Influence of oleogel composition on lipid digestibility and ß-carotene bioaccessibility during in vitro digestion.

This study explored how co-oleogelator type, concentration, and water addition affect lipid digestion and ß-carotene (ßC) bioaccessibility in corn oil oleogels. Oleogels containing 0.1% ßC, 20% glyceryl stearate (GS), with lecithin (L) or hydrogenated lecithin (HL) (at 0, 0.5, or 2.5%) and their water-filled counterparts (1% water) were examined. In vitro intestinal digestion revealed HL-oleogels experienced higher lipolysis due to their smaller crystal size enhancing surface area for lipase action, whereas L-oleogels presented lower digestibility, attributed to larger oil droplets and a minimized surface area. Water addition didn't significantly change lipid digestibility. ßC bioaccessibility was inversely related to co-oleogelator concentration, with L-oleogels demonstrating the largest decrease, likely due to less free fatty acids released for micelle formation. However, water-filled oleogels enhanced ßC bioaccessibility. These findings highlight that tailored microstructure in oleogels can control lipid digestion and ßC bioaccessibility, paving the way for designing efficient delivery systems for targeted nutrient delivery.

Combination of legume proteins and arabinoxylans are efficient emulsifiers to promote vitamin E bioaccessibility during digestion.

The emulsification potential of plant-based emulsifiers, that is, pea (PPI) and lentil (LPI) proteins (4%), corn arabinoxylans (CAX, 1%), and legume protein-arabinoxylan mixtures (4% proteins + 0.15 or 0.9% CAX), was evaluated by assessing: the surface tension and potential of emulsifiers, emulsifier antinutritional contents, emulsion droplet size, emulsion physical stability, and vitamin E bioaccessibility from 10% oil-in-water emulsions. Tween 80 (2%) was used as a control. All emulsions presented small droplet sizes, both fresh and upon storage, except 4% LPI + 0.9% CAX emulsion that exhibited bigger droplet sizes (d(4,3) of approximately 18.76 µm vs 0.59 µm for the control) because of droplet bridging. Vitamin E bioaccessibility from emulsions stabilized with the combination of 4% PPI and either 0.15% or 0.9% CAX (28 ± 4.48% and 28.42 ± 3.87%, respectively) was not significantly different from that of emulsions stabilized with Tween 80 (43.56 ± 3.71%), whereas vitamin E bioaccessibility from emulsions stabilized with individual emulsifiers was significantly lower.

Modulating edible-oleogels physical and functional characteristics by controlling their microstructure.

The influence of co-oleogelators like lecithin or hydrogenated lecithin together with the addition of dispersed water droplets to modulate the microstructure and thus the physical properties of glyceryl stearate (GS)-corn oil oleogels was investigated by thermal profile, microstructure, hardness, and oil binding capacity (OBC). The addition of ß-carotene (ßC) was also assessed. With lecithin, crystallization and melting temperatures were reduced, resulting in less-ordered crystal networks with a lower hardness and OBC, while with hydrogenated lecithin, the opposite effect was observed. In the presence of water, oleogels became harder but more brittle. Finally, ßC acted as a crystal modifier increasing the hardness and OBC in the presence of lecithin, but decreased these parameters in hydrogenated lecithin-containing and water-filled oleogels. This study provides a better understanding on how the composition of GS-based oleogels can affect their physical properties.

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.

Impact of the lipid phase composition and state on the in vitro digestibility and chlorophyllin bioaccessibility of W1/O/W2 emulsions into whole milk.

