Influence of emulsifier type on the in vitro digestion of fish oil-in-water emulsions in the presence of an anionic marine polysaccharide (fucoidan): Caseinate, whey protein, lecithin, or Tween 80

Milk fat crystal network as a strategy for delivering vegetable oils high in omega-9, -6, and -3 fatty acids

As an alternative to the strategies currently used to deliver unsaturated fatty acids, especially, the essentials omega-6 and 3- fatty acids, the aim of this work was to investigate the effect of the incorporation of 25 e 50% (w/w) of olive, corn and linseed oil into the crystal structure of anhydrous milk fat (AMF). Fatty acid composition, atherogenicity (AI), and thrombogenicity (TI) index, crystallization kinetics, polymorphism by Rietveld method (RM), microstructure, thermal behavior, solid fat content, and lipid compatibility was evaluated. The addition of vegetable oils reduced the saturated fatty acids, and the AI and TI indices of AMF, and increased the concentration of unsaturated, specifically omega-6 and -3 fatty acids. Although vegetable oils caused changes in nucleation and crystallization kinetics, the spherulitic and crystalline morphology and the β' polymorphism of AMF were maintained. The study demonstrated the possibility of using the crystal structure of AMF as a vehicle for unsaturated fatty acids in food formulations, as an alternative to nutritional supplementation. In addition, studies on the use of RM in blends made with AMF and vegetable oil have not been found in literature, thus demonstrating the relevance of the present study.

Synergistic interaction between exogenous and endogenous emulsifiers and its impact on in vitro digestion of lipid in crowded medium

Control of lipid digestibility by various food components has received great attention in recent decades. However, there is limited literature on investigating the synergistic effect of exogenous emulsifiers and endogenous sodium cholate (SC) on lipid digestion in a simulated physiological crowded medium. In this work, the synergistic interaction of Tween80 and SC according to the regular solution theory, and the hydrolysis of lipid emulsions containing tricaprylin, glyceryltrioleate or soybean oil in crowding medium was studied. The results show that emulsions stabilized by a combination of Tween80 and SC showed higher digestion rate and transformation than those with Tween80 or SC. The digestion rate could be increased by polyethylene glycols (PEGn) with varying crowding degree. The denaturation temperature of the lipase was increased in macromolecular crowded medium. This work allows for better understanding of the interaction between the amphiphiles and the macromolecular crowding effect on lipase digestion in the physiological environment.

Oral behaviour of emulsions stabilized by mixed monolayer

Controlled flavour release is highly important for the formulation of food emulsions. However, manipulating oral behavior and maintaining the stability of the flavoured emulsion is quite challenging. Hence, this study aims to investigate the effect of emulsion stability and oral behaviour using mixed emulsifier monolayers of different nature for their controlled flavour release. Orange oil flavoured (0.1% orange oil +10% sunflower oil) oil-in-water emulsions were prepared by microfluidization through modified starch (MS) and whey protein isolate (WPI) with different mass ratios (0.5:0.5, 0.5:1, 1:0.5, 1:1, 1:0 and 0:1) of emulsifiers. The fabricated emulsions were <0.13 μm in size (d₃₂) with stable oil droplets having strong negative charges. The 0.5:0.5 and 0:1 emulsion were depicted an increase in size d₃₂ (1.17 and 0.93 μm) and unstable during storage at 28 ± 1 °C than the emulsions stored at 4 ± 0.1 °C. All the emulsions were exhibited Newtonian flow; however once mixed with artificial saliva, the 1:0 emulsion showed shear thinning behaviour. During oral processing, in-vitro and in-vivo exhibited flocculation and coalescence; subsequently, structural deformation was observed with an increase in size (d₃₂) and weak negative charge in 1:0.5 and 1:0 emulsions. Backscattering profile revealed more destabilization for 1:0 and less for 1:0.5 emulsions. Contrarily, other emulsions did not show any changes. Therefore, oral processing of emulsions results suggested that 1:0 had quick destabilization and 1:0.5 changed gradually. Thus, mixed emulsifier monolayer contributed significantly to the behavior of emulsions when interacting with saliva and it can be useful for controlled flavour release.

