Understanding the digestion behavior of plant-based protein foods is essential for optimizing their health benefits. This study used two arrays of pH-responsive calcium salts and multivalent ion-responsive polysaccharides to modify the gastric digestion behavior of soy-based milk alternatives (SBMAs) in an in vitro semi-dynamic digestion model. Before digestion, the physicochemical properties of SBMAs were analyzed. Calcium chloride caused a decrease in pH, leading to protein aggregation and colloidal instability. In contrast, insoluble carbonate and phosphate salts did not alter the physicochemical properties of SBMAs. Additionally, sedimentation was prevented by adding 0.3 wt% alginate. Semi-dynamic gastric digestion of SBMAs was carried out for 85 min, with the gastric content removed in 5 gastric emptying (GE) steps. Soy protein aggregation began immediately after gastric digestion initiation, when the pH was similar to 5.9. Gradual pH reduction from 6 to 2 resulted in an increase in ionized calcium content, from 0.13 mg mL(-1) in GE1 (17 min) to 0.60 mg mL(-1) in GE5 (85 min). The formation of the calcium alginate hydrogel network began at 34 min, entrapping discrete protein aggregates and forming integrated coagula, visualized by confocal microscopy. The gel strength of gastric coagula, which resisted emptying, was measured as 60 g. This process resulted in delayed protein delivery and reduced the protein content of GE3 (51 min) and GE4 (68 min) from 11.84 and 9.92 mg mL(-1) in the control sample to 6.49 and 6.07 mg mL(-1) in the fortified SBMAs, respectively. This work demonstrates that insoluble calcium salts can gradually solubilize under gastric conditions and actively induce alginate structuring. These findings provide new mechanistic insight into how nutrient delivery rates of SBMAs can be controlled by modifying gastric structures through formulation with components sensitive to pH, enzymes, and ionic strength of the stomach.

Gastric emptying plays a critical role in food digestion and nutrient absorption, as well as hormonal responses that impact food consumption, such as satiety. It is regulated by a complex interplay of intrinsic physiological factors (e.g., hormonal feedback like cholecystokinin [CCK] and ghrelin, gastric contractions), the intragastric environment, and central nervous system signaling via the vagus nerve. The impact of food properties on gastric emptying has been investigated for over a century. However, a detailed understanding of how the properties of protein-rich foods affect gastric emptying has only recently emerged. This article begins with a review of the gastric emptying process, its neurohumoral regulation, and methods for monitoring these processes. It then discusses the influence of food properties and human physiology on the gastric emptying of proteins. We also describe how processing impacts protein digestion and satiety responses. The article concludes by highlighting how food matrix affects protein digestion and satiety responses. The information from this review may help guide the development of healthier protein-rich foods to control gastric emptying and improve satiety responses.

Obesity and diabetes pose a major threat to public health and brings huge economic and social burdens. Gastrointestinal tract (GIT) plays a crucial role in the occurrence of the metabolic disorder by sending key information to the brain through nervous system to control food intake. Understanding the underlying mechanisms on how the food structure mediates the brain-stomach neutrally regulating digestion process, especially gastric emptying, is thus paramount for precisely designing food structure and for effectively controlling appetite and reducing diet-related disease. This review discusses the role of gastric emptying in the whole digestion process and the regulatory mechanisms of the nervous system in gastric emptying. Emphasis is placed on the impact of food microstructure and dietary structure on gastric emptying. We then consider how Western and Oriental diet structure influence on gastric emptying in different historical periods.

In this study, the effect of the application of ultrasound for the extraction of sunflower pectin on the elaboration of gels with sucrose, stevia and saccharin was investigated at pH values of 3.0, 4.6 and 6.8. The results pointed out that, in all the conditions tested, gels formed with ultrasound-extracted pectin were stronger than those obtained from pectin extracted with conventional methods. Thus, the optimal conditions to form a gel were Ca2+ concentration 25 mg/g, pH 3.0 and 10% sucrose. Under the same conditions it was possible to make gels with similar characteristics to that of sucrose by replacing it with stevia or saccharin, obtaining gels with excellent properties and low glycemic index and caloric content, especially suitable for healthy fruit-derived products such as jams, to be used instead of those made with sucrose. These important differences in gelation could be probably due to differences in galacturonic acid (GalA) content, degree of methyl esterification and molecular weight (Mw) in pectin obtained by ultrasound.