Water-in-oil-in-water (W1/O/W2) emulsions offer the potential to deliver hydrophilic bioactive compounds into foods, yet their application remains limited due to their instability. Thus, the impact of lipid phase composition and state on the colloidal stability, in vitro lipid digestibility and chlorophyllin (CHL) bioaccessibility of W1/O/W2 emulsions before and after incorporation into whole milk was studied. Medium-chain triglyceride oil (MCT) was used as a liquid lipid phase and MCT with glyceryl stearate (GS) or pure hydrogenated palm oil (HPO) as gelled lipid phases. The lipid phase composition was crucial to forming W1/O/W2 emulsions. MCT or MCT+GS allowed the successful formation of W1/O/W2 emulsions, being more stable upon gastric conditions those formulated with MCT+GS than pure MCT. In contrast, the use of HPO led to phase separation, which was maintained after the gastric conditions. Regarding their lipid digestibility, W1/O/W2 emulsions formulated with MCT or MCT+GS were fully digested, whereas only 40% of the lipid was digested using HPO. In accordance, the CHL bioaccessibility was higher using MCT or MCT+GS than HPO. When co-digested with whole milk, the colloidal stability and lipid digestibility of the W1/O/W2 emulsions with MCT or MCT+GS were not altered, whereas the W1/O/W2 emulsion-HPO showed enhanced colloidal stability and lipid digestibility (57.71 ± 3.06%), due to the surface-active properties of milk protein. The present study provides useful information to develop stable functional foods enriched with hydrophilic bioactive compounds by using W1/O/W2 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.

Emulsion gels and oil-filled aerogels as curcumin carriers: Nanostructural characterization of gastrointestinal digestion products.

Agar and κ-carrageenan emulsion gels and oil-filled aerogels were investigated as curcumin carriers and their structure and mechanical properties, as well as their structural changes upon in vitro gastrointestinal digestion were characterized. Agar emulsion gels presented stiffer behaviour, with smaller and more homogeneous oil droplets (ϕ âˆ¼ 12 µm) than those from κ-carrageenan (ϕ âˆ¼ 243 µm). The structure of κ-carrageenan gels was characterized by the presence of rigid swollen linear chains, while agar produced more branched networks. After simulated gastrointestinal digestion bile salt lamellae/micelles (∼5 nm) and larger vesicles of partially digested oil (Rg âˆ¼ 20-50 nm) were the predominant structures, being their proportion dependent of the polysaccharide type and the physical state of the gel network. The presence of curcumin induced the formation of larger vesicles and limited the formation of mixed lamellae/micelles.

Fabrication of edible solid lipid nanoparticle from beeswax/propolis wax by spontaneous emulsification: Optimization, characterization and stability.

In the current study, the production and characterization of novel solid lipid nanoparticles (SLNs) using safe/low-cost natural beeswax (BW) and propolis wax (PW) and by the simple and inexpensive assay of spontaneous emulsification were studied. To fabricate SLNs, the optimum levels of surfactant/oil ratio (SOR), stirring speed, and time were obtained based on minimum particle size (PS) and polydispersity index (PDI). Therefore, the optimal conditions to produce PW and BW nanoparticles were SOR of 1.26 and 2 under stirring speed of 1050 rpm for 20 min, leading to PS of 21.9 and 23.2 nm, respectively. The contact angle of 73.7° and 62.9° for BW and PW SLNs respectively, showed suitable hydrophilicity to stabilize oil-in-water (O/W) Pickering emulsions. Temperatures over 70 °C led to a drastic increment of PS in both types of SLNs. Upon nanoparticles drying, the utilization of cryoprotectants could cause less aggregation and better reconstitution.

Lipid Digestibility and Polyphenols Bioaccessibility of Oil-in-Water Emulsions Containing Avocado Peel and Seed Extracts as Affected by the Presence of Low Methoxyl Pectin.

In this study, the digestibility of oil-in-water (O/W) emulsions using low methoxyl pectin (LMP) as surfactant and in combination with avocado peel (AP) or seed (AS) extracts was assessed, in terms of its free fatty acid (FFA) release and the phenolic compound (PC) bioaccessibility. With this purpose, AP and AS were characterized by UPLC-ESI-MS/MS before their incorporation into O/W emulsions stabilized using LMP. In that sense, AP extract had a higher content of PCs (6836.32 ± 64.66 mg/100 g of extract) compared to AS extract (1514.62 ± 578.33 mg/100 g of extract). Both extracts enhanced LMP's emulsifying properties, leading to narrower distributions and smaller particle sizes compared to those without extracts. Similarly, when both LMP and the extracts were present in the emulsions the FFA release significantly increased. Regarding bioaccessibility, the PCs from the AS extracts had a higher bioaccessibility than those from the AP extracts, regardless of the presence of LMP. However, the presence of LMP reduced the bioaccessibility of flavonoids from emulsions containing either AP or AS extracts. These results provide new insights regarding the use of PC extracts from avocado peel and seed residues, and the effect of LMP on emulsion digestibility, and its influence on flavonoids bioaccessibility.