Fatty acid composition and quality properties of chicken sausage formulated with pre-emulsified perilla-canola oil as an animal fat replacer

The potential use of an oil in water (o/w) emulsion made from perilla and canola oil in chicken sausage as an animal fat replacer was assessed. The (o/w) emulsion was made from 50% (wt/wt) perilla-canola oil mixture in a 30:70 ratio, 3.20% (wt/wt) polyglycerol polyricinoleate, 4.48% (wt/wt) soy protein isolate, 14% (wt/wt) inulin, and 28.32% (wt/wt) water. The sausages were manufactured with 60% (wt/wt) ground chicken breast, 20% (wt/wt) fat (beef tallow as a control), and 20% (wt/wt) ice water. Full replacement of animal fat with a perilla-canola oil (o/w) emulsion reduced the fat content and estimated calories but increased the moisture, protein, ash, and carbohydrate content. The proportion of α-linolenic acid (C18:3n3) was increased when animal fat was replaced with either a perilla-canola oil mixture or pre-emulsified perilla-canola oil, resulting in a lower n6 to n3 polyunsaturated fatty acid ratio than the control. The perilla-canola oil (o/w) emulsion improved emulsion stability and minimized cooking loss during sausage manufacturing. Higher L* value (lightness) and whiteness were observed in the sausages formulated with the perilla-canola oil mixture, followed by the pre-emulsified perilla-canola oil and the control. The perilla-canola oil (o/w) emulsion also increased the hardness but maintained an acceptable appearance, flavor, and overall impression similar to the control. The shelf life could be extended by vacuum packing and storing the cooked sausages formulated with a perilla-canola oil (o/w) emulsion for 30 D at 2 ± 1°C. Pre-emulsified perilla-canola oil could be used to replace animal fat in reduced-fat chicken sausage manufacture.

Effect of flaxseed polyphenols on physical stability and oxidative stability of flaxseed oil-in-water nanoemulsions

Recent studies have shown that the high susceptibility of flaxseed oil nanoemulsions to lipid oxidation limits their incorporation into functional foods and beverages. For this reason, the impact of various flaxseed phenolic extracts on the physical and oxidative stability of flaxseed oil nanoemulsions was investigated. Flaxseed lignan extract (FLE) and secoisolariciresinol (SECO) exhibited antioxidant activity whereas secoisolariciresinol diglucoside (SDG) and p-coumaric acid (CouA) exhibited prooxidant activity in the flaxseed oil nanoemulsions. The antioxidant potential of flaxseed phenolics in the nanoemulsions was as follows: SECO < CouA < SDG ≈ FLE. Moreover, the antioxidant/prooxidant activity of the phenolics was also related to their free radical scavenging activity and partitioning in the nanoemulsions. Our results suggested that both SECO and FLE were good plant-based antioxidants for improving the stability of flaxseed oil nanoemulsions.

Impact of Food Emulsions on the Bioaccessibility of Hydrophobic Pesticide Residues in Co-Ingested Natural Products: Influence of Emulsifier and Dietary Fiber Type

In the typical Western diet, fruits and vegetables are often consumed with food products that exist as oil-in-water emulsions, such as creams, dressings, and sauces. Studies have shown that coingestion of fruits and vegetables with emulsions can increase the bioavailability of beneficial lipophilic bioactive agents, such as nutraceuticals or vitamins. Agricultural produce, however, may also be contaminated with low levels of detrimental lipophilic agents, such as hydrophobic pesticides. We therefore examined the impact of coingesting a common agricultural product (tomatoes) with model food emulsions on the bioaccessibility of a hydrophobic pesticide (chlorpyrifos). The impact of emulsifier types (phospholipids, whey protein, Tween 80) and dietary fiber types (xanthan, chitosan, β-glucan) on the bioaccessibility of the pesticide was measured using a simulated gastrointestinal model. Chlorpyrifos bioaccessibility depended on the type of emulsifier used to formulate the emulsions: phospholipids > Tween 80 > whey protein. Dietary fiber type also influenced pesticide bioaccessibility by an amount that depended on the nature of the emulsifier used. Overall, our results suggest that the bioaccessibility of undesirable pesticides on fruits and vegetables will depend on the nature of the emulsions they are consumed with.

