Comparative behavior of protein or polysaccharide stabilized emulsion under in vitro gastrointestinal conditions

Soy protein isolate-xanthan gum complexes to stabilize Pickering emulsions for quercetin delivery

This study aimed to prepare soy protein isolate-xanthan gum complexes (SPI-XG) at pH 7.0 and as emulsifiers to prepare Pickering emulsions for delivering quercetin (Que). The results showed that SPI-XG exhibited a gel network structure in which protein particles were embedded. Fourier transform infrared spectroscopy (FTIR) and molecular docking elucidated that SPI-XG formed through hydrogen bonding, hydrophobic, and electrostatic interactions. Three-phase contact angle (θo/w) of SPI-XG approached 90° with biphasic wettability. SPI-XG adsorbed at the oil-water interface to form an interfacial layer with a gel network structure, which prevented droplet aggregation. Following in vitro simulated digestion, Que displayed higher bioaccessibility in SPI-XG stabilized Pickering emulsions (SPI-XG PEs) than SPI stabilized Pickering emulsions. In conclusion, SPI-XG PEs were a promising system for Que delivery.

In situ interaction of pea peptides and bile salts under in vitro digestion: Potential impact on lipolysis

The present work evaluated how a native pea protein isolate (PPI) affects the key roles carried out by bile salts (BS) in lipid digestion by means of the in vitro static INFOGEST protocol. Two gastric residence times were evaluated (10 and 60 min), and then the peptides obtained (GPPP) were mixed with BS at physiological concentration in simulated intestinal fluid to understand how they interact with BS both at the bulk and at the interface. Both GPPP give rise to a film with a predominant viscous character that does not constitute a barrier to the penetration of BS, but interact with BS in the bulk duodenal fluid. When the peptides flushing from the stomach after the different gastric residence times undergo duodenal digestion, it was found that for the longer gastric residence time the percentage of soluble fraction in the duodenal phase, that perform synergistically with BS micelles, was twice that of the lower residence time, leading to an increase in the solubilization of oleic acid. These results finally lead to a greater extent of lipolysis of olive oil emulsions. This work demonstrates the usefulness of in vitro models as a starting point to study the influence of gastric residence time of pea protein on its interaction with BS, affecting lipolysis. Pea proteins were shown to be effective emulsifiers that synergistically perform with BS improving the release and bioaccessibility of bioactive lipids as olive oil.

High-purity 1,2-dimyristoyl-sn-glycero-3-phosphocholine: synthesis and emulsifying performance evaluation

Introduction

1,2-Dimyristoyl-sn-glycero-3-phosphocholine (DMPC) is a promising emulsifier for bioactive delivery systems, but its industrial applications are limited by the lack of cost-effective and scalable synthetic routes. The purpose of this study was to economically produce high-purity DMPC by replacing commonly used column chromatography methods and to evaluate the emulsifying performance.

Methods

DMPC was synthesized from sn-glycero-3-phosphocholine using Steglich esterification followed by sequential recrystallization from ethyl acetate and acetone. The structure of DMPC was identified and its purity was confirmed using various spectroscopy and chromatography techniques. The emulsifying performance was evaluated by examining the effects of storage on the properties of o/w emulsions prepared using soybean oil with (i) soy PC, (ii) soy PC + DMPC (1:1, w/w), and (iii) DMPC as emulsifiers.

Results

The chemical impurities formed during the synthesis of DMPC was removed, and its final purity was 96%, and the melt transition temperature was 37.6°C. No visible difference between the three emulsions (soy PC, soy PC+DMPC, and DMPC) was observed during two-week storage, and the DMPC-based emulsion was more stable than soy PC emulsion, showing smaller particle size distribution during 6 months.

Discussion

The highly pure DMPC was synthesized by an economical method, and DMPC-based emulsions demonstrated physicochemical stable, highlighting its potential for food and pharmaceutical industry-related applications. Our findings suggest that DMPC holds promise as an emulsifier with broad applications in the food industry.

