Search

The in vitro digestion model developed by the INFOGEST international consortium is widely used to simulate the physicochemical processes occurring inside the human gastrointestinal tract (mouth, stomach, and small intestine) during the digestion of foods. In this review, we provide a brief overview of the INFOGEST method and the procedures used to measure the digestion of macronutrients (lipids, proteins, and starch), the bioaccessibility of bioactive agents (vitamins, minerals, and nutraceuticals), and the changes in the structure and physical properties of foods under gastrointestinal conditions (particle size, charge, and location). We then review the application of the INFOGEST method for monitoring the gastrointestinal fate of different kinds of foods and beverages, including dairy, egg, meat, seafood, fruit, vegetable, cereal, and emulsified products. We also discuss the application of this method for studying the digestibility of next-generation plant-based foods, such as meat, seafood, dairy, and egg analogs. Finally, the benefits and limitations of this standardized in vitro digestion model are assessed. Expected final online publication date for the

The production of plant-based fish alternatives that look, feel, taste, and cook like real fish is critical for widespread consumer acceptance. Consequently, a thorough understanding of the properties of real fish is critical for the successful design of high-performance plant-based fish analogs. In this study, we investigated changes in the optical, mechanical, and water holding properties of Atlantic salmon during simulated cooking at different temperatures. Differential scanning calorimetry and diffusive wave spectroscopy exhibited characteristic peaks around 40 °C (myosin and collagen) and 72 °C (actin), which caused appreciable changes in the salmons’ physicochemical properties. The textural properties of salmon during simulated cooking were characterized using a dynamic shear rheometer and texture analyzer. Changes in color, cook loss, and surface area were related to the cooking temperature. This study provides valuable insights into the relationship between protein denaturation, protein aggregation, microstructural changes, and texture of real fish. This information will be useful for creating higher quality plant-based fish analogs.

We systematically investigated the impact of oil droplet diameter (≈0.15, 1.6, and 11 μm) on the bioaccessibility of three oil-soluble vitamins (vitamin A palmitate, vitamin D, and vitamin E acetate) encapsulated within soybean oil-in-water emulsions stabilized by quillaja saponin. Lipid digestion kinetics decreased with increasing droplet size due to the reduction in oil-water interfacial area. Vitamin bioaccessibility decreased with increasing droplet size from 0.15 to 11 μm: 87 to 39% for vitamin A; 76 to 44% for vitamin D; 77 to 21% for vitamin E. Vitamin bioaccessibility also decreased as their hydrophobicity and molecular weight increased, probably because their tendency to remain inside the oil droplets and/or be poorly solubilized by the mixed micelles increased. Hydrolysis of the esterified vitamins also occurred under gastrointestinal conditions: vitamin A palmitate (∼90%) and vitamin E acetate (∼3%). Consequently, the composition and structure of emulsion-based delivery systems should be carefully designed when creating vitamin-fortified functional food products.

Food, nutrition, and pharmaceutical scientists are trying to elucidate the major factors impacting the bioavailability of macronutrients (e.g., lipids) and micronutrients (e.g., vitamins) so as to improve their efficacy. Currently, there is still a limited understanding of how food matrix effects impact digestion and bioaccessibility determined under the INFOGEST model, which is currently the most widely used standardized in vitro gastrointestinal model. Therefore, we examined the impact of corn oil concentration on lipid digestion and β-carotene bioaccessibility using model food emulsions. For all oil concentrations tested (2.5 to 20%), complete lipid digestion was achieved using fed-state gastrointestinal conditions, which could only be seen if a back-titration was performed. The particle size and negative surface potential on the mixed micelles formed at the end of the small intestine phase both increased with increasing oil concentration, which was attributed to the generation of more free fatty acids. The β-carotene bioaccessibility increased when the oil concentration was raised from 2.5 to 10% due to the increased solubilization capacity of the mixed micelles, but then it decreased when the oil concentration was raised further to 20% due to precipitation and sedimentation of some of the β-carotene. The maximum β-carotene bioaccessibility (93.2%) was measured at 10% oil. These results indicate that the oil concentration of emulsions influences β-carotene bioaccessibility by altering digestion, solubilization, and precipitation processes. This knowledge is important when designing more effective functional or medical food products.

Consumption of sufficiently high quantities of dietary fibers has been linked to a range of health benefits. Recent research, however, has shown that some dietary fibers interfere with lipid digestion, which may reduce the bioavailability of oil-soluble vitamins and nutraceuticals. For this reason, we examined the impact of a cationic polysaccharide (chitosan) on the bioaccessibility of vitamin D using the standardized INFOGEST in vitro digestion model. The vitamin D was encapsulated within an emulsion-based delivery system that contained whey protein-coated corn oil droplets. Our results showed that chitosan promoted severe droplet flocculation in the small intestine and reduced the amount of free fatty acids detected using a pH-stat method. However, a back-titration of the digested sample showed that the lipids were fully digested at all chitosan levels used (0.1-0.5%), suggesting that chitosan may have bound some of the free fatty acids released during lipid digestion. The presence of the chitosan decreased the bioaccessibility of vitamin D by about 37%, but this effect did not depend strongly on chitosan concentration (0.1-0.5%). It was hypothesized that chitosan bound to the vitamin-loaded mixed micelles and promoted their precipitation. The knowledge gained in this study might provide useful insights in designing emulsion-based delivery systems with high vitamin bioaccessibility.