BackgroundThe definition of the term ‘bioaccessibility' is not clear. In the fields of Nutrition and Food Sciences, the term bioaccessibility was introduced in the context of micronutrients, which can lead to some confusion when applied to macronutrients, the latter requiring hydrolysis (sometimes included in the definition of bioaccessibility).ScopeIn the context of macronutrient digestion, particularly in plant-based food where cell walls play a significant role, it seems coherent to differentiate between the release of nutrients from the food matrix, hydrolysis and absorption.Key findings and conclusionsWe concluded that the terms bioaccessibility, digestibility and bioavailability have been misused over time and have lost some of their meaning. Therefore, in this study, we suggest a definition for “bioaccessibility” and related vocabulary, as well as a possible classification of the biochemical events occurring during food or feed digestion. It is critical to use precise, specific vocabulary to describe the mechanisms involved while food transits through the different compartments of the gastro-intestinal tract. This goes hand in hand with a recent realisation of the importance of the food matrix, which has an impact on the breakdown of food in the digestive tract and thus on human and animal health.

The complex of oat beta-glucan (OBG) and flavonoids hampered the digestion of starch-based food and retarded the blood glucose response; however, its effect on gastric emptying and its relative mechanism have not been thoroughly investigated. By using Fourier transform infrared (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), antioxidant ability, and enzymic inhibitory tests for the characterization and in vitro semi-dynamic digestion of complexes of OBG (high and low molecular weights) and sea buckthorn flavonoids, we found that the higher molecular weight complex (FU) exhibited stronger ABTS and DPPH radical scavenging abilities and higher alpha-glucosidase and alpha-amylase inhibition rates. Mice fed with rice flour with FU addition exhibited the slowest gastric emptying and intestinal propulsion rates and blood glucose rise and had the lowest activity of digestive enzymes and levels of insulin, ghrelin, motilin (MTL), and relevant gene (ghrelin and GHSR mRNA) expression than those in the control and low-molecular-weight groups. This study provided scientific data for the development of foods with delayed gastric rate and hypoglycemic index for specific populations.

The bioaccessibility of phytochemicals is an important factor for new functional food design. The interaction of white mugwort extract (FE) and food ingredients (coconut oil, egg white albumen, brown rice powder, inulin, and mixtures thereof) was determined after in vitro digestion to inform the development of a functional soup for an aging population. Coconut oil exerted a protective effect on polyphenols, showing the highest bioaccessibility (62.9%) and antioxidant activity after intestinal digestion (DPPH 12.38 mg GAE/g DW, FRAP 0.88 mol Fe(ll)/g DW). In contrast, egg white albumen had the most significant negative effect on the polyphenol stability, resulting in the lowest bioaccessibility (12.49%). Moreover, FE promoted the emulsion stability and delayed starch digestion by inhibiting amylase activity via non-specific polyphenol–protein interactions, resulting in a decrease in the total reducing sugars (TRS) released during digestion. It also limited the protein digestion, probably due to the complex formation of polyphenols and proteins, consequently reducing the bioaccessibility of both amino acids and polyphenols. These findings provide useful information for designing functional food products that could promote the bioaccessibility and bioactivity of natural extracts.

Background: Interesterification is an industrial processing technique used to create hard fats where this is essential for functionality and consumer acceptability, e.g. margarines and lower fat spreads.