Influence of the Oil Structuring System on Lipid Hydrolysis and Bioaccessibility of Healthy Fatty Acids and Curcumin

Oleogels (OG) and gelled emulsions (GE) were elaborated with a mixture of olive and chia oils (80:20 ratio) without and with the incorporation of the health-related compound curcumin. These were studied to evaluate the influence of the oil structuring system on the lipid hydrolysis and bioaccessibility of three healthy fatty acids (FA) (palmitic, oleic, and α-linolenic acids) and of curcumin, compared to the oil mixture (bulk oil, BO). The oil structuring system influenced the firmness and texture, and the presence of curcumin significantly altered the color parameters. GE showed higher lipid digestibility, with a greater proportion of absorbable fraction (higher content of free FA and monoacylglycerides) than OG, which behaved similarly to BO. The presence of curcumin affected the degree of lipolysis, reducing lipid digestibility in OG and increasing it in GE. As for FA bioaccessibility, although GE presented higher percentages overall, curcumin significantly increased and decreased FA bioaccessibility in OG and GE, respectively. The oil structuring system also influenced the bioaccessibility of curcumin, which was higher in GE. Therefore, when selecting an oil structuring system, their physicochemical properties, the degree of lipid hydrolysis, and the bioaccessibility of both curcumin and the FA studied should all be considered.

The lipid digestion behavior of oil-in-water emulsions stabilized by different particle-sized insoluble dietary fiber from citrus peel

In this study, oil-in-water emulsions stabilized by insoluble dietary fibre from citrus peel (CIDF) exhibited an obviously delayed lipid digestion property through gastrointestinal tract (GIT) model. Our results suggested that the rate and extent of lipid digestion greatly relied on particle sizes and concentrations of CIDF, and the inhibition effect of lipolysis was markedly enhanced with decreasing particle sizes and increasing CIDF levels. Furthermore, compared with Tween80-stabilized emulsion, the maximum inhibition extent of lipolysis was 38.77% for CIDF400-stabilized one at 0.4 wt% concentration. Effects of CIDFs on lipid digestion was mainly due to the formation of protective layers around oil droplets, further blocking the entry of lipase to the internal lipids, and/or attributed to the increasing viscosity of emulsions caused by CIDFs, finally limiting the transportation of some substances in the simulated small intestine digestion. Our research would provide useful references for the application of CIDF-stabilized emulsions in low-calorie food.

Impact of Silicon Addition on the Development of Gelled Pork Lard Emulsions with Controlled Lipid Digestibility for Application as Fat Replacers

Pork lard gelled emulsions stabilized with two proteins [soy protein concentrate (SPC) or a pork rind protein extract (PRP)], both with and without added silicon (Si) from diatomaceous earth powder, were gelled by microbial transglutaminase and к-carrageenan. These gelled emulsions (GEs), intended as fat replacers, were evaluated in different aspects, including microstructure and technological properties during chilling storage. In addition, in vitro gastrointestinal digestion (GID) with an analysis of lipolysis and lipid digestibility was also evaluated. All GEs showed adequate technological properties after 28 days of chilling storage, although the SPC-stabilized GEs showed better gravitational and thermal stability (~4% and ~6%, respectively) during chilling storage than the PRP-stabilized ones (~8 and ~12%, respectively). PRP developed larger flocculates restricting pancreatic lipase-mediated lipolysis during intestinal digestion. The addition of Si to both GE structures protected them against disruption during in vitro digestion. Accordingly, Si appears to slow down fat digestion, as reflected by higher triacylglycerides content after GID (15 and 22% vs. 10 and 18% in GEs without Si) and could become a potential candidate for use in the development of healthier meat products.

Stabilized soy protein emulsion enriched with silicon and containing or not methylcellulose as novel technological alternatives to reduce animal fat digestion

During the last decade, the consumption of animal saturated fat has been associated with an increased risk of chronic disease. Experience shows that changing the dietary habits of the population is a complicated and slow process, so technological strategies offer new possibilities for the development of functional foods. The present work is focused on studying the impact of using a food-grade non-ionic hydrocolloid (methylcellulose; MC) and/or the inclusion of silicon (Si) as a bioactive compound in pork lard emulsions stabilized with soy protein concentrate (SPC), on the structure, rheology, lipid digestibility and Si bioaccesibility during in vitro gastrointestinal digestion (GID). Four emulsions (SPC, SPC/Si, SPC/MC and SPC/MC/Si) were prepared with a final biopolymer (SPC and/or MC) concentration of 4% and 0.24% Si. The results showed a lower degree of lipid digestion in SPC/MC compared with SPC, specifically at the end of the intestinal phase. Moreover, Si partially reduced fat digestion only when incorporated into the SPC-stabilized emulsion, while this effect was lost in SPC/MC/Si. This was probably due to its retention inside the matrix emulsion, which resulted in lower bioaccesibility than in SPC/Si. Additionally, the correlation between the flow behavior index (n) and the lipid absorbable fraction was significant, suggesting that n can be a predictive marker of the extent of lipolysis. Concretely, our results revealed that SPC/Si and SPC/MC can be used as pork fat digestion reducers and thus, they can replace pork lard in the reformulation of animal products with potential health benefits.

