Development and validation of a new artificial gastric digestive system

Expandable konjac fiber modulates appetite and chyme digestion in vivo by stomach-intestine-brain axis

Appetite regulation is a lifestyle intervention strategy to maintain health. The regulatory effects of dietary fiber (especially insoluble dietary fiber), as a crucial element of the nutritional composition, on appetite remain poorly understood. This study investigated modulatory effects of konjac fiber (KF, with high and low expansion) and konjac powder (KP) on chyme digestion, gastrointestinal hormones, intestinal microbiota, appetite genes in hypothalamus, GLP-1 receptor (GLP-1R) protein in various tissues of rats by dietary intervention. The results showed that highly-expanded konjac fiber (HKF) significantly delayed gastric emptying and inhibited hydrolysis of chyme. Konjac fiber (KF), especially HKF, and KP increased short-chain fatty acid (SCFA) content and plasma glucagon-like peptide-1 (GLP-1) levels. HKF upregulated the expression of GLP-1R protein in rat stomachs, nucleus tractus solitaries (NTS), and area postrema (AP) of rat brain, but down-regulated the expression of appetite gene AgRP/NPY in hypothalamus, thus, inhibiting appetite, reducing daily food intake and weight gain. Overall, this study reveals the mechanism through which expandable konjac fiber modulates appetite and chyme digestion in vivo by stomach-intestine-brain axis. Our findings provide an insight into the regulatory effects of insoluble dietary fiber on appetite and offered a valuable reference for the development of satiety-enhancing functional foods.

Structure changes and carotenoids release of tomato during in vitro dynamic digestion: Effect of heating and oil addition

There is still a gap between the food processing and carotenoids release and structure degradation during digestion. This study investigated the effect of heating and coconut oil addition on the digestion behavior of tomatoes during in vitro dynamic digestion. Coconut oil and heating increased gastric retention, and the value of heat-treated tomatoes with coconut oil maintained at a highest level throughout the gastric digestion. The contents of lycopene and β-carotene increased after heating and coconut oil addition. After stimulated intestinal digestion, coconut oil and heating increased the particle size of tomato slurry. Besides, heat-treated tomatoes released more particles under the light microscopy and SEM observation, while the oil-treated tomatoes showed rougher cell surfaces. Heating and coconut oil also significantly increased the bioaccessibility of lycopene to 70 % ± 5 % and 81 % ± 4 %, respectively. These findings would provide theoretical guidance to develop tomato-derived foods with high bioaccessibility.

Biomimic models for in vitro glycemic index: Scope of sensor integration and artificial intelligence

The accurate quantification of glycemic index (GI) remains crucial for diabetes management, yet current methodologies are constrained by resource intensiveness and methodological limitations. In vitro digestion models face challenges in replicating the dynamic conditions of the human gastrointestinal tract, such as enzyme variability and multi-time point analysis, leading to suboptimal predictive accuracy. This review proposes an integrated technological framework combining non-enzymatic electrochemical sensing with artificial intelligence to revolutionize GI assessment. Non-enzymatic sensors offer superior stability and repeatability in complex matrices, enabling real-time glucose quantification across multiple timepoints without enzyme degradation constraints. Machine learning algorithms, both supervised and unsupervised, enhance predictive accuracy by elucidating complex relationships within digestion data. This technological convergence represents a paradigm shift in food science analytics, promising improved throughput and precision in GI assessment. Future developments should focus on system scalability and broader applications across nutritional science, advancing diabetic management and personalized nutrition strategies.

A proposed framework to establish in vitro-in vivo relationships using gastric digestion models for food research

In vitro digestion methods have been utilized in food research to reduce in vivo studies. Although previous studies have related in vitro and in vivo data, there is no consensus on how to establish an in vitro-in vivo relationship (IVIVR) for food digestion. A framework that serves as a tool to evaluate the utility and limitations of in vitro approaches in simulating in vivo processes is proposed to develop IVIVRs for food digestion, with a focus on the gastric phase as the main location of food structural breakdown during digestion. The IVIVR consists of three quantitative levels (A, B, and C) and a qualitative level (D), which relate gastric digestion kinetic data on a point-to-point basis, parameters derived from gastric digestion kinetic data, in vitro gastric digestion parameters with in vivo absorption or appearance parameters, and in vitro and in vivo trends, respectively. Level A, B, and C IVIVRs can be used to statistically determine the agreement between in vitro and in vivo data. Level A and B IVIVRs can be utilized further evaluate the accuracy of the in vitro approach to mimic in vivo processes. To exemplify the utilization of this framework, case studies are provided using previously published static and dynamic gastric in vitro digestion data and in vivo animal study data. Future food digestion studies designed to establish IVIVRs should be conducted to refine and improve the current framework, and to improve in vitro digestion approaches to better mimic in vivo phenomena.