Formation and Stabilization of W1/O/W2 Emulsions with Gelled Lipid Phases.

Water-in-oil-in-water (W1/O/W2) emulsions are emulsion-based systems where the dispersed phase is an emulsion itself, offering great potential for the encapsulation of hydrophilic bioactive compounds. However, their formation and stabilization is still a challenge mainly due to water migration, which could be reduced by lipid phase gelation. This study aimed to assess the impact of lipid phase state being liquid or gelled using glyceryl stearate (GS) at 1% (w/w) as well as the hydrophilic emulsifier (T80: Tween 80 or lecithin) and the oil type (MCT:medium chain triglyceride or corn oil (CO) as long chain triglyceride) on the formation and stabilization of chlorophyllin W1/O/W2 emulsions. Their colloidal stability against temperature and light exposure conditions was evaluated. Gelling both lipid phases (MCT and CO) rendered smaller W1 droplets during the first emulsification step, followed by formation of W1/O/W2 emulsions with smaller W1/O droplet size and more stable against clarification. The stability of W1/O/W2 emulsions was sensitive to a temperature increase, which might be related to the lower gelling degree of the lipid phase at higher temperatures. This study provides valuable insight for the formation and stabilization of W1/O/W2 emulsions with gelled lipid phases as delivery systems of hydrophilic bioactive compounds under common food storage conditions.

Influence of lipid nanoparticle physical state on ß-carotene stability kinetics under different environmental conditions.

Carotenoids are lipophilic compounds that provide important health-related benefits for human body functions. However, they have low water solubility and chemical stability, hence their incorporation in aqueous-based foods requires the use of emulsion-based lipid carriers. This work aimed at elucidating whether their inclusion in emulsion-based Solid Lipid Nanoparticles (SLNs) can provide a protective effect against ß-carotene degradation under different environmental conditions in comparison to liquid lipid nanoemulsions. Glyceryl Stearate (GS) was mixed with Medium Chain Trygliceride (MCT) oil to formulate SLNs. SLNs presented a significantly enhanced ß-carotene retention and a slower ß-carotene degradation kinetics at increasing storage temperature, acidic conditions and light exposure. In fact, SLNs formulated with 5% GS in the lipid phase and stored at 4 °C and pH 7 retained almost 70% of the initially encapsulated ß-carotene after 55 days of storage, while it was completely degraded when it was encapsulated in liquid nanoemulsions. Moreover, it was observed that the solid lipid type affects the protective effect that SLNs may confer to the encapsulated lipophilic bioactives. Saturated long chain triglycerides, such as hydrogenated palm oil (HPO) presented slower and lower ß-carotene degradation kinetics in comparison to solid lipids composed of MCT, such as Coconut Oil (CNUT) or MCT + 5% of GS in the lipid phase. This work evidences that the incorporation of lipophilic bioactive compounds, such as ß-carotene, into SLNs slows down their degradation kinetics which might be attributed to a reduced diffusion of the oxidative species due to the lipid crystalline structure.

The lipid type affects the in vitro digestibility and ß-carotene bioaccessibility of liquid or solid lipid nanoparticles.

Solid lipid nanoparticles (SLNs) are emulsion-based carriers of lipophilic bioactive compounds. However, their digestibility may be affected by the solid lipid phase composition. Hence, the aim of this work was to study the in vitro lipolysis kinetics as well as the relationship between the lipid digestion, micelle fraction composition and ß-carotene bioaccessibility of SLNs with different solid lipids, being blends of medium chain triglyceride (MCT) oil, glyceryl stearate (GS) or hydrogenated palm oil (HPO) as compared to liquid lipid nanoparticles (LLNs) with pure MCT. SLNs formulated with GS were fully digested, similarly to LLNs. However, HPO-containing SLNs presented slower lipolysis kinetics during the intestinal phase at increasing HPO concentration. Despite this, HPO-SLNs showed higher ß-carotene bioaccessibility, which was related to the higher amount of monounstaturated free fatty acids in the micelle fraction. Thus, this work provides valuable insight for designing delivery systems of bioactive compounds with optimal functionality.