Recently, the standardized in vitro digestion model ("INFOGEST method") used to evaluate the gastrointestinal fate of foods has been revised and updated (Brodkorb et al., 2019, Nat. Protoc., 2019, 14, 991-1014). Under fed state conditions, the calcium level used in this model is fixed and relatively low: 0.525 mM. In practice, the calcium concentration in the human gut depends on the nature of the food consumed and may vary from person-to-person. For this reason, we examined the impact of calcium concentration on the gastrointestinal fate of a model nutraceutical delivery system. The effect of calcium level (0.525-10 mM) on lipid digestion and β-carotene bioaccessibility in corn oil-in-water nanoemulsion was investigated using the INFOGEST method. At all calcium levels, the lipids were fully digested, but this could only be established by carrying out a back titration (to pH 9) at the end of the small intestine phase. Conversely, the bioaccessibility of β-carotene decreased with increasing calcium levels: from 65.5% at 0.525 mM Ca2+ to 23.7% at 10 mM Ca2+. This effect was attributed to the ability of the calcium ions to precipitate the β-carotene-loaded mixed micelles by forming insoluble calcium soaps. The ability of calcium ions to reduce carotenoid bioaccessibility may have important nutritional implications. Our results show that the bioaccessibility of hydrophobic carotenoids measured using the INFOGEST method is highly dependent on the calcium levels employed, which may have important consequences for certain calcium-rich foods. Moreover, we have shown the importance of carrying out a back titration to accurately measure free fatty acid levels in the presence of low calcium levels.

For most people, the pesticide residues found on agriculture products are the main source of pesticide exposure, which may adversely influence consumer health. The potential health hazard of residual pesticides depends on the nature of the foods they are consumed with. Studies with fat-soluble vitamins and nutraceuticals have shown that their bioaccessibility depends on food matrix composition and structure. We used an in vitro method to investigate the influence of the dimensions of the lipid phase in model fatty foods (emulsified or bulk oil) on the bioaccessibility of various pesticides. Three pesticides that differed in their oil–water partition coefficients were selected: bendiocarb (log P = 1.7), parathion (log P = 3.8), and chlorpyrifos (log P = 5.3). These pesticides were mixed with tomato puree to represent pesticide-treated agricultural products. Three model foods with different oil phase dimensions were used to represent different kinds of food product: small emulsions (d32 = 0.14 μm); large emulsions (d32 = 10 μm); and, bulk oil. Our results showed that the oil droplets underwent extensive changes as they passed through the simulated gastrointestinal tract due to changes in environmental conditions, such as pH, ionic strength, bile salts, and enzyme activities. The initial rate and final amount of lipid hydrolysis decreased with increasing lipid phase dimensions. Pesticide bioaccessibility depended on both the hydrophobicity of the pesticide and the dimensions of the co-ingested lipid droplets. The least hydrophobic pesticide (bendiocarb) had a high bioaccessibility (>95%) that did not depend on lipid phase dimensions. The more hydrophobic pesticides (parathion and chlorpyrifos) has a lower bioaccessibility that increased with decreasing lipid phase dimensions. Our results demonstrate the critical role that food structure plays on the potential uptake of pesticides from agricultural products, like fruits and vegetables.

Multilayer emulsions were formed by sequential electrostatic deposition of anionic (pectin) and cationic (chitosan) biopolymers onto anionic saponin-coated lipid droplets. These emulsions were then tested for their ability to encapsulate and protect a hydrophobic nutraceutical (astaxanthin). The impact of chitosan and pectin concentration, pH, and ionic strength on the formation and stability of the multilayer emulsions was examined. Multilayer emulsions containing small uniform particles were produced using 2.5% lipid droplets, 0.05% chitosan, and 0.0125% pectin. The physical stability of the astaxanthin-loaded emulsions after exposure to heating, pH, and NaCl was determined. The multilayer-coatings improved the chemical stability of the encapsulated astaxanthin, as well as the aggregation stability of the lipid droplets at elevated ionic strengths and temperatures. Astaxanthin degradation during storage was 3- to 4-fold slower in multilayer emulsions than conventional ones. The multilayer emulsions developed in this study may be useful for encapsulating, protecting, and delivering hydrophobic carotenoids, which may aid in the development of more efficacious functional foods, supplements, and medical foods.

