Lipid digestion, micelle formation and carotenoid bioaccessibility kinetics: Influence of emulsion droplet size

Controlled lipid digestion in the development of functional and personalized foods for a tailored delivery of dietary fats

In recent decades, obesity and its associated health issues have risen dramatically. The COVID-19 pandemic has further exacerbated this trend, underscoring the pressing need for new strategies to manage weight. Functional foods designed to modulate lipid digestion and absorption rates and thereby reduce the assimilation of dietary fats have gained increasing attention in food science as a potentially safer alternative to weight-loss medications. This review provides insights into controlled lipid digestion and customized delivery of fats. The first section introduces basic concepts of lipid digestion and absorption in the human gastrointestinal tract. The second section discusses factors regulating lipid digestion and absorption rates, as well as strategies for modulating lipid assimilation from food. The third section focuses on applications of controlled lipid digestion in developing personalized foods designed for specific consumer groups, with particular emphasis on two target populations: overweight individuals and infants.

Beta-carotene-loaded Oleogels: Morphological analysis, cytotoxicity assessment, in vitro digestion and intestinal permeability

Composition and structure of oleogels significantly influence their digestive behaviour, impacting triacylglycerol breakdown and the bioavailability of incorporated compounds. Texture profile analysis showed that sterol-based oleogels (STOs) exhibited 20 times higher hardness than beeswax-based oleogels (BWOs), which showed stronger cohesion due to elasticity sustained by adhesive forces. Tribological assessments revealed similar initial coefficients of friction (COF) for both oleogels. However, fluctuations were observed in BWOs and a gradual decrease in STOs over time, enhancing lubrication, while BWOs recorded higher adhesion. These findings provide insights into their distinct digestive behaviour, with both oleogels undergoing structural disintegration and STOs displaying a higher lipolysis degree. Non-cytotoxicity was confirmed under Caco-2 cells. β-carotene bioaccessibility was influenced by the oleogels' structural modification and values of 4.0 ± 0.7 % for STOs and 2.6 ± 1.1 % for BWOs were recorded. Results highlight the need to optimize formulations to improve bioactive's bioavailability, emphasizing the role of structured gels in modulating digestion dynamics.

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

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

Rapeseed oleosomes facilitate intestinal lymphatic delivery and oral bioavailability of cannabidiol

Due to high lipophilicity and extensive first-pass metabolic loss, cannabidiol (CBD) has low oral bioavailability. Co-administration of CBD and long-chain lipids facilitates the intestinal lymphatic delivery, resulting in higher systemic bioavailability, as well as high levels of the drug within the intestinal lymphatic system. However, despite previous attempts with various lipid-based formulations, the oral bioavailability of CBD is still limited. In this work, we have developed a novel formulation of CBD based on natural rapeseed oleosomes. In vivo studies in rats demonstrated that oral administration of CBD-loaded rapeseed oleosomes leads to substantially higher oral bioavailability and intestinal lymphatic targeting of CBD in comparison with rapeseed oil or artificial emulsion made of rapeseed oil and lecithin. In vitro mechanistic assessments, including in vitro lipolysis and peroxide value determination suggest that the lower oxidative state of the oil in oleosomes in comparison to crude oil or artificial emulsion is likely to be the main factor responsible for the superior performance of the CBD-loaded rapeseed oleosomes in vivo. Although further investigation will be needed, the data suggest that natural seeds-derived oleosomes can be used as a promising lipid-based drug delivery platform promoting the bioavailability and lymphatic delivery of lipophilic drugs.

Antimicrobial activity of octyl gallate nanoemulsion combined with photodynamic technology and its effect on food preservation

Photodynamic inactivation, as a safe and effective antimicrobial technology that does not damage the organoleptic properties of the food itself, decreases the use of preservatives and is gradually gaining attention in the food industry. This study selected octyl gallate (OG) as an antimicrobial photosensitizer with eucalyptus oil as the oil phase and prepared it as an octyl gallate nanoemulsion (OG-NE) to ensure the delivery of the photosensitizer. Escherichia coli and Staphylococcus aureus inactivation with the OG-NE combined with photodynamic technology, as well as the effect on the quality of food products, was investigated. The results showed the successful preparation and homogeneous distribution of the OG-NE with an encapsulation rate of 85.18 %. The OG-NE's ability to produce single oxygen (1O2) was significantly higher, as shown by 1O2 production. The OG-NE combined photodynamic technique confirmed the effectiveness of microbial removal, demonstrating a significant increase in reactive oxygen species (ROS) and the permeability of the cell membrane. The effect of the OG-NE combined photodynamic technology on perch (microbiology, pH, whiteness, water holding capacity, TVB-N and TBA) and litchi (weight loss, titratable acid and sugar content) preservation was assessed. Food preservation experiments revealed that the OG-NE combined photodynamic technology exhibited a positive effect on food quality. The results indicated that the combination of the OG-NE and photodynamic technology provided a new alternative strategy for the food industry in antimicrobial and preservation.

Screening the carotenoid in vitro bioaccessibility of purple corn breakfast cereal consumed with milk and plant-based milk

Chronic non-communicable diseases (NCD), such as cardiovascular diseases, diabetes, and cancer, dominate global mortality, besides compromising the quality of life. Unhealthy habits like sedentary lifestyles and poor diets escalate NCD risks. Conversely, the consumption of phenolic compounds and carotenoids has shown promise in reducing NCD risks. The food industry responds by adapting products to meet demands for healthier options rich in bioactive compounds. For instance, breakfast cereals made from purple and yellow corn offer carotenoids and anthocyanins and form a nutrient-balanced meal when consumed with milk or alternatives. However, bioactive compounds in food do not guarantee absorption, necessitating bioaccessibility studies. In this study, we aimed to evaluate the bioaccessibility of the major carotenoids in two breakfast cereals, one made with 100% yellow corn and the other with 50% purple corn, co-digested with whole milk, semi-skimmed milk, skimmed milk, and almond "milk". The bioaccessibility of lutein in the breakfast cereals was evaluated using the INFOGEST 2.0 in vitro digestion method. Results showed that lutein bioaccessibility ranged from 9% to 29%. The bioaccessibility was lower than that observed in other food matrices, such as spinach and maize products. High fiber, low carotenoid contents, and anthocyanin presence negatively influenced the carotenoid bioaccessibility. Interestingly, the varying lipid content of milk showed no impact on lutein bioaccessibility under the examined conditions. In conclusion, the effects of lipids in a low range (0-7%) are not significant (p > 0.05) compared to other matrix components. When developing new products with health and nutritional benefits, it is important to consider that while fiber can reduce the bioaccessibility of carotenoids, it remains crucial for gut health.