In vitro digestibility and release of a mango peel extract encapsulated within water-in-oil-in-water (W1/O/W2) emulsions containing sodium carboxymethyl cellulose.

Mango peel is a rich source of phenolic compounds (PC), which can be used in food fortification. The use of water-in-oil-in-water (W1/O/W2) emulsions represents a potential strategy to encapsulate, protect and incorporate PC from mango peel into food products. Moreover, even though non-digestible biopolymers are usually incorporated into emulsions to enhance stability, little is known about the effect on the digestibility and release of PC. In this study, a mango peel extract (MPE) was encapsulated using W1/O/W2 emulsions containing sodium carboxymethyl cellulose (CMC; 0, 0.5, 1.0% w/w) in W2, and their colloidal stability, lipid digestibility kinetics (free fatty acid release), and release (in terms of antioxidant activity) under in vitro digestion conditions were evaluated. The presence of CMC in emulsions caused flocculation of droplets, which remained unchanged during the gastric phase, suggesting that bridging flocculation occurred. Moreover, a slower lipid digestion rate was observed in emulsions containing CMC, with k-values ranging between 0.21 and 0.25 min-1, compared to emulsions without CMC (around 0.14 min-1). However, although CMC may slow down the lipolysis reaction during the first 40 min due to physical or steric hindrance, at the end of the intestinal phase, emulsions with or without CMC had a similar final FFA release. Moreover, MPE release was triggered under gastric conditions, probably by osmotic imbalance, showing a constant antioxidant activity value during the intestinal phase only in emulsions containing CMC. This study provides relevant insights to design double emulsions as delivery systems of water-soluble bioactive compounds with antioxidant activity, such as PC.

Lipid nanoparticles with fats or oils containing ß-carotene: Storage stability and in vitro digestibility kinetics.

The aim of this work was to study the formation of lipid nanoparticles (LNPs) with low (corn and olive oil) or high temperature melting lipids (cocoa butter and hydrogenated coconut oil). Moreover, their ß-carotene stability and in vitro digestibility kinetics was evaluated. Submicron LNPs (d43 ≈ 570-780 nm) were stabilized with Tween 80 at a surfactant-to-oil ratio (SOR) of 0.1. It was reduced below 200 nm at an SOR of 1. The ß-carotene retention at 25 °C was not related to the lipid type but rather to the particle size, being lower in samples with smaller particle sizes. Cocoa butter LNPs presented an equally complete digestion as corn oil LNPs and a high ß-carotene bioaccessibility, which was related to the high degree of micellarization of monoacylglycerols. This work evidences the potential of LNPs to protect lipophilic bioactive compounds with a high digestibility and bioaccessibility.

Structurally modified pectin for targeted lipid antioxidant capacity in linseed/sunflower oil-in-water emulsions.

The present work explored the lipid antioxidant capacity of citrus pectin addition to 5%(w/v) linseed/sunflower oil emulsions stabilized with 0.5%(w/v) Tween 80, as affected by pectin molecular characteristics. The peroxide formation in the emulsions, containing tailored pectin structures, was studied during two weeks of storage at 35°C. Low demethylesterified pectin (≤33%) exhibited a higher antioxidant capacity than high demethylesterified pectin (≥58%), probably due to its higher chelating capacity of pro-oxidative metal ions (Fe2+), whereas the distribution pattern of methylesters along the pectin chain only slightly affected the antioxidant capacity. Nevertheless, pectin addition to the emulsions caused emulsion destabilization probably due to depletion or bridging effect, independent of the pectin structural characteristics. These results evidence the potential of structurally modified citrus pectin as a natural antioxidant in emulsions. However, optimal conditions for emulsion stability should be carefully selected.

Edible Nanoemulsions as Carriers of Active Ingredients: A Review.

There has been growing interest in the use of edible nanoemulsions as delivery systems for lipophilic active substances, such as oil-soluble vitamins, antimicrobials, flavors, and nutraceuticals, because of their unique physicochemical properties. Oil-in-water nanoemulsions consist of oil droplets with diameters typically between approximately 30 and 200 nm that are dispersed within an aqueous medium. The small droplet size usually leads to an improvement in stability, gravitational separation, and aggregation. Moreover, the high droplet surface area associated with the small droplet size often leads to a high reactivity with biological cells and macromolecules. As a result, lipid digestibility and bioactive bioavailability are usually higher in nanoemulsions than conventional emulsions, which is an advantage for the development of bioactive delivery systems. In this review, the most important factors affecting nanoemulsion formation and stability are highlighted, and a critical analysis of the potential benefits of using nanoemulsions in food systems is presented.

