Plant-Based Colloidal Delivery Systems for Bioactives.

The supplementation of plant-based foods and beverages with bioactive agents may be an important strategy for increasing human healthiness. Numerous kinds of colloidal delivery systems have been developed to encapsulate bioactives with the goal of improving their water dispersibility, chemical stability, and bioavailability. In this review, we focus on colloidal delivery systems assembled entirely from plant-based ingredients, such as lipids, proteins, polysaccharides, phospholipids, and surfactants isolated from botanical sources. In particular, the utilization of these ingredients to create plant-based nanoemulsions, nanoliposomes, nanoparticles, and microgels is covered. The utilization of these delivery systems to encapsulate, protect, and release various kinds of bioactives is highlighted, including oil-soluble vitamins (like vitamin D), ω-3 oils, carotenoids (vitamin A precursors), curcuminoids, and polyphenols. The functionality of these delivery systems can be tailored to specific applications by careful selection of ingredients and processing operations, as this enables the composition, size, shape, internal structure, surface chemistry, and electrical characteristics of the colloidal particles to be controlled. The plant-based delivery systems discussed in this article may be useful for introducing active ingredients into the next generation of plant-based foods, meat, seafood, milk, and egg analogs. Nevertheless, there is still a need to systematically compare the functional performance of different delivery systems for specific applications to establish the most appropriate one. In addition, there is a need to test their efficacy at delivering bioavailable forms of bioactives using in vivo studies.

Impact of Pesticide Type and Emulsion Fat Content on the Bioaccessibility of Pesticides in Natural Products.

There is interest in incorporating nanoemulsions into certain foods and beverages, including dips, dressings, drinks, spreads, and sauces, due to their potentially beneficial attributes. In particular, excipient nanoemulsions can enhance the bioavailability of nutraceuticals in fruit- and vegetable-containing products consumed with them. There is, however, potential for them to also raise the bioavailability of undesirable substances found in these products, such as pesticides. In this research, we studied the impact of excipient nanoemulsions on the bioaccessibility of pesticide-treated tomatoes. We hypothesized that the propensity for nanoemulsions to raise pesticide bioaccessibility would depend on the polarity of the pesticide molecules. Bendiocarb, parathion, and chlorpyrifos were therefore selected because they have Log P values of 1.7, 3.8, and 5.3, respectively. Nanoemulsions with different oil contents (0%, 4%, and 8%) were fabricated to study their impact on pesticide uptake. In the absence of oil, the bioaccessibility increased with increasing pesticide polarity (decreasing Log P): bendiocarb (92.9%) > parathion (16.4%) > chlorpyrifos (2.8%). Bendiocarb bioaccessibility did not depend on the oil content of the nanoemulsions, which was attributed to its relatively high water-solubility. Conversely, the bioaccessibility of the more hydrophobic pesticides (parathion and chlorpyrifos) increased with increasing oil content. For instance, for chlorpyrifos, the bioaccessibility was 2.8%, 47.0%, and 70.7% at 0%, 4%, and 8% oil content, respectively. Our findings have repercussions for the utilization of nanoemulsions as excipient foods in products that may have high levels of undesirable non-polar substances, such as pesticides.

Model-based analysis of HER activation in cells co-expressing EGFR, HER2 and HER3.

The HER/ErbB family of receptor tyrosine kinases drives critical responses in normal physiology and cancer, and the expression levels of the various HER receptors are critical determinants of clinical outcomes. HER activation is driven by the formation of various dimer complexes between members of this receptor family. The HER dimer types can have differential effects on downstream signaling and phenotypic outcomes. We constructed an integrated mathematical model of HER activation, and trafficking to quantitatively link receptor expression levels to dimerization and activation. We parameterized the model with a comprehensive set of HER phosphorylation and abundance data collected in a panel of human mammary epithelial cells expressing varying levels of EGFR/HER1, HER2 and HER3. Although parameter estimation yielded multiple solutions, predictions for dimer phosphorylation were in agreement with each other. We validated the model using experiments where pertuzumab was used to block HER2 dimerization. We used the model to predict HER dimerization and activation patterns in a panel of human mammary epithelial cells lines with known HER expression levels in response to stimulations with ligands EGF and HRG. Simulations over the range of expression levels seen in various cell lines indicate that: i) EGFR phosphorylation is driven by HER1-HER1 and HER1-HER2 dimers, and not HER1-HER3 dimers, ii) HER1-HER2 and HER2-HER3 dimers both contribute significantly to HER2 activation with the EGFR expression level determining the relative importance of these species, and iii) the HER2-HER3 dimer is largely responsible for HER3 activation. The model can be used to predict phosphorylated dimer levels for any given HER expression profile. This information in turn can be used to quantify the potencies of the various HER dimers, and can potentially inform personalized therapeutic approaches.

