Tracking the digestive performance of different forms of dairy products using a dynamic artificial gastric digestive system

Understanding the mechanism of high viscosity food delaying gastric emptying

Controlling the structure and viscosity of food can influence the development of diet-related diseases. Food viscosity has been linked with health through its impact on human digestion and gastrointestinal transit, however, there is limited understanding of how the viscosity of food regulates gastric emptying. Here, we used model food preparations with different viscosities using guar gum, to explore the mechanism underlying the influence of viscosity on gastric motility, gastric emptying and postprandial blood glucose. Based on experiments in human volunteers and animals, we demonstrated that high viscosity meals increased gastric antrum area and gastric retention rate. Viscosity also affected gut hormone secretion, reduced the gene expression level of interstitial cells of Cajal, resulting in a delay of gastric emptying and limiting the increase in postprandial glucose. This improved mechanistic understanding of food viscosity during gastric digestion is important for designing new foods to benefit human health.

Designing Gastric-Stable Adsorption Layers by Whey Protein-Pectin Complexation at the Oil-Water Interface

This work aims to design gastric-stable emulsions with food-grade biopolymers using a novel multiscale approach. The adsorption layer formation at the oil-water interface was based on opposite charge interactions between whey proteins and pectin (with different esterification levels) at pH 3.0 by a sequential adsorption method. The interfacial assembly and disassembly (interfacial complexation, proteolysis, lipolysis) during in vitro gastric digestion were evaluated using a quartz crystal microbalance with dissipation monitoring, ζ-potential, dynamic interfacial tension, and interfacial dilatational rheology. Besides, the evolution of the particle size and microstructure of bulk emulsions during the digestion was investigated by static light scattering and light microscopy. Compared with whey protein isolate (WPI)-stabilized emulsions, the presence of an additional pectin layer can prevent or at least largely delay gastric destabilization (giving rise to coalescence or/and oiling off). Especially, the esterification degree of the pectin used was found to largely affect the emulsion stability upon gastric digestion.

Improving shikonin solubility and stability by encapsulation in natural surfactant-coated shikonin nanoparticles

It is significant to develop a colloidal delivery system to improve the water solubility, stability, and bioavailability of shikonin, which is a hydrophobic plant polyphenol with a variety of physiological activities. In this study, three kinds of natural surfactants (saponin, sophorolipid, and rhamnolipid) were used to prepare shikonin nanoparticles by the pH-driven method. The physicochemical and structural properties of the shikonin nanoparticles were characterized, including particle size, zeta potential, and morphology. The encapsulation efficiencies of shikonin nanoparticles coated with saponin and sophorolipid were 97.6% and 97.3%, respectively, which were much higher than that of rhamnolipid-coated shikonin nanoparticles (19.0%). Shikonin nanoparticles coated with saponin and sophorolipid showed good resistance to heat and light and maintained long-term stability during storage. Moreover, shikonin nanoparticles coated with saponin and sophorolipid improved their in vitro-bioavailability. PRACTICAL APPLICATION: These article results are of great importance for improving the stability and bioavailability of shikonin in functional foods, dietary supplements, or pharmaceutical preparations. Moreover, this study provided theoretical and practical guides for further research of shikonin nanoparticles and may promote the development of natural colloidal delivery systems.

Orally administered octacosanol improves liver insulin resistance in high-fat diet-fed mice through the reconstruction of the gut microbiota structure and inhibition of the TLR4/NF-κB inflammatory pathway

1-Octacosanol (Octa) is reported to possess many physiological properties. However, its relative mechanism has not been illustrated yet. Herein, we aimed to investigate the effect of Octa on insulin resistance in mice fed with a high fat diet (HFD) and used an in vitro simulated gastrointestinal tract to analyze its digestive behavior. The effects of Octa on the gut microbiota were verified by in vitro fermentation using the mouse fecal microbiota. As a result, the Octa monomer was digested into shortened saturated and unsaturated fatty acids (C10-C24) in the simulated gastrointestinal tract. Octa improved the fasting blood glucose (FBG), insulin resistance (IR), plasma lipids, and inflammatory response in HFD-fed mice in a dose-dependent manner. This study also suggested that a high-dose of Octa effectively decreased the levels of toll-like receptor 4 (TLR4), nuclear factor kappa-B (NF-κB), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) in the plasma of HFD-fed mice. Octa improved the oxidative stress induced by a HFD and increased the expression of the Nrf2/ARE signaling pathway. Importantly, Octa reshaped gut microbiota through decreasing Firmicutes content and increasing Bacteroidota and Verrucomicrobiota contents at the phylum level, and the changes of intestinal flora structure caused by Octa were significantly correlated with the changes of inflammatory biomarkers. In conclusion, the effects of Octa on insulin resistance might be attributed to the reconstruction of the gut microbiota structure and inhibition of the TLR4/NF-κB inflammatory pathway in HFD-induced obese individuals.

