Enzymatic degradation and bioaccessibility of protein encapsulated β-carotene nano-emulsions during in vitro gastro-intestinal digestion

High-pressure microfluidization enhanced the stability of sodium caseinate-EGCG complex-stabilized fish oil emulsion

Improving the emulsion-stabilizing effect of protein by chemical or physical modification has been paid much attention recently. Here, sodium caseinate (CS) was treated by high-pressure-microfluidization (HPM) under 0-100 MPa, and was further complexed with (-)-epigallocatechin-3-gallate (EGCG) to form an excellent emulsifier that stabilized fish oil emulsions. Results showed that HPM treatment (especially 80 MPa) significantly changed the secondary structure of CS, and 80 MPa-PCS-EGCG had the best emulsifying and antioxidant activities. In addition, after HPM treatment and EGCG bonding, CS formed a thicker interface layer on the surface of oil droplets, which could better protect the fish oil from the influence by oxygen, temperature and ion concentration. Moreover, the fish oil emulsion stabilized by PCS-EGCG complex significantly delayed the release of free fatty acids subjected to in vitro digestion. Conclusively, HPM-treated CS-EGCG complex could be a potential emulsifier to improve the stability of fish oil emulsions.

The Effect of Whey Protein Isolate Hydrolysate on Digestive Properties of Phytosterol

Phytosterol (PS) is a steroid, and its bioavailability can be enhanced by interacting with protein in the C-24 hydroxyl group. The interaction between sterols and amino acid residues in proteins can be enhanced by enzymatic hydrolysis. Phytosterol and whey insulation hydrolysates (WPH1-4) fabricated by the Alcalase enzyme at different enzymatic hydrolysis times were selected as delivery systems to simulate sterol C-24 hydroxyl group interaction with protein. Increasing hydrolysis time can promote the production of β-Lg, which raises the ratio of β-turn in the secondary structure and promotes the formation of interaction between WPH and PS. The correlation coefficient between hydrogen bonds and encapsulation efficiency (EE) and bioaccessibility is 0.91 and 0.88 (P < 0.05), respectively, indicating that hydrogen bonds of two components significantly influenced the combination by concealing the hydrophobic amino acids and some residues, which improved PS EE and bioavailability by 3.03 and 2.84 times after PS was combined with the WPI hydrolysate. These findings are expected to enhance the absorption of PS and other macromolecules by protein enzymatic hydrolysis to broaden their applications for food.

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

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

Digestive characteristics of astaxanthin oil in water emulsion stabilized by a casein-caffeic acid-glucose ternary conjugate

To overcome the barrier of poor oral bioavailability of astaxanthin, a stable oil-in-water emulsion was constructed using casein-caffeic acid-glucose ternary conjugates (CSC) to deliver astaxanthin, and its gastrointestinal behavior was evaluated in vitro with sodium caseinate (CSN) as a control. Results showed that, CSC-stabilized emulsion shower better resistance to the adverse conditions of the gastric environment than CSN-stabilized emulsion, and exhibited lower average particle size and aggregation (4972.33 nm, -5.93 mv) after simulated gastric digestion. Besides, after simulated intestinal digestion, the reducing capacity and astaxanthin transfer efficiency of CSC emulsion into the micellar phase were 686.74 μmol Trolox/100 mL and 26.2 %, which were 2.6 and 4.05-fold higher than that of CSN emulsion. The above results suggest that CSC can be used for better delivery of astaxanthin, which could be useful in designing foods such as functional beverages, pharmaceuticals and nutritional supplements for delivery of lipophilic bioactives.

