Natural antioxidants (rosemary and parsley) in microwaved ground meat patties: effects of in vitro digestion

BACKGROUND

Minimizing food oxidation remains a challenge in several environments. The addition of rosemary extract (150 mg kg-1) and lyophilized parsley (7.1 g kg-1) at equivalent antioxidant activity (5550 μg Trolox equivalents kg-1) to meat patties was assessed in terms of their effect during microwave cooking and after being subjected to an in vitro digestion process.

RESULTS

Regardless of the use of antioxidants, cooking caused a decrease of the fat content as compared to raw samples, without noticing statistical differences in the fatty acid distribution between raw and cooked samples [44%, 47% and 6.8%, of saturated fatty acid (SFA), monounsaturated fatty acid (MUFA) and polyunsaturated fatty acid (PUFA), respectively]. However, the bioaccessible lipid fraction obtained after digestion was less saturated (around 34% SFA) and more unsaturated (35% MUFA +30% PUFA). Cooking caused, in all types of samples, an increased lipid [thiobarbituric acid reactive substances (TBARS)] and protein (carbonyls) oxidation values. The increase of TBARS during in vitro digestion was around 7 mg malondialdehyde (MDA) kg-1 for control and samples with parsley and 4.8 mg MDA kg-1 with rosemary. The addition of parsley, and particularly of rosemary, significantly increased the antioxidant activity (DPPH) of cooked and digested microwaved meat patties.

CONCLUSION

Whereas rosemary was effective in minimizing protein oxidation during cooking and digestion as compared to control samples, parsley could only limit it during digestion. Lipid oxidation was only limited by rosemary during in vitro digestion. © 2024 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Understanding the Anti-Obesity Potential of an Avocado Oil-Rich Cheese through an In Vitro Co-Culture Intestine Cell Model

Nowadays, with consumers' requirements shifting towards more natural solutions and the advent of nutraceutical-based approaches, new alternatives for obesity management are being developed. This work aimed to show, for the first time, the potential of avocado oil-fortified cheese as a viable foodstuff for obesity management through complex in vitro cellular models. The results showed that oleic and palmitic acids' permeability through the Caco-2/HT29-MTX membrane peaked at the 2h mark, with the highest apparent permeability being registered for oleic acid (0.14 cm/s). Additionally, the permeated compounds were capable of modulating the metabolism of adipocytes present in the basal compartment, significantly reducing adipokine (leptin) and cytokine (MPC-1, IL-10, and TNF-α) production. The permeates (containing 3.30 µg/mL of palmitic acid and 2.16 µg/mL of oleic acid) also presented an overall anti-inflammatory activity upon Raw 264.7 macrophages, reducing IL-6 and TNF-α secretion. Despite in vivo assays being required, the data showed the potential of a functional dairy product as a valid food matrix to aid in obesity management.

Interfacial compositions of fat globules modulate structural characteristics and lipolysis of its model emulsions during in-vitro digestion

BACKGROUND

This study investigated whether milk fat globule membrane as an emulsifier could make fat easier for infants to digest. An emulsion was formed using the membrane material, where anhydrous milk fat was used as the core material, milk fat globule membrane polar lipid (MPL) as the emulsifier, and soybean phospholipid (PL) and milk protein concentrate (MPC) incorporated as control emulsifiers. Structural characterization, glyceride composition, and fatty acid release from emulsions by in vitro digestion were investigated.

RESULTS

The average particle size at the end of intestinal digestion was in the order MPL < PL < MPC, with diameters of 3.41 ± 0.51 μm, 3.53 ± 0.47 μm, and 10.46 ± 2.33 μm respectively. Meanwhile, laser scanning confocal microscopy results also illustrated that MPL could reduce the degree of aggregation during digestion. The lipolysis degree of MPL emulsion was higher than that of PL and MPC emulsions. MPL not only released higher levels of long-chain fatty acids, such as C18:1, C18:2, C18:3, which are of great significance for infant growth and development, but also released increased levels of C20:4 (arachidonic acid) and C22:6 (docosahexaenoic acid) than PL and MPC emulsions did.

CONCLUSION

Fat droplets enveloped by milk fat globule MPLs were easier to digest and are therefore more suitable for infant formula. © 2023 Society of Chemical Industry.

Strategies for modulating the lipid digestion of emulsions in the gastrointestinal tract

The structural changes in emulsion products can be used to control the bioavailability of fatty acids and lipophilic compounds. After ingestion, lipid droplets undergo breakdown and structural changes as they pass through the gastrointestinal tract. The oil-water interface plays a critical role in modulating the digestive behavior of lipid droplets because changes in the interfacial layer control the adsorption of lipase and bile salts and determine the overall rate and extent of lipid digestion. Therefore, lipid digestibility can be tuned by selecting the appropriate types and levels of stabilizers. The stabilizer can change the lipase accessibility and exposure of lipid substrates, resulting in variable digestion rates. However, emulsified lipids are not only added to food matrixes but are also co-ingested from other dietary components. Therefore, overall consumption behaviors can affect the digestion rate and digestibility of emulsified lipids. Although designing an emulsion structure is challenging, controlling lipid digestion can improve the health benefits of products. Therefore, a thorough understanding of the process of emulsified lipid digestion is required to develop food products that enable specific physiological responses. The targeted or delayed release of lipophilic molecules and fatty acids through emulsion systems has significant applications in healthcare and pharmaceuticals.

