Effects of metformin on the glucose regulation, lipid levels and gut microbiota in high-fat diet with streptozotocin induced type 2 diabetes mellitus rats.

OBJECTIVE: Metformin, an anti-diabetic drug, regulates blood glucose by affecting gut microbiotas. However, the potential mechanism underlying this effect remains unclear. This study aimed to evaluate the effect of metformin on glucose regulation, lipid levels, and the gut microbiota in rats with type 2 diabetes mellitus induced by a high-fat diet with streptozotocin. RESEARCH DESIGN METHODS: Thirty Wistar rats was using in this experiment. T2DM rats were administered 300 mg/kg metformin for 8 weeks. The glucose regulation, lipid levels, organ coefficients, and gut microbiotawere measured by 16S rDNA. RESULT: The metformin-gavaged rats exhibited significant improvements in blood glucose and serum lipid levels, accompanied by alterations in short-chain fatty acid levels and the intestinal microbiota (p < 0.05). In the diabetic rats, metformin potentially increased specific probiotics, thus improving the hypoglycaemic effects of the oral anti-diabetic drug. Further, damage to the liver and kidney was effectively alleviated in the metformin-gavaged rats. CONCLUSION: This study's findings demonstrate that metformin exerts a positive anti-diabetic effect in HFD- and STZ-induced T2DM rats. These findings potentially provide a basis for the recommended use of metformin as a reliable oral drug for T2DM owing to its positive effect on the intestinal microbiota.

Stabilization mechanisms and digestion properties of Pickering emulsions prepared with tempo-oxidized hyaluronic acid/chitosan nanoparticles: From the perspective of oxidation degree.

In this study, the stabilization mechanism and digestion behavior of Pickering emulsion prepared by a combination of chitosan (CS) and TEMPO-oxidized hyaluronic acid (HA) were investigated. Conductometric titration was used to determine the degree of oxidation and carboxylate content of TEMPO-oxidized HA. The results showed that the degree of oxidation increased proportionally with increasing oxidation time, and the electrostatic and hydrogen bonding interactions with CS were significantly enhanced. The results of FTIR and TEM showed the formation of CS/oxidized HA nanoparticles (CS/oxidized-HANPs). In addition, the contact angle of CS/oxidized-HANPs is closed to 77°, thereby providing higher desorption energy at the interface. Rheological results showed that the Pickering emulsion exhibited a gel-like network structure and higher viscosity. In vitro digestion results suggested that the quercetin (Que) bioaccessibility of the CS/oxidation HANps-stabilized Pickering emulsion with an oxidation time of 20 min was better than that of the conventional emulsion prepared with CS alone. The research is expected to develop novel polysaccharide-based Pickering emulsion delivery systems for functional compounds.

The properties of the rice resistant starch processing and its application in skimmed yogurt.

Extrusion is typically employed to prepare resistant starch (RS). However, the process is complicated. In this study, the effects of twin-screw extrusion on the crystallinity, thermal properties, and functional properties of starch formed in different extrusion zones were investigated. The effects of this process on the rheological properties and microstructure of RS-added skimmed yogurt were also studied. According to the results, the RS content increased from 7.40 % in the raw material to 33.79 % in the extrudate. The A-type crystal structure of the starch was not observed. The dissociation temperature of the extruded starch ranged from 87.76 °C to 100.94 °C. The glycemic index (GI) of skimmed yogurt fortified with 0.4 % RS was 48.7, and the viscosity was also improved. The microstructure exhibited a uniform network of the starch-protein structure. The findings may serve as a theoretical basis for the application of RS in the food industry.

Effects of Panax notoginseng Saponins Encapsulated by Polymerized Whey Protein on the Rheological, Textural and Bitterness Characteristics of Yogurt.