Application of Curcumin Emulsion Carrier from Ultrasonic-Assisted Prepared Octenyl Succinic Anhydride Rice Starch

The emulsification of ultrasonic-assisted prepared octenyl succinic anhydride (OSA) rice starch on curcumin was investigated in the present study. The results indicated that the encapsulation efficiency of curcumin in emulsions stabilized by OSA-ultrasonic treatment rice starch was improved, from 81.65 ± 0.14% to 89.03 ± 0.09%. During the in vitro oral digestion, the particle size and Zeta potential of the curcumin emulsion did not change significantly (p > 0.05). During the in vitro digestive stage of the stomach and small intestine, the particle size of the curcumin emulsion continued to increase, and the absolute potential continued to decrease. Our work showed that OSA-pre-treatment ultrasonic rice starch could improve curcumin bioavailability by increasing the encapsulation efficiency with stronger stability to avoid the attack of enzymes and high intensity ion, providing a way to develop new emulsion-based delivery systems for bioactive lipophilic compounds using OSA starch.

Exploration of suitable in vitro simulated digestion model for lipid oxidation of flaxseed oil emulsion during digestion

BACKGROUND

The INFOGEST model is a standardized general in vitro digestion study, but it cannot accurately simulate the fatty acid release process of lipids in the stomach and small intestine. In this study, the internationally universal INFOGEST 2019 was used as the basic model and flaxseed oil emulsion was used as the research object. In various improvement models, the effect of fatty acid release rate on the oxidation stability of flaxseed oil was assessed by adding rabbit stomach extract and changing the order of bile salts addition.

RESULTS

With the presence of rabbit gastric extract, flaxseed oil emulsion flocculation and coalescence in stomach were reduced, and the absolute value of ζ-potential increased. Moreover, the release rate of fatty acids in the small intestine increased by 12.14%. The amount of lipid oxidation product (i.e. hexanal) in the gastric and intestinal phases increased by 0.08 ppb. In addition, the fatty acid release rate in the small intestine phase increased by 5.85% and the hexanal content increased by 0.011 ppb in the digestion model of adding bile salts before adjusting the pH in the small intestine phase compared with the model of adjusting the pH first and then adding bile salts.

CONCLUSION

The results obtained from this study will contribute to finding the most suitable static digestion model for simulating digestion and oxidation of lipid during lipid gastrointestinal digestion. © 2022 Society of Chemical Industry.

3D printed MCT oleogel as a co-delivery carrier for curcumin and resveratrol

Designing a suitable matrix to protect sensitive bioactive compounds is an important stage in nutraceutical development. In this study, emulsion templated medium-chain triglycerides (MCT) oleogel was developed as co-delivery carriers for synergistic nutraceuticals, curcumin, and resveratrol and to 3D print in customized shapes for personalized nutrition. To obtain the stable emulsion, gelatin and gellan gum were added such that their protein-polysaccharide interaction helps in the structuring of the oil phase. Increasing the amount of gellan gum had a positive effect on stabilizing the emulsion but became the critical parameter during 3D printing. Hence, gellan gum of 1.5% (w/v) and gelatin at 10% (w/v) of water were considered optimum to produce a stable 30% O/W emulsion for 3D printing. Upon analyzing the in-vitro digestion behavior of the oleogel, it was observed that the bioactives were protected under oral and gastric conditions and allowed intestinal targeted delivery. The total bioaccessible fraction increased up to 1.13-fold and 1.2-fold for curcumin and resveratrol respectively compared to control (MCT oil). The FFAs release profile also indicated that gelators play an important role in lipase activity. Also, the ex-vivo everted gut sac analysis showed enhanced permeation of about 1.83 times and 1.13 times for curcumin and resveratrol respectively. Thus, this study provides useful insights into the 3D printing of emulsion templated oleogel as personalized nutraceutical carriers.