Role of calcium on lipid digestion and serum lipids: a review

Calcium is an essential nutrient for humans that can be taken as supplement or in a food matrix (e.g. dairy products). It is suggested that dietary calcium may have a beneficial effect on cardiovascular risk but the mechanism is not clear. In this review, the main mechanisms of the possible cholesterol-lowering effect of calcium, i.e. interaction with fatty acids and bile acids, are described and clinical evidences are presented. The observations from interventional studies of the possible cholesterol-lowering effect in terms of the main related mechanisms are variable and do not seem to fulfill all the related aspects. It seems that the interplay of calcium in blood lipid metabolism might be due to its complex and multiple roles in the lipid digestion in the small intestine. The interactions between calcium and, fatty acids and bile may lead to impaired mixed micelle formation and solubilization, which is crucial in the lipid absorption and metabolism. In addition, the calcium source and its surrounding matrix will have an influence over the physiological outcome. This research is important for the delivery and formulation of calcium, particularly with the move toward plant-based diets.

Postprandial lipemic response in dairy-avoiding females following an equal volume of sheep milk relative to cow milk: A randomized controlled trial

Background

Sheep milk (SM) is an alternate dairy source, which despite many similarities, has both compositional and structural differences in lipids compared to cow milk (CM). Studies are yet to examine the apparent digestibility of SM lipids, relative to CM, and the potential impact on the plasma lipidome.

Objective

To determine the response of the circulatory lipidome to equal volume servings of SM and CM, in females who avoid dairy products.

Method

In a double-blinded, randomized, cross-over trial, self-described dairy avoiding females (n = 30; 24.4 ± 1.1 years) drank SM or CM (650 mL; 33.4 vs. 21.3 g total lipid content; reconstituted from spray dried milk powders) following an overnight fast. Blood samples were collected at fasting and at regular intervals over 4 h after milk consumption. The plasma lipidome was analyzed by LC-MS and fatty acids were quantified by GC-FID.

Results

The overall postprandial triglyceride (TG) response was similar between SM and CM. TG concentrations were comparable at fasting for both groups, however they were higher after CM consumption at 30 min (interaction milk × time p = 0.003), well before any postprandial lipemic response. This was despite greater quantities provided by SM. However, there were notable differences in the postprandial fatty acid response, with SM leading to an increase in short- and medium-chain fatty acids (MCFAs) (C6:0, C8:0, and C10:0) and several long-chain fatty acids (LCFAs) (C18:1 t11, c9, t11-CLA, and C20:0; interaction time × milk p < 0.05). This corresponded to a greater postprandial response for medium chain triglycerides (MCTs) C10:0, including TG(10:0/14:0/18:1), TG(16:0/10:0/12:0), and TG(16:0/10:0/14:0) (interaction time × milk p < 0.05).

Conclusions

Despite a higher fat content, SM ingestion resulted in a greater circulating abundance of MCTs, without increasing total postprandial triglyceride response, when compared to CM. The greater abundance and postprandial appearance of MCTs may provide advantageous metabolic responses in children and adults.

Unique identifier and registry

U1111-1209-7768; https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=375324.

Comparative Analysis of Lipid Digestion Characteristics in Human, Bovine, and Caprine Milk Based on Simulated In Vitro Infant Gastrointestinal Digestion

Lipid digestion characteristics in human, bovine, and caprine milk were investigated using an infant in vitro digestion model. Our results suggested that particle size in bovine and caprine milk increased initially and then decreased over time, whereas the particle size in human milk continuously decreased. The lipolysis degree of human milk (86.8%) was higher than that in bovine (80.2%) and caprine (82.7%) milk (P < 0.05). Compared to human milk, bovine and caprine milk released higher unsaturated fatty acids and lower SFAs. In addition, 12 and 84 glyceride species were significantly different between bovine and human milk, during gastrointestinal digestion (P < 0.05). Another 13 and 92 glyceride species were found to be significantly different between caprine and human milk. A total of 30 and 31 lipids were screened as biomarkers to further clarify the differences related to lipid digestion properties of human, bovine, and caprine milk.

Potential Hypolipidemic Effects of Banana Condensed Tannins Through the Interaction with Digestive Juice Components Related to Lipid Digestion

An in vitro intestinal model was used to evaluate the impact of banana condensed tannins (BCT) on the digestion of lipids (fat and cholesterol). BCT significantly suppressed the digestion of fat and cholesterol by interacting with digestive juice components. The interactions of BCT with a digestive juice mixture and its components (including bile acid, lipase, cholesterol esterase, CaCl₂, NaCl, and cholesterol) were analyzed using turbidity, isothermal titration calorimetry, particle size distribution, zeta potential, and molecular docking analyses. The results showed that BCT reduced the digestion of lipids mainly via interaction with lipase, cholesterol esterase, bile acid, and cholesterol. Electrostatic CT-calcium ion complexes might reduce the extent of lipid digestion by decreasing the surface area of the lipid droplets exposed to the enzymes. This research provides valuable insights into the molecular mechanisms of the interaction of BCT with digestive juice components related to lipid digestion that may affect the rate and extent of lipid digestion.

Role of calcium on lipid digestion and serum lipids: a review

Calcium is an essential nutrient for humans that can be taken as supplement or in a food matrix (e.g. dairy products). It is suggested that dietary calcium may have a beneficial effect on cardiovascular risk but the mechanism is not clear. In this review, the main mechanisms of the possible cholesterol-lowering effect of calcium, i.e. interaction with fatty acids and bile acids, are described and clinical evidences are presented. The observations from interventional studies of the possible cholesterol-lowering effect in terms of the main related mechanisms are variable and do not seem to fulfill all the related aspects. It seems that the interplay of calcium in blood lipid metabolism might be due to its complex and multiple roles in the lipid digestion in the small intestine. The interactions between calcium and, fatty acids and bile may lead to impaired mixed micelle formation and solubilization, which is crucial in the lipid absorption and metabolism. In addition, the calcium source and its surrounding matrix will have an influence over the physiological outcome. This research is important for the delivery and formulation of calcium, particularly with the move toward plant-based diets.