Panax notoginseng saponins (PNSs) have been used as a nutritional supplement for many years, but their bitter taste limits their application in food formulations. The effects of PNS (groups B, C, and D contained 0.8, 1.0 and 1.2 mg/mL of free PNS, respectively) or Panax notoginseng saponin-polymerized whey protein (PNS-PWP) nanoparticles (groups E, F, and G contained 26.68, 33.35 and 40.03 mg/mL of PNS-PWP nanoparticles, respectively) on the rheological, textural properties and bitterness of yogurt were investigated. Group G yogurt showed a shorter gelation time (23.53 min), the highest elastic modulus (7135 Pa), higher hardness (506 g), higher apparent viscosity, and the lowest syneresis (6.93%) than other groups, which indicated that the yogurt formed a stronger gel structure. The results of the electronic tongue indicated that the bitterness values of group E (-6.12), F (-6.56), and G (-6.27) yogurts were lower than those of group B (-5.12), C (-4.31), and D (-3.79), respectively, which might be attributed to PNS being encapsulated by PWP. The results indicated that PWP-encapsulated PNS could cover the bitterness of PNS and improve the quality of yogurt containing PNS.

Construction and properties of a carbon dots-decorated gelatin-dialdehyde starch hydrogel with pH response release and antibacterial activity.

An antibacterial carbon dot hydrogel (GDSS-PCD) was constructed based on gelatin, dialdehyde starch (DS) and carbon dots (S-PCDs). The formation mechanism of GDSS-PCD hydrogels was attributed to the synergistic cross-linking of hydrogen bonds and dynamic covalent bonds. With increasing S-PCD content, the mechanical and rheological properties of GDSS-PCD hydrogels can be improved, and the micropore size becomes denser. GDSS-PCD hydrogels had pH-dependent swelling and degradation behavior, with a high swelling rate under acidic conditions and relatively low swelling under neutral and alkaline conditions. The cumulative release of S-PCDs from the same hydrogel in an acidic environment was higher than that in an alkaline environment, indicating that the GDSS-PCD hydrogel had a pH-dependent controlled release ability. The release behavior of S-PCDs conformed to the first-order kinetic release model (R2 > 0.95), and the release mechanism was related to Fickian diffusion. The synergistic antibacterial mechanism of GDSS-PCD hydrogels against Staphylococcus aureus suggested that bacterial metabolism leads to an acidic culture environment, which releases S-PCDs and destroys the bacterial cell membrane for antibacterial purposes. In GDSS-PCD hydrogels, S-PCDs play the main antibacterial role, and the hydrogel plays a synergistic role in trapping bacteria. Carbon dot hydrogels are promising materials to fulfil the functions of antibacterial and controlled release in the food and biomedical fields.

Tuning whey protein isolate/hyaluronic acid emulsion gel structure to enhance quercetin bioaccessibility and in vitro digestive characteristics.

Quercetin (Que), a health-promoting polyphenol, has limited applicability in food products due to its susceptibility to degradation in the gastrointestinal tract. To overcome this problem, Que-loaded emulsion gels were produced using whey protein isolate (WPI) and hyaluronic acid (HA) by combining heating and CaCl2 treatment. The effects of HA addition on the structural and rheological properties of the emulsion gels were evaluated, and the protective effect of the gel on Que under simulated digestion was investigated in vitro. Microstructural observations indicated that HA leads to a more compact and uniform network structure, which significantly enhances the textural and rheological properties of emulsion gels. In vitro digestion experiments revealed that WPI-HA emulsion gels exhibited a higher Que bioaccessibility (55.01%) compared to that produced by WPI alone (21.26%). This innovative delivery carrier has potential applications in food products to accomplish sustained nutrient release along with improved stability.

Emulsions stabilised by casein and hyaluronic acid: Effects of high intensity ultrasound on the stability and vitamin E digestive characteristics.

This study aimed to prepare an emulsion stabilised by an ultrasound-treated casein (CAS)-hyaluronic acid (HA) complex and to protect vitamin E during in vitro digestion. It was found that high-intensity ultrasound (HIU) treatment significantly changed the hydrogen bonding, electrostatic interaction and hydrophobic interaction between CAS and HA, reduced the particle size of the CAS-HA complex, increased the intermolecular electrostatic repulsion, and thus significantly improved the emulsifying properties of the CAS-HA complex. Meanwhile, the creaming index (CI) and confocal laser scanning microscopy images showed that the stability of the CAS-HA-stabilised emulsion was the best when treated at 150 W for 10 min, which could be attributed to the enhanced adsorption capacity of the CAS-HA complex at the oil-water interface and the viscosity of the formed emulsion. In vitro digestion experiments revealed that the emulsion stabilised by the ultrasound-treated CAS-HA complex had a good protective effect on vitamin E. This study is significant for the development of emulsions for the delivery of lipophilic nutrients.

