Influence of anionic alginate and cationic chitosan on physicochemical stability and carotenoids bioaccessibility of soy protein isolate-stabilized emulsions

Utilization of layer-by-layer deposition to improve the stability of astaxanthin emulsions: Triple-layer coatings formed using sodium caseinate-pectin-chitosan

This study aimed to develop a good multilayered emulsion delivery system to improve the stability of astaxanthin. The layer-by-layer (LBL) electrostatic deposition technique was utilized to prepare sodium caseinate-pectin-chitosan astaxanthin multilayered emulsions. The stabilities of the emulsions and astaxanthin under different environmental stresses were investigated. Results showed that the droplet size of sodium caseinate-pectin double-layer emulsion (CS/P-e), sodium caseinate-chitosan double-layer emulsion (CS/CTS-e) and sodium caseinate-pectin-chitosan triple-layer emulsion (CS/P/CTS-e) varied less with pH and salt ions than that of sodium caseinate single-layer emulsion (CS-e). The droplet size of triple-layer emulsion changed the least after storage and freeze-thaw cycles compared with that of single- and double-layer emulsions. After thermal, freeze-thaw cycle, storage, and ultraviolet irradiation treatments, the stability of astaxanthin in multilayered emulsions was higher than that in single-layer emulsion, and the retention rate of astaxanthin increased as the number of interfacial layers increased. Furthermore, the free fatty acid (FFA) release of CS/P-e and CS-e was higher than that of CS/CTS-e and CS/P/CTS-e, and multilayered emulsions improved the bioaccessibility of astaxanthin. These findings provided a theoretical basis for triple-layer emulsions to deliver bioactive substances.

Impact of trypsin on interfacial conformational evolution of soy protein isolate/soy hull polysaccharide emulsion

The impact of trypsin on the demulsification mechanism of soy protein isolate (SPI)/soy hull polysaccharide (SHP) emulsion under trypsin treatment was investigated. We analyzed the conformational evolution of the emulsion interface induced during the bulk demulsification, focusing on the oil-water interface. During the enzymatic treatment for 0-120 min, various spectral analyses including spectrum analyses of Raman, FT-IR, intrinsic fluorescence, and ultraviolet spectral analyses demonstrated gradual hydrolysis and polymerization of protein molecules within SPI/SHP, SPI, and SHP on the oil-water interface by trypsin, particularly noticeable during 30-90 min. Notably, at 90 min, an increase in β-sheet content and a red shift of the IR spectrum from 3400 to 3380 cm-1 indicated the conjugate effect of small molecules due to large interfacial tension, accompanied by hydrophobic interaction and hydrogen bonding. These alterations in SPI/SHP, SPI, and SHP conformations at the oil-water interface led to droplet demulsification and oil phase release.

Preparation, characterization, and stability of chitosan-tremella polysaccharide layer-by-layer encapsulated astaxanthin nanoemulsion delivery system

In this study, a layer-by-layer (LBL) encapsulated astaxanthin (Ast) nanoemulsion delivery system based on chitosan (CS) and tremella polysaccharide (TP) was successfully developed. The system constructed an Ast-CS-TP emulsion with high encapsulation efficiency and an excellent stability profile by utilizing the opposite charge properties of CS and TP. This study evaluated the effects of different stresses (including temperature, salt addition, pH, UV irradiation, and centrifugal force) on the emulsion's stability. To further investigate the protective mechanism of the emulsions, we performed antioxidant activity experiments after UV treatment. Additionally, an in vitro digestion experiment was conducted to assess the behavior of Ast emulsion under simulated gastrointestinal conditions. The stability correlation coefficients were calculated using the Python database Pandas. The results showed that Ast-CS-TP emulsions exhibited turbidity and enhanced homogeneity with a small particle size of around 400 nm and a high absolute zeta potential of 35 mV and exhibited excellent stability under various stresses. The Ast-CS-TP emulsions also exhibited pH-responsive release at pH ≥ 7, consistent with pH changes in the gastrointestinal tract, and were stable in highly concentrated salt solutions. We found that the CS and TP layers significantly improved the photostability of Ast. CS and TP significantly enhanced Ast's oral bioavailability. The stability correlation coeffcients showed that pH and salt concentration were the largest factors that affected the stability of the emulsion. This study provided important insights into the encapsulation and targeting of Ast, providing a theoretical foundation and technical guidance for the comprehensive utilization of Ast.