Whey protein-stabilized Pickering emulsion was incorporated with dextrin under different concentrations, and their physicochemical properties and in vitro digestive behavior were examined. The result showed that these emulsions were relatively stable at low dextrin addition (7.5%), while droplet flocculation appeared at higher concentrations. With progressing dextrin, the apparent shear viscosity significantly increased from 1.7 to 7.3 mPa.s. Further insight into the digestive behaviors of emulsion incorporated with dextrin was determined using a standardized INFOGEST method. Less clump in the oral phase and increasing droplet size in the initial intestine were observed in the emulsion incorporated with dextrin. Based on dextrin incorporation, a significant decrease in the extent of lipid digestion and β-carotene bioaccessibility was presented. This study implies dextrin may be useful in controlling the texture and in vitro digestive behavior of Pickering emulsions, which may be advantageous for the designation of functional foods.

The food, cosmetics, and personal care industries are increasingly interested in replacing synthetic colorants with natural alternatives. Anthocyanin is a renewable and sustainable source of plant-derived pigment. However, their application in commercial products is often limited because of their susceptibility to chemical degradation, which leads to color fading and/or a change in hue. In this study, we examined the possibility of protecting anthocyanin from degradation by encapsulating them within the inner water phase of a water-in-oil-in-water (W/O/W) emulsion. Polyglycerol polyricinoleate (PGPR) was used as a hydrophobic emulsifier, while quillaja saponin was used as a hydrophilic emulsifier. First, W/O emulsions containing 20% aqueous phase and 80% oil phase (PGPR in corn oil) were prepared using a microfluidizer. Second, W/O/W emulsions were prepared by blending 20% W/O emulsion with 80% aqueous phase (saponin in water) using a high-shear mixer. Changes in color, particle size, charge, and anthocyanin leakage of the emulsions were measured when the external aqueous phase was changed from pH 7 to 3. Anthocyanin encapsulation significantly slowed down pH-induced color changes, possibly because the internal aqueous phase had a different pH to the external one. Anthocyanin transfer between aqueous phases depended on pH, temperature, and initial location. Our results suggest that multiple emulsions may be useful for encapsulation and protection of natural colors.

These is some interest in replacing digestible fats with indigestible ones to decrease the energy-density of foods. The utilization of indigestible oils, however, may have unforeseen nutritional consequences, such as the reduction of vitamin bioavailability. In this study, the impact of an indigestible oil on the bioaccessibility of emulsified vitamin D3 (VD) was examined. We prepared four kinds of nanoemulsions using different combinations of a digestible oil (DO) and an indigestible oil (IO): DO only; IO only; an oil mixture (OM) consisting of 1:1 DO:IO mixed before homogenization; and, an emulsion mixture (EM) consisting of 1:1 DO:IO nanoemulsions mixed after homogenization. A gastrointestinal tract (GIT) model was employed to elucidate the kinetics of VD bioaccessibility from the nanoemulsions. Both the lipid digestion rate and vitamin bioaccessibility decreased in the same order: DO > OM ≈ EM > IO. The change in vitamin bioaccessibility over time under simulated small intestine conditions was also measured. With the exception of the IO nanoemulsions, the vitamin bioaccessibility increased to a maximum value after around 30 min, but then decreased during the following 24 h. This effect was attributed to an initial solubilization of the vitamin within the mixed micelles, followed by their precipitation during prolonged incubation. Our results show that lipid digestion, micelle solubilization, and micelle aggregation impact the in vitro bioaccessibility of vitamin D. This knowledge may be helpful for designing more efficacious nanoemulsion-based delivery systems for fat-soluble vitamins.

Fine titanium dioxide (TiO2) particles have been used as additives (E171) to modify the optical properties of foods and beverages for many years. Commercial TiO2 additives, however, often contain a significant fraction of nanoparticles (diameter

The potency of oil-soluble vitamins (vitamins A, D, E and K) in fortified foods can be improved by understanding how food matrices impact their bioavailability. In this review, the major food matrix effects influencing the bioavailability of oil-soluble vitamins are highlighted: oil content, oil composition, particle size, interfacial properties, and food additives. Droplet size and aggregation state in the human gut impact vitamin bioavailability by modulating lipid digestion, vitamin release, and vitamin solubilization. Vitamins in small isolated oil droplets typically have a higher bioavailability than those in large or aggregated ones. Emulsifiers, stabilizers, or texture modifiers can therefore affect bioavailability by influencing droplet size or aggregation. The dimensions of the hydrophobic domains in mixed micelles depends on lipid type: if the domains are too small, vitamin bioavailability is low. Overall, this review highlights the importance of carefully designing food matrices to improve vitamin bioavailability.