Effect of structured lipids as dietary supplements on the fatty acid profile, carcass yield, blood chemistry, and abdominal fat deposition of female broilers

An experiment was conducted to evalute the effects of adding palm olein (POL), modified palm olein (high degree of acyl migration palm olein, H-AMD), and lard (total fatty acid saturation degree is similar to palm olein) to the diet of broilers. The study assessed production performance, fatty acid absorption, and abdominal fat deposition. A total of 100 one-week-old female broiler chicks were randomly assigned to three-tiered pens and fed five experimental diets. Enzymatic interesterification of POL causes acyl migration, transforming 1-palmitoyl-2,3-dioleoyl-sn-glycerol (sn-POO) and 1,3-dipalmitoyl-2-oleoyl-sn-glycerol (sn-POP) into 1,3-dioleoyl-2-palmitoyl-sn-glycerol (sn-OPO) and 1,2-dipalmitoyl-3-oleoyl-sn-glycerol (sn-PPO), which increases the saturated fatty acid content at the sn-2 position. Feeding broilers with this modified oil has improved the absorption effect of saturated fatty acids and increased the content of palmitic acid in abdominal tissue by 1.55%-1.69%. The impact on the content and positional distribution of fatty acids deposited in the body is limited. Low-density lipoprotein cholesterol (LDL-C) levels decreased by 34%, while high-density lipoprotein cholesterol (HDL-C) levels increased by 23%, resulting in a lower risk of atherosclerosis. No significant differences have been observed in carcass yield results of the POL and H-AMD groups. Compared with animal-derived oils such as lard which are also rich in saturated fatty acids at the sn-2 position, plant-derived oils such as POL and its modified products have a smaller effect on abdominal fat deposition.

Fabrication, digestion behavior and β-carotene bioaccessibility of emulsion-filled double-network gel: Effect of corn fiber gum/soy protein isolate ratio and surfactant types

Emulsion fortified with β-carotene was added to corn fiber gum (CFG)/soy protein isolate (SPI) double network gel matrix to obtain emulsion-filled gels (EFG) via dual induction of laccase and glucono-δ-lactone. Protein digestion was accompanied by the release of β-carotene from gel matrix during in vitro digestion. The surfactant types and corn fiber gum/soy protein isolate ratio affected the β-carotene bioaccessibility via changing oil-water interfacial composition and emulsion particle size during in vitro digestion. As compared with Tween-20 EFGs, emulsion droplets released from SPI EFGs was more susceptible to flocculation, followed with coalescence due to proteolysis of interfacial SPI during gastric digestion. The resulting oil droplets with large particle size exhibited lower lipase adsorption, thus reducing the free fatty acid content and β-carotene bioaccessibility. The confocal laser scanning microscope (CLSM) observation confirmed that protein hydrolysate from gel matrix were adsorbed onto the oil-water interface competing with Tween-20 during intestinal digestion. For EFGs with higher CFG content, steric hindrance of CFG molecules and less emulsion release could inhibit droplet flocculation, thus enhancing β-carotene bioaccessibility.

Revealing the potential effects of oil phase on the stability and bioavailability of astaxanthin contained in Pickering emulsions: In vivo, in vitro and molecular dynamics simulation analysis

This study investigated the effects of oil phases on the encapsulation rate, storage stability, and bioavailability of astaxanthin (ASTA) in Pickering emulsions (PEs). Results showed PEs of mixed oils (olive oil/edible tea oil) had excellent encapsulation efficiency (about 96.0%) and storage stability of ASTA. In vitro simulated gastrointestinal digestion results showed the mixed oil PE with a smaller interfacial area and higher monounsaturated fatty acid content may play a better role in improving ASTA retention and bioaccessibility. In vivo absorption results confirmed the mixed oil PE with an olive oil/edible tea oil of 7:3 was more favorable for ASTA absorption. Molecular dynamics simulation showed ASTA bound more strongly and stably to fatty acid molecules in the system of olive oil/edible tea oil of 7:3; and van der Waals force was the main binding force. NMR further proved there really were interactions between ASTA and four main fatty acids.

In vitro digestion and culture in Caco-2 cells to assess the bioavailability of fatty acids: A case study in meat matrix enriched with ω-3 microcapsules

This work aimed to evaluate the Caco-2 cells as a model to study the epithelial transport of intestinal lipid extracts subjected to in vitro digestion, to establish a standard protocol for the determination of bioaccessibility and bioavailability of fatty acids in meat matrix, especially in those enriched with ω-3 (eicosapentaenoic (EPA) and docosahexaenoic acids (DHA)). Samples were first subjected to in vitro digestion, and then, the intestinal extract was incubated with Caco-2 cells. A first trial was conducted to select the most influencing variables on the fatty acid transport during Caco-2 cell incubation: fat quantity on the intestinal extract, incubation time, and shaking. Then, a second experiment was carried out to determine the influence of these variables, being the fat quantity and the incubation time the most influencing factors on the transport and bioavailability of fatty acids. The effect of shaking was not so marked but seemed to improve the bioavailability of saturated fatty acids. This study also allows establishing the most suitable conditions: intestinal extracts with 30 mg of fat, longer incubation times (8 h), and shaking, achieving active and passive fatty acid transport without compromising the integrity of the Caco-2 cell monolayer. The accurate results obtained for major and minor fatty acids, especially EPA and DHA are remarkable, due to the interest in these bioactive compounds. Thus, this study provides a combined protocol based on static in vitro digestion followed by Caco-2 cell incubation to assess the bioaccessibility and bioavailability of fatty acids in meat samples.

Critical Review of Food Colloidal Delivery System for Bioactive Compounds: Physical Characterization and Application

Bioactive compounds (BACs) have attracted much attention due to their potential health benefits. However, such substances have problems such as difficulty dissolving in water, poor stability, and low intestinal absorption, leading to serious limitations in practical applications. Nowadays, food colloidal delivery carriers have become a highly promising solution due to their safety, controllability, and efficiency. The use of natural macromolecules to construct delivery carriers can not only regulate the solubility, stability, and intestinal absorption of BACs but also effectively enhance the nutritional added value of functional foods, improve sensory properties, and extend shelf life. Moreover, smart-responsive colloidal delivery carriers can control the release characteristics of BACs, thus improving their absorption rate in the human body. This review describes the characteristics of several typical food colloid delivery carriers, focuses on their physical properties from static structure to dynamic release, summarizes their applications in delivery systems, and provides an outlook on the future development of food colloid delivery carriers. The different compositions and structures of food colloids tend to affect their stability and release behaviors, and the different surface properties and rheological characteristics of the carriers predestine their different application scenarios. The control of in vivo release properties and the effect on food media should be emphasized in the future exploration of safer and more controllable carrier systems.