Effect of Bile Salts on the Interfacial Dilational Rheology of Lecithin in the Lipid Digestion Process

The effects of bile salts on the emulsifier adsorption layer play a crucial role in lipid digestion. The current study selected sodium cholate (NaCh) and lecithin as model compounds for bile salts and food emulsifiers, respectively. The interface dilational rheological and emulsification properties of NaCh and lecithin were carried out. The results showed that the NaCh molecules could quickly diffuse from the bulk to interface, which broke the tightly-arranged interfacial layer of lecithin and enhanced the viscoelasticity of interfacial film. As a result, the interfacial adsorption layer, which was originally dominated by the slow relaxation processes within the interface, was transformed into one controlled by the fast molecular diffusion exchange. This accelerated the exchange of materials between the bulk and interface, thereby creating suitable conditions for the interfacial adsorption of lipases, which promoted the digestion process. These results provided a mechanism for the promotion of lipid digestion by bile salts from the perspective of interfacial viscoelasticity and relaxation processes. A deeper understanding of the interfacial behavior of bile salts with emulsifiers would provide a basis for the rational design of interfacial layer for modulating lipid digestion.

Kinetic Modeling of In Vitro Small Intestinal Lipid Digestion as Affected by the Emulsion Interfacial Composition and Gastric Prelipolysis

This research evaluated the impact of the emulsion interfacial composition on in vitro small intestinal lipolysis kinetics with the inclusion of rabbit gastric lipase resulting in a gastric prelipolysis step. O/w emulsions contained 5% triolein (w/w) and 1% (w/w) of the following emulsifiers: sodium taurodeoxycholate, citrus pectin, soy protein isolate, soy lecithin, and tween 80. Emulsions were subjected to static in vitro digestion and diverse lipolysis species quantified via a HPLC-charged aerosol detector. Single-response modeling indicated that the kinetics of lipolysis in the small intestinal phase were impacted by the emulsion particle size at the beginning of this phase. Multiresponse modeling permitted the elucidation of the lipolysis mechanism under in vitro conditions. The final reaction scheme included enzymatic and chemical conversions. The modeling strategies used in this research allowed to gain more insights into the kinetics and mechanism of in vitro lipid digestion.

Food-Grade Titanium Dioxide Particles Decreased the Bioaccessibility of Vitamin D3 in the Simulated Human Gastrointestinal Tract

Food-grade titanium dioxide (E171) particles, as a "whiteness" additive, are often co-ingested with lipid-rich foods. Therefore, we explored the impact of E171 on lipid digestion and vitamin D₃ (VD₃) bioaccessibility encapsulated within oil-in-water emulsions in a simulated human gastrointestinal tract (GIT) model. VD₃ bioaccessibility significantly decreased from 80 to 74% when raising E171 from 0 to 0.5 wt %. The extent of lipid digestion was reduced by E171 addition in a dose-dependent manner. VD₃ bioaccessibility was positively correlated with the final amount of free fatty acids (FFAs) produced by lipid digestion (R² = 0.95), suggesting that the reduction in VD₃ bioaccessibility was due to the inhibition of lipid digestion by E171. Further experiments showed that E171 interacted with lipase and calcium ions, thereby interfering with lipid digestion. The findings of this study enhance our understanding toward the potential impact of E171 on the nutritional attributes of foods for human digestion health.

The Impact of Lipid Digestion on the Dynamic and Structural Properties of Micelles

Self-assembled, lipid-based micelles, such as those formed by the short-chain phosphocholine, dihexanoylphosphatidylcholine (2C6PC), are degraded by the pancreatic enzyme, phospholipase A₂ (PLA2). Degradation yields 1-hexanoyl-lysophosphocholine (C6LYSO) and hexanoic acid (C6FA) products. However, little is known about the behavior of these products during and after the degradation of 2C6PC. In this work, a combination of static and time-resolved small angle neutron scattering, as well as all-atom molecular dynamics simulations, is used to characterize the structure of 2C6PC micelles. In doing so a detailed understanding of the substrate and product aggregation behavior before, during and after degradation is gained. Consequently, the formation of mixed micelles containing 2C6PC, C6LYSO and C6FA is shown at every stage of the degradation process, as well as the formation of mixed C6LYSO/C6FA micelles after degradation is complete. The use of atomistic molecular dynamics has allowed us to characterize the structure of 2C6PC, 2C6PC/C6LYSO/C6FA, and C6LYSO/C6FA micelles throughout the degradation process, showing the localization of the different molecular species within the aggregates. In addition, the hydration of the 2C6PC, C6LYSO, and C6FA species both during micellization and as monomers in aqueous solution is documented to reveal the processes driving their micellization.

Effect of Particle Size and Interface Composition on the Lipid Digestion of Droplets Covered with Membrane Phospholipids

The particle size and fatty acid release of droplets covered with milk fat globule membrane phospholipids with different particle sizes (large/MPL-L; medium/MPL-M; and small/MPL-S) and emulsions with different sources (droplets covered with MPL/MPLs; human milk/HM; and infant formula/IF) were investigated using an infant digestion model. During digestion, droplets exhibited different degrees of aggregation, and the order of the particle size was MPL-L > MPL-M > MPL-S. MPL-M and MPL-S were significantly higher than MPL-L in the release of free fatty acids. No significant difference was observed in the FFA release rate between MPLs and HM. However, the rate was significantly higher than that of IF in the intestinal stage. Compared to IF, a higher content of long-chain polyunsaturated fatty acids and a lower content of saturated fatty acid were observed in MPLs and HM.