Use of somatic mutations to quantify random contributions to mouse development.

BACKGROUND: The C. elegans cell fate map, in which the lineage of its approximately 1000 cells is visibly charted beginning from the zygote, represents a developmental biology milestone. Nematode development is invariant from one specimen to the next, whereas in mammals, aspects of development are probabilistic, and development exhibits variation between even genetically identical individuals. Consequently, a single defined cell fate map applicable to all individuals cannot exist. RESULTS: To determine the extent to which patterns of cell lineage are conserved between different mice, we have employed the recently developed method of "phylogenetic fate mapping" to compare cell fate maps in siblings. In this approach, somatic mutations arising in individual cells are used to retrospectively deduce lineage relationships through phylogenetic and-as newly investigated here-related analytical approaches based on genetic distance. We have cataloged genomic mutations at an average of 110 mutation-prone polyguanine (polyG) tracts for about 100 cells clonally isolated from various corresponding tissues of each of two littermates of a hypermutable mouse strain. CONCLUSIONS: We find that during mouse development, muscle and fat arise from a mixed progenitor cell pool in the germ layer, but, contrastingly, vascular endothelium in brain derives from a smaller source of progenitor cells. Additionally, formation of tissue primordia is marked by establishment of left and right lateral compartments, with restricted cell migration between divisions. We quantitatively demonstrate that development represents a combination of stochastic and deterministic events, offering insight into how chance influences normal development and may give rise to birth defects.

Applications of the INFOGEST In Vitro Digestion Model to Foods: A Review.

The in vitro digestion model developed by the INFOGEST international consortium is widely used to simulate the physicochemical processes occurring inside the human gastrointestinal tract (mouth, stomach, and small intestine) during the digestion of foods. In this review, we provide a brief overview of the INFOGEST method and the procedures used to measure the digestion of macronutrients (lipids, proteins, and starch), the bioaccessibility of bioactive agents (vitamins, minerals, and nutraceuticals), and the changes in the structure and physical properties of foods under gastrointestinal conditions (particle size, charge, and location). We then review the application of the INFOGEST method for monitoring the gastrointestinal fate of different kinds of foods and beverages, including dairy, egg, meat, seafood, fruit, vegetable, cereal, and emulsified products. We also discuss the application of this method for studying the digestibility of next-generation plant-based foods, such as meat, seafood, dairy, and egg analogs. Finally, the benefits and limitations of this standardized in vitro digestion model are assessed.

Preparation of plant-based meat analogs using emulsion gels: Lipid-filled RuBisCo protein hydrogels.

RuBisCo from duckweed is a sustainable source of plant proteins with a high water-solubility and good gelling properties. In this study, we examined the impact of RuBisCo concentration (9-33 wt %) and oil droplet concentration (0 to 14 wt %) on the properties of emulsion gels designed to simulate the properties of chicken breast. The color (L*a*b*), water holding capacity (WHC), textural profile analysis, shear modulus, and microstructure of the emulsion gels were measured. The gel hardness and WHC increased significantly with increasing protein concentration, reaching values equivalent to chicken breast. The lightness of the emulsion gels was less than that of chicken breast, due to the presence of pigments (such as polyphenols) in the protein. Shear modulus versus temperature measurements showed that gelation began when the protein solutions were heated to around 40 °C and then the gels hardened appreciably when the temperature was further raised to 90 °C. The shear modulus of the gels then increased during cooling, which was attributed to the strengthening of hydrogen bonds at lower temperatures. The hardness of the gels increased slightly but then decreased when the oil droplet concentration was raised from 0 to 14 %. The lightness of the protein gels increased after adding the oil droplets, which was attributed to increased light scattering. Microstructure analysis showed that the RuBisCo proteins formed a particulate gel after heating, with the oil droplets being in the interstices between the particulates. In summary, RuBisCo proteins can be dissolved at high concentrations and can form strong emulsion gels. Consequently, they may be able to mimic the composition and textural attributes of real chicken.