Background: Industrial processing can alter the structural complexity of dietary proteins and, potentially, their digestion and absorption upon ingestion. High-moisture extrusion (HME), a common processing method used to produce meat alternative products, affects in vitro digestion, but human data are lacking. We hypothesized that HME of a mycoprotein/pea protein blend would impair in vitro digestion and in vivo postprandial plasma amino acid availability. Methods: In Study A, 9 healthy volunteers completed 2 experimental trials in a randomized, double-blind, crossover design. Participants consumed a beverage containing 25 g protein from a " dry " blend (CON) of mycoprotein/pea protein (39%/61%) or an HME contentmatched blend (EXT). Arterialized venous blood samples were collected in the postabsorptive state and regularly over a 5-h postprandial period to assess plasma amino acid concentrations. In Study B, in vitro digestibility of the 2 beverages were assessed using bicinchoninic acid assay and optical fl uorescence microscopy at baseline and during and following gastric and intestinal digestion using the INFOGEST model of digestion. Results: Protein ingestion increased plasma total, essential (EAA), and branched-chain amino acid (BCAA) concentrations (time effect, P < 0.0001) but more rapidly and to a greater magnitude in the CON compared with the EXT condition (condition x time interaction, P < 0.0001). This resulted in greater plasma availability of EAA and BCAA concentrations during the early postprandial period (0 - 150 min). These data were corroborated by the in vitro approach, which showed greater protein availability in the CON (2150 +/- 129 mg/mL) compared with the EXT (590 +/- 41 mg/mL) condition during the gastric phase. Fluorescence microscopy revealed clear structural differences between the 2 conditions. Conclusions: These data demonstrate that HME delays in vivo plasma amino acid availability following ingestion of a mycoprotein/pea protein blend. This is likely due to impaired gastric phase digestion as a result of HME-induced aggregate formation in the pea protein. This trial was registered at clinicaltrials.gov as NCT05584358.

Emulsions are commonly used to fortify beverages with oil-soluble nutrients. Such emulsions must be physically stable, prevent the cargo nutrient from chemical degradation, and release the nutrient at the right time during digestion. Wood hemicelluloses, with their proven capability in producing nanoemulsions and preventing oil oxidation, have the potential to facilitate such a fortification method. These hemicelluloses are unique, as the presence of residual lignin was proven essential in their functionality. However, the structural interplay between the residual lignin and the polysaccharide fraction at the oil-water interface is unknown, including their effects on the storage stability and digestibility of a loaded bioactive compound. We studied the performance of emulsions stabilized by two grades of birch glucuronoxylans (GX) as vessels for vitamin D3. Both GXs showed similar protective performance to methylcellulose regardless of the lignin content during storage and the gastric phase of digestion. The unrefined GX, which contained larger lignin moieties, delayed the release of vitamin D3 during intestinal digestion. We concluded that the interface is primarily built of a polysaccharide layer with the lignin moieties facing towards the oil phase. We have thus highlighted the potential of GX-stabilized emulsions as carriers of vitamin D3. Additionally, these results advance the understanding of lignin-polysaccharide interplay towards a rationalized strategy in biorefining of wood hemicelluloses, for which the ratio of lignin-to-polysaccharide can be adjusted during extraction and post-extraction treatments to obtain a tailor-made emulsifier for various emulsion-based products.

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.

Mycoprotein is a fungal-derived ingredient used for meat alternative products whose fungal cell walls are rich in dietary fibre (β-glucans and chitin) and defines its structure. Several health benefits have been reported after mycoprotein consumption, however, little is known about the impact of mycoprotein fermentation on the gut microbiota. This study aims to identify changes in microbiome composition and microbial metabolites during colonic fermentation of mycoprotein following simulated upper gastrointestinal digestion. Changes in microbial populations and metabolites produced by the fermentation of mycoprotein fibre were investigated and compared to a plant (oat bran) and an animal (chicken) comparator. In this model fermentation system, mycoprotein and oat showed different but marked changes in the microbial population compared to chicken, which showed minimal differentiation. In particular, Bacteroides species known for degrading β-glucans were found in abundance following fermentation of mycoprotein fibre. Mycoprotein fermentation resulted in short-chain fatty acid production comparable with oat and chicken at 72 h. Significantly higher branched-chain amino acids were observed following chicken fermentation. This study suggests that the colonic fermentation of mycoprotein can promote changes in the colonic microbial profile. These results highlight the impact that the unique structure of mycoprotein can have on digestive processes and the gut microbiota.

