revealed that 30 min HIU pretreatment significantly induced the unfolding of the 7S structure, with the smallest particle size (97.59 nm), the highest surface hydrophobicity (51.42), and the lowering and raising of the content of the α-helix and β-sheet, respectively. Gel solubility showed that HIU facilitated the formation of ε-(γ-glutamyl)lysine isopeptide bonds, which maintain the stability and integrity of the gel network. The SEM revealed that the three-dimensional network structure of the gel at 30 min exhibited filamentous and homogeneous properties. Among them, the gel strength and water-holding capacity were approximately 1.54 and 1.23 times higher than those of the untreated 7S gels, respectively. The 7S gel obtained the highest thermal denaturation temperature (89.39 °C), G′, and G″, and the lowest tan δ. Correlation analysis demonstrated that the gel functional properties were negatively correlated with particle size and the α-helix, while positively with Ho and β-sheet. By contrast, gels without sonication or with excessive pretreatment showed a large pore size and inhomogeneous gel network, and poor properties. These results will provide a theoretical basis for the optimization of HIU pretreatment conditions during TGase-induced 7S gel formation, to improve gelling properties.

This study evaluated the biological effects of exogenous advanced glycation end products (AGEs) on the induction of chronic kidney disease and the dose-effect relationship. Male C57BL/6 mice were placed on four diets, including saline and three other diets differing only in AGEs content (low-AGEs [LA], medium-AGEs [MA], and high-AGEs [HA] ratio, 1:3:5) for 4 weeks. With the increasing intake of AGEs, mice developed a significant increase in blood glucose and lipid levels, the fluorescence intensity of AGEs, N epsilon-(carboxymethyl)-lysine, N epsilon-(carboxyethyl)-lysine, and malondialdehyde levels, whereas their superoxide dismutase activity and glutathione levels were decreased significantly. HA had the highest urinary protein levels and the lowest creatinine clearance compared to the other groups. These suggested that AGEs are an essential contributor to increasing oxidative stress levels and intake of high-level AGEs induces more severe kidney function impairment. Meanwhile, the AGEs intake damaged the kidney structure in a dose-dependent manner, as evidenced by granular degeneration of kidney tubular epithelial cells and inflammatory cell infiltration. These findings shed light on the detrimental impacts of AGEs on human kidneys, which also will help reveal a dose-effect relationship of AGEs. The advanced glycation end products (AGEs) intake damaged the kidney structure in a dose-dependent manner. This study shed light on the detrimental impacts of AGEs on human kidneys and will be helpful in revealing a dose-effect relationship of AGEs.image

The beta-conglycinin (7S) was pre-treated with high-intensity ultrasonic (HIU) and subsequently formed into composite edible films with the transglutaminase (TGase) method. Effects of HIU pretreatment time (0, 5, 10, 15, and 20 min) on the conformation of 7S and structural and application properties of 7S-TGase films were evaluated. The analysis of 7S conformation results revealed that HIU pretreatment for 0-10 min significantly dissociated the 7S, exposed internal hydrophobic groups of protein, increased its intermolecular hydrogen bonds, and altered the protein secondary and tertiary structure. The structural properties of films were evaluated by SEM, XRD, and ATR-FTIR. SEM showed that HIU reduced film wrinkles and cracks and improved unevenness. XRD and ATR-FTIR indicated that the film obtained an enlarged crystallinity, and the amide I and amide II regions of films were peak-shifted which is usually associated with the formation of covalent bonds. Notably, analysis of intermolecular force showed that HIU facilitated the formation of hydrogen bonds, hydrophobic interactions, and epsilon-(gamma-glutamyl) lysine bonds in 7S-TGase films. The above structural changes in 7S and films were beneficial for the application properties of films. Results indicated that 10 min HIU pretreatment effectively improved the mechanical properties and water resistance, reduced water vapor permeability and oxygen permeability, and decreased the opacity of 7S-TGase films. However, the color of the film was not affected by the HIU, with an overall bright and yellowish color.

ABSTRACT:Beef is an important red meat that contains essential nutrients for human growth and development. Baking is a popular beef cooking method. Temperature and time play key roles in the final quality of beef. How temperature and time affect the changes of nutrients and the formation of harmful products in beef is not clear. The purpose of this study was to measure the content of water, fat, protein, ash, nitrite, total volatile base nitrogen, advanced glycation end products (AGEs) and their precursors, and polycyclic aromatic hydrocarbons (PAHs) at different temperatures (150, 190, 230, 270, and 310°C) for 20 min and at 190°C for different times (10, 20, and 30 min), so as to discuss the effect of different temperatures and times on beef nutrients and harmful products. The results showed that the moisture content of beef decreased with increased baking temperature and time, resulting in the increase of the relative content of fat, protein, and ash. The content of total volatile base nitrogen increased continuously. Compared with the control group, the content of glyoxal in beef decreased, whereas the content of methylglyoxal, pentosidine, and fluorescent AGEs increased, indicating the continuous accumulation of AGEs in beef. A total of 13 PAHs were identified by gas chromatography-mass spectrometry. The concentrations of 13 PAHs in beef increased with increases in baking temperature and time. The concentrations of BkP and BaP, which are the most carcinogenic to humans, were 0.36 and 0.35 μg/kg in raw meat, respectively; these were increased by high temperature and long baking times. After beef was baked at 270 and 310°C for 20 min, the concentration of BkP increased to 9.49 and 5.66 μg/kg, respectively, and the concentration of BaP increased to 5.45 and 4.42 μg/kg, respectively. After baking at 190°C for 30 and 40 min, the concentration of BkP increased to 4.81 and 24.20 μg/kg, respectively, and the concentration of BaP increased to 3.85 and 17.79 μg/kg, respectively. HIGHLIGHTS:

Spatial structure and amino acid residue side-chain oxidative modification of soybean isolated protein (SPI) at different dry heating temperatures (70, 100, 130, 160 and 190 °C) were investigated, respectively in this study. The results showed that the dry heating promoted the formation of disulfide bonds and oxidative modification of SPI, such as carboxylation and hydroxylation under the below 160 °C. With increasing temperature, β-sheet and α-helix shifted to random coil and β-turn. The conformation of SPI changed, the solubility decreased and the particle size became smaller resulting from the combination of protein oxidation and chemical bond redistribution, but the structural integrity of SPI was better ensured below 130 °C. SPI was severely hydrolyzed at 190 °C. These results provide a theoretical basis for the study of protein modification by dry heating, which is a guideline for controlling the degree of protein denaturation in the food industry.