Enhancement of non-covalent interaction between soy protein isolate and quercetin by sodium alginate

Effects of sodium alginate (SA) on the non-covalent interaction between soybean protein isolate (SPI) and quercetin (Que) were investigated by multispectral technology, molecular docking and dynamics simulation technology. Structural alterations of the binary complexes were observed after SA addition, characterized by a red shift of maximum fluorescence emission wavelength. The introduction of 0.1% (w/v) SA led to a reduction of 12.3% in the α-helix and β-sheet structures, accompanied by 12.6% increase in the β-turn and random coil conformations. The binding of SA to SPI provided electrostatic interactions and facilitated the subsequent binding of SPI to Que. Molecular docking confirmed that hydrophobic interactions and electrostatic interactions were also the main driving force. Molecular dynamics simulation emphasized that the ternary complexes with SA exhibited greater stability compared to the binary ones. The foaming and emulsifying properties of SPI-Que complexes were enhanced by 33.76% and 68.28%, respectively, due to the addition of SA.

Stability of Buriti Oil Microencapsulated in Mixtures of Azuki and Lima Bean Flours with Maltodextrin

Buriti oil (Mauritia flexuosa L.) is rich in carotenoids, mainly β-carotene, and has great value for application as a food, pharmaceutical, or cosmetic ingredient, as well as a natural pigment. Microencapsulation is a promising technique to protect compounds sensitive to degradation such as β-carotene. Materials composed of carbohydrates and proteins, such as azuki bean (Vigna angularis L.) and lima bean (Phaseolus lunatus L.) flours, are alternative matrices for microencapsulation, which additionally provide good amounts of nutrients. In combination with maltodextrin, the flours represent a protective barrier in stabilizing lipophilic compounds such as buriti oil for subsequent spray drying. In this work, the performance of mixtures of maltodextrin with whole azuki and lima bean flours was evaluated in the microencapsulation of buriti oil. The microcapsules showed good results for solubility (>80%), hygroscopicity (~7%), encapsulation efficiency (43.52 to 51.94%), and carotenoid retention (64.13 to 77.49%.) After 77 days of storage, the microcapsules produced maintained 87.79% and 90.16% of carotenoids, indicating that the powders have high potential for application as encapsulants in the food and pharmaceutical industries.

Mechanism for improving the in vitro digestive properties of coconut milk by modifying the structure and properties of coconut proteins with monosodium glutamate

In this paper, the effect of monosodium glutamate (MSG) on coconut protein (CP) solubility, surface hydrophobicity, emulsification activity, ultraviolet spectroscopy and fluorescence spectroscopy was investigated. Meanwhile, the changes in the in vitro digestive properties of coconut milk were also further analyzed. MSG treatment altered the solubility and surface hydrophobicity of CP, thereby improving protein digestibility. Molecular docking showed that CP bound to pepsin and trypsin mainly through hydrogen bonds and salt bridges. And MSG increased the cleavable sites of pepsin and trypsin on CP, thus further improving the protein digestibility. In addition, MSG increased the Na+ concentration in coconut milk, promoted flocculation and aggregation between coconut milk droplets, which prevented the binding of lipase and oil droplets and inhibited lipid digestion. These findings may provide new ideas and insights to improve the digestive properties of plant-based milk.

Design, characterization and digestibility of β-carotene-loaded emulsion system stabilized by whey protein with chitosan and potato starch addition

The physicochemical properties and gastrointestinal fate of β-carotene-loaded emulsions and emulsion gels were examined. The emulsion was emulsified by whey protein isolate and incorporated with chitosan, then the emulsion gels were produced by gelatinizing potato starch in the aqueous phase. The rheology properties, water distribution, and microstructure of emulsions and emulsion gels were modulated by chitosan combination. A standardized INFOGEST method was employed to track the gastrointestinal fate of emulsion systems. Significant changes in droplet size, zeta-potential, and aggregation state were detected during in vitro digestion, including simulated oral, stomach, and small intestine phases. The presence of chitosan led to a significantly reduced free fatty acids release in emulsion, whereas a slightly increasing released amount in the emulsion gel. β-carotene bioaccessibility was significantly improved by hydrogel formation and chitosan addition. These results could be used to formulate advanced emulsion systems to improve the gastrointestinal fate of hydrophobic nutraceuticals.