Effect of high hydrostatic pressure on the edible quality, health and safety attributes of plant-based foods represented by cereals and legumes: a review.

Consumers today are increasingly willing to reduce their meat consumption and adopt plant-based alternatives in their diet. As a main source of plant-based foods, cereals and legumes (CLs) together could make up for all the essential nutrients that humans consume daily. However, the consumption of CLs and their derivatives is facing many challenges, such as the poor palatability of coarse grains and vegetarian meat, the presence of anti-nutritional factors, and allergenic proteins in CLs, and the vulnerability of plant-based foods to microbial contamination. Recently, high hydrostatic pressure (HHP) technology has been used to tailor the techno-functionality of plant proteins and induce cold gelatinization of starch in CLs to improve the edible quality of plant-based products. The nutritional value (e.g., the bioavailability of vitamins and minerals, reduction of anti-nutritional factors of legume proteins) and bio-functional properties (e.g., production of bioactive peptides, increasing the content of γ-aminobutyric acid) of CLs were significantly improved as affected by HHP. Moreover, the food safety of plant-based products could be significantly improved as well. HHP lowered the risk of microbial contamination through the inactivation of numerous microorganisms, spores, and enzymes in CLs and alleviated the allergy symptoms from consumption of plant-based foods.

Enhancing the stability of oil-in-water emulsions by non-covalent interaction between whey protein isolate and hyaluronic acid.

This study aimed to investigate the effect of non-covalent interactions between different concentrations (0.1-1.2 %, w/v) of hyaluronic acid (HA) and 3 % (w/v) whey protein isolate (WPI) on the stability of oil-in-water emulsions. Non-covalent interactions between WPI and HA were detected using Fourier-transform infrared spectroscopy. The addition of HA increased the electrostatic repulsion between molecules and reduced the particle size of WPI. Circular dichroism spectroscopy results indicated that the addition of HA caused an increase in ß-sheet content and a decrease in α-helix and random coil content in WPI. Moreover, HA increased the emulsion viscosity and strength of the interfacial network structure. Micrographs obtained using confocal laser scanning microscopy indicated that the emulsion with 0.8 % (w/v) HA exhibited good dispersion and homogeneity after storage for 14 d. Complexation with HA significantly altered the rheological and emulsifying properties of WPI, providing an emulsion with excellent stability under heating treatment, freeze-thawing treatment and centrifugation. The results provide a potential for HA application in emulsified foods.

Effect of proanthocyanidins on protein composition, conformational structure, IgE binding capacities and functional properties in soybean protein.

This study was performed to determine the crosslinking formed by proanthocyanidins (PC) with respect to IgE binding capacities, functionality, structure and composition of soybean protein (SPI) following the alkali treatment at 60-100 °C. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed the formation of >180 kDa polymers, resulting from the formation of SPI-PC conjugates and protein cross-links. Structural analyses demonstrated that SPI-PC conjugates exhibited structural changes to unfold proteins and increase molecular flexibility. Liquid chromatography coupled to tandem mass spectrometry (LC/MS-MS) showed a decrease in unique protein and peptide numbers as well as major allergen and dominant epitopes abundance. When SPI was treated with PC under the alkali treatment at 80 °C, it exhibited a maximum reduction (68.8 %) in the immunoglobulin E (IgE) binding capacity and a maximum increase in DPPH radical scavenging activities (6.11-fold), ABTS + radical scavenging activities (4.80-fold), foaming stability (6.1 %) and emulsifying activity (27.3 %), compared to the control SPI. Overall, this study demonstrates that alkali treatment at 60-100 °C to form SPI-PC conjugates has potential applications for producing hypoallergenic soybean products with the desired functionality, most especially from alkali treatment at 80 °C. Moreover, the addition of PC pronouncedly alleviates the undesirable functional properties in heated SPI.

Heat-induced changes in epitopes and IgE binding capacity of soybean protein isolate.