Expansion of variant diversity associated with a high prevalence of pathogen strain superinfection under conditions of natural transmission.

Superinfection occurs when a second, genetically distinct pathogen strain infects a host that has already mounted an immune response to a primary strain. For antigenically variant pathogens, the primary strain itself expresses a broad diversity of variants over time. Thus, successful superinfection would require that the secondary strain express a unique set of variants. We tested this hypothesis under conditions of natural transmission in both temperate and tropical regions where, respectively, single-strain infections and strain superinfections of the tick-borne pathogen Anaplasma marginale predominate. Our conclusion that strain superinfection is associated with a significant increase in variant diversity is supported by progressive analysis of variant composition: (i) animals with naturally acquired superinfection had a statistically significantly greater number of unique variant sequences than animals either experimentally infected with single strains or infected with a single strain naturally, (ii) the greater number of unique sequences reflected a statistically significant increase in primary structural diversity in the superinfected animals, and (iii) the increase in primary structural diversity reflected increased combinations of the newly identified hypervariable microdomains. The role of population immunity in establishing temporal and spatial patterns of infection and disease has been well established. The results of the present study, which examined strain structure under conditions of natural transmission and population immunity, support that high levels of endemicity also drive pathogen divergence toward greater strain diversity.

Fabrication, characterization and in vitro digestive behavior of Pickering emulsion incorporated with dextrin.

Whey protein-stabilized Pickering emulsion was incorporated with dextrin under different concentrations, and their physicochemical properties and in vitro digestive behavior were examined. The result showed that these emulsions were relatively stable at low dextrin addition (<7.5%), while droplet flocculation appeared at higher concentrations. With progressing dextrin, the apparent shear viscosity significantly increased from 1.7 to 7.3 mPa.s. Further insight into the digestive behaviors of emulsion incorporated with dextrin was determined using a standardized INFOGEST method. Less clump in the oral phase and increasing droplet size in the initial intestine were observed in the emulsion incorporated with dextrin. Based on dextrin incorporation, a significant decrease in the extent of lipid digestion and ß-carotene bioaccessibility was presented. This study implies dextrin may be useful in controlling the texture and in vitro digestive behavior of Pickering emulsions, which may be advantageous for the designation of functional foods.

Production of Plant-Based Seafood: Scallop Analogs Formed by Enzymatic Gelation of Pea Protein-Pectin Mixtures.

This study investigated the possibility of using a phase separation, mixing, and enzymatic gelation approach to construct seafood analogs from plant protein-polysaccharide mixtures with properties mimicking real seafood. Heat-denatured pea protein (10%, w/w) and pectin (0-1%, w/w) were mixed to produce phase separated biopolymer blends. These blends were then subjected to mild shearing (350 rpm) to obtain fiber-like structures, which were then placed in molds and set by gelling the pea proteins using transglutaminase (2%, w/w). The appearance, texture, and cooking properties of the resulting scallop analogs were characterized and compared to those of real scallop. The presence of the pectin promoted the formation of a honeycomb structure in the scallop analogs, and microscopic orientation of the proteins was observed in the plane parallel to the applied shear flow. Lower pectin concentrations (0.5%, w/w) led to stronger gels with better water holding capacity than higher ones (1.0%, w/w). The appearance and texture of the plant-based scallop analogs were like those of real scallop after grilling, indicating the potential of using this soft matter physics approach to create plant-based seafood analogs. One of the main advantages of this method is that it does not require any expensive dedicated equipment, such as an extruder or shear cell technology, which may increase its commercial viability.