The Drosophila E78 nuclear receptor regulates dietary triglyceride uptake and systemic lipid levels

BACKGROUND

Lipid levels are maintained by balancing lipid uptake, synthesis, and mobilization. Although many studies have focused on the control of lipid synthesis and mobilization, less is known about the regulation of lipid digestion and uptake.

RESULTS

Here we show that the Drosophila E78A nuclear receptor plays a central role in intestinal lipid homeostasis through regulation of the CG17192 digestive lipase. E78A mutant adults fail to maintain proper systemic lipid levels following eclosion, with this effect largely restricted to the intestine. Transcriptional profiling by RNA-seq revealed a candidate gene for mediating this effect, encoding the predicted adult intestinal lipase CG17192. Intestine-specific disruption of CG17192 results in reduced lipid levels similar to that seen in E78A mutants. In addition, dietary supplementation with free fatty acids, or intestine-specific expression of either E78A or CG17192, is sufficient to restore lipid levels in E78A mutant adults.

CONCLUSION

These studies support the model that E78A is a central regulator of adult lipid homeostasis through its effects on CG17192 expression and lipid digestion. This work also provides new insights into the control of intestinal lipid uptake and demonstrate that nuclear receptors can play an important role in these pathways.

Characterizing the Interactions of Dietary Condensed Tannins with Bile Salts

This study aimed to reveal the mechanisms underlying the interaction between condensed tannins (CTs) and bile salts. The interaction mechanism was analyzed by transmission electron microscopy, exposure to various physicochemical conditions, electrophoresis, fluorescence spectroscopy, isothermal titration calorimetry, and molecular modeling. A new complex was formed from CTs and bile salts. The complex showed a negative enthalpy change and a positive entropy change, demonstrating that the main thermodynamic driving force was both entropy and enthalpy and indicating that binding occurred through hydrogen bonds and hydrophobic interactions. The analysis of the effects of CTs on the stability and digestion properties of bile salt emulsions indicated that CTs were able to inhibit lipid digestion to an extent. Our findings may provide evidence that foods rich in CTs offer health benefits by aggregating with bile salts and reducing the absorption of fat.

In vitro Lipolysis as a Tool for the Establishment of IVIVC for Lipid-Based Drug Delivery Systems

In vitro lipolysis has emerged as a powerful tool in the development of in vitro in vivo correlation for Lipid-based Drug Delivery System (LbDDS). In vitro lipolysis possesses the ability to mimic the assimilation of LbDDS in the human biological system. The digestion medium for in vitro lipolysis commonly contains an aqueous buffer media, bile salts, phospholipids and sodium chloride. The concentrations of these compounds are defined by the physiological conditions prevailing in the fasted or fed state. The pH of the medium is monitored by a pH-sensitive electrode connected to a computercontrolled pH-stat device capable of maintaining a predefined pH value via titration with sodium hydroxide. Copenhagen, Monash and Jerusalem are used as different models for in vitro lipolysis studies. The most common approach used in evaluating the kinetics of lipolysis of emulsion-based encapsulation systems is the pH-stat titration technique. This is widely used in both the nutritional and the pharmacological research fields as a rapid screening tool. Analytical tools for the assessment of in vitro lipolysis include HPLC, GC, HPTLC, SEM, Cryo TEM, Electron paramagnetic resonance spectroscopy, Raman spectroscopy and Nanoparticle Tracking Analysis (NTA) for the characterization of the lipids and colloidal phases after digestion of lipids. Various researches have been carried out for the establishment of IVIVC by using in vitro lipolysis models. The current publication also presents an updated review of various researches in the field of in vitro lipolysis.

Vitamin E Encapsulation within Oil-in-Water Emulsions: Impact of Emulsifier Type on Physicochemical Stability and Bioaccessibility

The influence of plant-based (gum arabic and quillaja saponin) and animal-based (whey protein isolate, WPI) emulsifiers on the production and stability of vitamin E-fortified emulsions was investigated. Their impact on lipid digestibility and vitamin bioaccessibility was also studied utilizing an in vitro gastrointestinal tract. WPI and saponin produced smaller emulsions than gum arabic. All emulsions had good storage stability at room temperature (4 weeks, pH 7). Saponin- and gum arabic-emulsions were resistant to droplet aggregation from pH 2 to 8 because these emulsifiers generated strong electrosteric repulsion. WPI-coated droplets flocculated around pH 5 due to a reduction in charge near their isoelectric point. Lipid digestion was slower in saponin-emulsions, presumably because the high surface activity of saponins inhibited their removal by bile acids and lipase. Vitamin bioaccessibility was higher in WPI- than in saponin- or gum arabic-emulsions. This information may facilitate the design of more efficacious vitamin-fortified delivery systems.

In Vitro Digestion of Oil-in-Water Emulsions Stabilized by Regenerated Chitin

Regenerated chitin (R-chitin) can stabilize oil-in-water (O/W) emulsions containing up to 50% oil at a low chitin dosage of 2 mg/g oil. The mean droplet size of the resulting emulsion decreased as more R-chitin was used. Confocal laser scanning microscopy (CLSM) demonstrated the adsorption of R-chitin on emulsion droplets surface, confirming the emulsions were stabilized via Pickering mechanism. The effects of R-chitin concentration on storage stability, microstructure, and lipid digestion properties were investigated. Pickering emulsions stabilized by R-chitin above 1.0% w/w exhibited outstanding physical stability against coalescence and Ostwald ripening. In particular, highly consistent emulsions that remained almost unchanged during oral, gastric, and intestine digestion could be prepared using R-chitin. The emulsions could enhance fullness and satiety perceptions at gastric level, and R-chitin could be used as a substitute for food emulsifiers for weight management via increasing satiation perception and reducing lipid digestion.