The effects of heating temperature on epitopes, IgE-binding capacity, and conformation of soybean protein isolate (SPI) were investigated in this study. Indirect ELISA demonstrated that the IgE binding capacity of SPI was increased by 13.1 %-31.6 % after being heated at 60-100 °C for 20 min. SDS-PAGE demonstrated no changes in protein profiles, and native PAGE revealed the formation of aggregates. Structural analyses demonstrated the protein unfolding, appearing temperature-dependent, thus exposing conformational epitopes. Peptide mapping analysis revealed the changes in peptide profiles of major allergens (Gly m 4, Gly m 5, Gly m 6, P28, and Kunitz trypsin inhibitor). LC/MS-MS demonstrated that heating caused the masking or exposure of linear epitopes in Gly m 4 - Gly m 6 and P28. Therefore, heating caused structural changes to expose epitopes to increase IgE binding capacity in SPI. Patients with soybean allergy should avoid the heated SPI until the results of clinical trials are confirmed.

Protein modification, IgE binding capacity, and functional properties of soybean protein upon conjugation with polyphenols.

The modification, structure, functionality and IgE binding capacity of soybean protein (SPI) upon covalent conjugation with gallic acid (GA), caffeic acid (CA), and tannic acid (TA) under alkali treatment were assessed. SDS-PAGE showed the formation of SPI-polyphenol conjugates and the cross-linking of SPI. Protein unfolding in the conjugates was observed, characterized by a reduction in α-helix and an increase in UV ultraviolet absorption, surface hydrophobicity and free sulfhydryl groups. LC/MS-MS demonstrated that the modification of protein and major allergens varied with the types of polyphenols. Western-blot and ELISA demonstrated that SPI-polyphenol conjugates exhibited a significant reduced IgE binding capacity due to the masking or destruction of epitopes among Gly m 4, Gly m 5, Gly m 6 and P28, resulting from structural changes. Additionally, antioxidant capacity and emulsifying properties were increased in SPI-polyphenol conjugates. Therefore, polyphenol treatment may be a promising method to prepare hypoallergenic soybean products with desired functionality.

Nanofibrils of food-grade proteins: Formation mechanism, delivery systems, and application evaluation.

Due to the high aspect ratio, appealing mechanical characteristics, and various adjustable functional groups on the surface proteins, food-grade protein nanofibrils have attracted great research interest in the field of food science. Fibrillation, known as a process of peptide self-assembly, is recognized as a common attribute for food-grade proteins. Converting food-grade proteins into nanofibrils is a promising strategy to broaden their functionality and applications, such as improvement of the properties of gelling and emulsifying, especially for constructing various delivery systems for bioactive compounds. Protein source and processing conditions have a great impact on the size, structure, and morphology of nanofibrils, resulting in extreme differences in functionality. With this feature, it is possible to engineer nanofibrils into four different delivery systems, including gels, microcapsules, emulsions, and complexes. Construction of nanofibril-based gels via multiple cross-linking methods can endow gels with special network structures to efficiently capture bioactive compounds and extra mechanical behavior. The adsorption behavior of nanofibrils at the interface is highly complex due to the influence of several intrinsic factors, which makes it challenging to form stabilized nanofibril-based emulsion systems. Based on electrostatic interactions, microcapsules and complexes prepared using nanofibrils and polysaccharides have combined functional properties, resulting in adjustable release behavior and higher encapsulation efficiency. The bioactive compounds delivery system based on nanofibrils is a potential solution to enhance their absorption in the gastrointestinal tract, improve their bioavailability, and deliver them to target organs. Although food-grade protein nanofibrils show unknown toxicity to humans, further research can contribute to broadening the application of nanofibrils in delivery systems.

Novel nano-encapsulated probiotic agents: Encapsulate materials, delivery, and encapsulation systems.

Gut microbes are closely associated with most human health. When ingested orally, probiotics can effectively regulate the composition and quantity of human intestinal microorganisms, which is beneficial to human health. However, probiotics will be affected by the harsh environment of the digestive tract during the in vivo transportation process, and ensuring the viability of probiotics is a great challenge. Probiotic encapsulating technology provides an effective solution to this problem. The introduction of extreme temperatures, large probiotic microcapsule sizes and the difficulty in controlling probiotic microcapsule particle sizes mean that traditional microcapsule encapsulation methods have some limitations. From traditional microcapsule technology to the bulk encapsulation of probiotics with nanofibers and nanoparticles to the recent ability to wear nano "armor" for a single probiotic through biofilm, biological membrane and nanocoating. Emerging probiotic nanoagents provides a new conceptual and development direction for the field of probiotic encapsulation. In this review, we presented the characteristics of encapsulated probiotic carrier materials and digestive tract transport systems, we focused on the encapsulation systems of probiotic nanoagents, we analyzed the shortcomings and advantages of the current agent encapsulation systems, and we stated the developmental direction and challenges for these agents for the future.

