13 results on '"Mengxiao Yang"'
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2. Dynamic In Vitro Gastric Digestion Behaviour of Commercial Infant Formulae Made with Cow, Goat and Sheep Milk
- Author
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Xuan Song, Xin Wang, Mengxiao Yang, Alejandra Acevedo-Fani, Harjinder Singh, and Aiqian Ye
- Subjects
infant formulae ,sheep milk ,goat milk ,gastric digestion ,heat treatment ,coagulation ,Chemical technology ,TP1-1185 - Abstract
There are a wide range of commercial infant formulae available on the market. These are made using milk from different species, such as goat, sheep, and cow. The different protein compositions of these milks and the process used during infant-formulae manufacture, such as heat treatment, may impact the digestion of nutrients. This study compared the effect of protein composition and heat treatment on the in vitro gastric digestion behaviour of commercial infant formulae made with cow, goat, and sheep milk using a dynamic infant human gastric simulator (IHGS). During the simulated dynamic gastric digestion, the goat milk infant formula (GIF) showed earlier signs of aggregate formation compared to cow milk infant formula (CIF) and sheep milk infant formula (SIF). In addition, the microstructures of GIF chyme showed fragmented and porous structures. On the contrary, CIF formed dense protein networks that trapped oil droplets, whereas SIF exhibited a microstructure of smooth oil droplets surrounded by fewer protein networks. The different aggregation behaviours and aggregate structures of the three infant-formulae chyme were related to their different protein compositions, especially the different casein compositions. Furthermore, the open fragile structure of GIF aggregates provided easier access to pepsin, allowing it to hydrolyse protein. The results from the present study provided some information to assist in understanding the coagulation and digestion behaviours of commercial infant formulae made from different species of milk.
- Published
- 2024
- Full Text
- View/download PDF
3. Gut microbiota of two invasive fishes respond differently to temperature
- Author
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Lixia Zhang, Zi Yang, Fan Yang, Gege Wang, Ming Zeng, Zhongxin Zhang, Mengxiao Yang, Zhanqi Wang, and Zhibing Li
- Subjects
gut microbiota ,invasive fishes ,temperature ,Cyprinus carpio ,Micropterus salmoides ,Microbiology ,QR1-502 - Abstract
Temperature variation structures the composition and diversity of gut microbiomes in ectothermic animals, key regulators of host physiology, with potential benefit to host or lead to converse results (i.e., negative). So, the significance of either effect may largely depend on the length of time exposed to extreme temperatures and how rapidly the gut microbiota can be altered by change in temperature. However, the temporal effects of temperature on gut microbiota have rarely been clarified. To understand this issue, we exposed two juvenile fishes (Cyprinus carpio and Micropterus salmoides), which both ranked among the 100 worst invasive alien species in the world, to increased environmental temperature and sampled of the gut microbiota at multiple time points after exposure so as to determine when differences in these communities become detectable. Further, how temperature affects the composition and function of microbiota was examined by comparing predicted metagenomic profiles of gut microbiota between treatment groups at the final time point of the experiment. The gut microbiota of C. carpio was more plastic than those of M. salmoides. Specifically, communities of C. carpio were greatly altered by increased temperature within 1 week, while communities of M. salmoides exhibit no significant changes. Further, we identified 10 predicted bacterial functional pathways in C. carpio that were temperature-dependent, while none functional pathways in M. salmoides was found to be temperature-dependent. Thus, the gut microbiota of C. carpio was more sensitive to temperature changes and their functional pathways were significantly changed after temperature treatment. These results showed the gut microbiota of the two invasive fishes differ in response to temperature change, which may indicate that they differ in colonization modes. Broadly, we have confirmed that the increased short-term fluctuations in temperatures are always expected to alter the gut microbiota of ectothermic vertebrates when facing global climate change.