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

The potency of oil-soluble vitamins (vitamins A, D, E and K) in fortified foods can be improved by understanding how food matrices impact their bioavailability. In this review, the major food matrix effects influencing the bioavailability of oil-soluble vitamins are highlighted: oil content, oil composition, particle size, interfacial properties, and food additives. Droplet size and aggregation state in the human gut impact vitamin bioavailability by modulating lipid digestion, vitamin release, and vitamin solubilization. Vitamins in small isolated oil droplets typically have a higher bioavailability than those in large or aggregated ones. Emulsifiers, stabilizers, or texture modifiers can therefore affect bioavailability by influencing droplet size or aggregation. The dimensions of the hydrophobic domains in mixed micelles depends on lipid type: if the domains are too small, vitamin bioavailability is low. Overall, this review highlights the importance of carefully designing food matrices to improve vitamin bioavailability.

Digestibility and gastrointestinal fate of meat versus plant-based meat analogs: An in vitro comparison.

Plant-based meat analogs are likely to have different gastrointestinal fates than real meat products due to differences in their compositions and structures. Here, we compared the gastrointestinal fate of ground beef and ground beef analogs using the INFOGEST in vitro digestion model, focusing on differences in microstructure, physicochemical properties, lipid digestion, and protein digestion in different regions of the model gut. The presence of dietary fibers in the beef analogs increased their apparent shear viscosity in the gastrointestinal fluids, which may have inhibited lipid digestion in the small intestine. The proteins in the beef analogs were digested more rapidly in the stomach but less rapidly in the small intestine, which may have been due to differences in protein type (globular soy versus fibrous beef proteins), structural organization, and the presence of dietary fibers in the meat analogs.

Correction: Factors impacting lipid digestion and nutraceutical bioaccessibility assessed by standardized gastrointestinal model (INFOGEST): oil droplet size.

Correction for 'Factors impacting lipid digestion and nutraceutical bioaccessibility assessed by standardized gastrointestinal model (INFOGEST): oil droplet size' by Yunbing Tan et al., Food Funct., 2020, 11, 9936-9946, DOI: 10.1039/D0FO01505A.

Bioaccessibility of oil-soluble vitamins (A, D, E) in plant-based emulsions: impact of oil droplet size.

We systematically investigated the impact of oil droplet diameter (≈0.15, 1.6, and 11 µm) on the bioaccessibility of three oil-soluble vitamins (vitamin A palmitate, vitamin D, and vitamin E acetate) encapsulated within soybean oil-in-water emulsions stabilized by quillaja saponin. Lipid digestion kinetics decreased with increasing droplet size due to the reduction in oil-water interfacial area. Vitamin bioaccessibility decreased with increasing droplet size from 0.15 to 11 µm: 87 to 39% for vitamin A; 76 to 44% for vitamin D; 77 to 21% for vitamin E. Vitamin bioaccessibility also decreased as their hydrophobicity and molecular weight increased, probably because their tendency to remain inside the oil droplets and/or be poorly solubilized by the mixed micelles increased. Hydrolysis of the esterified vitamins also occurred under gastrointestinal conditions: vitamin A palmitate (∼90%) and vitamin E acetate (∼3%). Consequently, the composition and structure of emulsion-based delivery systems should be carefully designed when creating vitamin-fortified functional food products.

Enhancing emulsion functionality using multilayer technology: Coating lipid droplets with saponin-polypeptide-polysaccharide layers by electrostatic deposition.