Influence of Dairy Emulsifier Type and Lipid Droplet Size on Gastrointestinal Fate of Model Emulsions: In Vitro Digestion Study

Human breast milk is a natural emulsion containing relatively large triacylglycerol droplets coated by a distinct interfacial layer known as the milk fat globule membrane (MFGM). The unique properties of the MFGM impact the release of nutrients from breast milk in an infant's gastrointestinal tract (GIT), but the membrane architecture is susceptible to disruption by industrial processes. To formulate infant formula that simulates the gastrointestinal behavior of breast milk, food manufacturers require knowledge of the impact of the interfacial properties on the gastrointestinal fate of fat globules. In this study, a simulated GIT was utilized to monitor the gastrointestinal fate of emulsified corn oil with different dairy emulsifiers, including sodium caseinate, lactoferrin (LF), whey protein isolate (WPI), and milk phospholipids (MPL) isolated from MFGM. The influence of droplet size on the gastrointestinal fate of the MPL-stabilized emulsions was also examined. Our findings provide valuable information for the optimization of infant formula and dairy-based nutritional beverages.

Impact of Drug Physicochemical Properties on Lipolysis-Triggered Drug Supersaturation and Precipitation from Lipid-Based Formulations

In this study we investigated lipolysis-triggered supersaturation and precipitation of a set of model compounds formulated in lipid-based formulations (LBFs). The purpose was to explore the relationship between precipitated solid form and inherent physicochemical properties of the drug. Eight drugs were studied after formulation in three LBFs, representing lipid-rich (extensively digestible) to surfactant-rich (less digestible) formulations. In vitro lipolysis of drug-loaded LBFs were conducted, and the amount of dissolved and precipitated drug was quantified. Solid form of the precipitated drug was characterized with polarized light microscopy (PLM) and Raman spectroscopy. A significant solubility increase for the weak bases in the presence of digestion products was observed, in contrast to the neutral and acidic compounds for which the solubility decreased. The fold-increase in solubility was linked to the degree of ionization of the weak bases and thus their attraction to free fatty acids. A high level of supersaturation was needed to cause precipitation. For the weak bases, the dose number indicated that precipitation would not occur during lipolysis; hence, these compounds were not included in further studies. The solid state analysis proved that danazol and griseofulvin precipitated in a crystalline form, while niclosamide precipitated as a hydrate. Felodipine and indomethacin crystals were visible in the PLM, whereas the Raman spectra showed presence of amorphous drug, indicating amorphous precipitation that quickly crystallized. The solid state analysis was combined with literature data to allow analysis of the relationship between solid form and the physicochemical properties of the drug. It was found that low molecular weight and high melting temperature increases the probability of crystalline precipitation, whereas precipitation in an amorphous form was favored by high molecular weight, low melting temperature, and positive charge.

Triglyceride Structure Modulates Gastrointestinal Digestion Fates of Lipids: A Comparative Study between Typical Edible Oils and Triglycerides Using Fully Designed in Vitro Digestion Model

Three typical edible oils (palm oil, PO; leaf lard oil, LO; rapeseed oil, RO) and triacylglycerols (TAGs) (glycerol tripalmitate, GTP; glycerol tristearate, GTS; glycerol trioleate, GTO) were selected to conduct digestion experiments using fully designed in vitro digestion model. The evolutions in mean particle diameter, ζ-potential, and microstructural changes during different digestion stages were investigated. Free fatty acid (FFA) release extent and kinetics were monitored by pH-Stat method. The particle characterization of different lipids during passage through the GIT depended on lipid type and the microenvironment they encountered. Absorbed surface protein can hardly be the obstacle for pancreas lipase to catalyze lipid hydrolysis after gastric digestion. The maximum FFA release level and apparent rate constant in small intestine digestion stage of the three oils and TAGs were: PO > RO > LO, GTP > GTS > GTO, respectively. PO showed the highest FFA release level and rate mainly due to the short chain length saturated palmitic acid (C16:0) specifically located in the Sn-1, 3 positions of TAG molecules in palm oil, while the Sn-1, 3 positions of TAG molecules in RO and LO were mainly mono- or polyunsaturated fatty acids (C18:1 or C18:2), restricting the continuous hydrolysis reaction. These findings can provide some basic understanding of the digestion differences of different lipids, which may be useful for their nutritional and functional evaluation and the applicability in the food area.

Tailoring Emulsions for Controlled Lipid Release: Establishing in vitro-in Vivo Correlation for Digestion of Lipids

The use of oil-in-water emulsions for controlled lipid release is of interest to the pharmaceutical industry in the development of poorly water soluble drugs and also has gained major interest in the treatment of obesity. In this study, we focus on the relevant in vitro parameters reflecting gastric and intestinal digestion steps to reach a reliable in vitro-in vivo correlation for lipid delivery systems. We found that (i) gastric lipolysis determines early lipid release and sensing. This was mainly influenced by the emulsion stabilization mechanism. (ii) Gastric mucin influences the structure of charge-stabilized emulsion systems in the stomach, leading to destabilization or gel formation, which is supported by in vivo magnetic resonance imaging in healthy volunteers. (iii) The precursor structures of these emulsions modulate intestinal lipolysis kinetics in vitro, which is reflected in plasma triglyceride and cholecystokinin concentrations in vivo.