Origami-Inspired Bionic Soft Robot Stomach with Self-Powered Sensing

The stomach is a vital organ in the human digestive system, and its digestive condition is critical to human health. The physical movement of the stomach during digestion is controlled by the circular and oblique muscles. Existing stomach simulators are unable to realistically reproduce the physical movement of the stomach. Due to the complexity of gastric motility, it is challenging to simulate and sense gastric motility. This study proposes for the first time a bionic soft robotic stomach (BSRS) with an integrated drive and sensing structure inspired by origami and self-powered sensing technology. This soft stomach (SS) can realistically simulate and sense the movements of various parts of the human stomach in real-time. The contraction force and contraction rate of the BSRS are investigated with different viscosity contents, and the experimental values are similar to the physiological range (maximum contraction force is 3.2 N, and maximum contraction rate is 0.8). This paper provides an experimental basis for the study of gastric digestive medicine and food science by simulating the peristaltic motion of the BSRS according to the human stomach and by combining the triboelectric nanogenerator (TENG) sensing technology to monitor the motion of the BSRS in real-time.

Effects of Postprandial Factors and Second Meal Intake Time on Bioequivalence Investigation of Tadalafil-Loaded Orodispersible Films in Human Volunteers

Tadalafil (TD) has poor water solubility but is well absorbed without affecting food intake when administered orally. Owing to patient adherence and therapeutic characteristics, a TD-loaded orodispersible film (TDF) is preferable. However, the mechanistic role of dietary status on the clinical pharmacokinetic analysis of TDF in human volunteers should be investigated because the gastrointestinal environment varies periodically according to meal intervals, although commercial 20 mg TD-loaded tablets (TD-TAB, Cialis® tablet) may be taken with or without food. TDF was prepared by dispersing TD in an aqueous solution and polyethylene glycol 400 to ensure good dispersibility of the TD particles. In the fasting state, each T/R of Cmax and AUC between TD-TAB and TDF showed bioequivalence with 0.936-1.105 and 1.012-1.153, respectively, and dissolution rates in 1000 mL water containing 0.5% SLS were equivalent. In contrast, TDF was not bioequivalent to TD-TAB under the fed conditions by the Cmax T/R of 0.610-0.798. The increased dissolution rate of TDF via the micronization of drug particles and the reduced viscosity of the second meal content did not significantly affect the bioequivalence. Interestingly, an increase in second meal intake time from 4 h to 6 h resulted in the bioequivalence by the Cmax T/R of 0.851-0.998 of TD-TAB and TDF. The predictive diffusion direction model for physical digestion of TD-TAB and TDF in the stomach after the first and second meal intake was successfully simulated using computational fluid dynamics modeling, accounting for the delayed drug diffusion of TDF caused by prolonged digestion of stomach contents under postprandial conditions.

Liposomes delivery systems of functional substances for precision nutrition

Natural bioactive compounds with antioxidant, antimicrobial, anticancer, and other biological activities are vital for maintaining the body's physiological functions and enhancing immunity. These compounds have great potential as nutritional therapeutic agents, but they can be limited due to their poor flavor, color, unstable nature, and poor water solubility, and degradation by gastrointestinal enzymes. Liposomes, as ideal carriers, can encapsulate both water-soluble and fat-soluble nutrients, enhance the bioavailability of functional substances, promote the biological activity of functional substances, and control the release of nutrients. Despite their potential, liposomes still face obstacles in nutrient delivery. Therefore, the design of liposomes for special needs, optimization of the liposome preparation process, enhancement of liposome encapsulation efficiency, and industrial production are key issues that must be addressed in order to develop food-grade liposomes. Moreover, the research on surface-targeted modification and surface functionalization of liposomes is valuable for expanding the scope of application of liposomes and achieving the release of functional substances from liposomes at the appropriate time and site. The establishment of in vivo and in vitro digestion models of nutrient-loaded liposomes, in-depth study of gastrointestinal digestive behavior after liposome ingestion, targeted nutrient release, and deciphering the nutritional intervention of human diseases and positive health promotion are promising fields with broad development prospects.