Gastrointestinal Fate and Fatty Acid Release of Pickering Emulsions Stabilized by Mixtures of Plant Protein Microgels + Cellulose Particles: an In Vitro Static Digestion Study

The present study aims to investigate the in vitro intestinal digestion fate of Pickering emulsions with complex dual particle interfaces. Pickering oil-in-water emulsions (PPM-E) stabilized by plant (pea) protein-based microgels (PPM), as well as PPM-E where the interface was additionally covered by cellulose nanocrystals (CNC), were designed at acidic pH (pH 3.0). The gastrointestinal fate of the PPM-E and free fatty acid (FFA) release, was tested via the INFOGEST static in vitro digestion model and data was fitted using theoretical models. Lipid digestion was also monitored using lipase alone bypassing the gastric phase to understand the impact of proteolysis on FFA release. Coalescence was observed in the PPM-stabilized emulsions in the gastric phase, but not in those co-stabilized by CNC. However, coalescence occurred during the intestinal digestion stage, irrespective of the CNC concentration added (1–3 wt % CNC). The presence of CNC lowered the lipolysis kinetics but raised the extent of FFA release as compared to in its absence (p < 0.05), due to lower levels of gastric coalescence, i.e., a higher interfacial area. The trends were similar when just lipase was added with no prior gastric phase, although the extent and rate of FFA release was reduced in all emulsions, highlighting the importance of prior proteolysis in lipolysis of such systems. In summary, an electrostatically self-assembled interfacial structure of two types of oppositely-charged particles (at gastric pH) might be a useful strategy to enable enhanced delivery of lipophilic compounds that require protection in the stomach but release in the intestines.

Chlorophyll Inhibits the Digestion of Soybean Oil in Simulated Human Gastrointestinal System

Nowadays, much available processed and highly palatable food such as cream products and fried and convenient food, which usually showed a high energy density, had caused an increase in the intake of dietary lipids, further leading to significant growth in the prevalence of obesity. Chlorophyll, widespread in fruits and vegetables, was proven to have beneficial effects on alleviating obesity. This study investigated the effects of chlorophyll on the digestive characteristics of lipids under in vitro simulated adult and infant gastrointestinal systems. Chlorophyll decreased the release rate of free fatty acid (FFA) during in vitro adult and infant intestinal digestion by 69.2% and 60.0%, respectively. Meanwhile, after gastrointestinal digestion, chlorophyll changed the FFA composition of soybean oil emulsion and increased the particle size of oil droplets. Interestingly, with the addition of chlorophyll, the activity of pancreatic lipase was inhibited during digestion, which may be related to pheophytin (a derivative of chlorophyll after gastric digestion). Therefore, the results obtained from isothermal titration calorimetry and molecular docking further elucidated that pheophytin could bind to pancreatic lipase with a strong affinity of (4.38 ± 0.76) × 10⁷ M^-1 (K_a), while the binding site was amino acid residue Trp253. The investigation not only explained why chlorophyll inhibited digestive enzyme activity to reduce lipids digestion but also provided exciting opportunities for developing novel chlorophyll-based healthy products for dietary application in preventing obesity.

Compositional, Structural, and Kinetic Aspects of Lipid Digestion and Bioavailability: In Vitro, In Vivo, and Modeling Approaches

Lipid digestion and bioavailability are usually investigated separately, using different approaches (in vitro, modeling, in vivo). However, a few inclusive studies show that their kinetics are closely linked. Lipid bioavailability kinetics is likely involved in the development and evolution of several diseases, so lipid digestion kinetics could be involved as well and can be modulated by food design or combination. To illustrate this possibility, the compositional and structural aspects of lipid digestion kinetics, as investigated using in vitro and modeling approaches, are presented first. Then, in vivo and mixed approaches enabling the study of both kinetics are reviewed and discussed. Finally, disparate modeling approaches are introduced, and a unifying modeling scheme is proposed, opening new perspectives for understanding the role and interactions of various factors (chemical, physical, and biological) involved in lipid metabolism.

Expected final online publication date for the Annual Review of Food Science and Technology, Volume 13 is March 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Enhancing the bioaccessibility of puerarin through the collaboration of high internal phase Pickering emulsions with β-carotene

Puerarin is a medicinal and edible flavonoid compound found in the traditional Chinese medicine Pueraria lobata rhizome that has potential biological benefifits, including for the treatment of diabetes and memory...