Effect of synbiotic yogurt fortified with monk fruit extract on hepatic lipid biomarkers and metabolism in rats with type 2 diabetes.

Monk fruit extract (MFE) is widely used as a sweetener in foods. In this study, the effects of the consumption of MFE-sweetened synbiotic yogurt on the lipid biomarkers and metabolism in the livers of type 2 diabetic rats were evaluated. The results revealed that the MFE-sweetened symbiotic yogurt affected the phosphatidylcholines, phosphatidylethanolamines, phosphatidylglycerol, lysophosphatidic acids, lysophosphatidylcholines, lysophosphatidylethanolamines, lysophosphatidylglycerols, lysophosphatidylinositols, lysophosphatidylserines, and fatty acid-hydroxy fatty acids biomarkers in the livers of type 2 diabetic rats. In addition, the consumption of the MFE-sweetened synbiotic yogurt significantly altered 12 hepatic metabolites, which are involved in phenylalanine metabolism, sphingolipid metabolism, bile secretion, and glyoxylate and dicarboxylate metabolism in the liver. Furthermore, a multiomics (metabolomic and transcriptomic) association study revealed that there was a significant correlation between the MFE-sweetened synbiotic yogurt and the metabolites and genes involved in fatty acid biosynthesis, bile secretion, and glyoxylate and dicarboxylate metabolism. The findings of this study will provide new insights on exploring the function of sweeteners for improving type 2 diabetes mellitus liver lipid biomarkers.

Physicochemical, Digestive, and Sensory Properties of Panax Notoginseng Saponins Encapsulated by Polymerized Whey Protein.

Panax Notoginseng Saponins (PNS) may be beneficial to human health due to their bioactive function. The application of PNS in functional foods was limited due to the bitter taste and low oral bioavailability. PNS were encapsulated by polymerized whey protein (PWP) nanoparticles. The physicochemical, digestive, and sensory properties of the nanoparticles were investigated. Results showed that the nanoparticles had a particle size of 55 nm, the zeta potential of -28 mV, and high PNS encapsulation efficiency (92.94%) when the mass ratio of PNS to PWP was 1:30. Differential Scanning Calorimetry (DSC) results revealed that PNS were successfully encapsulated by PWP. The mainly intermolecular forces between PNS and PWP were hydrogen bonding and electrostatic attraction confirmed by Fourier Transform Infrared Spectroscopy (FTIR). Results of simulated gastrointestinal digestion indicated that the PNS-PWP (1:30) nanoparticles had smaller average particle size (36 nm) after treatment with gastric fluids and increased particle size (75 nm) after treatment with intestinal fluids. Transmission Electron Microscopy (TEM) micrographs reflected that the nanoparticles had irregular spherical structures. The encapsulated PNS exhibited significantly (p < 0.05) decreased bitterness compared to the non-encapsulated PNS confirmed by the electronic tongue. The results indicated that encapsulation of PNS with PWP could facilitate their application in functional foods.

Gelation and microstructural properties of a millet-based yogurt-like product using polymerized whey protein and xanthan gum as thickening agents.