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.

Dynamic Stomach Model-Capillary Electrophoresis-ICPMS for Evaluation of Release and Transformation Behaviors of Arsenic Species from Microplastics during Digestion

Microplastics (MPs) can act as carriers of environmental arsenic species into the stomach with food and release arsenic species during digestion, which threatens human health. Herein, an integrated dynamic stomach model (DSM)-capillary electrophoresis-inductively coupled plasma mass spectrometry (CE-ICPMS) is developed for online monitoring of the release and transformation behaviors of arsenic species loaded on MPs (As-MPs) in the simulated human stomach. The 3D-printed DSM with a soft stomach chamber enables the behaviors of gastric peristalsis, gastric and salivary fluid addition, pH adjustment, and gastric emptying (GE) to be controlled by a self-written program after oral ingestion of food with As-MPs. The gastric extract during digestion is introduced into the spiral channel to remove the large particulate impurity and online filtered to obtain the clarified arsenic-containing solution for subsequent speciation analysis of arsenic by CE-ICPMS. The digestion conditions and pretreatment processes of DSM are tracked and validated, and the release rates of As-MPs digested by DSM are compared with those digested by the static stomach model and DSM without GE. The release rate of inorganic arsenic on MPs is higher than that of organic arsenic throughout the gastric digestion process, and 8% of As(V) is reduced to As(III). The detection limits for As(III), DMA, MMA, and As(V) are 0.5-0.9 μg L-1 using DSM-CE-ICPMS, along with precisions of ≤8%. This present method provides an integrated and convenient tool for evaluating the release and transformation of As-MPs during human gastric digestion and provides a reference for exploring the interactions between MPs and metals/metalloids in the human body.

In Vitro Human Gastrointestinal Tract Simulation Systems: A Panoramic Review

Simulated human gastrointestinal (GI) tract systems are important for their applications in the fields of probiotics, nutrition and health. To date, various in vitro gut systems have been available to study GI tract dynamics and its association with health. In contrast to in vivo investigations, which are constrained by ethical considerations, in vitro models have several benefits despite the challenges involved in mimicking the GI environment. These in vitro models can be used for a range of research, from simple to dynamic, with one compartment to several compartments. In this review, we present a panoramic development of in vitro GI models for the first time through an evolutionary timeline. We tried to provide insight on designing an in vitro gut model, especially for novices. Latest developments and scope for improvement based on the limitations of the existing models were highlighted. In conclusion, designing an in vitro GI model suitable for a particular application is a multifaceted task. The bio-mimicking of the GI tract specific to geometrical, anatomical and mechanical features remains a challenge for the development of effective in vitro GI models. Advances in computer technology, artificial intelligence and nanotechnology are going to be revolutionary for further development. Besides this, in silico high-throughput technologies and miniaturisation are key players in the success of making in vitro modelling cost-effective and reducing the burden of in vivo studies.

Modulating in vitro digestion of whey protein cold-set emulsion gels via gel properties modification with gallic acid and EGCG

Gallic acid (GA) and epigallocatechin gallate (EGCG), cooperated at varied ratios (1:0, 3:1, 1:1, 1:3, and 0:1), were employed to modify gel properties of calcium induced-whey protein emulsion gel. The effects of GA/EGCG on emulsion morphology, as well as gel properties and in vitro digestive behavior of the emulsion gels were investigated. Compared with emulsions without phenolics, GA/EGCG induced slightly smaller particle size and stronger electrostatic repulsion between emulsion droplets. Moreover, GA/EGCG, notably at a ratio of 3:1, promoted electrostatic and hydrophobic interactions between protein molecules and the formation of a compact and filamentous gel microstructure, resulting in a remarkable increment in the gel strength (up to 106 %). Furthermore, in vitro oral digestion, dynamic gastric digestion (using an artificial gastric digestive system, AGDS), and intestinal digestion of the emulsion gels were simulated. Particle size and protein hydrolysis results revealed that GA/EGCG was prone to weaken the physical disintegration of gels, reduce protein hydrolysis, and enhance the stability of emulsified oil droplets during dynamic gastric digestion. As a consequence, delayed release of oil droplets was observed in the gels and more free fatty acids were released in the intestinal digestion, particularly in the gel with GA/EGCG (3:1). These findings would provide novel strategies for application of phenolic compounds in developing protein gel-based delivery systems.