Microgel-in-Microgel Biopolymer Delivery Systems: Controlled Digestion of Encapsulated Lipid Droplets under Simulated Gastrointestinal Conditions

Structural design principles are increasingly being used to develop colloidal delivery systems for bioactive agents. In this study, oil droplets were encapsulated within microgel-in-microgel systems. Initially, a nanoemulsion was formed that contained small whey protein-coated oil droplets ( d₄₃ = 211 nm). These oil droplets were then loaded into either carrageenan-in-alginate (O/M_C/M_A) or alginate-in-carrageenan (O/M_A/M_C) microgels. A vibrating nozzle encapsulation unit was used to form the smaller inner microgels ( d₄₃ = 170-324 μm), while a hand-held syringe was used to form the larger outer microgels ( d₄₃ = 2200-3400 μm). Calcium alginate microgels (O/M_A) were more stable to simulated gastrointestinal tract (GIT) conditions than potassium carrageenan microgels (O/M_C), which was attributed to the stronger cross-links formed by divalent calcium ions than the monovalent potassium ions. As a result, the microgel-in-microgel systems had different gastrointestinal fates depending upon the nature of the external microgel phase; i.e., the O/M_C/M_A system was more resistant to rupture than the O/M_A/M_C system. The rate of lipid digestion under simulated small intestine conditions decreased in the following order: free oil droplets > O/M_C > O/M_A > O/M_A/M_C > O/M_C/M_A. This effect was attributed to differences in the integrity and dimensions of the microgels in the small intestine, because a hydrogel network surrounding the oil droplets inhibits lipid hydrolysis by lipase. The structured microgels developed in this study may have interesting applications for the protection or controlled release of bioactive agents.

Development of Pickering Emulsions Stabilized by Gliadin/Proanthocyanidins Hybrid Particles (GPHPs) and the Fate of Lipid Oxidation and Digestion

This work attempted to engineer emulsions' interface using the special affinity between proline-rich gliadin and proanthocyanidins (PA), to develop surfactant-free antioxidant Pickering emulsions with digestive-resistant properties. This binding interaction between gliadin and PA benefited the interfacial adsorption of the particles to corn oil droplets. Pickering droplets as building units assembled into an interconnected three-dimensional network structure, giving the emulsions viscoelasticity and ultrastability. Oxidative markers in Pickering emulsions were periodically monitored under thermally accelerated storage. Lipid digestion and oxidation fates were characterized using in vitro gastrointestinal (GI) models. The interfacial membrane constructed by antioxidant particles served as a valid barrier against lipid oxidation and digestion, in a PA dose-dependent manner. Briefly, lipid oxidation under storage and simulated GI tract was retarded. Free fatty acid (FFA) fraction released decreased by 55% from 87.9% (bulk oil) to 39.5% (Pickering emulsion), implying engineering interfacial architecture potentially benefited to fight obesity. This study opens a facile strategy to tune lipid oxidation and digestion profiles through the cooperation of the Pickering principle and the interfacial delivery of antioxidants.

Influence of Homogenization and Thermal Processing on the Gastrointestinal Fate of Bovine Milk Fat: In Vitro Digestion Study

Dairy lipids are an important source of energy and nutrients for infants and adults. The dimensions, aggregation state, and interfacial properties of fat globules in raw milk are changed by dairy processing operations, such as homogenization and thermal processing. These changes influence the behavior of fat globules within the human gastrointestinal tract (GIT). The gastrointestinal fate of raw milk, homogenized milk, high temperature short time (HTST) pasteurized milk, and ultrahigh temperature (UHT) pasteurized milk samples was therefore determined using a simulated GIT. The properties of particles in different regions of the GIT depended on the degree of milk processing. Homogenization increased the initial lipid digestion rate but did not influence the final digestion extent. Thermal processing of homogenized milk decreased the initial rate and final extent of lipid digestion, which was attributed to changes in interfacial structure. These results provide insights into the impact of dairy processing on the gastrointestinal fate of milk fat.

Mapping the intermediate digestion phases of human healthy intestinal contents from distal ileum and caecum at fasted and fed state conditions

OBJECTIVES

To investigate at the ultrastructural level, the colloidal phases formed in the lumen of the distal ileum and caecum of healthy adults.

METHODS

Cryogenic transmission electron microscopy (Cryo-TEM) was employed to image the intermediate colloidal phases of human intestinal contents collected from distal ileum and caecum of two healthy volunteers under fasted and fed state conditions.

KEY FINDINGS

In samples collected both in the fasted and fed states, Cryo-TEM study revealed the presence of large spherical unilamellar and occasionally bi-lamellar and oligolamellar vesicles with diameters ranging from 50 to 200 nm for both volunteers in distal ileum and caecum. Bilayer fragments were frequently observed in caecal samples. Plate-like structures resembling the morphology of cholesterol plates were visualised in all samples. Elongated structures were observed in the fed state in distal ileum and caecum for both volunteers, whereas no micellar structures could be detected for all samples.

CONCLUSIONS

This study provides a framework for understanding the structure of colloidal phases, and it may assist in elucidating the role of dosing conditions on drug absorption from the distal ileum and caecum.

Mechanisms of Body Weight Reduction by Black Tea Polyphenols

Obesity is one of the most common nutritional diseases worldwide. This disease causes health problems, such as dyslipidemia, hyperglycemia, hypertension and inflammation. There are drugs used to inhibit obesity. However, they have serious side effects outweighing their beneficial effects. Black tea, commonly referred to as “fermented tea”, has shown a positive effect on reducing body weight in animal models. Black tea polyphenols are the major components in black tea which reduce body weight. Black tea polyphenols are more effective than green tea polyphenols. Black tea polyphenols exert a positive effect on inhibiting obesity involving in two major mechanisms: (i) inhibiting lipid and saccharide digestion, absorption and intake, thus reducing calorie intake; and (ii) promoting lipid metabolism by activating AMP-activated protein kinase to attenuate lipogenesis and enhance lipolysis, and decreasing lipid accumulation by inhibiting the differentiation and proliferation of preadipocytes; (iii) blocking the pathological processes of obesity and comorbidities of obesity by reducing oxidative stress. Epidemiological studies of the health relevance between anti-obesity and black tea polyphenols consumption remain to be further investigated.