Fabrication of soy protein nanoparticles based on metal-phenolic networks for stabilization of nano-emulsions delivery system

The use of soy protein isolate (SPI) nanoparticles as a stabilizer in nano-emulsion systems has garnered significant interest. While metal-phenolic networks (MPNs) have been explored for their multifunctional surface modification capabilities, their integration with food protein-based delivery systems remains less explored. In this study, we attempt to develop a novel strategy to encapsulate cinnamaldehyde using MPNs (EGCG-Fe3+) with self-assembling soy protein nanoparticles (SE-Fe NPs) as a stabilizer for nano-emulsions. UV, Raman, and X-ray photoelectron spectroscopy analyses demonstrated that SE-Fe NPs were generated through metal-phenolic coordination and covalent interactions. SE-Fe NPs had a narrower particle size distribution and enhanced radical scavenging (up to 3.35-fold), as well as thermal stability. Furthermore, the smaller droplet size, higher modulus, higher cinnamaldehyde encapsulation efficiency (from 63.5% to 84.2%), and improved bio-accessibility of SE-Fe NPs stabilized nano-emulsions delivery system demonstrated in this study shows promising future applications in the food industry.

Effects of removing phytic acid on the bioaccessibility of Ca/Fe/Zn and protein digestion in soymilk

BACKGROUND

Soymilk is a high-quality source of protein and minerals, such as calcium (Ca), iron (Fe), and zinc (Zn). However, phytic acid in soymilk restricts mineral and protein availability. We here investigated the effects of removing phytic acid on the physicochemical properties, mineral (Ca, Fe, and Zn) bioaccessibility, and protein digestibility of soymilk.

RESULTS

Physicochemical property analysis revealed that the removal of phytic acid reduced protein accumulation at the gastric stage, thereby facilitating soymilk matrix digestion. The removal of phytic acid significantly increased Zn bioaccessibility by 18.19% in low-protein soymilk and Ca and Fe bioaccessibility by 31.20% and 30.03%, respectively, in high-protein soymilk.

CONCLUSION

Removing phytic acid was beneficial for the hydrolysis of high-molecular-weight proteins and increased the soluble protein content in soymilk, which was conducive to protein digestion. This study offers a feasible guide for developing plant-based milk with high nutrient bioaccessibility. © 2024 Society of Chemical Industry.

Stability and bioaccessibility of micronutrients and phytochemicals present in processed leek and Brussels sprouts during static in vitro digestion

Vegetables are frequently processed before consumption. However, vegetable functionalization continues beyond ingestion as the human digestive tract exposes vegetable products to various conditions (e.g. elevated temperature, pH alterations, enzymes, electrolytes, mechanical disintegration) which can affect the stability of micronutrients and phytochemicals. Besides the extent to which these compounds withstand the challenges posed by digestive conditions, it is equally important to consider their accessibility for potential absorption by the body. Therefore, this study investigated the impact of static in vitro digestion on the stability (i.e. concentration) and bioaccessibility of vitamin C, vitamin K1, glucosinolates, S-alk(en)yl-l-cysteine sulfoxides (ACSOs) and carotenoids in Brussels sprouts (Brassica oleracea var. gemmifera) and leek (Allium ampeloprasum var. porrum). Water-soluble compounds, glucosinolates and ACSOs, remained stable during digestion while vitamin C decreased by >48%. However, all water-soluble compounds were completely bioaccessible. Lipid-soluble compounds were also stable during digestion but were only bioaccessible for 26-81%.

Performance of β-carotene-loaded nanostructured lipid carriers under dynamic in vitro digestion system: Influence of the emulsifier type

A better understanding of how emulsifier type could differently influence the behavior of nanostructured lipid carriers (NLC) under the gastrointestinal digestion process, as well as at the cellular level, is of utmost importance for the NLC-based formulations' optimization and risk assessment in the food field. In this study, NLC composed by fully hydrogenated soybean and high-oleic sunflower oils were prepared using soy lecithin (NLC Lβ) or Tween 80 (NLC Tβ) as an emulsifier. β-Carotene was entrapped within NLC developed as a promising strategy to overcome β-carotene's low bioavailability and stability. The effect of emulsifier type on the digestibility of β-carotene-loaded NLC was evaluated using an in vitro dynamic digestion model mimicking peristalsis motion. The influence of β-carotene-loaded NLC on cell viability was assessed using Caco-2 cells in vitro. NLC Tβ remained stable in the gastric compartment, presenting particle size (PS) similar to the initial NLC (PS: 245.68 and 218.18 nm, respectively), while NLC Lβ showed lower stability (PS > 1000 nm) in stomach and duodenum phases. NLC Tβ also provided high β-carotene protection and delivery capacity (i.e., β-carotene bioaccessibility increased 10-fold). Based on the results of digestion studies, NLC Tβ has shown better physical stability during the passage through the in vitro dynamic gastrointestinal system than NLC Lβ. Moreover, the developed NLC did not compromise cell viability up to 25 µg/mL of β-carotene. Thus, the NLC developed proved to be a biocompatible structure and able to incorporate and protect β-carotene for further food applications. PRACTICAL APPLICATION: The findings of this study hold significant implications for industrial applications in terms of developing nanostructured lipid carriers from natural raw materials widely available and used to produce other lipid-based products in the food industry, as an alternative to synthetic ones. In this respect, the β-carotene-loaded NLC developed in this study would find a great industrial application in the food industry, which is in constant search to develop functional foods capable of increasing the bioavailability of bioactive compounds.

Delivery of encapsulated bioactive compounds within food matrices to the digestive tract: recent trends and future perspectives

Encapsulation technologies have achieved encouraging results improving the stability, bioaccessibility and absorption of bioactive compounds post-consumption. There is a bulk of published research on the gastrointestinal behavior of encapsulated bioactive food materials alone using in vitro and in vivo digestion models, but an aspect often overlooked is the impact of the food structure, which is much more complex to unravel and still not well understood. This review focuses on discussing the recent findings in the application of encapsulated bioactive components in fabricated food matrices. Studies have suggested that the integration of encapsulated bioactive compounds has been proven to have an impact on the physicochemical characteristics of the finished product in addition to the protective effect of encapsulation on the fortified bioactive compound. These products containing bioactive compounds undergo further structural reorganization during digestion, impacting the release and emptying rates of fortified bioactive compounds. Thus, by manipulation of various food structures and matrices, the release and delivery of these bioactive compounds can be altered. This knowledge provides new opportunities for designing specialized foods for specific populations.