The oil droplets in commercial emulsified foods have dimensions that vary widely, from hundreds of nanometers to tens of micrometers. Previously, the size of the droplets in oil-in-water emulsions has been shown to impact their gastrointestinal behavior, which may influence their physiological effects. In this study, we analyzed the impact of oil droplet diameter (0.16, 1.1 and 8.2 μm) on lipid digestion and nutraceutical bioaccessibility using a widely used standardized gastrointestinal tract model: the INFOGEST method. The emulsions used consisted of corn oil droplets stabilized using a food-grade non-ionic surfactant (Tween 20), and the droplet size was controlled by preparing them with a microfluidizer (small), sonicator (medium), or high-shear blender (large). The surfactant-coated oil droplets were relatively resistant to size changes in the mouth and stomach, due to the strong surface activity and steric stabilization mechanism of the non-ionic surfactant used. As expected, the kinetics of lipid digestion were enhanced for smaller droplets because of their greater specific surface area. The degree of lipid digestion fell from 117% to 78% (p < 0.001) as the initial droplet diameter was raised from 0.16 to 8.2 μm. In addition, there was a reduction in β-carotene bioaccessibility from 83 to 15% (p < 0.001) with increasing droplet diameter. This result was ascribed to several effects: (i) some carotenoids were trapped inside the undigested oil phase; (ii) fewer mixed micelles were produced to internalize the carotenoids; and, (iii) a fraction of the carotenoids crystallized and sedimented. Our results underline the critical importance of considering droplet size when developing emulsified foods loaded with carotenoids. The results obtained by the INFOGEST method are consistent with those found using other in vitro methods in earlier studies.

Electrically charged food-grade biopolymers can be used to form multilayer coatings around the lipid droplets in oil-in-water emulsions using a sequential layer-by-layer electrostatic deposition approach. In principle, this approach can be used to improve the stability and enhance the functionality of food emulsions. In this study, multilayer coatings were formed from saponins, polypeptides, and polysaccharides using medium chain triglyceride (MCT) lipid droplets as templates (pH 4.0). First, an emulsion containing negatively charged lipid droplets was created using quillaja saponin (QS) as an anionic emulsifier. Second, these anionic droplets were coated with a cationic polypeptide (poly-L-lysine, PLL) to form positively-charged droplets. Finally, these cationic droplets were coated with a negatively-charged polysaccharide, either pectin (PE) or κ-carrageenan (KC), to form anionic droplets. Overall, the 1-layer emulsions had the best resistance to salt, pH, and heat, indicating that quillaja saponins were effective emulsifiers. The 2-layer emulsions had better pH-stability than the 3-layer emulsions, which tended to strongly aggregate under acidic conditions. Conversely, the 3-layer emulsions had better salt-stability than the 2-layer emulsions, which tended to aggregate strongly even at low salt levels (50–100 mM NaCl). All the emulsions were relatively stable to heating (90 °C, 30 min). Overall, our results provide useful insights into the formulation of stable multilayer emulsions from food-grade emulsifiers and biopolymers. There appears to be little advantage to using the multilayer technology to enhance the physical stability of saponin-coated lipid droplets, but there may be advantages in terms of extending their functional properties, which will be explored in future studies.

Water-in-oil-in-water (W/O/W) emulsions can be designed to encapsulate, protect, and release both hydrophilic and hydrophobic functional compounds. In this study, we examined the impact of crystallizing the fat phase on the resistance of W/O/W emulsions to osmotic stress, with the aim of developing osmotic-responsive systems. Polyglycerol polyricinoleate (PGPR) was used as a hydrophobic surfactant to stabilize the inner water droplets, while Quillaja saponin and whey protein isolate (WPI) were used as hydrophilic surfactants to coat the oil droplets. The impact of fat crystallization was examined by using either a liquid (soybean oil, SO) or semi-solid (hydrogenated soybean oil, HSO) fat as the oil phase. An osmotic stress was generated by establishing a sucrose concentration gradient between the internal and external water phases. Alterations in the droplet size, morphology, and stability of the W/O/W emulsions was measured when the sucrose concentration gradient was changed. The W/O droplets in the SO-emulsions swelled/shrank when the external sucrose concentration was below/above the internal sucrose concentration, which is indicative of water diffusing into/out of the droplets. Conversely, there was no change in the size of the W/O droplets in the HSO-emulsions under the same conditions, which was attributed to the mechanical strength of the fat crystal network resisting swelling or shrinking. HSO-emulsions did exhibit swelling when they were heated above a critical temperature, due to melting of the fat crystals and disruption of the crystal network. Our results demonstrate that crystallization of the oil phase of W/O/W emulsions can prevent water transport due to osmotic stress, which may be useful for developing temperature-triggered delivery systems for application in foods, cosmetics, pharmaceuticals, or personal care products.