Advances in the Preparation, Stability, Metabolism, and Physiological Roles of Anthocyanins: A Review

Anthocyanins are natural flavonoid polyphenolic compounds widely found in fruits and vegetables. They exhibit antioxidant properties and prophylactic effects in the immune and cardiovascular systems, confer protection against cancer, and contribute to the prevention of cardiovascular diseases. Thus, their incorporation into functional foods, pharmaceuticals, supplements, and cosmetic formulations aims at promoting human well-being. This review comprehensively outlined the structural attributes of anthocyanins, expanding upon diverse methodologies employed for their extraction and production. Additionally, the stability, metabolic pathways, and manifold physiological functions of anthocyanins were discussed. However, their constrained fat solubility, susceptibility to instability, and restricted bioavailability collectively curtail their applicability and therapeutic efficacy. Consequently, a multidimensional approach was imperative, necessitating the exploration of innovative pathways to surmount these limitations, thereby amplifying the utilitarian significance of anthocyanins and furnishing pivotal support for their continual advancement and broader application.

Effect of chewing ability on in vivo oral digestive characteristics and in vitro gastrointestinal starch hydrolysis of three different types of cooked rice

Chewing ability has a strong effect on food digestion. However, little is known about the relationship between the food mastication degree and the subsequent gastric emptying. This study was to explore the effects of individual chewing ability (strong and weak) on the in vivo oral processing characteristics and in vitro dynamic gastrointestinal starch hydrolysis of three types of rice (japonica rice, indica rice and waxy rice). Results showed that the swallowable bolus in the weak chewing group had larger holes and a looser microstructure with more small rice particles, while the strong chewing ones obtained a bolus with higher saliva content (up to 28%) and starch hydrolysis degree (up to 13.55%). Moreover, the gastric retention and starch hydrolysis of the strong chewing ability group were higher in the artificial gastric dynamic system (AGDS). The indica rice particles with the higher degree of fragmentation contacted enzymes easier and hydrolyzed quicker, thus emptying through the stomach faster (81.76%). However, the oral chewing properties of rice mainly influenced the starch digestion in the stomach and the initial stage of the small intestine (∼5 min). This study suggested that the chewing ability and rice variety can influence the bolus properties, which in turn affected the gastric emptying and the degree of starch hydrolysis during digestion.

Development and analysis of a multi-module peristaltic simulator for gastrointestinal research

Many existing in vitro digestion systems do not accurately represent the peristaltic contractions of the gastrointestinal system; most of the systems that have physiologically-relevant peristaltic contractions have low throughput and can only test one sample at a time. A device has been developed that provides simulated peristaltic contractions for up to 12 digestion modules simultaneously using rollers of varying width to modulate the dynamics of the peristaltic motion. The force applied to a simulated food bolus varied from 2.61 ± 0.03 N to 4.51 ± 0.16 N (p < 0.05) depending on roller width. Video analysis showed that the degree of occlusion of the digestion module varied from 72.1 ± 0.4% to 84.6 ± 1.2% (p < 0.05). A multiphysics, computational fluid dynamics model was created to understand the fluid flow. The fluid flow was also examined experimentally using video analysis of tracer particles. The model-predicted maximum fluid velocity in the peristaltic simulator incorporating the thin rollers was 0.016 m/s, and the corresponding value measured using tracer particles was 0.015 m/s. The occlusion, pressure, and fluid velocity in the new peristaltic simulator fell within physiologically representative ranges. Although no in vitro device perfectly recreates the conditions of the gastrointestinal system, this novel device is a flexible platform for future gastrointestinal research and could allow for high-throughput screening of food materials for health-promoting properties under conditions representative of human gastrointestinal motility.

Evaluation of the performance of the human gastric simulator using durum wheat-based foods of contrasting food structure