Cereal-based fermented products are becoming popular in the world. A millet-based yogurt-like product (MYP) using polymerized whey protein (PWP) and xanthan gum (XG) as thickeners was developed. The present study aimed to investigate the effects of PWP (0.3 to 0.5%, w/v) and XG (0 to 0.2%, w/v) on the gelation properties and microstructure of MYP. All samples were analyzed for rheological properties, textural properties, microstructure, and pH value during fermentation. The MYP Ⅲ (0.4% PWP and 0.1% XG) registered the highest elastic modulus (G') throughout the fermentation and cooling steps (P < 0.05), but MYP Ⅳ (0.35% PWP and 0.15% XG) had the highest apparent viscosity compared with the other samples. No significant differences in the pH values among the samples were observed during the fermentation process (P > 0.05). The hardness value of MYP Ⅳ reached a maximum after 4 hr and then stabilized during fermentation. Scanning electron microscopy showed a compact and uniform network for the MYP with PWP and XG. MYP Ⅳ had the best texture properties (hardness, springiness, and gumminess). Overall, PWP (0.35%, w/v) and XG (0.15%, w/v) were the best combination for MYP as a thickening system. PRACTICAL APPLICATION: Cereal-based fermented products have attracted much attention in the food industry. However, due to absence of a natural protein network, it is hard to produce a set-type millet-based yogurt with a firm texture under the studied conditions without adding any thickening agents. In this study, PWP (0.35%, w/v) and XG (0.15%, w/v) can be used for fermentation of millet-based yogurt-like products. The new cereal-based fermented product would be a promising food in the market.

Effect of feeding type 2 diabetes mellitus rats with synbiotic yogurt sweetened with monk fruit extract on serum lipid levels and hepatic AMPK (5' adenosine monophosphate-activated protein kinase) signaling pathway.

Monk fruit extract (MFE) is a natural sweetener that has been used as an ingredient of food and pharmaceutical products. The effects of feeding synbiotic yogurt fortified with MFE to rats with type 2 diabetes induced by high-fat diet and streptozotocin on serum lipid levels and hepatic AMPK signaling pathway were evaluated. Results showed that oral administration of the synbiotic yogurt fortified with MFE could improve serum lipid levels, respiratory exchange rate, and heat level in type 2 diabetic rats. Transcriptome analysis showed that synbiotic yogurt fortified with MFE may affect the expression of genes involved in binding, catalytic activity, and transporter activity. The Kyoto Encyclopedia of Genes and Genomes enrichment analysis revealed that these differentially expressed genes were related to AMPK signaling pathway, linoleic acid metabolism, and α-linolenic acid metabolism. Western blotting confirmed that synbiotic yogurt fortified with MFE could activate AMPK signaling and improve the protein level of the hepatic gluconeogenic enzyme G6Pase in diabetic rats. The results indicated that MFE could be a novel sweetener for functional yogurt and related products.

Physiochemical, rheological, microstructural, and antioxidant properties of yogurt using monk fruit extract as a sweetener.

A yogurt using monk fruit extract (MFE) as a sweetener was developed. The aim of the study was to investigate the viability of using MFE to develop sweetened yogurts without the calories of added sugar. The physiochemical, rheological, microstructural, and antioxidant properties of yogurt were studied. Rheological results showed that MFE affected the yogurt fermentation process and its rheological properties. Yogurt sweetened with MFE had similar microstructural properties to yogurt sweetened with sucrose. Yogurt with MFE showed higher levels of gly-pro-p-nitroanilide and dipeptidyl peptidase IV inhibitory activities, 1,1-diphenyl-2-picrylhydrazyl radical scavenging capacity, α-glucosidase inhibitory activities, and superoxide anion radical scavenging ability compared with other yogurt samples. Results indicated that MFE could be a novel sweetener and a food antioxidant for functional yogurt and related products.

Effects of a synbiotic yogurt using monk fruit extract as sweetener on glucose regulation and gut microbiota in rats with type 2 diabetes mellitus.

We developed a synbiotic yogurt using monk fruit extract as a sweetener and investigated the effects of feeding the yogurt to rats with type 2 diabetes induced by streptozotocin and a high-fat diet. The rats fed the synbiotic yogurt showed greater blood glucose regulation and a significant decrease in insulin resistance and glycosylated hemoglobin compared with rats fed yogurt sweetened with sucrose, and they showed a remarkable improvement in short-chain fatty acid levels and gut microbiota status. Liver and kidney damage was also ameliorated in the rats fed the synbiotic yogurt. Immunohistochemistry analysis showed that the synbiotic yogurt inhibited ß-cell loss compared with the control yogurt. Consuming the synbiotic yogurt helped to restore the islets of Langerhans. Our results indicated that monk fruit extract may be a good alternative to sucrose for synbiotic yogurt products in people with type 2 diabetes to delay the progression of diabetes and associated complications.