Preparation of Gum Arabic-Maltose-Pea Protein Isolate Complexes for 1-Octacosanol Microcapsule: Improved Storage Stability, Sustained Release in the Gastrointestinal Tract, and Its Effect on the Lipid Metabolism of High-Fat-Diet-Induced Obesity Mice

1-Octacosanol (Octa) is a natural compound with several beneficial properties. However, its poor water solubility and metabolism in the digestive tract reduce its efficacy. The Octa-GA-Malt-PPI microcapsule was prepared as follows: gum Arabic (GA):maltose (Malt):pea protein isolate (PPI) = 2:1:2; core:shell = 1:7.5; emulsification temperature 70 °C; pH 9.0. An in vitro simulated gastrointestinal tract was used to analyze the digestion behavior. C57BL/6 mice were selected to establish an obesity model induced by a high-fat diet (HFD) to evaluate the effect of Octa monomer and the microcapsule. The diffusivity in water and storage stability of Octa improved after encapsulation. The microcapsule was ascribed to electrostatic interactions, hydrogen bonding, and hydrophobic interactions. The sustained release of Octa from the microcapsule was observed in a simulated gastrointestinal tract. Compared with Octa monomer, the microcapsule was more effective in alleviating the symptoms of weight gain, hypertension, and hyperlipidemia induced by HFD in mice. In conclusion, the construction of microcapsule structure can improve the dispersibility and stability of Octa in water, achieve sustained release of Octa in the gastrointestinal tract, and improve its efficiency in alleviating the effects of HFD on the body.

In vitro digestion of tofu with different textures using an artificial gastric digestive system

Two kinds of tofu with obvious differences in texture ["GDL" and "CaSO₄", standing for tofus made with the application of either glucono-δ-lactone (GDL) or calcium sulfate, with measured hardness 23.1 ± 3.3 g and 105.2 ± 25.1 g, respectively] were used as to investigate the in vitro progress and extent of tofu digestion, using an independently-developed artificial gastric digestion system (AGDS). The particle size distributions of both CaSO₄ and GDL tofu shifted towards smaller particles as the digestion time increased, while the viscosity of the gastric digesta also increased. Tofu proteins were hydrolyzed in the simulated stomach, with GDL tofu showing a higher hydrolysis rate, based on the temporal evolution of SDS-PAGE bands, and had a higher amino acids accumulation than CaSO₄ tofu at the end of gastric digestion. In the absence of peptic enzymes, the protein was acidically-hydrolyzed, but the degree of hydrolysis was much lower than in the presence of enzymes; these findings are in accord with the changes in microstructure observed by scanning electron microscopy. The results indicated that the in vitro extent of tofu digestion is related to its hardness, which is in turn related to its microstructure; they also indicated the potential of our developed in vitro dynamic stomach in studying semi-solid foods.

An evolving view on food viscosity regulating gastric emptying

Viscosity is a property of most foods. The consumption of the high-viscosity food is associated with a variety of physiological responses, one of which is their ability to regulate gastric emptying and modulate postprandial glycemic response. Gastric emptying has been proven to be a key step affecting the digestion and absorption of food, whereas, the relationship between viscosity and gastric emptying is still far away from being understood. Here, we reviewed the factors that influence food viscosity and food viscosity changes during digestion. Besides, the effect of food viscosity on gastric emptying and food-viscosity-physiological response were highlighted. Finally, "quantitative relationship" of viscosity and gastric emptying was discussed. This review can contribute to the understanding that how food viscosity affects gastric emptying, and help for developing foods that could control satiety and manage body weight for the specific populations.

Interaction of DPPC liposomes with cholesterol and food protein during in vitro digestion using Dynamic Light Scattering and FTIR spectroscopy analysis

The influence of cholesterol (CHO), bovine serum albumin (BSA) and lactoferrin (LF), on the phase transition temperature (T_m) and structure of DPPC liposomes during in vitro digestion was investigated using Dynamic Laser Scattering (DLS) and Fourier Transform Infrared Spectroscopy technologies (FTIR). CHO enhanced bilayers thickness and acyl chain order, especially in DPPC:CHO of 6:1, with the average size increase to 1.77 ± 0.20 μm and broaden of phase transition (T_m 45.8 °C). Protein critically impacted on the liposomal structure through formation of hydrogen bonds between in DPPC and protein. Liposomal size and T_m were significantly changed after simulated gastric digestion, whereas the pancreatic incubation can broaden transition phase and weaken functional groups of liposomes. Our data provided a better understanding on structure changes of CHO-containing membrane and protein addition by revealing T_m and chemical bonds details, and added to current knowledge for evaluating the different component on liposomal digestibility in food area.