Stability and gastrointestinal behavior of curcumin-loaded emulsion stabilized by multi-conformation soy proteins: Influence of oil volume fraction

The aim of this work was to assess the potential of nanoemulsions stabilized by mixed soy protein with multi-conformation as curcumin carrier, and the influence of oil volume fraction on stability and gastrointestinal behavior of curcumin-loaded emulsion was investigated. Loading efficiency showed a slight increase with higher oil content, though the difference was not statistically significant. With the increase of oil, the viscosity (Pa‧s), thixotropy (area of hysteresis loop) and particle size of the emulsion increased, which facilitated the physical and chemical stability of curcumin-loaded emulsion. However, the free fatty acid release rate and bioaccessibility of curcumin was negatively correlated with the oil volume fraction and the particle size of emulsion after gastric digestion. Notably, the digestion in stomach did not affect the structure of interfacial protein, demonstrating that protein-based nanoemulsions exhibited resistance to gastric digestion. This study provides theoretical guidance for the application of protein-based emulsion in curcumin delivery.

Phycocyanin-chitosan complex stabilized emulsion: Preparation, characteristics, digestibility, and stability

Phycocyanin is a natural pigment protein with antioxidant, anti-tumor, and anti-inflammatory properties, but its relatively poor emulsibility limits its use in the food industry. In order to improve the emulsifying capacity of phycocyanin, a novel phycocyanin-chitosan complex was prepared, and the characteristics, digestibility, and stability of emulsion containing oil droplets stabilized by the complex were investigated. The results showed that the phycocyanin-chitosan complex had better stability and lower interfacial tension at pH 6.5 than phycocyanin, and it significantly improved the stability of emulsion and inhibited the aggregation of oil droplets. The phycocyanin-chitosan complex stabilized emulsion showed better physical stability, digestibility, and oxidation stability than the phycocyanin emulsion. The particle size of the phycocyanin-chitosan complex stabilized emulsion was very small (from 0.1 to 2 μm), and its absolute value of zeta potential was high. Overall, this study suggests that the phycocyanin-chitosan complex effectively improved the emulsifying capacity of phycocyanin.

Physical properties and in-vitro gastrointestinal digestion of oil-in-water emulsions stabilized by single- and dual-modified cassava starches with cross-linking and octenylsuccinylation

The different modified cassava starches (MCS) obtained by either single or dual modifications with cross-linking (CL) and octenylsuccinylation (OS), including 2%CL, 3%OS, 2%CL-3%OS, and 3%OS-2%CL, were used to stabilize soybean oil-in-water emulsions (oil content 10% (w/w)) at a concentration of 4.5% (w/w) compared to native cassava starch (NCS) and their physical properties and in-vitro gastrointestinal digestion were investigated. The emulsions stabilized with NCS and 2%CL-MCS had larger oil droplet sizes, higher viscosity, and lower negative charge than the emulsions stabilized by single- or dual-MCS with 3%OS. All MCS-stabilized emulsions showed a higher emulsion stability against creaming than the NCS-stabilized emulsion. Under a simulated gastrointestinal tract, all 3%OS-MCS promoted droplet flocculation, while the less ionic NCS and the 2%CL-MCS showed a decrease in droplet size after passing through the mouth and stomach stages. The lipid digestion rate of emulsions stabilized with different MCS and NCS followed the following order: 3%OS >2%CL-3%OS > 3%OS-2%CL > 2%CL > NCS. The NCS- and 2%CL-stabilized emulsions had a lower lipid digestion rate, possibly due to the larger droplet sizes and higher viscosity of the initial emulsions, which delays access of lipase enzymes to lipid droplet surfaces, compared to all 3%OS-MCS-stabilized emulsions.

Co-delivery of vitamin C and β-carotene in W/O/W emulsions stabilized by modified aggregated insoluble soybean protein hydrolysate-xanthan gum complexes

Environmentally friendly emulsifiers safe for human consumption are urgently needed to stabilize emulsions for applications in the food industry. In this study, we prepared complexes combining modified aggregated insoluble soybean protein hydrolysate (AISPH) mixed with xanthan gum (XG) (0.05-0.3 %, w/v), and further to construct water-in-oil-in-water (W/O/W) emulsions to deliver vitamin C and β-carotene. We observed a decrease in the AISPH α-helix and β-sheet content, surface hydrophobicity, and fluorescence intensity all decreased after binding. In contrast, the particle size and absolute ξ-potential significantly increased, indicating that molecular non-covalent interactions occurred in the solution. The emulsification property of AISPH was also improved by adding XG, and the AISPH-XG-stabilized emulsion showed improved stability, encapsulation efficiency, and rheological properties. Among them, AISPH-XG-0.25-stabilized emulsion exhibited a smaller particle size (8.41 ± 0.49 μm) and the highest encapsulation efficiency for vitamin C (90.03 ± 0.23 %) and β-carotene (70.56 ± 0.06 %). Additionally, simulated gastric digestion indicated that vitamin C and β-carotene bioavailability increased by 3.6 and 5.8 times, respectively. Finally, the emulsion exhibited good pH, ionic, and thermal stability. In general, AISPH-XG-stabilized W/O/W emulsions showed good stability and carrying capacity, providing a theoretical basis for improving their application.

Sucrose Stearates Stabilized Oil-in-Water Emulsions: Gastrointestinal Fate, Cell Cytotoxicity and Proinflammatory Effects after Simulated Gastrointestinal Digestion

Different structural composition ratios of sucrose stearates with hydrophilic-hydrophobic balance (HLB) values ranging from 1 to 16 on lipolysis in emulsion were investigated using a simulated gastrointestinal tract (GIT). Results showed a direct correlation between the HLB values of sucrose stearates and the lipolysis rate of emulsions, and a lower HLB value led to diminished lipolysis in the GIT simulation model. Mechanism study indicated that poor emulsifying capacity of sucrose stearates and lipolysis of sucrose stearates with lower HLB value inhibited the digestive behavior of oil. In addition, monoester was mainly hydrolyzed in the gastric phase, whereas sucrose polyesters caused lipolysis in the intestinal phase using an in vitro digestive model and HPLC analysis, further suppressing lipid digestion. Furthermore, a decrease in cell cytotoxicity and proinflammatory effects on Caco-2 and Raw264.7 were observed post-digestion, respectively. This work offers important insights into the effects of the degree of esterification of sucrose stearate on lipid digestion behavior in oil-in-water emulsions.

Excipient emulsion prepared with pectin and sodium caseinate to improve the bioaccessibility of carotenoids in mandarin juice: The effect of emulsifier and polymer concentration

Excipient emulsions were prepared using different emulsifiers (pectin and sodium caseinate, individually or compositely) to study the emulsifying properties and their co-digested effects on the retention and bioaccessibility of carotenoids in mandarin juice, which is a good source of carotenoids in people's diet. Results showed that both pectin (PC) and pectin-sodium caseinate (PC-SC) emulsion significantly increased the carotenoids retention and bioaccessibility of mandarin juice, with the effects depending on both emulsifiers and polymer concentration. Whether for PC or PC-SC emulsion, lower pectin content accompanied with lower viscosity showed higher carotenoids bioaccessibility. And for the complexed emulsions, appropriate sodium caseinate addition could be more beneficial in improving carotenoids bioaccessibility. It had been found that the viscosity comparing with particle size seemed to play a more important role in affecting carotenoid bioaccessibility during the co-digestion. This study could provide a basis for improving the carotenoids bioaccessibility in the real system of fruits and vegetables with excipient emulsions.