Nanostructured Montmorillonite Clay for Controlling the Lipase-Mediated Digestion of Medium Chain Triglycerides

Biocompatible lipid hybrid particles composed of montmorillonite and medium chain triglycerides were engineered for the first time by spray drying oil-in-water emulsions stabilized by montmorillonite platelets to form montmorillonite-lipid hybrid (MLH) microparticles containing up to 75% w/w lipid. In vitro lipolysis studies under simulated intestinal conditions indicated that the specific porous nanoarchitecture and surface chemistry of MLH particles significantly increased the rate (>10-fold) and extent of lipase-mediated digestion compared to that of coarse and homogenized submicrometer triglyceride emulsions. Proton nuclear magnetic resonance studies verified the rapid and enhanced production of fatty acids for MLH particles; these are electrostatically repelled by the negatively charged montmorillonite platelet faces and avoid the "interfacial poisoning" caused by incomplete digestion that retards lipid droplet digestion. MLH particles are a novel biomaterial and encapsulation system that optimize lipase enzyme efficiency and have excellent potential as a smart delivery system for lipophilic biomolecules owing to their exceptional physicochemical and biologically active properties. These particles can be readily fabricated with varying lipid loads and thus may be tailored to optimize the solubilization of specific bioactive molecules requiring reformulation.

Bioaccessibility and Antioxidant Activity of Calendula officinalis Supercritical Extract as Affected by in Vitro Codigestion with Olive Oil

Supercritical extracts of marigold (ME) were produced and characterized. The bioaccessibility of terpenes, especially that of pentacyclic triterpenes (PT), the particle-size distribution, and antioxidant activity after the in vitro codigestion of ME with olive oil (OO) were determined. ME produced without cosolvent was richer in taraxasterol, lupeol, α-amyrin, and β-amyrin than extracts with cosolvent. All terpenes showed high bioaccessibility without OO (>75%). Significant correlations were found between the molecular properties of compounds (logP and number of rotatable bonds) and their bioaccessibility. Codigestion with OO enhanced the bioaccessibility (around 100% for PT), which could be related to a higher abundance of low-size particles of the digestion medium. The antioxidant activity of the digested ME increased around 50%, regardless of OO. PT-rich extracts from marigold display high bioaccessibility and improved antioxidant activity after in vitro digestion, although complete bioaccessibility of PT can be reached by codigestion with oil, without affecting antioxidant activity.

Nanostructuring Biomaterials with Specific Activities towards Digestive Enzymes for Controlled Gastrointestinal Absorption of Lipophilic Bioactive Molecules

This review describes the development of novel lipid-based biomaterials that modulate fat digestion for the enhanced uptake of encapsulated lipophilic bioactive compounds (e.g. drugs and vitamins). Specific focus is directed towards analysing how key material characteristics affect the biological function of digestive lipases and manipulate lipolytic digestion. The mechanism of lipase action is a complex, interfacial process, whereby hydrolysis can be controlled by the ability for lipase to access and adsorb to the lipid-in-water interface. However, significant conjecture exists within the literature regarding parameters that influence the activities of digestive lipases. Important findings from recent investigations that strategically examined the interplay between the interfacial composition of the lipid microenvironment and lipolysis kinetics in simulated biophysical environments are presented. The correlation between lipolysis and the rate of solubilisation and absorption of lipophilic compounds in the gastrointestinal tract (GIT) is detailed. Greater insights into the mechanism of lipase action have provided a new approach for designing colloidal carriers that orally deliver poorly soluble compounds, directly impacting the pharmaceutical and food industries.

Improvement of β-Carotene Bioaccessibility from Dietary Supplements Using Excipient Nanoemulsions

The influence of excipient nanoemulsions on β-carotene bioaccessibility from commercial dietary supplements (tablets or soft gels) was studied employing an in vitro gastrointestinal tract (GIT) model. Excipient nanoemulsions were formulated from long or medium chain triglycerides (LCT or MCT) to determine the impact of lipid type on carotenoid bioaccessibility. Dietary supplements were tested using the GIT model in the absence or presence of excipient nanoemulsions. β-carotene bioaccessibility from tablets (0.3%) or soft gels (2.4%) was low when tested in isolation. LCT nanoemulsions greatly improved β-carotene bioaccessibility from tablets (20%) and slightly improved it from soft gels (5%), whereas MCT nanoemulsions only slightly improved bioaccessibility. These results were attributed to the ability of large carotenoid molecules to be incorporated into large mixed micelles formed by LCT digestion but not by small ones formed by MCT digestion. Our results indicate that excipient nanoemulsions have considerable potential for improving nutraceutical bioavailability from dietary supplements.

Bioactive Hybrid Particles from Poly(D,L-lactide-co-glycolide) Nanoparticle Stabilized Lipid Droplets

Biodegradable and bioactive hybrid particles composed of poly(D,L-lactide-co-glycolide) (PLGA) nanoparticles and medium-chain triglycerides were prepared by spray drying lipid-in-water emulsions stabilized by PLGA nanoparticles, to form PLGA-lipid hybrid (PLH) microparticles approximately 5 μm in mean diameter. The nanoparticle stabilizer was varied and mannitol was also incorporated during the preparation to investigate the effect of stabilizer charge and cryoprotectant content on the particle microstructure. An in vitro lipolysis model was used to demonstrate the particles' bioactivity by manipulating the digestion kinetics of encapsulated lipid by pancreatic lipase in simulated gastrointestinal fluid. Lipid digestion kinetics were enhanced in PLH and PLGA-lipid-mannitol hybrid (PLMH) microparticles for both stabilizers, compared to a coarse emulsion, in biorelevant media. An optimal digestion rate was observed for the negatively charged PLMH system, evidenced by a 2-fold increase in the pseudo-first-order rate constant compared to a coarse emulsion. Improved microparticle redispersion, probed by dual dye confocal fluorescence microscopy, increased the available surface area of lipid for lipase adsorption, enhancing digestion kinetics. Thereby, lipase action was controlled in hybrid microparticles by altering the surface charge and carbohydrate content. Our results demonstrate that bioactive microparticles composed of versatile and biodegradable polymeric particles and oil droplets have great potential for use in smart food and nutrient delivery, as well as safer and more efficacious oral delivery of drugs and drug combinations.