- Published
- 2023
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- View/download PDF
4. Kinetics of pepsin-induced hydrolysis and the coagulation of milk proteins
- Author
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Mengxiao Yang, Aiqian Ye, Zhi Yang, David W. Everett, Elliot Paul Gilbert, and Harjinder Singh
- Subjects
pepsin ,milk coagulation ,rheology ,microstructure ,enzymatic hydrolysis kinetics ,Dairy processing. Dairy products ,SF250.5-275 ,Dairying ,SF221-250 - Abstract
ABSTRACT: Hydrolysis-induced coagulation of casein micelles by pepsin occurs during the digestion of milk. In this study, the effect of pH (6.7–5.3) and pepsin concentration (0.110–2.75 U/mL) on the hydrolysis of κ-casein and the coagulation of the casein micelles in bovine skim milk was investigated at 37°C using reverse-phase HPLC, oscillatory rheology, and confocal laser scanning microscopy. The hydrolysis of κ-casein followed a combined kinetic model of first-order hydrolysis and putative pepsin denaturation. The hydrolysis rate increased with increasing pepsin concentration at a given pH, was pH dependent, and reached a maximum at pH ∼6.0. Both the increase in pepsin concentration and decrease in pH resulted in a shorter coagulation time. The extent of κ-casein hydrolysis required for coagulation was independent of the pepsin concentration at a given pH and, because of the lower electrostatic repulsion between para-casein micelles at lower pH, decreased markedly from ∼73% to ∼33% when pH decreased from 6.3 to 5.3. In addition, the rheological properties and the microstructures of the coagulum were markedly affected by the pH and the pepsin concentration. The knowledge obtained from this study provides further understanding on the mechanism of milk coagulation, occurring at the initial stage of transiting into gastric conditions with high pH and low pepsin concentration.
- Published
- 2022
- Full Text
- View/download PDF
5. High-pressure processing of bovine milk: Effects on the coagulation of protein and fat globules during dynamic in vitro gastric digestion
- Author
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Xiaoye He, Mengxiao Yang, Fang Yuan, Harjinder Singh, and Aiqian Ye
- Subjects
Bovine milk ,High-pressure processing (HPP) ,In vitro gastric digestion ,Protein coagulation ,Nutrition. Foods and food supply ,TX341-641 ,Food processing and manufacture ,TP368-456 - Abstract
The effect of high-pressure processing (HPP) on the digestion behavior of skim and whole bovine milks was investigated using a human gastric simulator. Both milks formed clots during gastric digestion. HPP treatment led to the formation of a coagulum with a fragmented and crumbled structure, compared with the coagulum formed from untreated milk. At pressures over 400 MPa, more intense pressure resulted in looser and more fragmented gastric clot structures. The weight of the dried clots and the moisture content in the clots of the skim milk treated at 600 MPa were significantly lower and higher than that of untreated skim milk, respectively. The looser and more fragmented gastric clot structures consequently led to faster hydrolysis of the proteins by pepsin during gastric digestion. The denaturation of the whey proteins induced by HPP may have also altered the resistance of α-lactalbumin and β-lactoglobulin in the HPP-treated milk samples to pepsin hydrolysis. This study provides insights into the differences among untreated skim milk, untreated whole milk and HPP-treated milk under in vitro gastric digestion conditions. The structure of the clots formed in the gastric environment affects their breakdown and consequently their emptying rate into the intestine.