Water-soluble biopolymers from heat-treated and high pressure homogenized vegetable purées: investigating their emulsion forming and stabilizing capacities

The emulsion forming and stabilizing capacities of water-soluble biopolymers originating from the aqueous (serum) phase of heat-treated and high pressure homogenized purées were investigated. The serum biopolymers were characterized and then utilized as emulsifier/stabilizer in simple oil-in-water emulsions. The resulting emulsions were stored at 4 °C and monitored for 2 weeks. Results revealed that carrot and tomato sera contained higher amounts of pectin and lower protein compared to broccoli. The serum pectic biopolymers exhibited distinct molecular structures, depending on the vegetable origin. Given these natural biopolymer composition and characteristics, emulsions with small droplet sizes were observed at pH 3.5. However, emulsions at pH 6.0 showed large mean droplet sizes, except for the emulsion formulated with carrot serum. Regardless of the pH, emulsions containing carrot serum biopolymers exhibited high capacity to form fine emulsions that were stable during the 2-week storage period at low temperature. This study clearly shows the capacity of natural water-soluble biopolymers isolated from the serum phase of vegetable purées to form fine emulsion droplets and maintain its stability during storage, especially in the case of carrot serum biopolymers.

Differences in fat digestion from milk of different Species: In vitro gastrointestinal digestion model for infants

The differences in the milk fat digestion from goat milk (GM), camel milk (CM), bovine milk (BM), sheep milk (SM), mare milk (MM) and human milk (HM) using an in vitro gastrointestinal digestion model for simulated infants were investigated. The particle size distributions in goat and mare milk were similar to that of HM after digestion in the small intestine. During in vitro digestion, the zeta-potential change of MM was more consistent with that of HM. After 60 min of gastric digestion, the lipolysis degree (LD) of different milks were<2%, of which the highest LD was MM (1.84%), followed by HM (1.45%). At the end of intestinal digestion, the LD of HM was the highest, reaching 88.47%, and the LD of SM was similar to that of HM, reaching 83.92%, followed by GM (57.00%), BM (40.98%) and MM (39.37%), respectively, the LD of CM was only 29.99%, which was much lower than HM. The results of the glyceride composition hierarchical clustering analysis revealed that MM and HM were clustered into one category at the end of gastric and intestinal digestion. This study provides a scientific basis for the development of lipid ingredients in infant formula.

Effect of digestible versus non-digestible citral nanoemulsions on human gut microorganisms: An in vitro digestion study

Essential oil (EO) nanoemulsions have been recently studied due to their antimicrobial properties. Nevertheless, little is known about their possible negative effect against human gut microorganisms during their passage though the gastrointestinal tract. This work studied the effect of digestible (corn oil) or non-digestible (paraffin oil) citral nanoemulsions against specific microorganisms of human microflora under in vitro digestion conditions. The use of a citral lipid carrier (paraffin oil or corn oil) decreased the nanoemulsion particle size and increased its stability after gastric conditions with regards to the pure citral nanoemulsions. Digestible nanoemulsions formulated with corn oil and citral presented a lower bactericidal activity against Lactobacillus acidophilus and Escherichia coli after being subjected to in vitro digestion conditions in comparison to the initial nanoemulsion. However, a non-digestible nanoemulsion formulated with paraffin oil and citral presented a similar antimicrobial activity against L. acidophilus and E. coli to the one of the initial nanoemulsion. This evidences that non-digestible nanoemulsions may entrap the citral in the lipid core and thus retaining its antimicrobial potential during their passage though the gastrointestinal tract. Hence, this work evidences the impact of the lipid carrier digestibility when formulating antimicrobial nanoemulsions on certain intestinal probiotic bacteria.

Oleogelation of extra virgin olive oil by different gelators affects lipid digestion and polyphenol bioaccessibility

The possibility to steer extra virgin olive oil (EVOO) digestion and polyphenol bioaccessibility through oleogelation was investigated. EVOO was converted into oleogels using lipophilic (monoglycerides, rice wax, sunflower wax, phytosterols) or hydrophilic (whey protein aerogel particles, WP) gelators. In-vitro digestion demonstrated that the oleogelator nature influenced both lipid digestion and polyphenol bioaccessibility. WP-based oleogels presented ∼100% free fatty acid release compared to ∼64% for unstructured EVOO and ∼40 to ∼55% for lipophilic-based oleogels. This behavior was attributed to the ability of WP to promote micelle formation through oleogel destructuring. Contrarily, the lower lipolysis of EVOO gelled with lipophilic gelators compared to unstructured EVOO suggested that the gelator obstructed lipase accessibility. Tyrosol and hydroxytyrosol bioaccessibility increased for WP oleogels (∼27%), while liposoluble-based oleogels reduced it by 7 to 13%. These findings highlight the deep effect of the gelator choice on the digestion fate of EVOO components in the human body.

Soy Protein Isolate-Chitosan Nanoparticle-Stabilized Pickering Emulsions: Stability and In Vitro Digestion for DHA

The purpose of the study was to investigate the stability and oral delivery of DHA-encapsulated Pickering emulsions stabilized by soy protein isolate-chitosan (SPI-CS) nanoparticles (SPI-CS Pickering emulsions) under various conditions and in the simulated gastrointestinal (GIT) model. The stability of DHA was characterized by the retention rate under storage, ionic strength, and thermal conditions. The oral delivery efficiency was characterized by the retention and release rate of DHA in the GIT model and cell viability and uptake in the Caco-2 model. The results showed that the content of DHA was above 90% in various conditions. The retention rate of DHA in Pickering emulsions containing various nanoparticle concentrations (1.5 and 3.5%) decreased to 80%, while passing through the mouth to the stomach, and DHA was released 26% in 1.5% Pickering emulsions, which was faster than that of 3.5% in the small intestine. After digestion, DHA Pickering emulsions proved to be nontoxic and effectively absorbed by cells. These findings helped to develop a novel delivery system for DHA.