Preparation and characterization of astaxanthin-loaded microcapsules stabilized by lecithin-chitosan-alginate interfaces with layer-by-layer assembly method

Astaxanthin is a kind of keto-carotenes with various health benefits. However, its solubility and chemical stability are poor, which leads to low bio-availability. Microcapsules have been reported to improve the solubility, chemical stability, and bio-availability of lipophilic bioactives. Freeze-dried astaxanthin-loaded microcapsules were prepared by layer-by-layer assembly of tertiary emulsions with maltodextrin as the filling matrix. Tertiary emulsions were fabricated by performing chitosan and sodium alginate electrostatic deposition onto soybean lecithin stabilized emulsions. 0.9 wt% of chitosan solution, 0.3 wt% of sodium alginate solution and 20 wt% of maltodextrin were optimized as the suitable concentrations. The prepared microcapsules were powders with irregular blocky structures. The astaxanthin loading was 0.56 ± 0.05 % and the encapsulation efficiency was >90 %. A slow release of astaxanthin could be observed in microcapsules promoted by the modulating of chitosan, alginate and maltodextrin. In vitro simulated digestion displayed that the microcapsules increased the bio-accessibility of astaxanthin to 69 ± 1 %. Chitosan, alginate and maltodextrin can control the digestion of microcapsules. The coating of chitosan and sodium alginate, and the filling of maltodextrin in microcapsules improved the chemical stability of astaxanthin. The constructed microcapsules were valuable to enrich scientific knowledge about improving the application of functional ingredients.

Fabrication and characterization of dihydromyricetin-loaded microcapsules stabilized by glyceryl monostearate and whey protein-xanthan gum

Dihydromyricetin (DMY) is a lipophilic nutrient with various potential health benefits; however, its poor storage stability and low solubility and bioavailability limit its applications. This study aims to encapsulate DMY in microcapsules by membrane emulsification and freeze-drying methods to overcome these issues. Glyceryl monostearate (GMS, solid lipid) and octyl and decyl glycerate (ODO, liquid lipid) were applied as the inner cores. Whey protein and xanthan gum (XG) were used as wall materials. The prepared microcapsules had an irregular blocky aggregated structure with rough surfaces. All the microcapsules had a DMY loading of 0.85 %-1.1 % and encapsulation efficiency (EE) >85 %. GMS and XG increased the DMY loading and EE. The addition of GMS and an increased XG concentration led to a decrease in the rehydration rate. The in vitro release and digestion studies revealed that GMS and XG controlled the release and digestion of DMY. The chemical stability results indicated that GMS and XG protected DMY against oxidation. An antioxidant capacity study showed that GMS and XG helped DMY in the microcapsules exert antioxidant effects. This research study provides a platform for designing microcapsules with good stability and high bioavailability to deliver lipophilic bioactive compounds.

Improving stability and bioavailability of curcumin by quaternized chitosan coated nanoemulsion

This study aims to enhance the stability and bioavailability of curcumin (Cur) using nanoemulsion coating technology. The nanoemulsion system was developed by encapsulating Cur with quaternized chitosan (QMNE), and the nanoemulsion containing Cur and medium-chain triglyceride (MCT) oil (MNE) was used as control sample. The microstructure of the nanoemulsion was examined using Dynamic light scattering (DLS), Transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FT-IR). The storage, thermal, ionic strength, and pH stability of QMNE were also evaluated, respectively. The results indicate that QMNE demonstrates superior stability, in vitro gastric fluid stability, bioavailability compared to MNE. QMNE exhibits excellent emulsification activity and stability. In addition, QMNE shows significant protection against oxidation in both emulsion systems after different heat treatments. The antimicrobial activity results reveal that QMNE exhibits greater efficacy than that of MNE. Consequently, this study provides valuable insights into the formulation of a system to encapsulate Cur and the improvement of its stability and bioavailability.

The influence of ionic polysaccharides on the physicochemical and techno-functional properties of soy proteins; a comprehensive review

Since the world's population has surged in recent decades, the need for sustainable as well as environmentally friendly protein sources is growing. However, there are daunting challenges in utilizing these protein sources in the food industry due to their poor techno-functional properties compared with animal proteins. Numerous procedures have been introduced to improve plant protein functionalities with related pros and cons. Among them, complexation with polysaccharides is considered a safe and effective process for modulating plant proteins' technological and industrial applications. Notwithstanding the nutritional value of soy protein (SP) as a "complete protein," it is a crucial protein commercially because of its rank as the highest-traded plant-based protein worldwide. The current review deals with SP complexation with ionic polysaccharides, including chitosan, alginate, carrageenan, and xanthan gum, and their effects on the physicochemical and techno-functional properties of SP. Accordingly, the structure of SP and the abovementioned polysaccharides have been considered for a better understanding of the possible interactions. Then, the changes in the physicochemical and functional properties of SP and their potential applications in the formulation of plant-based food products have been discussed. Overall, ionic polysaccharides at optimum conditions would improve the functional properties of SP by altering its secondary structure, making it suitable for a wide range of applications in the food industry.