Mixed Pickering emulsions were prepared by blending anionic nanocellulose-stabilized lipid droplets with cationic nanochitin-stabilized lipid droplets. Changes in the surface potential, particle size, shear viscosity, and morphology of the mixed emulsions were characterized when the droplet mixing ratio was varied. Emulsion properties could be tailored by altering the pH and mixing ratio. Surface potential measurements suggested that the nanochitin-coated lipid droplets adsorbed to the surfaces of the nanocellulose-coated lipid droplets, thereby dominating the overall electrical characteristics of the mixed emulsions. As a result, the mixed emulsions had better stability to coalescence than the single emulsions containing only nanocellulose-coated lipid droplets. Our results suggest that the physicochemical properties, shelf life, and functional performance of Pickering emulsions may be modulated by blending different kinds of particle-stabilized lipid droplets together.

The effect of two plant-based emulsifiers (quillaja saponin, QS and gum arabic, GA) and a polyphenol (tannic acid) on the formation, stability, digestibility, and β-carotene (BC) bioaccessibility of flaxseed oil-in-water emulsions was investigated. The gastrointestinal behavior of the emulsions was studied using a simulated gastrointestinal tract (GIT) consisting of mouth, stomach, and small intestine regions. In the absence of tannic acid, the initial extent of lipid digestion depended strongly on emulsifier type, with 45% and 76% of the free fatty acids being released after 5 min digestion for QS- and GA-emulsions, respectively. Even so, the lipid droplets were completely digested in both emulsions after 2 h incubation in the small intestine phase. Tannic acid addition (0.01% and 0.1% w/w) slowed down lipid digestion, but did not impact the final extent. The droplets in the QS-emulsions containing 0.1% tannic acid were highly flocculated in the stomach phase. Molecular docking simulations indicated that the interactions between tannic acid and the saponins were mainly driven by hydrogen bonding and hydrophobic interactions. Moreover, they showed that the interactions between tannic acid and QS were stronger at pH 2.5 than at pH 7.0, which would account for the extensive droplet flocculation observed under acidic conditions in the stomach. Emulsifier type and tannic acid addition had no significant influence on BC bioaccessibility. The GA-emulsions exhibited better stability than the QS-emulsions when stored at elevated temperatures (55 °C for 7 days). Tannic acid addition effectively inhibited temperature-induced BC degradation. These results may facilitate the design of more efficacious nutraceutical-loaded functional foods and beverages.

Plant-based meat analogs are likely to have different gastrointestinal fates than real meat products due to differences in their compositions and structures. Here, we compared the gastrointestinal fate of ground beef and ground beef analogs using the INFOGEST in vitro digestion model, focusing on differences in microstructure, physicochemical properties, lipid digestion, and protein digestion in different regions of the model gut. The presence of dietary fibers in the beef analogs increased their apparent shear viscosity in the gastrointestinal fluids, which may have inhibited lipid digestion in the small intestine. The proteins in the beef analogs were digested more rapidly in the stomach but less rapidly in the small intestine, which may have been due to differences in protein type (globular soy versus fibrous beef proteins), structural organization, and the presence of dietary fibers in the meat analogs.

The supplementation of plant-based foods and beverages with bioactive agents may be an important strategy for increasing human healthiness. Numerous kinds of colloidal delivery systems have been developed to encapsulate bioactives with the goal of improving their water dispersibility, chemical stability, and bioavailability. In this review, we focus on colloidal delivery systems assembled entirely from plant-based ingredients, such as lipids, proteins, polysaccharides, phospholipids, and surfactants isolated from botanical sources. In particular, the utilization of these ingredients to create plant-based nanoemulsions, nanoliposomes, nanoparticles, and microgels is covered. The utilization of these delivery systems to encapsulate, protect, and release various kinds of bioactives is highlighted, including oil-soluble vitamins (like vitamin D), ω-3 oils, carotenoids (vitamin A precursors), curcuminoids, and polyphenols. The functionality of these delivery systems can be tailored to specific applications by careful selection of ingredients and processing operations, as this enables the composition, size, shape, internal structure, surface chemistry, and electrical characteristics of the colloidal particles to be controlled. The plant-based delivery systems discussed in this article may be useful for introducing active ingredients into the next generation of plant-based foods, meat, seafood, milk, and egg analogs. Nevertheless, there is still a need to systematically compare the functional performance of different delivery systems for specific applications to establish the most appropriate one. In addition, there is a need to test their efficacy at delivering bioavailable forms of bioactives using in vivo studies.

The impact of natural emulsifier type on the fabrication, stability, and release attributes of water-in-oil-in-water (W/O/W) emulsions prepared with a high-shear mixer were investigated: gum arabic, high-methoxy pectin, whey protein isolate (WPI), and soy protein isolate (SPI). At 1 wt%, all emulsifiers produced W/O/W emulsions with similar mean droplet diameters (d32 = 23–25 μm). However, less pectin was required to form small droplets than gum arabic, WPI or SPI. The impact of emulsifier type on the transport of small ions between the aqueous phases was then examined by placing iodine and starch in the external and internal water phases, respectively. Iodine turned blue when it came into contact with starch. W/O/W emulsions prepared using proteins (SPI and WPI) were more effective at inhibiting mass transport than those prepared using polysaccharides (gum arabic and pectin). These results are useful for rationalizing the selection of biopolymer emulsifiers for application in double emulsions.