In vitro ß-Carotene Bioaccessibility and Lipid Digestion in Emulsions: Influence of Pectin Type and Degree of Methyl-Esterification.

Citrus pectin (CP) and sugar beet pectin (SBP) were demethoxylated and fully characterized in terms of pectin properties in order to investigate the influence of the pectin degree of methyl-esterification (DM) and the pectin type on the in vitro ß-carotene bioaccessibility and lipid digestion in emulsions. For the CP based emulsions containing ß-carotene enriched oil, water and pectin, the ß-carotene bioaccessibility, and lipid digestion were higher in the emulsions with pectin with a higher DM (57%; "CP57 emulsion") compared to the emulsions with pectin with a lower DM (30%; "CP30 emulsion") showing that the DM plays an important role. In contrast, in SBP-based emulsions, nor ß-carotene bioaccessibility nor lipid digestion were dependent on pectin DM. Probably here, other pectin properties are more important factors. It was observed that ß-carotene bioaccessibility and lipid digestion were lower in the CP30 emulsion in comparison with the CP57, SBP32, and SBP58 emulsions. However, the ß-carotene bioaccessibility of CP57 emulsion was similar to that of the SBP emulsions, whereas the lipid digestion was not. It seems that pectin type and pectin DM (in case of CP) are determining which components can be incorporated into micelles. Because carotenoids and lipids have different structures and polarities, their incorporation may be different. This knowledge can be used to engineer targeted (digestive) functionalities in food products. If both high ß-carotene bioaccessibility and high lipid digestion are targeted, SBP emulsions are the best options. The CP57 emulsion can be chosen if high ß-carotene bioaccessibility but lower lipid digestion is desired.

Improvement of ß-Carotene Bioaccessibility from Dietary Supplements Using Excipient Nanoemulsions.

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

Excipient Nanoemulsions for Improving Oral Bioavailability of Bioactives.

The oral bioavailability of many hydrophobic bioactive compounds found in natural food products (such as vitamins and nutraceuticals in fruits and vegetables) is relatively low due to their low bioaccessibility, chemical instability, or poor absorption. Most previous research has therefore focused on the design of delivery systems to incorporate isolated bioactive compounds into food products. However, a more sustainable and cost-effect approach to enhancing the functionality of bioactive compounds is to leave them within their natural environment, but specifically design excipient foods that enhance their bioavailability. Excipient foods typically do not have functionality themselves but they have the capacity to enhance the functionality of nutrients present in natural foods by altering their bioaccessibility, absorption, and/or chemical transformation. In this review article we present the use of excipient nanoemulsions for increasing the bioavailability of bioactive components from fruits and vegetables. Nanoemulsions present several advantages over other food systems for this application, such as the ability to incorporate hydrophilic, amphiphilic, and lipophilic excipient ingredients, high physical stability, and rapid gastrointestinal digestibility. The design, fabrication, and application of nanoemulsions as excipient foods will therefore be described in this article.

Modulating Biopolymer Electrical Charge to Optimize the Assembly of Edible Multilayer Nanofilms by the Layer-by-Layer Technique.

The aim of this work was to study the influence of biopolymer (alginate, ALG; chitosan, CHI) charge on the formation of multilayer nanofilms by the layer-by-layer (LbL) technique. The electrical charge of ALG and CHI (high, medium, or low) was modulated by adjusting the pH of biopolymer solutions. The amount of biopolymer deposited in multilayers depended on the charge of ALG and CHI solutions. The lower the charge the higher the deposition rate due to the higher number of biopolymer molecules needed to neutralize the previous layer. Medium and low charge biopolymers led to a drastic change in the wettability of multilayers, with ALG layers being strongly hydrophilic and CHI layers strongly hydrophobic. The surface ζ-potential alternatively changed from negative to positive using ALG or CHI. This effect was more pronounced using highly charged biopolymers. Results obtained in this study evidenced that the multilayers properties can be tuned by controlling the biopolymer electrical charge.