The selection of gastric digestion parameters in food digestion studies using in vitro models is critical to properly represent structural changes in the stomach. This study aimed to evaluate the performance of digestion in the human gastric simulator (HGS) using generalized in vitro gastric digestion parameters (secretion rate of 4.1 mL min^-1, gastric emptying rate of 5.68 g min^-1) that were derived from a previous in vivo study using six starch-rich foods. Two of the six foods used in the in vivo study (cooked durum wheat porridge/semolina and pasta) were digested in the HGS for up to 240 min, then the properties of the emptied and remaining digesta were measured. The properties of the in vitro remaining digesta were compared to those measured in vivo (growing pig stomach). The trends in the gastric breakdown rate and mechanisms, dry matter emptying kinetics, and starch hydrolysis of pasta and semolina were similar to those of in vivo. Gastric breakdown and dilution kinetics in vitro and in vivo were well-related but did not have a 1 : 1 correlation, whereas gastric acidification kinetics in the HGS deviated from that observed in vivo. The results suggest that generalized digestion parameters could be used to predict the effect of food structure on in vivo gastric breakdown and emptying, but care should be taken in interpretation of results, as the gastric acidification process was different from what was observed in vivo. This information will help refine in vitro digestion model parameters to provide more physiologically-relevant data in future studies.

Changes Caused by Bisphenols in the Chemical Coding of Neurons of the Enteric Nervous System of Mouse Stomach

Bisphenol A (BPA), an organic chemical compound which is widely used in the production of plastics, can severely damage live organisms. Due to these findings, the plastic industry has started to replace it with other substances, most often with bisphenol S (BPS). Therefore, during the present investigation, with the use of double immunofluorescence labeling, we compared the effect of BPA and BPS on the enteric nervous system (ENS) in the mouse corpus of the stomach. The obtained results show that both studied toxins impact the amount of nerve cells immunoreactive to substance P (SP), galanin (GAL), vesicular acetylcholine transporter (VAChT is used here as a marker of cholinergic neurons) and vasoactive intestinal polypeptide (VIP). Changes observed under the impact of both bisphenols depended on the neuronal factor, the type of the enteric ganglion and the doses of bisphenols studied. Generally, the increase in the percentage of neurons immunoreactive to SP, GAL and/or VIP, and the decrease in the percentage of VAChT-positive neurons, was noted. Severity of changes was more visible after BPA administration. However, the study has shown that long time exposure to BPS also significantly affects the ENS.

Evaluation and prediction of oral drug absorption and bioequivalence with food-drug interaction

This article reviews the impacts on the in vivo prediction of oral bioavailability (BA) and bioequivalence (BE) based on Biopharmaceutical classification systems (BCS) by the food-drug interaction (food effect) and the gastrointestinal (GI) environmental change. Various in vitro and in silico predictive methodologies have been used to expect the BA and BE of the test oral formulation. Food intake changes the GI physiology and environment, which affect oral drug absorption and its BE evaluation. Even though the pHs and bile acids in the GI tract would have significant influence on drug dissolution and, hence, oral drug absorption, those impacts largely depend on the physicochemical properties of oral medicine, active pharmaceutical ingredients (APIs). BCS class I and III drugs are high soluble drugs in the physiological pH range, food-drug interaction may not affect their BA. On the other hand, BCS class II and IV drugs have pH-dependent solubility, and the more bile acid secretion and the pH changes by food intake might affect their BA. In this report, the GI physiological changes between the fasted and fed states are described and the prediction on the oral drug absorption by food-drug interaction have been introduced.

Coating Materials to Increase the Stability of Liposomes

Liposomes carry various compounds with applications in pharmaceutical, food, and cosmetic fields, and the administration route is especially parenteral, oral, or transdermal. Liposomes are used to preserve and release the internal components, thus maintaining the properties of the compounds, the stability and shelf life of the encapsulated products, and their functional benefits. The main problem in obtaining liposomes at the industrial level is their low stability due to fragile phospholipid membranes. To increase the stability of liposomes, phospholipid bilayers have been modified or different coating materials have been developed and studied, both for liposomes with applications in the pharmaceutical field and liposomes in the food field. In the cosmetic field, liposomes need no additional coating because the liposomal formulation is intended to have a fast penetration into the skin. The aim of this review is to provide current knowledge regarding physical and chemical factors that influence stability, coating materials for liposomes with applications in the pharmaceutical and food fields to increase the stability of liposomes containing various sensitive compounds, and absorption of the liposomes and commercial liposomal products obtained through various technologies available on the market.

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.