Effect of NaCl concentration (0–500 mM) on the oil/water interfacial and emulsifying properties of walnut protein-xanthan gum complex (WP-XG) was investigated. In solution system, NaCl at 150–500 mM promoted the aggregation of WP-XG with a maximum hydrodynamic diameter of 553.1 nm. Compared with pure mixture, WP-XG solutions at 150–500 mM NaCl showed higher interfacial pressure and diffusion rate at the oil/water interface, and the maximum values, 18.05 mN/m and 0.431 mN m−1 s−0.5 respectively, were obtained at 350 mM NaCl. With a maximum dilatational modulus of 48.47 mN/m at 150 mM NaCl, higher NaCl concentration would negatively influence the interfacial dilatational properties of WP-XG. In emulsion system, NaCl decreased ζ-potential, while increased surface protein concentration. According to the CLSM graphs, NaCl would aggravate depletion flocculation which was observed in pure emulsion. Large droplets were observed at 500 mM NaCl, with significant increase in mean particle diameter (d4,3 = 2.90 μm).

Encapsulated essential oils are being developed as natural antimicrobials and insecticides for use in sustainable agriculture applications. Although these plant-based pesticides are considered to be more environmentally friendly, they can have adverse effects on agricultural crops, thereby reducing yields. Our aim was therefore to establish the potential phytotoxicity of carvacrol nanoemulsions on a commercially important crop (spinach, Spinacia oleracea). Carvacrol oil-in-water nanoemulsions were fabricated by homogenizing 10 wt% oil phase (1:1 carvacrol and medium chain triglycerides) with 90% aqueous phase (1% quillaja saponin in 5 mM sodium citrate buffer, pH 3.5). Nanoemulsions were sprayed onto the spinach leaves by foliar exposure for three days and then the health status of the plants was assessed. At relatively low carvacrol concentrations (0.005–0.5%), the plants remained healthy, but at the highest concentration employed (5%) there was a significant reduction in the biomass and chlorophyll content of the spinach, as well as an increase in electrolyte leakage and malondialdehyde formation. We demonstrated that this strong phytotoxicity was due to the carvacrol oil, rather than due to other constituents in the nanoemulsions. Our results show that there is a critical threshold concentration for use of essential oil nanoemulsions as pesticides on crop plants.

There is growing interest in the identification of plant-based functional ingredients for utilization within the food industry. Complexes were fabricated from pea protein (PP) and tannic acid (TA) and then their ability to act as antioxidant emulsifiers in flaxseed oil-in-water emulsions was studied. PP-TA complex formation was investigated using isothermal titration calorimetry and turbidity analysis, which suggested hydrogen bonding and hydrophobic interactions were important in their assembly. PP-TA-stabilized emulsions containing small droplets could be formed at relatively high TA levels. Moreover, PP-TA complexes had strong antioxidant activity, which extended the shelf life of flaxseed oil emulsions. The composition of the PP-TA complexes impacted the aggregation state of the lipid droplets under simulated gastric conditions, which affected the rate and extent of lipid digestion. This study shows PP-TA complexes can be used for fabricating flaxseed oil delivery systems with enhanced oxidative stability and good digestibility.

Complex coacervation is a useful approach for creating biopolymer-based colloidal particles for the oral delivery of bioactives, such as nutraceuticals, vitamins, and pharmaceuticals. In this study, we examined the possibility of using anionic ɣ-poly-glutamic acid (PGA) and cationic ɛ-poly- l -lysine (PLL) to form polyelectrolyte complexes. Initially, the formation and properties of the complexes were characterized using visual observations, UV–visible spectrophotometry, microelectrophoresis (ζ-potential), and isothermal titration calorimetry (ITC). The impact of pH, ionic strength, temperature, and polymer ratio on complex formation was examined. The electrostatic complexes formed had a 1:4 mass ratio of polyanion-to-polycation at saturation (pH 7.4). The surface potential and aggregation stability of the complexes was highly dependent on solution pH (2–12), which was attributed to alterations in the electrical characteristics of the two polyelectrolytes. In particular, insoluble complexes were formed under pH conditions where there was a strong electrostatic attraction between the two polyelectrolytes, whereas soluble complexes were formed when there was only a weak attraction. The addition of salt (≥20 mM NaCl) promoted aggregation of the complexes, presumably due to screening of the electrostatic interactions between them. Conversely, temperature (25–90 °C) did not have a major impact on the stability of the complexes. These results may be useful for the design of effective oral delivery systems for bioactive agents in foods and other products.