There is increasing interest in including pulse proteins into food products due to their nutrient-rich and sustainable character. However, little is known regarding the consequences of different extraction approaches on the pulse protein structure and the subsequent protein (micro)structural organization and protein digestion kinetics. Therefore, three green pea protein extracts were created: (i) cooking followed by cotyledon cell isolation, (ii) alkaline extraction followed by isoelectric precipitation, or (iii) salt extraction, and compared to the original pea flour as well as to sodium caseinate. The results showed that encapsulated, denatured protein inside pea cotyledon cells presented the (s)lowest digestion, while accessible and more native protein (e.g., pea flour, pea protein salt extract) presented much faster and higher digestion. Moreover, the alkali extracted pea protein was denatured to some extent, significantly lowering in vitro digestion kinetics. In the second part, three different in vitro approaches were applied to digest the salt extracted pea protein. Semi-dynamic gastric digestion approaches simulate in vivo conditions more closely which especially impacted the rate of digestion.

Viscosity has been shown to affect food breakdown and nutrient release in the gastrointestinal tract, and the subsequent postprandial glycaemic response and satiety. However, the correlation between food viscosity and gastric emptying is not fully understood. This study investigated the in vitro gastric emptying behavior of peanut butter with different viscosities using semi-dynamic and the artificial gastric digestive system (AGDS) models. Results from both digestion models showed that high viscosity peanut butter had a slower pH decrease, higher buffering capacity, slower phase separation of gastric chyme and less protein hydrolysis and lipid digestion than the control and low viscosity groups. However, the AGDS displayed slower gastric emptying rate, smaller chyme particle size and less proteolysis than the semi-dynamic model, particularly in the high-viscosity group (e.g. -60% of gastric emptying rate for AGDS and -20% for semi-dynamic model at 120 min), due to the different mechanical shearing forces and gastric emptying patterns in these two models. This study demonstrated the role of food viscosity on the gastric emptying process, and it also suggested that viscosity should be taken into account when designing future functional foods with particular structure.

Industrially generated trans-fats have been linked with cardiovascular disease (CVD) and have thus been replaced by interesterified (IE) fats, in foods. Interesterification rearranges fatty acids on the glycerol backbone of a triacylglycerol molecule. However, the impact of IE fat on health is unknown. We recently reported differences in lipid absorption kinetics between IE and rapeseed oil (RO). Here, we investigated the mechanisms underpinning IE fat digestion kinetics in the same muffins baked using an IE fat, non-IE fat [with the same fatty acid composition] and rapeseed oil (RO) under simulated conditions. IE and non-IE fats were largely solid in the gastric phase and strongly associated within the muffin matrix, whereas RO formed liquid droplets which separated from the matrix. No significant difference in lipolysis rates was detected between IE and non-IE fats. The lipolysis of the RO fat was slower, due to long-chain PUFAs. Interesterification itself did not affect digestibility, but the strong interaction between the hard fats and the muffin matrix resulted in extensive creaming of the matrix in the stomach, leading to delayed gastric emptying compared to the RO sample. The rate and extent of lipolysis were determined by the amount of fat available and the structure of the fat. This demonstrates the importance of the physical behaviour of the fats during digestion and provides a mechanistic understanding of the overall lipid digestion of IE fats, which relates to their physiological response.

Formulating poorly soluble drugs with polymers in the form of solid dispersions has been widely used for improving drug dissolution. Endogenous surface-active species present in the gut, such as bile salts, lecithin and other phospholipids, have been shown to play a key role in facilitating lipids and poorly soluble drugs solubilisation in the gut. In this study, we examined the possible occurrence of interactions between a model bile salt, sodium taurocholate (NaTC), and model spray dried solid dispersions comprising piroxicam and Hydroxypropyl Methylcellulose (HPMC), a commonly used hydrophilic polymer for solid dispersion preparation. Solubility measurements revealed the good solubilisation effect of NaTC on the crystalline drug, which was enhanced by the addition of HPMC, and further boosted by the drug formulation into solid dispersion. The colloidal behaviour of the solid dispersions upon dissolution in biorelevant media, with and without NaTC, revealed the formation of NaTC-HPMC complexes and other mixed colloidal species. Cellular level drug absorption studies obtained using Caco-2 monolayers confirmed that the combination of drug being delivered by solid dispersion and the presence of bile salt and lecithin significantly contributed to the improved drug absorption. Together with the role of NaTC-HPMC complexes in assisting the drug solubilisation, our results also highlight the complex interplay between bile salts, excipients and drug absorption.