Effects of the long-term influence of bisphenol A and bisphenol S on the population of nitrergic neurons in the enteric nervous system of the mouse stomach

Bisphenol A (BPA) is an endocrine disruptor commonly used in the production of plastics. Due to its relatively well-known harmful effects on living organisms, BPA is often replaced by its various analogues. One of them is bisphenol S (BPS), widely used in the plastics industry. Until recently, BPS was considered completely safe, but currently, it is known that it is not safe for various internal organs. However, knowledge about the influence of BPS on the nervous system is scarce. Therefore, the aim of this study was to investigate the influence of two doses of BPA and BPS on the enteric nitrergic neurons in the CD1 strain mouse stomach using the double-immunofluorescence technique. The study found that both substances studied increased the number of nitrergic neurons, although changes under the impact of BPS were less visible than those induced by BPA. Therefore, the obtained results, for the first time, clearly indicate that BPS is not safe for the innervation of the gastrointestinal tract.

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.

Simulating human gastrointestinal motility in dynamic in vitro models

The application of dynamic in vitro gastrointestinal (GI) models has grown in popularity to understand the impact of food structure and composition on human health. Given that GI motility is integral to digestion and absorption, a predictive in vitro model should faithfully replicate the motility patterns and motor functions in vivo. In this review, typical characteristics of gastric and small intestinal motility in humans as well as the biomechanical and hydrodynamic events pertinent to gut motility are summarized. The simulation of GI motility in the presently existing dynamic in vitro models is discussed from an engineering perspective and categorized into hydraulic, piston/probe-driven, roller-driven, pneumatic, and other systems. Each system and its representative models are evaluated in terms of their motility patterns, the key hydrodynamic characteristics concerning gut motility, their performance in simulating the key physiological events, and their ability to establish in vitro-in vivo correlations. Practical Application: The review paper provided useful information in the design of dynamic GI models and the simulation of human gastric and small intestinal motility which are important for understanding food and health.

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.

Nondairy Probiotic Products: Functional Foods That Require More Attention

The potential health benefits of probiotics have been illustrated by many studies. However, most functional foods containing probiotics are from dairy sources. This review provides an overview of potential strains and raw materials for nondairy probiotic products together with the role of its in vitro assessment. Probiotic-containing products from raw nondairy materials are known both in terms of quality and nutritional values. The sensory properties of raw plant-based materials are generally improved as a result of fermentation with probiotics. Increased market shares for plant-based probiotic products may also help to curb environmental challenges. The sustainability of this food results from reductions in land use, greenhouse gas emissions, and water use during production. Consuming nondairy probiotic food can be a personal step to contribute to climate change mitigation. Since some people cannot or do not want to eat dairy products, this creates a market gap in the supply of nutritious food. Therefore, the promotion and broader development of these foods are needed. Expanding our knowledge on how to best produce these functional foods and increasing our understanding of their in vivo behaviours are crucial. The latter may be efficiently achieved by utilizing available in vitro digestion systems that reliably recapitulate the in vivo situation without introducing any ethical concerns.

Starch structure and nutritional functionality - Past revelations and future prospects

Starch exists naturally as insoluble semi-crystalline granules assembled by amylose and amylopectin. Acknowledging the pioneers, we have reviewed the major accomplishments in the area of starch structure from the early 18th century and further established the relation of starch structure to nutritional functionality. Although a huge array of work is reported in the area, the review identified that some features of starch are still not fully understood and needs further elucidation. With the rise of diet-related diseases, it has never been more important to understand starch structure and use that knowledge to improve the nutritional value of the world's principal energy source.

In vitro models to evaluate ingestible devices: Present status and current trends

Orally ingestible medical devices offer significant opportunity in the diagnosis and treatment of gastrointestinal conditions. Their development necessitates the use of models that simulate the gastrointestinal environment on both a macro and micro scale. An evolution in scientific technology has enabled a wide range of in vitro, ex vivo and in vivo models to be developed that replicate the gastrointestinal tract. This review describes the landscape of the existing range of in vitro tools that are available to characterize ingestible devices. Models are presented with details on their benefits and limitations with regards to the evaluation of ingestible devices and examples of their use in the evaluation of such devices is presented where available. The multitude of models available provides a suite of tools that can be used in the evaluation of ingestible devices that should be selected on the functionality of the device and the mechanism of its function.