Plant Protein-Based Delivery Systems: An Emerging Approach for Increasing the Efficacy of Lipophilic Bioactive Compounds

The development of plant protein-based delivery systems to protect and control lipophilic bioactive compound delivery (such as vitamins, polyphenols, carotenoids, polyunsaturated fatty acids) has increased interest in food, nutraceutical, and pharmaceutical fields. The quite significant ascension of plant proteins from legumes, oil/edible seeds, nuts, tuber, and cereals is motivated by their eco-friendly, sustainable, and healthy profile compared with other sources. However, many challenges need to be overcome before their widespread use as raw material for carriers. Thus, modification approaches have been used to improve their techno-functionality and address their limitations, aiming to produce a new generation of plant-based carriers (hydrogels, emulsions, self-assembled structures, films). This paper addresses the advantages and challenges of using plant proteins and the effects of modification methods on their nutritional quality, bioactivity, and techno-functionalities. Furthermore, we review the recent progress in designing plant protein-based delivery systems, their main applications as carriers for lipophilic bioactive compounds, and the contribution of protein-bioactive compound interactions to the dynamics and structure of delivery systems. Expressive advances have been made in the plant protein area; however, new extraction/purification technologies and protein sources need to be found Their functional properties must also be deeply studied for the rational development of effective delivery platforms.

Physiological fluid interfaces: Functional microenvironments, drug delivery targets, and first line of defense

Fluid interfaces, i.e. the boundary layer of two liquids or a liquid and a gas, play a vital role in physiological processes as diverse as visual perception, oral health and taste, lipid metabolism, and pulmonary breathing. These fluid interfaces exhibit a complex composition, structure, and rheology tailored to their individual physiological functions. Advances in interfacial thin film techniques have facilitated the analysis of such complex interfaces under physiologically relevant conditions. This allowed new insights on the origin of their physiological functionality, how deviations may cause disease, and has revealed new therapy strategies. Furthermore, the interactions of physiological fluid interfaces with exogenous substances is crucial for understanding certain disorders and exploiting drug delivery routes to or across fluid interfaces. Here, we provide an overview on fluid interfaces with physiological relevance, namely tear films, interfacial aspects of saliva, lipid droplet digestion and storage in the cell, and the functioning of lung surfactant. We elucidate their structure-function relationship, discuss diseases associated with interfacial composition, and describe therapies and drug delivery approaches targeted at fluid interfaces. STATEMENT OF SIGNIFICANCE: Fluid interfaces are inherent to all living organisms and play a vital role in various physiological processes. Examples are the eye tear film, saliva, lipid digestion & storage in cells, and pulmonary breathing. These fluid interfaces exhibit complex interfacial compositions and structures to meet their specific physiological function. We provide an overview on physiological fluid interfaces with a focus on interfacial phenomena. We elucidate their structure-function relationship, discuss diseases associated with interfacial composition, and describe novel therapies and drug delivery approaches targeted at fluid interfaces. This sets the scene for ocular, oral, or pulmonary surface engineering and drug delivery approaches.

Use of Oleogels to Replace Margarine in Steamed and Baked Buns

Bakery products are usually formulated with solid fats, like margarines and shortenings, which contain high levels of saturated and trans-fatty acids and have negative effects on human health. In this study, hydroxypropyl methylcellulose (HPMC) and xanthan gum (XG) were used as oleogelators to prepare oleogels, using sunflower and olive oil, as substitutes for margarine in baked or steamed buns. The effect of oleogels on the physical properties of the buns was evaluated by analyzing the crumb structure, specific volume, height, and texture. In addition, a triangular discriminatory sensory test was conducted, and lipid digestibility was assessed through in vitro digestion studies. Replacement of margarine with oleogels produced steamed buns with no differences in the crumb structure, volume, height, and texture; however, in baked buns, a less porous and harder structure was produced. No differences in texture were observed between the margarine buns and buns made with oleogels when the triangular test was conducted. The extent of lipolysis was not affected when margarine was replaced by oleogels in the baked and steamed buns. The results suggest that using oleogels instead of margarine in buns could represent an interesting strategy to prepare healthier bakery products.