Effect of gelation technique on lipid digestibility of emulsion-loaded alginate microparticles: a systematic review and meta-analysis

Alginate microparticles fabricated via calcium gelation or layer-by-layer assembly are commonly used for encapsulating emulsions. In this study, the impact of these two gelation methods on the lipid digestibility of emulsions was reviewed through a systematic screening of relevant studies. From the literature search (Scopus, PubMed, and Web of Science databases), 604 records were screened and 25 articles were included in the analysis. The fold change of free fatty acid release rate at the end of in vitro digestion process between alginate-encapsulated emulsion and emulsions not encapsulated by alginate was calculated for calcium gelation (weighted mean of response ratio 0.64, 95% CI 0.54-0.75) and layer-by-layer assembly (weighted mean of response ratio 0.89, 95% CI 0.81-0.98). Alginate-calcium hydrogels showed stronger inhibition of the extent of lipid digestion than alginate-coated multilayer emulsions. The structural and particle size differences between alginate microparticles acquired using different techniques may contribute to this phenomenon.

The Effect of Different Induction Methods on the Structure and Physicochemical Properties of Glycosylated Soybean Isolate Gels

Soybean protein isolate (SPI), as a full-valued protein, is rich in nutrients, such as amino acids. However, the isolated structure of soybeans makes it difficult to react and thus prepare good gels. In order to further improve the properties of SPIs and to prepare plant-based gels with good performance, this experiment was conducted to prepare maltodextrin glycosylated soybean isolate (MGSI) by the glycosylation of SPI and maltodextrin (MD), and the gels were prepared by thermal induction, transglutaminase (TGase) induction, and TG-MgCl₂ co-induction of this glycosylated protein to investigate the effects of different induction methods on the structure and properties of the gels produced by MGSIs. Moreover, the effects of different induction methods on the structure and properties of the gels produced by MGSI were investigated. SDS-PAGE protein electrophoresis, FTIR spectroscopy, and endogenous fluorescence spectroscopy revealed that all three inductions result in the covalent bond cross-linking of MGSI during the gel formation process. Compared with thermal induction, the TGase-induced MGSI secondary structure had a higher content of β-folded structures, increased fluorescence intensity of tertiary structures, and produced a red shift. The gel induced by TGase in collaboration with MgCl₂ contains a more β-folded structure and irregular curl and increases the β-turned angle and α-helix content further, the endogenous fluorescence λmax is significantly red-shifted, and the fluorescence intensity increases, demonstrating that the tertiary structure of MGSI unfolds the most, forming multilayered gels with the tightest structures. The three gels were analyzed by rheology and SEM, showing that the TGase-MgCl₂ synergistically induced gel had the highest energy-storage modulus G', viscoelasticity, and water-holding capacity, as well as the densest gel structure. In conclusion, the combined treatment of enzyme and MgCl₂ might be an effective way of improving the structure and gel properties of SPI. This study helps to promote the high-value utilization of SPI and the development of plant protein gels.

Property and Stability of Astaxanthin Emulsion Based on Pickering Emulsion Templating with Zein and Sodium Alginate as Stabilizer

Astaxanthin loaded Pickering emulsion with zein/sodium alginate (SA) as a stabilizer (named as APEs) was developed, and its structure and stability were characterized. The encapsulation efficiency of astaxanthin (Asta) in APEs was up to 86.7 ± 3.8%, with a mean particle size of 4.763 μm. Freeze-dried APEs showed particles stacked together under scanning electronic microscope; whereas dispersed spherical nanoparticles were observed in APEs dilution under transmission electron microscope images. Confocal laser scanning microscope images indicated that zein particles loaded with Asta were aggregated with SA coating. X-ray diffraction patterns and Fourier transform infrared spectra results showed that intermolecular hydrogen bonding, electrostatic attraction and hydrophobic effect were involved in APEs formation. APEs demonstrated non-Newtonian shear-thinning behavior and fit well to the Cross model. Compared to bare Asta extract, APEs maintained high Asta retention and antioxidant activity when heated from 50 to 10 °C. APEs showed different stability at pH (3.0-11.0) and Na+, K+, Ca2+, Cu2+ and Fe2+ conditions by visual, zeta potential and polydispersity index measurements. Additionally, the first order kinetics fit well to describe APEs degradation at pH 3.0 to 9.0, Na+, and K+ conditions. Our results suggest the potential application of Asta-loaded Pickering emulsion in food systems as a fortified additive.