Electrically charged food-grade biopolymers can be used to form multilayer coatings around the lipid droplets in oil-in-water emulsions using a sequential layer-by-layer electrostatic deposition approach. In principle, this approach can be used to improve the stability and enhance the functionality of food emulsions. In this study, multilayer coatings were formed from saponins, polypeptides, and polysaccharides using medium chain triglyceride (MCT) lipid droplets as templates (pH 4.0). First, an emulsion containing negatively charged lipid droplets was created using quillaja saponin (QS) as an anionic emulsifier. Second, these anionic droplets were coated with a cationic polypeptide (poly-L-lysine, PLL) to form positively-charged droplets. Finally, these cationic droplets were coated with a negatively-charged polysaccharide, either pectin (PE) or κ-carrageenan (KC), to form anionic droplets. Overall, the 1-layer emulsions had the best resistance to salt, pH, and heat, indicating that quillaja saponins were effective emulsifiers. The 2-layer emulsions had better pH-stability than the 3-layer emulsions, which tended to strongly aggregate under acidic conditions. Conversely, the 3-layer emulsions had better salt-stability than the 2-layer emulsions, which tended to aggregate strongly even at low salt levels (50-100 mM NaCl). All the emulsions were relatively stable to heating (90 °C, 30 min). Overall, our results provide useful insights into the formulation of stable multilayer emulsions from food-grade emulsifiers and biopolymers. There appears to be little advantage to using the multilayer technology to enhance the physical stability of saponin-coated lipid droplets, but there may be advantages in terms of extending their functional properties, which will be explored in future studies.

Factors impacting lipid digestion and nutraceutical bioaccessibility assessed by standardized gastrointestinal model (INFOGEST): Emulsifier type.

This paper is part of a series examining the impact of the main factors influencing lipid digestion and nutraceutical bioaccessibility in ß-carotene-loaded oil-in-water emulsions using the harmonized INFOGEST simulated gastrointestinal model. Here, the impact of emulsifier type was examined since food emulsions and nutraceutical delivery systems are often stabilized by various types of emulsifier. The INFOGEST method was adopted to investigate the in vitro gastrointestinal fate of emulsions stabilized by five kinds of food-grade emulsifier representing different classes: synthetic surfactants (Tween 20); natural surfactants (quillaja saponin); proteins (caseinate); polysaccharides (gum arabic); and phospholipids (soy lysolecithin). Microfluidization produced emulsions with small droplet sizes for all emulsifiers, except soy lysolecithin. Within the gastrointestinal model, the caseinate-coated oil droplets had the worst gastric stability, with severe droplet flocculation and coalescence occurring in the stomach. The fraction of the lipid phase that had been digested by the end of the gastrointestinal model was considerably lower for the emulsions stabilized by soy lysolecithin (93%) or caseinate (93%), than those stabilized by gum arabic (99%), quillaja saponin (111%) or Tween 20 (117%). This effect was attributed to lower surface area of lipids available for lipase to attach to for the lysolecithin and caseinate emulsions. The overall bioaccessibility of the ß-carotene increased in this order: lysolecithin (25%) < gum arabic (51%) < caseinate (55%) < quillaja saponin (56%) < Tween 20 (62%). The impact of emulsifier type on carotenoid bioaccessibility was ascribed to various factors: (i) some emulsifiers inhibited lipid digestion and so a fraction of the ß-carotene remained inside the undigested droplets and the mixed micelle phase had less solubilization capacity, i.e., lysolecithin, and caseinate; (ii) some emulsifiers protected ß-carotene from chemical degradation, i.e., lysolecithin and caseinate; and (iii) some emulsifiers promoted sedimentation of the ß-carotene-loaded micelles, i.e., lysolecithin. These results suggest that food emulsion behavior in the human gut may be influenced by the nature of the emulsifier employed, which is important knowledge when creating functional food and beverage products.

Impact of pesticide polarity and lipid phase dimensions on the bioaccessibility of pesticides in agricultural produce consumed with model fatty foods.