Upper digestion fate of citrus pectin-stabilized emulsion: An interfacial behavior perspective

Citrus pectin can serve as a naturally digestion-resistant emulsifier, although how it achieves this effect is still unknown. In this study, the upper digestion fate of an emulsion stabilized by different concentrations of citrus pectin, and changes in its interfacial properties during digestion, were investigated. Emulsions stabilized by high-concentration citrus pectin (3 %) were relatively stable during digestion and had a lower free fatty acid (FFA) release rate than emulsions stabilized by low-concentration citrus pectin (1 %). At the low concentration, the citrus pectin interface had a thin absorbing layer and was largely replaced by bile salts, while at high concentration the citrus pectin interface possessed a uniform and thick adsorbing layer that resisted the replacement of bile salts and enabled lipase adsorption. This study has improved our understanding of the digestion of emulsion from the interface and will be useful for designing emulsion-based functional foods that can achieve targeted release.

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.

Biopolymer Additives Enhance Tangeretin Bioavailability in Emulsion-Based Delivery Systems: An In Vitro and In Vivo Study

The oral bioavailability of tangeretin, a poly(methoxyflavone) found in citrus fruits, is typically very low because of its extremely limited solubility. In this research, tangeretin was encapsulated within whey protein-stabilized emulsions containing ingredients that may alter their behavior under gastrointestinal conditions and enhance the bioavailability of tangeretin after oral administration: cinnamaldehyde (CA), gum arabic (GA), or hydroxypropyl methylcellulose (HPMC). The presence of these ingredients altered the size, aggregation state, and encapsulation efficiency of tangeretin in the emulsions. In vitro studies demonstrated that the bioaccessibility of the encapsulated tangeretin was much higher than that of a crude tangeretin oil suspension. Particularly, the addition of HPMC increased the bioaccessibility of tangeretin from around 36 to 90%. In vivo pharmacokinetics results using rats indicated that tangeretin concentration in the plasma increased from 4- to 20-fold after encapsulation, especially in the presence of HPMC. HPMC also prolonged the release of tangeretin to 22 h. Tangeretin preferentially accumulated within the liver and kidney of the animals. Overall, the knowledge confirmed that structured emulsion-based delivery systems could be used to improve the oral bioavailability of hydrophobic functional ingredients.

Improving the bioavailability of oil-soluble vitamins by optimizing food matrix effects: A review

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.

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

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

Effect of emulsifiers on linseed oil emulsion structure, lipolysis and oxidation during in vitro digestion

Health benefits have been associated with the consumption of omega-3 polyunsaturated fatty acids (PUFA). Linseed oil is rich in long chain omega-3 PUFA, but can generate toxic compounds due to its high susceptibility to oxidation. The nature of the emulsifier can affect both lipolysis and oxidation during digestion since these phenomena occur at the oil-water interface. The objective of this study was to compare the effect of low-molecular weight surfactants (cetyltrimethylammonium bromide (CTAB), Citrem), protein (sodium caseinate, fish gelatin) and polysaccharides (gum arabic, modified starch) on the structure of linseed oil emulsions, lipolysis and formation of reactive oxidation species during in vitro digestion. The emulsion stabilized with Citrem underwent extensive coalescence in the gastric phase, which strongly decreased the extent of lipid digestion and reduced the formation of oxidation markers relative to other emulsions. Emulsions stabilized by proteins and modified starch showed aggregation with partial coalescence in the gastric phase, but protein-stabilized emulsions showed better resistance to oxidation. This study shows that emulsifier properties affect the susceptibility of the emulsion to aggregation and coalescence in the gastrointestinal environment, and strongly influence the extent of lipid digestion and the formation of reactive oxidation products. These findings point out the importance of the choice of the emulsifier to control the lipid digestibility and the protection of sensible lipids thus promoting optimal nutritional properties in omega-3-enriched foods.

Preparation and characterization of curcumin solid dispersion using HPMC

Curcumin solid dispersions were prepared using hydroxypropyl methylcellulose (HPMC) to enhance water solubility of curcumin. The particle size of curcumin solid dispersions was in range from 371 to 528 nm and particles were shaped as spherical with wrinkles. The encapsulation efficiency was over 93% for all samples, and water solubility of curcumin was significantly improved to 238 µg/mL when the ratio of curcumin to HPMC was 20:80. The results of X-ray diffraction, differential scanning calorimeter, and Fourier transform infrared spectroscopy showed that crystalline form of curcumin changed to amorphous form. Curcumin solid dispersions showed improved dissolution behavior compared to pure curcumin and the curcumin release kinetic studies were applied to find best-fitting model. This study showed a great potential of solid dispersion using HPMC as curcumin delivery system with improved water solubility and oral absorption. PRACTICAL APPLICATION: Curcumin has limited applications in the food industry because of low water solubility. Dongoh water-soluble curcumin (DW-CURs) were prepared by solid dispersion method with HPMC. Our results indicated that curcumin solid dispersions improved the water solubility of curcumin and showed a sustained release, demonstrating its possibility of body application. Therefore, DW-CURs are a promising formulation for application as a functional ingredient in the food industry.