Fine titanium dioxide (TiO

These is some interest in replacing digestible fats with indigestible ones to decrease the energy-density of foods. The utilization of indigestible oils, however, may have unforeseen nutritional consequences, such as the reduction of vitamin bioavailability. In this study, the impact of an indigestible oil on the bioaccessibility of emulsified vitamin D

Both organic and inorganic nanoparticles are often added to food and beverage products to modify their quality attributes, such as their look, feel, flavor, or shelf life. However, there is still poor understanding of how these nanoparticles behave inside the human gut after ingestion, particularly their impact on macronutrient digestion and vitamin bioavailability. In this study, nanocellulose, nanoemulsion, and titanium dioxide (TiO2) particles were used as examples of functional organic and inorganic nanoparticles, while vitamin D-fortified plant-based milks were used to model food products. The plant-based milks were fortified with this vitamin by mixing them with vitamin-D loaded nanoemulsion droplets. The TiO2 nanoparticles were shown to be most effective at increasing the whiteness of the fortified milk, whereas the nanocellulose ones were most effective at increasing the shear viscosity. Alterations in the physicochemical and structural properties of the nanoparticle-loaded model foods were measured as they passed through a harmonized (INFOGEST) in vitro gastrointestinal tract (GIT). The oil bodies in the plant-based milks were strongly flocculated in the stomach but they were still fully digested in the small intestine. The distribution of the nanoparticles in the intestinal fluids was analyzed by optical and transmission electron microscopy, which showed that they were well dispersed, presumably due to protein-adsorption to their surfaces and the mechanical action of the GIT fluids. The addition of TiO2 or nanocellulose to the fortified milks did not significantly affect lipid digestion or vitamin bioaccessibility. Interestingly, our results showed that the bioaccessibility of vitamin D in the plant-based milk was relatively low (~20%) in all samples analyzed. We hypothesized that this may have been due to aggregation and precipitation of the vitamin-loaded micelles in the presence of other components in the GIT fluids, such as calcium ions. Our results are useful for understanding the impact of different kinds of nanoparticles on the behavior of foods in the gastrointestinal tract.

Correction for ‘Factors impacting lipid digestion and nutraceutical bioaccessibility assessed by standardized gastrointestinal model (INFOGEST): oil droplet size’ by Yunbing Tan et al., Food Funct., 2020, 11, 9936–9946, DOI: 10.1039/D0FO01505A.

This paper is part of a series examining the impact of the main factors influencing lipid digestion and nutraceutical bioaccessibility in β-carotene-loaded oil-in-water emulsions using the harmonized INFOGEST simulated gastrointestinal model. Here, the impact of emulsifier type was examined since food emulsions and nutraceutical delivery systems are often stabilized by various types of emulsifier. The INFOGEST method was adopted to investigate the in vitro gastrointestinal fate of emulsions stabilized by five kinds of food-grade emulsifier representing different classes: synthetic surfactants (Tween 20); natural surfactants (quillaja saponin); proteins (caseinate); polysaccharides (gum arabic); and phospholipids (soy lysolecithin). Microfluidization produced emulsions with small droplet sizes for all emulsifiers, except soy lysolecithin. Within the gastrointestinal model, the caseinate-coated oil droplets had the worst gastric stability, with severe droplet flocculation and coalescence occurring in the stomach. The fraction of the lipid phase that had been digested by the end of the gastrointestinal model was considerably lower for the emulsions stabilized by soy lysolecithin (93%) or caseinate (93%), than those stabilized by gum arabic (99%), quillaja saponin (111%) or Tween 20 (117%). This effect was attributed to lower surface area of lipids available for lipase to attach to for the lysolecithin and caseinate emulsions. The overall bioaccessibility of the β-carotene increased in this order: lysolecithin (25%) gum arabic (51%) caseinate (55%) quillaja saponin (56%) Tween 20 (62%). The impact of emulsifier type on carotenoid bioaccessibility was ascribed to various factors: (i) some emulsifiers inhibited lipid digestion and so a fraction of the β-carotene remained inside the undigested droplets and the mixed micelle phase had less solubilization capacity, i.e., lysolecithin, and caseinate; (ii) some emulsifiers protected β-carotene from chemical degradation, i.e., lysolecithin and caseinate; and (iii) some emulsifiers promoted sedimentation of the β-carotene-loaded micelles, i.e., lysolecithin. These results suggest that food emulsion behavior in the human gut may be influenced by the nature of the emulsifier employed, which is important knowledge when creating functional food and beverage products.