Interaction of a dietary fiber (pectin) with gastrointestinal components (bile salts, calcium, and lipase): a calorimetry, electrophoresis, and turbidity study

An in vitro gastrointestinal model consisting of oral, gastric, and intestinal phases was used to elucidate the impact of pectin on the digestion of emulsified lipids. Pectin reduced the extent of lipid digestion, which was attributed to its binding interactions with specific gastrointestinal components. The interaction of pectin with bile salts, lipase, CaCl2, and NaCl was therefore investigated by turbidity, microstructure, electrophoresis, and isothermal titration calorimetry (ITC) at pH 7.0 and 37 °C. ITC showed that the interaction of pectin was endothermic with bile salts, but exothermic with CaCl2, NaCl, and lipase. Electrophoresis, microstructure, and turbidity measurements showed that anionic pectin formed electrostatic complexes with calcium ions, which may have decreased lipid digestion due to increased lipid flocculation or microgel formation because this would reduce the surface area of lipid exposed to the lipase. This research provides valuable insights into the physicochemical and molecular mechanisms of the interaction of pectin with gastrointestinal components that may affect the rate and extent of lipid digestion.

Enhanced oral absorption and therapeutic effect of acetylpuerarin based on D-α-tocopheryl polyethylene glycol 1000 succinate nanoemulsions

Background

Acetylpuerarin (AP), because of its lower water solubility, shows poor absorption that hinders its therapeutic application. Thus, the aim of this study was to prepare nanoemulsions for AP, enhance its oral bioavailability, and thus improve the therapeutic effect.

Methods

The nanoemulsions stabilized by D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) were prepared by high-pressure homogenization and characterized in terms of particle size, drug loading, morphology, and in vitro drug release. A lipid digestion model was used to predict in vivo drug solubilization in the gastrointestinal environment. The pharmacokinetics of AP formulations were performed in rats; meanwhile, a chylomicron flow-blocking rat model was used to evaluate the lymphatic drug transport. Moreover, the therapeutic effects of AP nanoemulsions on the model of focal cerebral ischemia-reperfusion for brain injury were also assessed.

Results

The nanoemulsions with a droplet size of 150 nm were well stabilized by TPGS and showed a high loading capacity for AP. In the digestion model, the distribution of AP in aqueous phase/pellet phase was about 90%/10% for nanoemulsions and 5%/95% for oil solution, indicating that the drug encapsulated in nanoemulsions would present in solubilized form after transportation into the gastrointestinal tract, whereas drug precipitation would occur as the oil solution was orally administered. The area under the curve value of AP nanoemulsions was 5.76±0.56 μg·hour·mL⁻¹, or was about 2.6 and 1.7 times as great as that of suspension and oil solution, respectively, indicating enhanced drug absorption and thus achieving a better neuroprotection effect on cerebral ischemic reperfusion injury. The values of peak plasma concentration and area under the curve from the blocking model were significantly less than those of the control model, suggesting that the lymphatic transport performed a very important role in absorption enhancement.

Conclusion

Enhanced oral bioavailability in nanoemulsions was achieved via the mechanism of the maintenance of drug solubilization in the gastrointestinal tract and the enhancement of lymphatic transport, which resulted in therapeutic improvement of cerebral ischemic reperfusion injury.

Bile acids via FXR initiate the expression of major transporters involved in the enterohepatic circulation of bile acids in newborn mice

The enterohepatic circulation (EHC) of bile acids (BAs) plays a pivotal role in facilitating lipid absorption. Therefore, initiation of the EHC in newborns is of crucial importance for lipid absorption from milk. The purpose of this study was to determine at what age BA transporters in liver are expressed, and the mechanism for their initiation. Serum and liver samples were collected from C57BL/6 mice at 2 days before birth and various postnatal ages. Messenger RNA assays revealed a dramatic increase at birth in the expression of the BA transporters (Ntcp, Bsep, Mrp4, Ostβ), as well as the phospholipid floppase Mdr2 in mouse liver, with the highest expression at 1 day of age. The mRNA expression of the ileal BA transporters (Ostα and Ostβ) also markedly increased at birth. Meanwhile, taurine-conjugated cholic acid markedly increased in both serum and liver of newborns, correlated with upregulation of the classic pathway of BA biosynthesis in newborn liver. The mRNA levels of the major BA sensors, FXR and PXR, were increased at 1 day of age, and their prototypical target genes were upregulated in liver. The mRNA expression of transporters involved in the EHC of BAs was similar in wild-type and PXR-null mice. In contrast, in FXR-null mice, the "day 1 surge" pattern of Ntcp, Bsep, Ostβ, and Mdr2 was blocked in newborn mouse liver, and the induction of Ostα and Ostβ was also abolished in ileums of FXR-null mice. In conclusion, at birth, BAs from the classic pathway of synthesis trigger the induction of transporters involved in EHC of BAs in mice, through activation of the nuclear receptor FXR.