Emulsion-filled hydrogels for food applications: influence of pH on emulsion stability and a coating on microgel protection

Encapsulation structures for oral administration have been widely employed by the food, personal care, and pharmaceutical industries. Emulsion-filled microgels can be used to encapsulate bioactive compounds, allowing the entrapment of lipid droplets in biopolymer networks and promoting bioactive protection. The influence of pH and biopolymer concentration on the formation and structure of emulsions was evaluated, allowing the production of emulsion-filled hydrogels with potato starch as the main compound, a low alginate concentration, and gelatin in the continuous phase. Potato starch was used because it is generally recognized as safe (GRAS) and has phosphate groups, which allow electrostatic interactions with biopolymers and provide resistance to the network. Emulsion stability was achieved at pH 6, while complexation was verified under acidic conditions, which made the ionic gelation process unfeasible for the production of microgels. After defining the pH for emulsion production, microgels were formed by ionic gelation and coated microgels by electrostatic interactions, as evidenced by quartz crystal microbalance. The alginate and gelatin coating did not affect the morphology of the microparticles. An in vitro digestion assay showed that microgels composed mainly of potato starch were not degraded in the simulated mouth step. The coating layer provided extra microgel protection during digestion, demonstrating the ability of encapsulation systems to promote targeted delivery of bioactive compounds.

In Vitro Gastrointestinal Digestion of Palm Olein and Palm Stearin-in-Water Emulsions with Different Physical States and Fat Contents

The impacts of lipid physical state and content on lipid digestion behavior were investigated using 4 and 20% palm olein-in-water emulsions (4% PO and 20% PO) and 4 and 20% palm stearin-in-water emulsions (4% PS and 20% PS). The changes of lipid physical state, particle size, and microstructure during gastrointestinal digestion; the free fatty acid (FFA) released in the intestinal phase; and the fatty acid composition of micellar phases were investigated. After gastric digestion, all emulsions underwent flocculation and coalescence, with 20% PS showing the most extensive aggregation. During intestinal digestion, the FFA release rate and level decreased as the lipid content increased from 4 to 20%, with 4% PO presenting the highest digestion rate and extent. Besides, the solid fat in 4% PS and 20% PS decreased and increased the maximum lipid digestibility, respectively. These results highlighted the combined roles of lipid physical state and content in modulating dietary lipid digestion.

Contribution of soybean polysaccharides in digestion of oil-in-water emulsion-based delivery system in an in vitro gastric environment

This study aims to evaluate the effects of soy soluble polysaccharide and soy hull polysaccharide on stability and characteristics of emulsions stabilised by soy protein isolate in an in vitro gastric environment. Zeta potential and particle size were used to investigate the changes of physico-chemical and stability in the three emulsions during in vitro gastric digestion, following the order: soy protein isolate-stability emulsion < soy protein isolate-soy soluble polysaccharide -stability emulsion < soy protein isolate-soy hull polysaccharide-stability emulsion, confirming that coalescence in the soy protein isolate-stability emulsion occurred during in vitro gastric digestion. Optical microscopy and stability measurement (backscattering) also validate that addition of polysaccharide (soy soluble polysaccharide and soy hull polysaccharide) can reduce the effect of simulated gastric fluid (i.e., pH, ionic strength and pepsin) on emulsion stability, especially, soy protein isolate-soy hull polysaccharide-stability emulsion, compared with soy protein isolate-stability emulsion. This suggests that the flocculation behaviours of these emulsions in the stomach lead to a difference in the quantity of oil and the size and structure of the oil droplets, which play a significant role in emulsion digestion in the gastrointestinal tract. This work may indicate a potential application of soy hull polysaccharide for the construction of emulsion food delivery systems.