Effects of Different Ionic Polysaccharides in Cooked Lean Pork Batters on Intestinal Health in Mice

The effects of cooked lean pork batters with three ionic types of polysaccharides (anionic xanthan-gum/sodium-alginate, neutral curdlan-gum/konjac-gum and cationic chitosan) on the intestinal health of mice were investigated in this study. The results showed that the zeta potential in the sodium-alginate group (−31.35 mV) was higher (p < 0.05) than that in the chitosan group (−26.00 mV), thus promoting the protein hydrolysis in the anionic group because of electrostatic repulsion. The content of total free amino acids in the small intestine in the xanthan-gum and sodium-alginate groups (2754.68 μg and 2733.72 μg, respectively) were higher (p < 0.05) than that in the chitosan group (1949.78 μg), which could decrease the amount of undigested protein entering the colon. The two anionic groups could also increase the abundance of Lactobacillus and the balance of Faecalibaculum and Alistipes in the colon. The content of proinflammatory factor IL−6 of colon tissues in the sodium-alginate group (1.02 ng/mL) was lower (p < 0.05) than that in chitosan, curdlan-gum and konjac-gum groups (1.29, 1.31 and 1.31 ng/mL, respectively). The result of haematoxylin-eosin staining of the colon also revealed that sodium alginate was beneficial for colonic health. The two neutral groups increased the content of faecal short-chain fatty acids in mice. These results demonstrated that anionic polysaccharides have potential for developing functional low-fat meat products.

The impact of pH on mechanical properties, storage stability and digestion of alginate-based and soy protein isolate-stabilized emulsion gel beads with encapsulated lycopene

In alginate-based emulsion gels containing protein-coated droplets, pH can influence the gelation mechanism of alginate gels, and the interactions between alginate molecules and protein-coated droplets, and thus properties of emulsion gels. This study investigated the impact of pH 3-7 on the properties (e.g., surface structures of droplets, mechanical properties, storage stability, digestion behavior) of alginate gel beads containing soy protein isolate(SPI)-stabilized oil droplets. Emulsion droplets were SPI-coated droplets at pH 6-7 and alginate/SPI-coated droplets at pH 3-5. Emulsion droplet flocculation only occurred in emulsions at pH 7.0. Emulsion gel beads at pH 3.0 had lower mechanical strength, higher storage stability, faster release of encapsulated lycopene during in-vitro digestion, and higher bioaccesibility of lycopene after 2 h of intestinal digestion than those at pH 7.0 and 5.0. The findings of this study are crucial to emulsion gel beads with controlled release and improved storage stability of encapsulated compounds by changing the pH of emulsions.

Soy Protein Isolate/Sodium Alginate Microparticles under Different pH Conditions: Formation Mechanism and Physicochemical Properties

The effects of sodium alginate (SA) and pH value on the formation, structural properties, microscopic morphology, and physicochemical properties of soybean protein isolate (SPI)/SA microparticles were investigated. The results of ζ-potential and free sulfhydryl (SH) content showed electrostatic interactions between SPI and SA, which promoted the conversion of free SH into disulfide bonds within the protein. The surface hydrophobicity, fluorescence spectra, and Fourier transform infrared spectroscopy data suggested that the secondary structure and microenvironment of the internal hydrophobic groups of the protein in the SPI/SA microparticles were changed. Compared with SPI microparticles, the surface of SPI/SA microparticles was smoother, the degree of collapse was reduced, and the thermal stability was improved. In addition, under the condition of pH 9.0, the average particle size of SPI/SA microparticles was only 15.92 ± 0.66 μm, and the distribution was uniform. Rheological tests indicated that SA significantly increased the apparent viscosity of SPI/SA microparticles at pH 9.0. The maximum protein solubility (67.32%), foaming ability (91.53 ± 1.12%), and emulsion activity (200.29 ± 3.38 m²/g) of SPI/SA microparticles occurred at pH 9.0. The application of SPI/SA microparticles as ingredients in high-protein foods is expected to be of great significance in the food industry.

Effect of the chitosan second layer on the gelation and controlled digestion of Citrem-chitosan bilayer emulsions