Titanium Dioxide Nanoparticles Do Not Adversely Impact Carotenoid Bioaccessibility from Tomatoes Consumed with Different Nanoemulsions: In Vitro Digestion Study

Titanium dioxide (TiO₂) is used as an additive to whiten some foods and beverages that contain lipid nanoparticles. We therefore investigated the combined influence of TiO₂ and lipid nanoparticles on carotenoid bioaccessibility from tomatoes. TiO₂ nanoparticles ( d = 167 nm) were combined with nanoemulsions ( d ≈ 150 nm) stabilized by various emulsifiers: Tween 80, whey protein, or sodium caseinate. The mixed systems were then mixed with tomatoes and passed through a simulated gastrointestinal tract (GIT). The emulsifier type significantly influenced carotenoid bioaccessibility ( p < 0.05), mainly because of differences in the ability of the emulsifier-coated lipid droplets to extract carotenoids from tomatoes and form mixed micelles. TiO₂ addition did not impact lipid digestion and carotenoid bioaccessibility ( p > 0.05). These results suggested that carotenoid bioaccessibility was not influenced by TiO₂ addition but did depend on the type of emulsifier used to stabilize lipid nanoparticles.

DHA rich algae oil delivered by O/W or gelled emulsions: strategies to increase its bioaccessibility

BACKGROUND

The bioaccessibility of bioactive compounds for functional food deserves evaluation. An in vitro gastrointestinal digestion model was applied to provide information about the extent of lipid hydrolysis, oxidative stability and bioaccessibility of algae oil (42% of docosahexaenoic acid; DHA), comparing three lipid delivery systems: bulk oil, soy protein stabilized O/W emulsion and carrageenan gelled emulsion.

RESULTS

Lipid digestion kinetics was slightly influenced by the delivery systems. Nevertheless, at the end of intestinal digestion, lipolysis in the three samples ranged between 49% and 52%, showing a partial oil digestion. Lipid oxidation, measured by malondialdehyde, was significantly lower (P < 0.01) in both emulsified oils after intestinal digestion compared to the bulk oil. Bioaccessibility of DHA was 58%, 71% and 84% for bulk oil, O/W emulsion and gelled emulsion, respectively.

CONCLUSION

These results suggest that both emulsified delivery systems used in the present study enhanced the solubilization of free fatty acids, in particular omega-3 fatty acids, and therefore their potential intestinal absorption. © 2018 Society of Chemical Industry.

Physicochemical Properties and Cellular Uptake of Astaxanthin-Loaded Emulsions

Astaxanthin, a natural pigment carotenoid, is well known for its potential benefits to human health. However, its applications in the food industry are limited, due to its poor water-solubility and chemical instability. Six different emulsifiers were used to prepare astaxanthin-loaded emulsions, including whey protein isolate (WPI), polymerized whey protein (PWP), WPI-lecithin, PWP-lecithin, lecithin, and Tween20. The droplet size, zeta potential, storage stability, cytotoxicity, and astaxanthin uptake by Caco-2 cells were all investigated. The results showed that the droplet size of the emulsions ranged from 194 to 287 nm, depending on the type of emulsifier used. The entrapment efficiency of astaxanthin was as high as 90%. The astaxanthin-loaded emulsions showed good physicochemical stability during storage at 4 °C. The emulsifier type had a significant impact on the degradation rate of astaxanthin (p < 0.05). Cellular uptake of astaxanthin encapsulated into the emulsions was significantly higher than free astaxanthin (p < 0.05). Emulsion stabilized with WPI had the highest cellular uptake of astaxanthin (10.0 ± 0.2%), followed, in order, by that with PWP (8.49 ± 0.1%), WPI-lecithin (5.97 ± 0.1%), PWP-lecithin (5.05 ± 0.1%), lecithin (3.37 ± 0.2%), and Tween 20 (2.1 ± 0.1%). Results indicate that the whey protein-based emulsion has a high potential for improving the cellular uptake of astaxanthin.