- Published
- 2022
- Full Text
- View/download PDF
6. Copper-induced oxidative stress, transcriptome changes, intestinal microbiota, and histopathology of common carp (Cyprinus carpio)
- Author
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Lixia Zhang, Zi Yang, Mengxiao Yang, Fan Yang, Gege Wang, Dandan Liu, Xuejun Li, Lianlian Yang, and Zhanqi Wang
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Copper ,Cyprinus carpio ,Oxidative stress ,Liver transcriptome ,Intestinal microbiota ,Histopathology ,Environmental pollution ,TD172-193.5 ,Environmental sciences ,GE1-350 - Abstract
Copper (Cu) is a common contaminant in aquatic environments, which could cause physiological dysfunction in aquatic organisms. However, few studies have comprehensively examined the impact of copper toxicity in freshwater fish over the past decade. In this research, the oxidative stress, liver transcriptome, intestinal microbiota, and histopathology of common carp (C. carpio) in response to Cu exposure were studied, by exposing juvenile carp to 0.2 mg/ml Cu2+ for 30 days. The results revealed that Cu2+ could induce significant changes in malondialdehyde (MDA) content and antioxidant enzyme (superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx)) activity. The changes in antioxidant enzyme activities indicate that Cu can induce oxidative stress by generating reactive oxygen species (ROS) content. RNA-seq analysis of the liver identified 1069 differentially expressed genes (DEGs) after treatment with 2.0 mg/L Cu2+. Among the DEGs, 490 genes were upregulated and 579 genes were downregulated. GO functional enrichment analysis revealed that Cu could affect the fatty acid biosynthetic process, carnitine biosynthetic process, and activity of carboxylic acid transmembrane transporter. Meanwhile, the most significantly enriched KEGG pathway also included the lipid metabolism pathway. In addition, Cu2+ exposure increased bacterial richness and changed bacterial composition. At the phylum level, we found that the ratio of Bacteroidetes to Firmicutes was increased in the treatment carps, which can regulate intestinal epithelium function and reduce inflammation and immune responses. At the genus level, the abundances of 11 genera were significantly altered after exposure to Cu2+. The altered composition of the microbial community caused by Cu exposure may play a useful role in compensation of the intestinal lesions by Cu exposure. Furthermore, we found that Cu2+ exposure could cause histological alterations such as structural damage to the liver and intestines. The results of this research contribute to a better understanding of mechanisms related to Cu toxicity in fish.
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- 2022
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7. Earnings Management, Enterprise Scale and Enterprise Value—Research Based on Data and Statistical Analysis Tools
- Author
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Mengxiao Yang
- Subjects
Environmental sciences ,GE1-350 - Abstract
This paper takes China’s A-share listed companies in Shanghai and Shenzhen Stock Exchange from 2012 to 2016 as samples to analyze the impact of earnings management on current and subsequent enterprise value. It is found that real earnings management not only affects the current value, but also damages the long-term value of enterprises continuously. Further research finds that the size of the firm has a moderating effect, that is, the larger the size of the firm, the damage effect of real earnings management on the firm value is mitigated.
- Published
- 2021
- Full Text
- View/download PDF
8. Kinetics of pepsin-induced hydrolysis and the coagulation of milk proteins
- Author
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David Everett, Mengxiao Yang, Harjinder Singh, Zhi Yang, Elliot Gilbert, and Aiqian Ye
- Subjects
Kinetics ,Hydrolysis ,Genetics ,Animals ,Caseins ,Cattle ,Animal Science and Zoology ,Hydrogen-Ion Concentration ,Milk Proteins ,Rheology ,Micelles ,Pepsin A ,Food Science - Abstract
Hydrolysis-induced coagulation of casein micelles by pepsin occurs during the digestion of milk. In this study, the effect of pH (6.7-5.3) and pepsin concentration (0.110-2.75 U/mL) on the hydrolysis of κ-casein and the coagulation of the casein micelles in bovine skim milk was investigated at 37°C using reverse-phase HPLC, oscillatory rheology, and confocal laser scanning microscopy. The hydrolysis of κ-casein followed a combined kinetic model of first-order hydrolysis and putative pepsin denaturation. The hydrolysis rate increased with increasing pepsin concentration at a given pH, was pH dependent, and reached a maximum at pH ∼6.0. Both the increase in pepsin concentration and decrease in pH resulted in a shorter coagulation time. The extent of κ-casein hydrolysis required for coagulation was independent of the pepsin concentration at a given pH and, because of the lower electrostatic repulsion between para-casein micelles at lower pH, decreased markedly from ∼73% to ∼33% when pH decreased from 6.3 to 5.3. In addition, the rheological properties and the microstructures of the coagulum were markedly affected by the pH and the pepsin concentration. The knowledge obtained from this study provides further understanding on the mechanism of milk coagulation, occurring at the initial stage of transiting into gastric conditions with high pH and low pepsin concentration.