This research aimed to induce repulsive gelation in Citrem-stabilized O/W emulsions by creating a secondary layer of chitosan around the droplets. A range of chitosan concentrations (0-0.25 wt%) and degrees of deacetylation (DDA 50% and 93%) were used to establish the conditions for repulsive gelation in 36 wt% O/W emulsion. The bilayer emulsions were prepared by the electrostatic deposition of positively charged chitosan on negatively charged Citrem-stabilized droplets at pH 4. The droplet size increased from <0.5 μm for the primary emulsion to 5-10 μm at an intermediate chitosan concentration (0.05-0.15 wt%) due to bridging flocculation and again dropped to 1.7-3.6 μm at higher concentrations (0.2 and 0.25 wt%). The droplet charge changed from -48 mV for the primary emulsion to +41.4 and +54.5 mV after surface saturation by DDA 50 and DDA 93 chitosan, respectively. The strain and frequency-dependent rheology indicated that with an increase in the chitosan concentration, emulsions changed from a viscoelastic liquid for monolayer emulsions to strong attractive gel due to bridging flocculation at an intermediate chitosan concentration. At a higher concentration, repulsive gels were formed at complete coverage due to an increase in the effective oil volume fraction towards close packing resulting from the expansion of the interfacial steric barrier and charge cloud thickness. The overall lipid digestibility during in vitro digestion was 25.7% for monolayer emulsions, which decreased with increased chitosan concentration and reached the lowest at surface saturation (17.5%). It was proposed that the formation of the Citrem-chitosan bilayer controlled lipid digestibility by delaying the action of gastric and pancreatic lipases. Such bilayer emulsion gels can be utilized for structure formation in reduced-fat foods.

Effects of cold-renneted and pre-heated milk protein concentrates (MPCs) addition on the properties of alginate composite gels

This study investigated the effects of milk protein concentrate (MPC85) (untreated, cold-renneted, and pre-heated (80 °C, 30 min)) addition on the physical/mechanical properties of sodium alginate (2% w/w) composite gels in millimeter-size (bead) and centrimeter-size gel forms. The gels were characterized for the degree of syneresis, swelling behavior, hardness, stiffness, viscoelastic behavior, and surface morphology of freeze-dried gel. The results showed that the addition of untreated and treated MPCs reduced the hardness, the stiffness and the solid-like behavior of the alginate gels. Untreated MPC and pre-heated MPC caused no effect on syneresis of alginate gels. The addition of cold-renneted MPC reduced the degree of syneresis in composite gels by 13.7%. Similarly, the addition of cold-renneted MPC reduced (by 16.4%) the degree of syneresis of the alginate composite gels after incubation in simulated gastric fluid (SGF). After incubation in simulated intestinal fluid (SIF), the gel containing alginate only swelled while gels containing untreated MPC and pre-heated MPC experienced degradation and a severe mass loss. Meanwhile, the gels containing cold-renneted MPC swelled and at the same time eroded. Moreover, only cold-renneted MPC composite gels showed lower shrinkage and wrinkles on the surface of the beads during lyophilization. Therefore, based on these results, it is indicated that cold-rennet induced gelation method could increase the effectiveness of MPC as a composite material for alginate gels.

Enhancing bioaccessibility and bioavailability of carotenoids using emulsion-based delivery systems

The consumption of foods rich in antioxidants, vitamins, minerals including carotenoids etc. can boost the immune system to help fight off various infections including SARS- CoV 2 and other viruses. Carotenoids have been gaining attention particularly in food and pharmaceutical industries owing to their diverse functions including their role as pro-vitamin A activity, potent antioxidant properties, and quenching of reactive oxygen (ROS), such as singlet oxygen and lipid peroxides within the lipid bilayer of the cell membrane. Nevertheless, carotenoids being lipophilic, have poor solubility in aqueous medium and are also chemically instable. They are susceptible to degrade under stimuli environmental conditions during food processing, storage and gastrointestinal passage. They also exhibit poor oral bioavailability, thus, their applications in aqueous-based foods are limited. As a consequent, suitable delivery systems including colloids-based are needed to enhance the solubility, stability and bioavailability of carotenoids. This review presents challenges of incorporation and delivery of carotenoids focusing on stability and factors affecting bioavailability. Furthermore, designed factors impacting bioaccessibility and bioavailability of carotenoids using emulsion-based delivery systems are explicitly explained. Each delivery system exhibits its own advantages and disadvantages; thus, the delivery systems should be designed based on their targets and their further applications.

Encapsulation of Lutein via Microfluidic Technology: Evaluation of Stability and In Vitro Bioaccessibility