Fish Oil Emulsions Stabilized with Caseinate Glycated by Dextran: Physicochemical Stability and Gastrointestinal Fate

Incorporation of fish oil containing ω-3 polyunsaturated fatty acids (PUFAs) into functional foods remains challenging. In this study, caseinate and glycoconjugates (CD6, CD40, CD70, CD100) of caseinate to dextrans of different molecular weights (D6, D40, D70, D100 kDa) were used to stabilize fish oil emulsions, and the impact on physicochemical stability and gastrointestinal fate was investigated. The glycoconjugate of CD6 exhibited significantly higher conjugation efficiency, lower surface hydrophobicity ( H0), and lower surface activity than other glycoconjugates. The glycoconjugate of CD70 displayed the best emulsifying activity and emulsion stability. Except CD6 stabilized emulsions, all other emulsions showed fine storage stability over 14 d at 22 ± 1 °C. The glycoconjugate stabilized emulsions exhibited significantly lower peroxide value (PV) ( P < 0.05) than that of the caseinate stabilized one. During in vitro gastrointestinal tract digestion, the glycation of caseinate with dextrans changed the ζ-potential, average particle size ( D₃₂), and particle size distribution of the emulsions, which influenced flocculation and coalescence of droplets, as demonstrated by confocal microscopy. Caseinate after glycation with dextrans significantly retarded the release of free fatty acids from emulsions ( P < 0.05) during in vitro lipolysis. These results suggested that the dextrans attached to caseinate by glycation played a vital role in physicochemical stability and gastrointestinal fate of emulsions, mainly by its steric hindrance to effectively prevent flocculation and coalescence of droplets.

Advances and challenges in liposome digestion: Surface interaction, biological fate, and GIT modeling

During the past 50 years, there has been increased interest in liposomes as carriers of pharmaceutical, cosmetic, and agricultural products. More recently, much progress has been made in the use of surface-modified formulas in experimental food matrices. However, before the viability and the applications of nutrients in liposomal form in the edible field can be determined, the digestion behavior along the human gastrointestinal tract (GIT) must be clarified. In vitro digestion models, from static models to dynamic mono-/bi-/multi-compartmental models, are increasingly being developed and applied as alternatives to in vivo assays. This review describes the surface interactions of liposomes with their encapsulated ingredients and with external food components and updates the biological fate of liposomes after ingestion. It summarizes current models for the human stomach and intestine that are available and their relevance in nutritional studies. It highlights limitations and challenges in the use of these models for liposomal colloid system digestion and discusses crucial factors, such as enzymes and bile salts, that affect liposomal bilayer degradation.

Stability and in vitro digestibility of beta-carotene in nanoemulsions fabricated with different carrier oils

Beta-carotene, the main dietary source of provitamin A, is required for maintaining optimum human health. The bioaccessibility of beta-carotene can be greatly improved when ingested with fat. Therefore, the aim of the current study was to select proper oils (palm oil, coconut oil, fish oil, and corn oil) as a carrier to form stable nanoemulsion that can effectively enhance the bioaccessibility of beta-carotene. The nanoemulsion was formulated with 90% (v/v) aqueous solution (2% whey protein isolate, WPI, w/v) and 10% (v/v) dispersed oil. The in vitro digestion experiment of nanoemulsions showed that the bioaccessibility of beta-carotene was as followed in order: palm oil = corn oil > fish oil > coconut oil (p < 0.05). The particle size of the nanoemulsion (initial particle size = 168-185 nm) was below 200 nm during 42 days' storage at 25°C. The retention rates of beta-carotene in nanoemulsions were 69.36%, 63.81%, 49.58%, and 54.91% with palm oil, coconut oil, fish oil, and corn oil, respectively. However, the particle size of the nanoemulsion increased significantly in the accelerated experiment at 55°C (p < 0.05), in which the retention rates of beta-carotene were 48.56%, 43.41%, 29.35%, and 33.60% with palm oil, coconut oil, fish oil, and corn oil, respectively. From above, we conclude that WPI-stabilized beta-carotene nanoemulsion with palm oil as the carrier is the most suitable system to increase bioaccessibility and stability of lipid-soluble bioactive compounds such as beta-carotene.