This study sought to explore the combined use of confocal Raman microscopy and microfluidic channels to probe the location and mobility of hydrophobic antioxidant (β-carotene) incorporated at the interface of food-grade droplet-stabilized emulsions (DSEs).Microfluidic channels were used to isolate emulsion droplets for efficient investigation of antioxidant mobility. This approach proved more conclusive than fixing the sample in agarose, because a single layer of droplets could be obtained. Results also indicated that the migration of β-carotene incorporated in shell droplets of olive oil and trimyristin DSEs to core droplets was minimal and beta-carotene remained mostly localised at the interface even after 3 days of production.This work demonstrates that microfluidic isolation of emulsion droplets combined with confocal Raman microscopy can give new insights into the spatial variation of chemical composition within emulsions.This study revealed that the migration of β-carotene between shell and core was minimal and hence it may be possible to concurrently deliver two incompatible compounds by spatially segregating them between shell and core compartments of DSEs.

White mugwort (Artemisia lactiflora Wall.), a traditional Chinese medicine, has been widely consumed in different forms for health care purposes. In this study, the in vitro digestion model of INFOGEST was used to investigate the bioaccessibility, stability, and antioxidant activity of polyphenols from two different forms of white mugwort, including dried powder (P 50, 100, and 150 mg/mL) and fresh extract (FE 5, 15, and 30 mg/mL). During digestion, the bioaccessibility of TPC and antioxidant activity were influenced by the form and ingested concentration of white mugwort. The highest bioaccessibility of the total phenolic content (TPC) and relative antioxidant activity were found at the lowest P and FE concentrations, as calculated relative to the TPC and antioxidant activity of P-MetOH and FE-MetOH based on the dry weight of the sample. Post-digestion, in comparison to P, FE had higher bioaccessibility (FE = 287.7% and P = 130.7%), relative DPPH radical scavenging activity (FE = 104.2% and P = 47.3%), and relative FRAP (FE = 673.5% and P = 66.5%). Nine compounds, 3-caffeoylquinic acid, 5-caffeoylquinic acid, 3,5-di-caffeoylquinic acid, sinapolymalate, isovitexin, kaempferol, morin, rutin, and quercetin, identified in both samples were modified during digestion, yet still provided strong antioxidant activity. These findings suggest that white mugwort extract possesses a higher polyphenol bioaccessibility, showing great potential as a functional ingredient.

Background: The consumption of foods rich in anthocyanins (ACN) have been associated with beneficial properties in chronic inflammatory disorders such as intestinal bowel diseases (IBD). These effects were attributed not only to a direct antioxidant mechanism but also to the modulation of cell redox-dependent signaling. However, ACN bioavailability is low for their poor stability in the digestive tract, so ACN gastrointestinal digestion should be considered. Methods: To have a more realistic knowledge of the effects of ACN, we performed an in vitro simulated gastrointestinal digestion of an ACN-rich purified and standardized bilberry and blackcurrant extract (BBE), followed by an evaluation of ACN composition modification (HPLC-DAD and pH differential method) and antioxidant activity (FRAP assay). Then, we studied the effects of BBE gastrointestinal extract on Caco-2 exposed to TNF-α. Results: The results confirmed the high instability of ACN in the mild alkaline environment of the small intestine (17% recovery index). However, the digested BBE maintained part of its bioactivity. Additionally, BBE gastrointestinal extract inhibited the TNF-α-induced NF-κB pathway in Caco-2 and activated the Nrf2 pathway. Conclusions: Although ACN stability is affected by gastrointestinal digestion, the anti-inflammatory and antioxidant activity of digested extracts were confirmed; thus, the loss of ACN can probably be counterweighed by their metabolites. Then, ACN introduced by diet or food supplements could represent an approach for IBD prevention.