- Published
- 2022
9. Effect of ingestion temperature on the pepsin-induced coagulation and the in vitro gastric digestion behavior of milk
- Author
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Mengxiao Yang, Aiqian Ye, Zhi Yang, David W. Everett, Elliot Paul Gilbert, and Harjinder Singh
- Subjects
General Chemical Engineering ,Food sciences ,General Chemistry ,Food Science - Abstract
Pepsin-induced protein coagulation occurs in the gastric environment when the milk pH is above the isoelectric point of casein proteins. In this study, the effect of milk temperature (4–48 °C) on the hydrolysis of κ-casein by pepsin and the consequent protein coagulation was studied at pH 6.0 for 120 min. Quantitative determination of the released para-κ-casein showed that both the κ-casein hydrolysis reaction rate constant and the pepsin denaturation rate constant increased with an increase in temperature. The temperature coefficient (Q10) of the specific hydrolysis of κ-casein was calculated to be ∼1.95. The coagulation process was investigated by the evolution of the storage modulus (Gʹ). At higher temperature, the milk coagulated faster but had a lower firming rate and Gʹmax with larger aggregates and voids were observed. The digestion behavior of the milk ingested at 4 °C, 37 °C, or 50 °C was investigated for 240 min in a human gastric simulator, in which the milk temperature increased or decreased to 37 °C (body temperature) over ∼ 60 min. The coagulation of the 4 °C milk was slower than for the 37 °C and 50 °C milk. The curd obtained from the 4 °C milk had a looser and softer structure with a significantly higher moisture content at the initial stage of digestion (20 min) which, in turn, facilitated the breakdown and hydrolysis of the caseins by pepsin. During the digestion, the curd structure became more cohesive, along with a decrease in moisture content. The knowledge gained from this study provides insight into the effect of temperature on the kinetics of pepsin-induced milk coagulation and the consequent digestion behavior.
- Published
- 2023
- Full Text
- View/download PDF
10. Green Finance and Industrial Structure Optimization- Research Based on Data and Statistical Analysis Tools
- Author
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Mengxiao Yang
- Published
- 2022
11. Leather waste as precursor to prepare bifunctional catalyst for alkaline and neutral zinc-air batteries
- Author
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Zeyu Zhu, Jing Zhu, Yangshen Chen, Xinxin Liu, Mengchun Zhang, Mengxiao Yang, Mengyu Liu, Jiansheng Wu, Sheng Li, and Fengwei Huo
- Subjects
General Chemistry - Published
- 2023
12. Pepsin-induced coagulation of casein micelles: Effect of whey proteins and heat treatment
- Author
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Mengxiao Yang, Aiqian Ye, Zhi Yang, David W. Everett, Elliot Paul Gilbert, and Harjinder Singh
- Subjects
Hot Temperature ,Food sciences ,Caseins ,Water ,General Medicine ,Hydrogen-Ion Concentration ,Milk Proteins ,Pepsin A ,Analytical Chemistry ,Whey Proteins ,Milk ,Animals ,Micelles ,Food Science - Abstract
The effect of whey proteins and heat treatment (90 °C, 5 min) on pepsin-induced hydrolysis of κ-casein, and subsequent coagulation of casein micelles, was investigated at pH 6.3 and 6.0 using reverse-phase HPLC, oscillatory rheology, and confocal laser scanning microscopy. Whey proteins did not affect the hydrolysis of κ-casein but retarded the coagulation process. Heat treatment did not affect the hydrolysis kinetics in whey protein (WP)-free samples, but slightly impaired the hydrolysis rate in WP-containing samples. The coagulation process of WP-free samples was little affected by heat-treatment. However, compared with unheated WP-contained sample at the same pH, the coagulation process of the heated sample was retarded at pH 6.3 but enhanced at pH 6.0. The curd in heated samples with smaller pores had higher water holding capacity. This knowledge provides further understanding on the role of whey proteins and heat treatment on the coagulation mechanisms of milk under gastric conditions.
- Published
- 2022
13. Design, Synthesis and Characterization of 2‐Methylimidazole/Zeolitic Imidazolate Framework‐8 for Curing with Epoxy Resin
- Author
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Mengxiao Yang, Haiming Yang, Xue Wang, Yunfeng Lu, Xigao Yu, Fengfeng Chen, Junkuo Gao, and Ningyu Di
- Subjects
Inorganic Chemistry - Published
- 2022
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