Development of stable curcumin nanoemulsions: effects of emulsifier type and surfactant-to-oil ratios

Curcumin, a natural polyphenolic compound, offers a wide range of pharmacological benefits such as antioxidant, anti-inflammatory and anti-cancer. The oil-in-water nanoemulsions containing curcumin were obtained by high pressure homogenization and effects of various emulsifiers (Tween-80, lecithin, whey protein isolate and acacia) and different surfactant-to-oil ratios (SOR) on physicochemical characteristics, physical stability and storage stability of curcumin loaded nanoemulsions were evaluated in this study. The result showed that smaller particle size, better physical and storage stabilities and higher curcumin content were found in curcumin loaded nanoemulsions stabilized with Tween-80 and lecithin. Compared with nanoemulsions prepared with lecithin, nanoemulsions fabricated with Tween-80 exhibited better uniformity and distribution as demonstrated by microscopic observations. It was found that SOR was positively correlated with particle size but negatively correlated with curcumin content in the emulsion droplets. Neither the emulsifier nor SOR values were found to have significant effects on zeta-potentials of the droplets. This result implied that curcumin loaded nanoemulsions prepared with Tween-80 and higher SOR values helped curcumin to achieve better physical stability and storage stability.

Enhanced delivery of lipophilic bioactives using emulsions: a review of major factors affecting vitamin, nutraceutical, and lipid bioaccessibility

Many researchers are currently developing emulsion-based delivery systems to increase the bioavailability of lipophilic bioactive agents, such as oil-soluble vitamins, nutraceuticals, and lipids. Oil-in-water emulsions can be specifically designed to improve the bioavailability of these bioactives by altering their composition and structural organization. This article reviews recent progress in understanding the impact of emulsion properties on the bioaccessibility of lipophilic bioactive agents, including oil phase composition, aqueous phase composition, droplet size, emulsifier type, lipid physical state, and droplet aggregation state. This knowledge can be used to design emulsions that can enhance the bioavailability and efficacy of encapsulated hydrophobic bioactives.

In vitro digestibility of normal and waxy corn starch is modified by the addition of Tween 80

Aqueous dispersions of normal and waxy corn starch (3% w/w) were mixed with Tween 80 (0, 7.5, 15, 22.5 and 30 g/100 g of starch), and gelatinized (90 °C, 20 min). Optical microscopy of the gelatinized starch dispersions (GSD_x; x = Tween 80 concentration) revealed that the microstructure was characterized by a continuous phase of leached amylose and amylopectin entangled chains, and a dispersed phase of insoluble remnants, called ghosts, on whose surface small granules were observed, imputed to Tween 80. The apparent viscosity of the GSD_x decreased as the concentration of Tween 80 increased (up to about 70-90%). FTIR analysis of dried GSD_x indicated that Tween 80 addition decreased short-range ordering. The content of rapidly digestible starch (RDS) and resistant starch (RS) fractions tended to increase significantly, at the expense of a significant decrease of slowly digestible starch (SDS) fraction, an effect that may be attributed to the increase of amorphous structures and starch chain-surfactant complexes. The RDS and RS increase was more pronounced for normal than for waxy corn starch, and the significance of the increase was dependent on Tween 80 concentration. Overall, the results showed that surfactant can affect largely the digestibility of starch chains.

Encapsulation, protection, and delivery of bioactive proteins and peptides using nanoparticle and microparticle systems: A review

There are many examples of bioactive proteins and peptides that would benefit from oral delivery through functional foods, supplements, or medical foods, including hormones, enzymes, antimicrobials, vaccines, and ACE inhibitors. However, many of these bioactive proteins are highly susceptible to denaturation, aggregation or hydrolysis within commercial products or inside the human gastrointestinal tract (GIT). Moreover, many bioactive proteins have poor absorption characteristics within the GIT. Colloidal systems, which contain nanoparticles or microparticles, can be designed to encapsulate, retain, protect, and deliver bioactive proteins. For instance, a bioactive protein may have to remain encapsulated and stable during storage and passage through the mouth and stomach, but then be released within the small intestine where it can be absorbed. This article reviews the application of food-grade colloidal systems for oral delivery of bioactive proteins, including microemulsions, emulsions, nanoemulsions, solid lipid nanoparticles, multiple emulsions, liposomes, and microgels. It also provides a critical assessment of the characteristics of colloidal particles that impact the effectiveness of protein delivery systems, such as particle composition, size, permeability, interfacial properties, and stability. This information should be useful for the rational design of medical foods, functional foods, and supplements for effective oral delivery of bioactive proteins.