Inadequate intake of lutein is relevant to a higher risk of age-related eye diseases. However, lutein has been barely incorporated into foods efficiently because it is prone to degradation and is poorly bioaccessible in the gastrointestinal tract. Microfluidics, a novel food processing technology that can control fluid flows at the microscale, can enable the efficient encapsulation of bioactive compounds by fabricating suitable delivery structures. Hence, the present study aimed to evaluate the stability and the bioaccessibility of lutein that is encapsulated in a new noodle-like product made via microfluidic technology. Two types of oils (safflower oil (SO) and olive oil (OL)) were selected as a delivery vehicle for lutein, and two customized microfluidic devices (co-flow and combination-flow) were used. Lutein encapsulation was created by the following: (i) co-flow + SO, (ii) co-flow + OL, (iii) combination-flow + SO, and (iv) combination-flow + OL. The initial encapsulation of lutein in the noodle-like product was achieved at 86.0 ± 2.7%. Although lutein’s stability experienced a decreasing trend, the retention of lutein was maintained above 60% for up to seven days of storage. The two types of device did not result in a difference in lutein bioaccessibility (co-flow: 3.1 ± 0.5%; combination-flow: 3.6 ± 0.6%) and SO and OL also showed no difference in lutein bioaccessibility (SO: 3.4 ± 0.8%; OL: 3.3 ± 0.4%). These results suggest that the types of oil and device do not affect the lutein bioaccessibility. Findings from this study may provide scientific insights into emulsion-based delivery systems that employ microfluidics for the encapsulation of bioactive compounds into foods.

Investigation of the Formation Mechanism and Curcumin Bioaccessibility of Emulsion Gels Based on Sugar Beet Pectin and Laccase Catalysis

In this study, modified whey protein hydrolysates (WPH) were obtained after succinic anhydride succinylation and linear dextrin glycation, and emulsion gels were prepared on the basis of unmodified/modified WPH stabilized emulsions with sugar beet pectin (SBP) addition and laccase-catalyzed cross-linking. The influences of emulsifier types and SBP contents on the texture of emulsion gels were estimated. The texture and rheological properties of emulsion gels were characterized. An ideal gel emulsion was formed when the SBP content was 3% (w/w). A uniform network was observed in emulsion gels stabilized by W-L, W-L-S, and W-S-L. In addition, the effect of the emulsifier type on the bioaccessibility of curcumin encapsulated in emulsion gels was investigated and the W-S-L stabilized emulsion gel exhibited the highest curcumin bioaccessibility (65.57%). This study provides a theoretical basis for the development of emulsion gels with different textures by SBP addition and laccase cross-linking as encapsulation delivery systems.

Effect of Interfacial Ionic Layers on the Food-Grade O/W Emulsion Physical Stability and Astaxanthin Retention during Spray-Drying

The utilization of astaxanthin in food processing is considered to be narrow because of its substandard solubility in aqueous matrices and the instability of chemical compounds during the processing of food and the instability of chemical compounds during the processing of food. The investigation sought to evaluate multilayer emulsions stabilized by ionic interfacial layers of lupin protein isolate (LPI), ι-carrageenan (CA), and chitosan (CHI) on the physical stability of the emulsion as well as the retention of astaxanthin during the spray drying process. Primary emulsion (Pr-E) was prepared by adding LPI on oil droplet surfaces containing astaxanthin. The homogenization pressure and cycles to obtain the Pr-E were investigated. The secondary emulsion (Se-E) and tertiary emulsion (Te-E) were elaborated by mixing CA/Pr-E and CHI/Se-E, respectively. Emulsion stability was assessed under different environmental stresses (pH and NaCl). Astaxanthin retention of emulsions was determined immediately after finishing the spray-drying process. The results showed that Pr-E was stabilized with 1.0% (w/v) of LPI at 50 MPa and three cycles. Se-E and Te-E were obtained with CA/Pr-E and Se-E/CHI of 70/30 and 50/50% (w/w), respectively. The Se-E was the most stable compared to the Pr-E and Te-E when subjected to different pHs; nevertheless, once the NaCl concentration rose, no variations in the ζ-potential of all emulsions studied or destabilization were observed. The Se-E and Te-E derived provided higher astaxanthin retention (>95%) during the spray-drying process compared to Pr-E (around 88%). The results indicated that these astaxanthin multilayer emulsions show considerable potential as a functional ingredient in food products.

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.

Chitosan reduces vitamin D bioaccessibility in food emulsions by binding to mixed micelles

Consumption of sufficiently high quantities of dietary fibers has been linked to a range of health benefits. Recent research, however, has shown that some dietary fibers interfere with lipid digestion, which may reduce the bioavailability of oil-soluble vitamins and nutraceuticals. For this reason, we examined the impact of a cationic polysaccharide (chitosan) on the bioaccessibility of vitamin D using the standardized INFOGEST in vitro digestion model. The vitamin D was encapsulated within an emulsion-based delivery system that contained whey protein-coated corn oil droplets. Our results showed that chitosan promoted severe droplet flocculation in the small intestine and reduced the amount of free fatty acids detected using a pH-stat method. However, a back-titration of the digested sample showed that the lipids were fully digested at all chitosan levels used (0.1-0.5%), suggesting that chitosan may have bound some of the free fatty acids released during lipid digestion. The presence of the chitosan decreased the bioaccessibility of vitamin D by about 37%, but this effect did not depend strongly on chitosan concentration (0.1-0.5%). It was hypothesized that chitosan bound to the vitamin-loaded mixed micelles and promoted their precipitation. The knowledge gained in this study might provide useful insights in designing emulsion-based delivery systems with high vitamin bioaccessibility.