Application of spray drying, spray chilling and the combination of both methods to produce tucumã oil microparticles: characterization, stability, and β-carotene bioaccessibility

The aim of this work was to produce tucumã oil (PO) microparticles using different encapsulation methods, and to evaluate their properties, storage stability and bioaccessibility of the encapsulated β-carotene. Gum Arabic was used as carrier for spray drying (SD), while vegetable fat was the wall material for spray chilling (SC) and the combination of the methods (SDC). Powders were yellow (hue angle around 80°) and presented particles with small mean diameters (1.57-2.30 µm). PO and the microparticles possess high β-carotene contents (∼0.35-22 mg/g). However, some carotenoid loss was observed in the particles after encapsulation by SD and SDC (around 20%). After 90 days of storage, SDC particles presented the lowest degradation of total carotenoids (∼5%), while SD samples showed the highest loss (∼21%). Yet, the latter had the lowest contents of conjugated dienes (4.1-5.3 µmol/g) among treatments. At the end of simulated digestion, PO and the microparticles provided low β-carotene bioaccessibility (<10%), and only SC increased this parameter compared to the pure oil. In conclusion, carotenoid-rich microparticles with attractive color were obtained through microencapsulation of PO by SD, SC and SDC, revealing their potential as natural additives for the development of food products with improved nutritional properties. The SC method stood out for providing microparticles with high carotenoid content and retention, high oxidative stability, and improved β-carotene bioaccessibility.

Bioaccessibility and bioactive potential of different phytochemical classes from nutraceuticals and functional foods

Nutraceuticals and functional foods are composed of especially complex matrices, with polyphenols, carotenoids, minerals, and vitamins, among others, being the main classes of phytochemicals involved in their bioactivities. Despite their wide use, further investigations are needed to certify the proper release of these phytochemicals into the gastrointestinal medium, where the bioaccessibility assay is one of the most frequently used method. The aim of this review was to gather and describe different methods that can be used to assess the bioaccessibility of nutraceuticals and functional foods, along with the most important factors that can impact this process. The link between simulated digestion testing of phytochemicals and their in vitro bioactivity is also discussed, with a special focus on the potential of developing nutraceuticals and functional foods from simple plant materials. The bioactive potential of certain classes of phytochemicals from nutraceuticals and functional foods is susceptible to different variations during the bioaccessibility assessment, with different factors contributing to this variability, namely the chemical composition and the nature of the matrix. Regardless of the high number of studies, the current methodology fails to assume correlations between bioaccessibility and bioactivity, and the findings of this review indicate a necessity for updated and standardized protocols.

The impact of age-related digestive disorders on in vitro digestibility of macronutrients and bioaccessibility of minor components of chia seeds

Gastrointestinal (GI) functions deteriorate with age, primarily affecting protein digestion. The consumption of chia seeds may be helpful for the elderly because they offer a vegetable-based source of proteins, healthy lipids, fibre and micronutrients. The impact of common age-related GI deterioration on chia seed digestibility was assessed using in vitro digestion models. The goal was to study the potential of chia seeds as part of the diet of seniors. Deterioration in the oral, gastric and intestinal stages of digestion was cumulatively assessed in three digestion models: E1 (deterioration in oral conditions), E2 (deterioration in oral and gastric conditions) and E3 (deterioration in oral, gastric and intestinal conditions). Less efficient chewing (E1) decreased proteolysis, lipolysis and antioxidant capacity (p < 0.05). In contrast, deterioration in gastric functions seemed to affect only total polyphenolic content. Finally, in the model simulating the greatest deterioration in digestive functions (E3), all measured variables were negatively affected (proteolysis, lipolysis, amino acid release, total phenolic content, antioxidant capacity and calcium). Calcium bioaccessibility fell by 24 % with a decrease in pancreatic enzymes and bile secretion (E3). Age-related reduced digestive function did not affect the ratio of essential to non-essential amino acids in the digested samples in any case. However, under suboptimal GI conditions (E3), amino acids such as valine, leucine and isoleucine, which are important for sarcopenia prevention in the elderly, fell by 39 %, 49 % and 44 %, respectively. These findings might be helpful for further in vitro studies of chia seeds as a possible food ingredient. They may also be useful for the development of more targeted nutrition strategies in the elderly.

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.

Emulsifying properties, in vitro digestive characteristics, and β-carotene bioaccessibility of mandarin peel pectin emulsions prepared with different carrier oil phases

Mandarin peel pectin (MPP) emulsions were prepared with different oil phase loadings with or without β-carotene, and their emulsifying characteristics, digestive properties and β-carotene bioaccessibility were investigated. Results revealed that all MPP emulsions exhibited good loading efficiency for β-carotene, while their apparent viscosity and interfacial pressure (π) of MPP emulsions increased significantly after the addition of β-carotene. Emulsification of MPP emulsions as well as digestibility were significantly dependent on the kind of oil. MPP emulsions prepared with long-chain triglycerides (LCT) oil (soybean, corn, and olive oil) exhibited higher volume average particle size (D_4,3), apparent viscosity, π values, and bioaccessibility of carotene compared to those prepared with medium-chain oils (MCT). MPP emulsions with LCT rich in monosaturated fatty acids (olive oil) had the highest β-carotene encapsulation efficiency, bioaccessibility, etc. than from other oils. This study provides a theoretical basis for the efficient encapsulation and high bioaccessibility of carotenoids with pectin emulsions.

Polysaccharide-based structured lipid carriers for the delivery of curcumin: An in vitro digestion study

The present work aimed at studying the in vitro digestion fate of κ-carrageenan (KC) or agar (AG) emulsion gels (EG), and KC oil-filled aerogels (OAG) in terms of their structural changes, lipolysis kinetics and curcumin bioaccessibility. On the one hand, both EG and aerogels showed large (70-200 µm) and heterogeneous particles after gastric conditions, indicating the release of bulk oil and gelled material. Nonetheless, this material release in the stomach phase was lower in the case of EG-AG and OAG-KC compared to EG-KC. After small intestinal conditions, EG and oil-filled aerogels presented a wide range of particle sizes probably due to the presence of undigested lipid material, gelled structures, as well as lipid digestion products. For the most part, adding curcumin to the structures' lipid phase did not cause of the structural modifications that occurred at the different in vitro digestion phases. On the other hand, the lipolysis kinetics was different depending on the type of structure. Amongst emulsion-gels, those formulated with κ-carrageenan presented a slower and lower lipolysis kinetics compared to those formulated with agar, which could be attributed to their higher initial hardness. Overall, the addition of curcumin in the lipid phase decreased the lipolysis in all the structures, which evidenced its interference in the lipid digestion process. The curcumin bioaccessibility reached high values (≈ 100 %) for all the studied structures, presenting a high solubility in intestinal fluids. This work unravels the implications of microstructural changes of emulsion-gels and oil-filled aerogels during digestion and their impact on their digestibility and subsequent functionality.