Anti-aging properties of phytoconstituents and phyto-nanoemulsions and their application in managing aging-related diseases

Aging is spontaneous and inevitable process in all living beings. It is a complex natural phenomenon that manifests as a gradual decline of physiological functions and homeostasis. Aging inevitably leads to age-associated injuries, diseases, and eventually death. The research on aging-associated diseases aimed at delaying, preventing or even reversing the aging process are of great significance for healthy aging and also for scientific progress. Numerous plant-derived compounds have anti-aging effects, but their therapeutic potential is limited due to their short shelf-life and low bioavailability. As the novel delivery system, nanoemulsion can effectively improve this defect. Nanoemulsions enhance the delivery of drugs to the target site, maintain the plasma concentration for a longer period, and minimize adverse reaction and side effects. This review describes the importance of nanoemulsions for the delivery of phyto-derived compounds and highlights the importance of nanoemulsions in the treatment of aging-related diseases. It also covers the methods of preparation, fate and safety of nanoemulsions, which will provide valuable information for the development of new strategies in treatment of aging-related diseases.

Achieving realistic gastric emptying curve in an advanced dynamic in vitro human digestion system: experiences with cheese-a difficult to empty material

Nowadays, in vitro digestion models have received growing interest in recent years to track the digestive fate of foods in the gastrointestinal tract. A major challenge in the development of more physiologically relevant in vitro gastric models is to simulate realistic gastric emptying. In this study, an advanced dynamic in vitro human gastric system was investigated for its potential in achieving the above. The mechanisms for controlling the gastric emptying rate by modulations of the peristaltic moving distance, the pylorus opening size/frequency, and the stomach tilting angle in relation to time are illustrated. With solid cheese, a difficult food material for emptying, different combinations of the operational parameters of the stomach system were evaluated. The system was steered to attain consistent gastric emptying curve with the theoretical data by optimizing operational parameters. By fitting the gastric retention data with a power-exponential model, which is a common approach for describing gastric emptying, the total meal achieved an average emptying half-time (t1/2) of 84.5 min and a curve shape coefficient (β) of 1.69, similar to the theoretical data reported in the literature, where the values of t1/2 and β were 85 min and 1.8, respectively (p > 0.05). Furthermore, the mean median particle size was significantly decreased from the initial 2.80 mm (cheese cubes) to the final 1.35 mm (p < 0.05). There are few particles greater than 2 mm observed in the emptied cheese digesta throughout the digestion process. These suggest the powerful gastric grinding and sieving capacity exhibited by the in vitro system. The current study demonstrates that a well-considered in vitro system can offer a reasonable approach for tracking the structural and physicochemical changes of foods during digestion in the stomach, which is practically meaningful.

A review on the food digestion in the digestive tract and the used in vitro models

It is crucial to replicate or mimic the human digestive system conditions closely in model systems to have the food digestion-related data as accurate as possible. Thus, the data obtained could contribute to studies like those on the relationship between health and nutrition. This review aims to express the human digestion system's role in food digestion and compare the capability of the models used in simulations, especially the dynamic in vitro models. Activities of the human digestive system governing food digestion and the food matrix's disintegration mechanism in the digestive system were discussed. Dynamic in vitro models and their relevance to the human digestive system were described. Advancements in the last 20 years, as well as limitations of those artificial systems, with prospects, were discussed. Extensive use and improvement on these models will extend our knowledge of the food matrix and digestive system's complex interaction. Thus, it will be possible to design next-generation foods with improved health benefits.

New insights into in vivo gastroduodenal digestion of oil-in-water emulsions: gastric stability and in vitro digestion modeling

In this paper, effect of emulsion stability on gastroduodenal emptying/secretion was reviewed and differentiated. Moreover, novel perspectives on physiology of gastric lumen, duodenum, and gall bladder were achieved using mathematical models, being useful for designing artificial digestive systems. In this regard, numerical data for dynamic gastric emptying/secretion were offered for gastric-stable and gastric-unstable emulsion intakes. It was shown that alterations in human gastric and duodenal volume follow, respectively, linear and sinusoidal curves, with high correlation coefficients (r² > 0.93). For both emulsions, about 30-40 mL ingesta discharged rapidly from stomach upon ingestion; However, further gastric emptying was regulated for the rest of digestion period, so that 0.1 mL/min oil was passing through duodenum. Intragastric evacuation of both emulsions started with a lag phase during which stomach stored secretions incrementally by slow gastric discharge. Lag phase ended with fat layering, when emptying considerably enhanced. This reduction was gradual for stable emulsion while unstable emulsion experienced a rapid emptying before slow declining trend. Along with initial gastric emptying, 87% of gallbladder content discharged into duodenum, prolonged up to the gradual reduction phase of stomach. Supplementary investigations are needed to quantify gastroduodenal secretions, particularly pepsin and pancreas in response to emulsion ingesta.