Nature-derived nanoparticles are increasingly being explored for their potential to regulate the digestion of ingested lipids. In this study, we examined the impact of emulsifier format (molecular versus particle) on the gastrointestinal fate of vitamin D3-fortified emulsions by measuring their physicochemical properties, microstructure, digestibility, and bioaccessibility using an in vitro human gastrointestinal tract (GIT) model. Nanochitin (NCh) was used as an example of a particle-based (Pickering) emulsifier, whereas Tween 80 (T80) was used as an example of a small molecule surfactant. A series of 2 wt% oil-in-water emulsions containing different initial levels and locations of nanochitin and Tween 80 were prepared: (i) nanochitin-emulsions (0.02 wt% NCh); (ii) Tween 80-emulsions (0.02 wt% T80); (iii) nanochitin-emulsions (0.02 wt% NCh) plus Tween 80 (0.02 wt% T80); and (iv) Tween 80-emulsions (0.02 wt% T80) plus nanochitin (0.02 wt% NCh). The nanochitin-emulsions were much more prone to droplet aggregation within the simulated GIT than the T80-stabilized ones. Lipid digestion was 30% less and vitamin bioaccessibility was 45% less for the nanochitin-emulsions than for the T80-stabilized ones. Adding T80 to the nanochitin-emulsions, increased the rate of lipid digestion, whereas adding nanochitin to the Tween 80-stabilized ones, decreased the rate. The reduction in lipid digestion and bioaccessibility in the emulsions containing nanochitin may have been for a number of reasons: the adsorbed nanochitin layer hindered the ability of lipase to reach the lipid phase; the nanochitin-coated droplets were highly aggregated in the GIT, which reduced the area of lipids accessible to the lipase; and, the cationic nanochitin bound to anionic bile acids, fatty acids, or lipase. Our results suggest that nanochitin slows down lipid digestion, which may be advantageous for developing high-satiety foods, but that it also reduces vitamin bioaccessibility, which would be undesirable from a nutritional perspective.

Anthocyanin-loaded W/O/W emulsions were fabricated using polyglycerol polyricinoleate (PGPR) as a hydrophobic emulsifier, quillaja saponin as a hydrophilic emulsifier, and gum arabic as an additional biopolymer-based stabilizer. Hydrogenated soybean oil (HSO) was used to create a crystalline lipid phase. The impact of emulsifier, stabilizer, and lipid phase crystallization on emulsion formation, stability, and rheology was investigated. W/O droplets with a solidified oil phase aggregated, leading to an increase in emulsion viscosity. Gum arabic inhibited droplet aggregation and emulsion thickening, presumably by forming a protective coating around the W/O droplets. Conversely, PGPR promoted droplet aggregation, possibly by adsorbing to the fat crystal surfaces and changing their location or interactions. Optimized W/O/W emulsions (2.5% gum arabic, 5% PGPR, and 1% saponin) had a relatively low initial anthocyanin encapsulation efficiency (

There is interest in incorporating nanoemulsions into certain foods and beverages, including dips, dressings, drinks, spreads, and sauces, due to their potentially beneficial attributes. In particular, excipient nanoemulsions can enhance the bioavailability of nutraceuticals in fruit- and vegetable-containing products consumed with them. There is, however, potential for them to also raise the bioavailability of undesirable substances found in these products, such as pesticides. In this research, we studied the impact of excipient nanoemulsions on the bioaccessibility of pesticide-treated tomatoes. We hypothesized that the propensity for nanoemulsions to raise pesticide bioaccessibility would depend on the polarity of the pesticide molecules. Bendiocarb, parathion, and chlorpyrifos were therefore selected because they have Log P values of 1.7, 3.8, and 5.3, respectively. Nanoemulsions with different oil contents (0%, 4%, and 8%) were fabricated to study their impact on pesticide uptake. In the absence of oil, the bioaccessibility increased with increasing pesticide polarity (decreasing Log P): bendiocarb (92.9%) &gt, parathion (16.4%) &gt, chlorpyrifos (2.8%). Bendiocarb bioaccessibility did not depend on the oil content of the nanoemulsions, which was attributed to its relatively high water-solubility. Conversely, the bioaccessibility of the more hydrophobic pesticides (parathion and chlorpyrifos) increased with increasing oil content. For instance, for chlorpyrifos, the bioaccessibility was 2.8%, 47.0%, and 70.7% at 0%, 4%, and 8% oil content, respectively. Our findings have repercussions for the utilization of nanoemulsions as excipient foods in products that may have high levels of undesirable non-polar substances, such as pesticides.

Previous studies have shown that, anode block electrical stimulation of the sacral nerve root can produce physiological urination and reconstruct urinary bladder function in rabbits. However, whether long-term anode block electrical stimulation causes damage to the sacral nerve root remains unclear, and needs further investigation. In this study, a complete spinal cord injury model was established in New Zealand white rabbits through T9-10 segment transection. Rabbits were given continuous electrical stimulation for a short period and then chronic stimulation for a longer period. Results showed that compared with normal rabbits, the structure of nerve cells in the anterior sacral nerve roots was unchanged in spinal cord injury rabbits after electrical stimulation. There was no significant difference in the expression of apoptosis-related proteins such as Bax, Caspase-3, and Bcl-2. Experimental findings indicate that neurons in the rabbit sacral nerve roots tolerate electrical stimulation, even after long-term anode block electrical stimulation.