For most people, the pesticide residues found on agriculture products are the main source of pesticide exposure, which may adversely influence consumer health. The potential health hazard of residual pesticides depends on the nature of the foods they are consumed with. Studies with fat-soluble vitamins and nutraceuticals have shown that their bioaccessibility depends on food matrix composition and structure. We used an in vitro method to investigate the influence of the dimensions of the lipid phase in model fatty foods (emulsified or bulk oil) on the bioaccessibility of various pesticides. Three pesticides that differed in their oil-water partition coefficients were selected: bendiocarb (log P = 1.7), parathion (log P = 3.8), and chlorpyrifos (log P = 5.3). These pesticides were mixed with tomato puree to represent pesticide-treated agricultural products. Three model foods with different oil phase dimensions were used to represent different kinds of food product: small emulsions (d32 = 0.14 µm); large emulsions (d32 = 10 µm); and, bulk oil. Our results showed that the oil droplets underwent extensive changes as they passed through the simulated gastrointestinal tract due to changes in environmental conditions, such as pH, ionic strength, bile salts, and enzyme activities. The initial rate and final amount of lipid hydrolysis decreased with increasing lipid phase dimensions. Pesticide bioaccessibility depended on both the hydrophobicity of the pesticide and the dimensions of the co-ingested lipid droplets. The least hydrophobic pesticide (bendiocarb) had a high bioaccessibility (>95%) that did not depend on lipid phase dimensions. The more hydrophobic pesticides (parathion and chlorpyrifos) has a lower bioaccessibility that increased with decreasing lipid phase dimensions. Our results demonstrate the critical role that food structure plays on the potential uptake of pesticides from agricultural products, like fruits and vegetables.

Factors impacting lipid digestion and ß-carotene bioaccessibility assessed by standardized gastrointestinal model (INFOGEST): oil droplet concentration.

Food, nutrition, and pharmaceutical scientists are trying to elucidate the major factors impacting the bioavailability of macronutrients (e.g., lipids) and micronutrients (e.g., vitamins) so as to improve their efficacy. Currently, there is still a limited understanding of how food matrix effects impact digestion and bioaccessibility determined under the INFOGEST model, which is currently the most widely used standardized in vitro gastrointestinal model. Therefore, we examined the impact of corn oil concentration on lipid digestion and ß-carotene bioaccessibility using model food emulsions. For all oil concentrations tested (2.5 to 20%), complete lipid digestion was achieved using fed-state gastrointestinal conditions, which could only be seen if a back-titration was performed. The particle size and negative surface potential on the mixed micelles formed at the end of the small intestine phase both increased with increasing oil concentration, which was attributed to the generation of more free fatty acids. The ß-carotene bioaccessibility increased when the oil concentration was raised from 2.5 to 10% due to the increased solubilization capacity of the mixed micelles, but then it decreased when the oil concentration was raised further to 20% due to precipitation and sedimentation of some of the ß-carotene. The maximum ß-carotene bioaccessibility (93.2%) was measured at 10% oil. These results indicate that the oil concentration of emulsions influences ß-carotene bioaccessibility by altering digestion, solubilization, and precipitation processes. This knowledge is important when designing more effective functional or medical food products.

Factors impacting lipid digestion and nutraceutical bioaccessibility assessed by standardized gastrointestinal model (INFOGEST): oil.

The oil droplets in commercial emulsified foods have dimensions that vary widely, from hundreds of nanometers to tens of micrometers. Previously, the size of the droplets in oil-in-water emulsions has been shown to impact their gastrointestinal behavior, which may influence their physiological effects. In this study, we analyzed the impact of oil droplet diameter (0.16, 1.1 and 8.2 µm) on lipid digestion and nutraceutical bioaccessibility using a widely used standardized gastrointestinal tract model: the INFOGEST method. The emulsions used consisted of corn oil droplets stabilized using a food-grade non-ionic surfactant (Tween 20), and the droplet size was controlled by preparing them with a microfluidizer (small), sonicator (medium), or high-shear blender (large). The surfactant-coated oil droplets were relatively resistant to size changes in the mouth and stomach, due to the strong surface activity and steric stabilization mechanism of the non-ionic surfactant used. As expected, the kinetics of lipid digestion were enhanced for smaller droplets because of their greater specific surface area. The degree of lipid digestion fell from 117% to 78% (p < 0.001) as the initial droplet diameter was raised from 0.16 to 8.2 µm. In addition, there was a reduction in ß-carotene bioaccessibility from 83 to 15% (p < 0.001) with increasing droplet diameter. This result was ascribed to several effects: (i) some carotenoids were trapped inside the undigested oil phase; (ii) fewer mixed micelles were produced to internalize the carotenoids; and, (iii) a fraction of the carotenoids crystallized and sedimented. Our results underline the critical importance of considering droplet size when developing emulsified foods loaded with carotenoids. The results obtained by the INFOGEST method are consistent with those found using other in vitro methods in earlier studies.