Extracts from the edible seaweed, Ascophyllum nodosum, inhibit lipase activity in vitro: contributions of phenolic and polysaccharide components

A polyphenol-rich extract (PRE) from the edible seaweed, Ascophyllum nodosum, inhibited pancreatic lipase activity in an oil-based turbidimetric assay with an IC50 of 200 μg gallic acid equivalents (GAE) perassay) [∼230 μg DW] whereas the known inhibitor, Orlistat, gave an IC50 at 0.4 μg per assay. A phlorotannin-enriched fraction (TRF) purified from the PRE was more potent with an IC50 = 60 μg GAE per assay (∼65 μg DW). When the assay was started by the addition of lipase, both Orlistat and TRF were much less effective which suggests that pre-incubation of enzyme and inhibitor improved inhibition. Based on phenol content, water extracts from Ascophyllum were more potent lipase inhibitors than PRE (IC50 ∼ 150 μg GAE per assay). However, this was equivalent to ∼580 μg DW and these extracts contained polysaccharides (e.g. alginate content = 110 μg mL-1) which may also contribute to inhibition. Indeed, a polysaccharide-enriched fraction obtained by ethanol precipitation gave an IC50 of 1000 μg DW which was equivalent to 130 μg GAE and 420 μg alginate per assay. Therefore a >3 fold increase in alginate content did not markedly improve inhibition. Re-precipitation increased alginate content and reduced polyphenol content but lipase inhibition was markedly reduced (i.e. IC50 at ∼1100 μg DW per assay, 700 μg alginate and 25 μg GAE). Purifying the polysaccharide fraction by ion exchange removed all phenolics but the IC50 increased to >2500 μg DW, equivalent to >1970 μg alginate per assay. In conclusion, polysaccharides and phlorotannins may inhibit lipase in an additive fashion, with phlorotannins apparently more effective in vitro. However, interactions between these components may be important when food products containing this edible seaweed are consumed.

Preparation of eggshell membrane protein hydrolysates and culled banana resistant starch-based emulsions and evaluation of their stability and behavior in simulated gastrointestinal fluids

This study aims to evaluate the effect of resistant starch (RS) derived from culled banana on the stability and characteristics of emulsions stabilized by eggshell membrane (ESM) protein hydrolysates. It was observed that incorporation of resistant starch improved the properties of the emulsions. Furthermore, the most stable emulsions developed (using a combination of RS and pretreated alcalase hydrolysates) were assessed for their behavior in an in-vitro gastrointestinal model system and changes in their particle size, zeta potential and morphology were evaluated. It was seen that these emulsions underwent flocculation and coalescence in the presence of pepsin and at higher concentrations of mucin enzyme and further coalescence and fatty acid release were observed after their passage through the small intestine. These insightful results about emulsion behavior in the gastrointestinal tract can be useful for designing delivery systems for controlled release of bioactive compounds.

The Physical State of Emulsified Edible Oil Modulates Its in Vitro Digestion

Emulsified lipid digestion was tailored by manipulating the physical state of dispersed oil droplets in whey protein stabilized oil-in-water (O/W) emulsions, where the oil phase consisted of one of five ratios of soybean oil (SO) and fully hydrogenated soybean oil (FHSO). The evolution in particle size distribution, structural changes during oral, gastric, and intestinal digestion, and free fatty acid release during intestinal digestion were all investigated. Irrespective of the physical state and structure of the dispersed oil/fat, all emulsions were stable against droplet size increases during oral digestion. During gastric digestion, the 50:50 SO:FHSO emulsion was more stable against physical breakdown than any other emulsion. All emulsions underwent flocculation and coalescence or partial coalescence upon intestinal digestion, with the SO emulsion being hydrolyzed the most rapidly. The melting point of all emulsions containing FHSO was above 37 °C, with the presence of solid fat within the dispersed oil droplets greatly limiting lipolysis. Fat crystal polymorph and nanoplatelet size did not play an important role in the rate and extent of lipid digestion. Free fatty acid release modeled by the Weibull distribution function showed that the rate of lipid digestion (κ) decreased with increasing solid fat content, and followed an exponential relationship (R² = 0.95). Overall, lipid digestion was heavily altered by the physical state of the dispersed oil phase within O/W emulsions.