Effect of interfacial layer number on the storage stability and in vitro digestion of fish oil-loaded multilayer emulsions consisting of gelatin particle and polysaccharides

The purpose of this study is to investigate the effects of the interfacial layer number on the storage stability and in vitro digestion of fish oil-loaded primary, secondary, tertiary, and quaternary multilayer emulsions stabilized by gelatin particle and polysaccharides (anionic alginate and cationic chitosan), prepared using a layer-by-layer electrostatic deposition technique. The results demonstrate that the emulsion creaming stability during the storage process and the emulsion droplet stability against the gastric phase are dependent on the interfacial layer number. But, the interfacial layer number in the multilayer emulsions has no obvious effects on the droplet stability against droplet coalescence during the storage process and against the small intestinal phases of gastrointestinal tract models. Moreover, it also has no obvious effect on the sustained free fatty acid release of multilayer emulsions. This study can advance the fundamental understanding of multilayer emulsions and promote their potential applications.

Reducing carotenoid loss during storage by co-encapsulation of pequi and buriti oils in oil-in-water emulsions followed by freeze-drying: Use of heated and unheated whey protein isolates as emulsifiers

Buriti and pequi oils are rich in carotenoids and beneficial to human health; however, carotenoid oxidation during storage causes color loss in foods, making it difficult to use these oils in food products. This research aimed to encapsulate pequi oil and co-encapsulate pequi and buriti oils by emulsification using whey protein isolate (WPI) as an emulsifier in two forms, natural (unheated) and heated, followed by freeze-drying. The emulsions were studied by droplet size under different stress conditions, instability index, and rheology. The freeze-dried (FD) samples were studied after accelerated oxidation and the total carotenoid retention was determined; for the reconstituted FD, the zeta potential and droplet size were recorded after storage at 37 °C for 30 days. The emulsions were stable in all conditions, with average droplet sizes between 0.88 ± 0.03 and 2.33 ± 0.02 μm, and formulations with heated WPI presented the lowest instability index values. The FD's zeta potential values ranged from -50 ± 3 to -32 ± 3 mV. The co-encapsulated oils presented higher carotenoid retention (50 ± 1 and 48 ± 1%) than the free oils (31 ± 2%) after 30 days. The oxidative stability indexes were 51 ± 4 and 46 ± 3 for the co-encapsulated oils with unheated and heated WPI, respectively, and 20.5 ± 0.1 h for the free oils. FD formulations with 1:3 ratio of oil: aqueous phase and heated or unheated WPI showed the best carotenoid retention and oxidative stability, indicating that FD oil emulsions have potential as next-generation bioactive compound carriers.

Nanostructured Lipid-Based Delivery Systems as a Strategy to Increase Functionality of Bioactive Compounds

Acquisition of a healthy lifestyle through diet has driven the food manufacturing industry to produce new food products with high nutritional quality. In this sense, consumption of bioactive compounds has been associated with a decreased risk of suffering chronic diseases. Nonetheless, due to their low solubility in aqueous matrices, high instability in food products during processing and preparation as well as poor bioavailability, the use of such compounds is sometimes limited. Recent advancements in encapsulation and protection of bioactive compounds has opened new possibilities for the development of novel food products. In this direction, the present review is attempting to describe encapsulation achievements, with special attention to nanostructured lipid-based delivery systems, i.e., nanoemulsions, multi-layer emulsions and liposomes. Functionality of bioactive compounds is directly associated with their bioavailability, which in turn is governed by several complex processes, including the passage through the gastrointestinal tract and transport to epithelial cells. Therefore, an overview of recent research on the properties of these nanostructured lipid-based delivery systems with a strong impact on the functionality of bioactive compounds will be also provided. Nanostructured lipid-based delivery systems might be used as a potential option to enhance the solubility, stability, absorption and, ultimately, functionality of bioactive compounds. Several studies have been performed in this line, modifying the composition of the nanostructures, such as the lipid-type or surfactants. Overall, influencing factors and strategies to improve the efficacy of encapsulated bioactive compounds within nanostructures have been successfully identified. This knowledge can be used to design effective targeted nanostructured lipid-based delivery systems for bioactive compounds. However, there is still a lack of information on food interactions, toxicity and long-term consumption of such nanostructures.