Influence of the particle size and hydrocolloid type on lipid digestion of thickened emulsions

Hydrocolloids are used as stabilizing agents in order to enhance the physical stability of emulsions during their storage. However, they can also play an important role in nutrient release and bioavailability. In this context, the aim of this research was to study the effect of the emulsion type and thickener type on the physical-structural changes and free fatty acid release during in vitro digestion. Oil-in-water emulsions were prepared with different particle sizes (CE: conventional emulsions and NE: nanoemulsions) and thickening agents (starch and xanthan gum). The experimental conditions of homogenization used allowed food emulsions to be obtained at the microscale and nanoscale, with particle sizes ranging among 3.2-3.4 μm and 78-107 nm for CE and NE, respectively. The addition of thickening agents (XG and ST) modified the physical properties of emulsions (particle size, zeta potential and stability) slightly, and thickened samples with similar viscosity were obtained. The kinetics of FFAs released during the in vitro intestinal digestion showed no significant differences (p > 0.05) in the digestion rate among samples; however, emulsion and thickener types decreased the final extent of free fatty acids, being more evident for those samples with starch. Xanthan gum kept the particle size of nanoemulsions stable during the oral and gastric phases, which promoted the release of FFAs during the intestinal phase. Therefore, xanthan gum could be used as a thickening agent of nanoemulsions exerting a minor impact on their lipid bioaccessibility.

Oil-in-water emulsions containing tamarind seed gum during in vitro gastrointestinal digestion: rheological properties, stability, and lipid digestibility

BACKGROUND

Polysaccharides may enhance/inhibit lipid digestibility of oil-in-water (O/W) emulsions because of their emulsifying and/or stabilizing ability and can also affect the formation, stability, and viscosity of emulsions. Tamarind seed gum (TSG) was used as the sole emulsifier/stabilizer to stabilize an O/W emulsion prepared using high-speed homogenization. We investigated the effects of various TSG concentrations (50-150 g kg^-1 ) on the lipid digestibility, rheological properties, and stability of O/W emulsions during in vitro gastrointestinal digestion.

RESULTS

A low concentration (50 g kg^-1 ) and a high concentration (150 g kg^-1 ) of TSG reduced lipid digestibility by about 33% and 45%, respectively, compared to the control sample (without TSG). However, the emulsion containing the intermediate TSG concentration at 100 g kg^-1 was the most efficient in the inhibition of lipid digestion, reducing lipid digestibility by about 70% compared to that of the control sample. The stability of emulsion tended to enhance as the concentration of TSG increased. The size of oil droplets before passing through the intestinal phase and the viscosity of the intestinal digested system may be important factors for enhancing/inhibiting lipid digestibility of emulsions. The destabilization of the emulsion during digestion was not clearly detected by rheological analysis because rheological characteristics (e.g. flow behavior index) were mainly driven by TSG.

CONCLUSIONS

The addition of TSG in O/W emulsions inhibited lipid digestibility. TSG at a concentration of 100 g kg^-1 was the most efficient in the inhibition of lipid digestibility, suggesting that TSG is an attractive alternative ingredient for control of lipid digestibility of emulsion foods. © 2020 Society of Chemical Industry.

Interactions of bile salts with a dietary fibre, methylcellulose, and impact on lipolysis

Methylcellulose (MC) has a demonstrated capacity to reduce fat absorption, hypothetically through bile salt (BS) activity inhibition. We investigated MC cholesterol-lowering mechanism, and compared the influence of two BS, sodium taurocholate (NaTC) and sodium taurodeoxycholate (NaTDC), which differ slightly by their architecture and exhibit contrasting functions during lipolysis. BS/MC bulk interactions were investigated by rheology, and BS behaviour at the MC/water interface studied with surface pressure and ellipsometry measurements. In vitro lipolysis studies were performed to evaluate the effect of BS on MC-stabilised emulsion droplets microstructure, with confocal microscopy, and free fatty acids release, with the pH-stat method. Our results demonstrate that BS structure dictates their interactions with MC, which, in turn, impact lipolysis. Compared to NaTC, NaTDC alters MC viscoelasticity more significantly, which may correlate with its weaker ability to promote lipolysis, and desorbs from the interface at lower concentrations, which may explain its higher propensity to destabilise emulsions.

Digestion behavior and gastrointestinal fate of oil-in-water emulsions stabilized by different modified rice starches

This study highlights how starch modification and the concentration of resistant starch may alter the lipid digestion behavior in oil-in-water emulsions.