Stabilization of soybean oil-in-water emulsions using polypeptide multilayers: Cationic polylysine and anionic polyglutamic acid.

Oil-in-water emulsions are used as delivery systems for non-polar functional ingredients in various industries, including foods, cosmetics, personal care products, agrochemicals, and pharmaceuticals. Emulsions, however, tend to breakdown under the conditions found in many commercial products. In this study, the functional performance of the lipid droplets in emulsions was tailored by sequential layer-by-layer electrostatic deposition of oppositely charged polypeptides onto their surfaces. Cationic poly-L-lysine (PLL) and anionic poly-glutamic acid (PGA) were used as a pair of oppositely charged polypeptides (pH 4.0). First, a primary emulsion (10% w/w soybean oil-in-water emulsion) was formed consisting of small lipid droplets (d32 = 500 µm) coated by a natural surfactant (0.05% w/w quillaja saponin). Second, cationic PLL was deposited onto the surfaces of the anionic saponin-coated droplets. Third, anionic PGA was deposited onto the surfaces of the cationic PLL-saponin-coated droplets. We then assessed the ability of the coatings to protect the lipid droplets from aggregation when the pH (2.0-9.0), ionic strength (0-350 mM), or temperature (30-90 °C) were altered. The properties of the primary, secondary, and tertiary emulsions were monitored by measuring the mean particle diameter (d32), electrical characteristics (ζ-potential), and microstructure of the lipid droplets. The electrical characteristics of the droplets could be modulated by controlling the number and type of layers used. The primary emulsion had the best resistance to varying environmental conditions, while the secondary emulsion had the worst, suggesting electrostatic deposition should only be used to obtain specific functionalities. Interestingly, PLL detached from the surfaces of the secondary emulsions at high salt concentrations due to electrostatic screening, which improved their salt stability. This phenomenon may be useful for some food applications, e.g., having cationic droplets during food storage, but anionic ones inside the human body.

Impact of fat crystallization on the resistance of W/O/W emulsions to osmotic stress: Potential for temperature-triggered release.

Water-in-oil-in-water (W/O/W) emulsions can be designed to encapsulate, protect, and release both hydrophilic and hydrophobic functional compounds. In this study, we examined the impact of crystallizing the fat phase on the resistance of W/O/W emulsions to osmotic stress, with the aim of developing osmotic-responsive systems. Polyglycerol polyricinoleate (PGPR) was used as a hydrophobic surfactant to stabilize the inner water droplets, while Quillaja saponin and whey protein isolate (WPI) were used as hydrophilic surfactants to coat the oil droplets. The impact of fat crystallization was examined by using either a liquid (soybean oil, SO) or semi-solid (hydrogenated soybean oil, HSO) fat as the oil phase. An osmotic stress was generated by establishing a sucrose concentration gradient between the internal and external water phases. Alterations in the droplet size, morphology, and stability of the W/O/W emulsions was measured when the sucrose concentration gradient was changed. The W/O droplets in the SO-emulsions swelled/shrank when the external sucrose concentration was below/above the internal sucrose concentration, which is indicative of water diffusing into/out of the droplets. Conversely, there was no change in the size of the W/O droplets in the HSO-emulsions under the same conditions, which was attributed to the mechanical strength of the fat crystal network resisting swelling or shrinking. HSO-emulsions did exhibit swelling when they were heated above a critical temperature, due to melting of the fat crystals and disruption of the crystal network. Our results demonstrate that crystallization of the oil phase of W/O/W emulsions can prevent water transport due to osmotic stress, which may be useful for developing temperature-triggered delivery systems for application in foods, cosmetics, pharmaceuticals, or personal care products.