Oral bioavailability of bioactive compounds; modulating factors, in vitro analysis methods, and enhancing strategies

Foods are complex biosystems made up of a wide variety of compounds. Some of them, such as nutrients and bioactive compounds (bioactives), contribute to supporting body functions and bring important health benefits; others, such as food additives, are involved in processing techniques and contribute to improving sensory attributes and ensuring food safety. Also, there are antinutrients in foods that affect food bioefficiency and contaminants that increase the risk of toxicity. The bioefficiency of food is evaluated with bioavailability which represents the amount of nutrients or bioactives from the consumed food reaching the organs and tissues where they exert their biological activity. Oral bioavailability is the result of some physicochemical and biological processes in which food is involved such as liberation, absorption, distribution, metabolism, and elimination (LADME). In this paper, a general presentation of the factors influencing oral bioavailability of nutrients and bioactives as well as the in vitro techniques for evaluating bioaccessibility and is provided. In this context, a critical analysis of the effects of physiological factors related to the characteristics of the gastrointestinal tract (GIT) on oral bioavailability is discussed, such as pH, chemical composition, volumes of gastrointestinal (GI) fluids, transit time, enzymatic activity, mechanical processes, and so on, and the pharmacokinetics factors including BAC and solubility of bioactives, their transport across the cell membrane, their biodistribution and metabolism. The impact of matrix and food processing on the BAC of bioactives is also explained. The researchers' recent concerns for improving oral bioavailability of nutrients and food bioactives using both traditional techniques, for example, thermal treatments, mechanical processes, soaking, germination and fermentation, as well as food nanotechnologies, such as loading of bioactives in different colloidal delivery systems (CDSs), is also highlighted.

Food nanoemulsions: how simulated gastrointestinal digestion models, nanoemulsion, and food matrix properties affect bioaccessibility of encapsulated bioactive compounds

Food nanoemulsions are known as very effective and excellent carriers for both lipophilic and hydrophilic bioactive compounds (BCs) and have been successfully used for controlled delivery and protection of BCs during gastrointestinal digestion (GID). However, due to sensitive and fragile morphology, BCs-loaded nanoemulsions have different digestion pathways depending on their properties, food matrix properties, and applied models for testing their digestibility and BCs bioaccessibility. Thus, this review gives a critical review of the behavior of encapsulated BCs into food nanoemulsions during each phase of GID in different static and dynamic in vitro digestion models, as well as of the influence of nanoemulsion and food matrix properties on BCs bioaccessibility. In the last section, the toxicity and safety of BCs-loaded nanoemulsions evaluated on in vitro and in vivo GID models have also been discussed. Better knowledge of food nanoemulsions' behavior in different models of simulated GI conditions and within different nanoemulsion and food matrix types can help to standardize the protocol for their testing aiming for researchers to compare results and design BCs-loaded nanoemulsions with better performance and higher targeted BCs bioaccessibility.

Pre-duodenal lipid digestion of emulsions: Relevance, colloidal aspects and mechanistic insight

The digestion of lipids in the human body has several health and nutritional implications. Lipid digestion is an interfacial phenomenon meaning that water-soluble lipases need to first adsorb to the oil-water interface before enzymatic conversions can start. The digestion of lipids mainly occurs on colloidal structures dispersed in water, such as oil-in-water (o/w) emulsions, which can be designed during food formulation/processing or structured during digestion. From a food design perspective, different in vitro studies have demonstrated that the kinetics of lipid digestion can be influenced by emulsion properties. However, most of these studies have been performed with pancreatic enzymes to simulate lipolysis in the small intestine. Only few studies have dealt with lipid digestion in the gastric phase and its subsequent impact on intestinal lipolysis. In this aspect, this review compiles information on the physiological aspects of gastric lipid digestion. In addition, it deals with colloidal and interfacial aspects starting from emulsion design factors and how they evolve during in vitro digestion. Finally, molecular mechanisms describing gastric lipolysis are discussed.

Encapsulation of lycopene into electrospun nanofibers from whey protein isolate-Tricholoma lobayense polysaccharide complex stabilized emulsions: Structural characterization, storage stability, in vitro release, and cellular evaluation

In this study, lycopene-loaded nanofibers were successfully fabricated by electrospinning of oil-in-water (O/W) emulsions stabilized by whey protein isolate-polysaccharide TLH-3 (WPI-TLH-3) complexes. The lycopene encapsulated in the emulsion-based nanofibers exhibited enhanced photostability and thermostability, and achieved improved targeted small intestine-specific release. The release of lycopene from the nanofibers followed Fickian diffusion mechanism in simulated gastric fluid (SGF) and first-order model in simulated intestinal fluid (SIF) with the enhanced release rates. The bioaccessibility and cellular uptake efficiency of lycopene in micelles by Caco-2 cells after in vitro digestion were significantly improved. The intestinal membrane permeability and transmembrane transport efficiency of lycopene in micelles across Caco-2 cells monolayer were greatly elevated, thus promoting the effective absorption and intracellular antioxidant activity of lycopene. This work opens a potential approach for electrospinning of emulsions stabilized by protein-polysaccharide complexes as a novel delivery system for liposoluble nutrients with enhanced bioavailability in functional food industries.

Carotenoids and Their Health Benefits as Derived via Their Interactions with Gut Microbiota

Carotenoids have been related to a number of health benefits. Their dietary intake and circulating levels have been associated with a reduced incidence of obesity, diabetes, certain types of cancer, and even lower total mortality. Their potential interaction with the gut microbiota (GM) has been generally overlooked but may be of relevance, as carotenoids largely bypass absorption in the small intestine and are passed on to the colon, where they appear to be in part degraded into unknown metabolites. These may include apo-carotenoids that may have biological effects because of higher aqueous solubility and higher electrophilicity that could better target transcription factors, i.e., NF-κB, PPARγ, and RAR/RXRs. If absorbed in the colon, they could have both local and systemic effects. Certain microbes that may be supplemented were also reported to produce carotenoids in the colon. Although some bactericidal aspects of carotenoids have been shown in vitro, a few studies have also demonstrated a prebiotic-like effect, resulting in bacterial shifts with health-associated properties. Also, stimulation of IgA could play a role in this respect. Carotenoids may further contribute to mucosal and gut barrier health, such as stabilizing tight junctions. This review highlights potential gut-related health-beneficial effects of carotenoids and emphasizes the current research gaps regarding carotenoid-GM interactions.

Anti-inflammatory effect of two pomegranate seed oils obtained by green technologies in Caco-2 cells using the bioaccessible fraction from in vitro gastrointestinal digestion

Pomegranate seeds contain up to 20% oil with a high content of punicic acid (85%), which is responsible for several biological activities. In this work, two pomegranate oils obtained by a two-step sequential extraction, first with an expeller and then via supercritical CO₂ technologies, have been studied in a static gastrointestinal in vitro digestion model to evaluate their bioaccessibility. The micellar phases obtained were evaluated by an in vitro model of intestinal inflammation and Caco-2 cells exposed to the inflammatory mediator lipopolysaccharide (LPS). Inflammatory response was assessed by measuring the production of interleukins IL-6 and IL-8, and tumor necrosis factor α (TNF-α), and by evaluating the monolayer integrity. The results obtained indicate that expeller pomegranate oil (EPO) provides the highest amount of micellar phase (ca. 93%) with free fatty acids and monoacylglycerols as major components. The micellar phase obtained with supercritical CO₂ pomegranate oil (SCPO) is ca. 82% with similar lipid composition. Micellar phases of EPO and SCPO showed high stability and adequate particle size. EPO shows an anti-inflammatory response, reducing the production of IL-6, IL-8 and TNF-α in LPS stimulated caco-2 cells and increasing the integrity of the cell monolayer as measured by transepithelial electrical resistance (TEER). In the case of SCPO, the anti-inflammatory effect was only evident for IL-8. The present work demonstrates good digestibility, bioaccessibility and anti-inflammatory response of both EPO and SCPO oils.

Stability and digestibility of encapsulated lycopene in different emulsion systems stabilized by acid-modified soybean lipophilic protein

BACKGROUND

Owing to the harsh acidic environment of the stomach, acid-resistant emulsion products have wide-ranging applications in the food industry. Herein, natural soybean lipophilic protein (LP) was used to establish coarse emulsions, nanoemulsions, emulsion gels, and high internal phase Pickering emulsions (HIPPE) under acidic conditions. Furthermore, the carrying characteristics of the acid-resistant emulsion system with lycopene were explored.

RESULTS

Comparisons of particle sizes, potentials, microstructures, and rheology of the four carrier systems revealed that HIPPE has a single particle-size distribution, the largest zeta potential, and an elastic gel-like network structure. Comparison of encapsulation rates indicated that HIPPE had the best effect on encapsulating lycopene, reaching approximately 90%. The pH stability, storage stability, and simulated in vitro digestion experiments showed that the four emulsions that were stable under acidic conditions had good acid resistance. Among them, the acid-induced LP-stabilized HIPPE had the best storage stability and superior compatibility with the harsh acidic environment of the stomach, which not only achieved the purpose of delaying the release of lipids but also conferred better protection to lycopene in the gastric tract; moreover, it achieved the best bioavailability.

CONCLUSION

LP-stabilized HIPPE has the best stability and can yield better absorption and utilization of lycopene by the body. The results of this study are helpful for the development of acid-resistant functional emulsion foods that are conducive to the absorption of lycopene. © 2022 Society of Chemical Industry.

Storage stability and in vitro digestion of apigenin encapsulated in Pickering emulsions stabilized by whey protein isolate–chitosan complexes

Few studies have investigated the encapsulation of apigenin in solid particle-stabilized emulsions. In this work, Pickering emulsions containing apigenin and stabilized by whey protein isolate-chitosan (WPI-CS) complexes were created to enhance the bioavailability of apigenin. Different lipids including medium-chain triglycerides (MCTs), ethyl oleate (EO), and corn oil (CO) were selected to fabricate lipid-based delivery systems. The microstructure of the Pickering emulsions, as revealed by optical and cryo-scanning electron microscopies, showed that the oil droplets were dispersed evenly and trapped by a three-dimensional network formed by the WPI-CS complexes, which was further confirmed by rheology properties. After 30 days of storage, Pickering emulsions with MCTs achieved the highest apigenin retention rate, exhibiting 95.05 ± 1.45% retention when stored under 4°C. In vitro gastrointestinal tract experiments indicated that the lipid types of the emulsions also affected the lipid digestion and release rate of apigenin. Pickering emulsions with MCTs achieved a higher bioaccessibility compared to that of the other two emulsions (p < 0.01). These results indicate that the delivery system of Pickering emulsions with MCTs stabilized by WPI-CS complexes offers good storage stability and improved bioaccessibility of apigenin.

Steering protein and lipid digestibility by oleogelation with protein aerogels

The aim of the present work was to assess the effect of an innovative oleogelation strategy, the aerogel-template approach, on protein and lipid digestibility. Whey protein isolate (WP) was converted into aerogel particles via supercritical CO₂ drying. Oleogels were then prepared by absorption of sunflower (SO) or flaxseed (FLX) oil (80%, w/w) into the aerogel particle template and subjected to in vitro digestion. WP aerogel-templated oleogels showed a specific destructuring behaviour during digestion. Confocal micrographs clearly demonstrated that the original oleogel structure was lost at the gastric level, with the release of oil droplets smaller (D₃₂ < 10 μm) than those observed in the case of the unstructured oils (D₃₂ > 30 μm), stabilised by undigested aerogel proteins. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and bicinchoninic acid (BCA) assay confirmed that aerogelation reduced the gastric proteolysis of WP from nearly 100% to 70%. The digestion of the SO oleogel led to similar gastric protein digestibility. In contrast, in the case of the FLX oleogel, gastric proteolysis decreased to 40%, suggesting a role of the oil nature in steering WP aerogel digestion. In all cases, upon intestinal digestion aerogel proteins resulted completely hydrolysed. The lipolysis degree of SO (75%) and FLX (34%) oil in the oleogels was higher than that of the unstructured SO (66%) and FLX (24%) oils, due to the larger surface offered by smaller oil droplets to the action of intestinal lipases. This was confirmed by dynamic light scattering, showing a shift towards smaller size in the digestive micelle distribution of oleogels at the end of the intestinal phase. Oleogelation through the WP aerogel-template approach could be regarded as a strategy to steer lipid digestibility while also modulating the release of bioaccessible peptides.

Impact of internal aqueous phase gelation on in vitro lipid digestion of epigallocatechin gallate-loaded W1 /O/W2 double emulsions incorporated in alginate hydrogel beads

Our objective was to investigate if the internal aqueous phase gelation of Water-in-oil-in-water double emulsions encapsulated in alginate beads would affect their structural stability and lipid hydrolysis during in vitro digestion. Therefore, bioactive molecules such as (-)-epigallocatechin gallate were encapsulated into different types of delivery systems: original double emulsions (as control) and incorporated double emulsions (filled in alginate hydrogel beads), both with non-gelled or gelled internal aqueous phase by locust bean gum and κ-carrageenan. After 2 h of gastric digestion, the gelled original emulsions showed smaller mean droplet diameters and less coalescence during the in vitro simulated gastrointestinal digestion compared to the non-gelled original emulsions. For the incorporated emulsions, oil droplets released from beads aggregated under intestinal conditions, and the rate of lipolysis was delayed. Interestingly, the internal aqueous phase gelation also impacted the rate and cumulative amount of free fatty acids (FFA) released. PRACTICAL APPLICATION: The combination of incorporating (-)-epigallocatechin gallate-loaded double emulsions into the alginate hydrogel matrix and gelling the internal aqueous phase was a benefit to regulating the rate and extent of lipid digestion for specific applications in foods, such as to control blood lipid levels and appetite.