Approaches for reducing chemo/radiation-induced cardiotoxicity by nanoparticles

Nanoparticles are fascinating and encouraging carriers for cancer treatment due to their extraordinary properties and potential applications in targeted drug delivery, treatment, and diagnosis. Experimental studies including in vitro and in vivo examinations show that nanoparticles can cause a revolution in different aspects of cancer therapy. Normal tissue toxicity and early and late consequences are the major limitations of cancer therapy by radiotherapy and chemotherapy. However, the delivery of drugs into tumors or reducing the accumulation of drugs in normal tissues can permit a more satisfactory response of malignancies to therapy with more inferior side effects. Cardiac toxicity is one of the major problems for chemotherapy and radiotherapy. Therefore, several experimental studies have been performed to minimize the degenerative impacts of cancer treatment on the heart and also enhance the influences of radiotherapy and chemotherapy agents in cancers. This review article emphasizes the benefits of nanoparticle-based drug delivery techniques, including minimizing the exposure of the heart to anticancer drugs, enhancing the accumulation of drugs in cancers, and expanding the effectiveness of radiotherapy. The article also discusses the challenges and problems accompanied with nanoparticle-based drug delivery techniques such as toxicity, which need to be addressed through further research. Moreover, the article emphasizes the importance of developing safe and effective nanoparticle-based therapies that can be translated into clinical practice.

Effect of protein oxidation on the emulsion carrier prepared by rice bran protein for improving stability and bioavailability of β-carotene

The emulsion carriers which prepared by rice bran protein (RBP) with different oxidation extents were utilized to deliver β-carotene (BC). The effects of RBP oxidation extent on stability and bioaccessibility of BC in rice bran protein emulsion (RBPE) were investigated by measuring the droplet size, microstructure, digestive stability, cellular antioxidant, and delivery property of BC-RBPE. The results showed that BC-RBPE prepared by moderately oxidized RBP (extracted from rice bran with a storage time of 5 d) presented excellent digestive stability and delivery property during gastrointestinal digestion. The particle size of initial BC-RBPE, BC-RBPE after gastric digestion, and BC-RBPE after intestinal digestion were 509.73, 2149.33, and 997.82 nm, respectively. Compared with free BC suspension, the BC retention after gastric digestion and the BC bioavailability of BC-RBPE prepared by moderately oxidized RBP increased by 23.50% and 27.54%, respectively. In addition, the BC cellular antioxidant activity and BC cellular uptake of BC-RBPE prepared by moderately oxidized RBP were significantly higher than that of free BC-suspension, which increased by 29.63% and 13.84%, respectively. In summary, the study showed that oil-in-water emulsion prepared by moderately oxidized protein is a potential delivery system of BC, which can provide a theoretical basis for improving the utilization of protein by adjusting the extent of protein oxidation.

Influence of Proteins on Bioaccessibility of α-Tocopherol Encapsulation within High Diacylglycerol-Based Emulsions

α-Tocopherol has been widely used in medicine, cosmetics, and food industry as a nutritional supplement and antioxidant. However, α-tocopherol showed low bioaccessibility, and there is a widespread α-tocopherol deficiency in society today. The preparation of oil-in-water emulsions with high safety and low-calorie property is necessary. The aim of this research was to investigate the effects of different protein emulsifiers (whey protein isolate (WPI), soy protein isolate (SPI), and sodium casein (SC)) on the properties of emulsions delivery system, and diacylglycerol (DAG) was picked as a low-accumulated lipid. The interfacial changes, microstructural alterations, and possible interactions of the protein-stabilized DAG emulsions were investigated during the in vitro digestion. The results show that different proteins affect the degree of digestibility and α-tocopherol bioaccessibility of the emulsions. Both WPI- and SPI-coated emulsions showed good digestibility and α-tocopherol bioaccessibility (77.64 ± 2.93%). This might be due to the strong hydrolysis resistance of WPI (β-lactoglobulin) and the good emulsification ability of SPI. The SC-coated emulsion showed the lowest digestibility and α-tocopherol bioaccessibility, this might be due to the emulsification property of hydrolysis products of SC and the potential interaction with calcium ions. This study provides new possibilities for the application of DAG emulsions in delivery systems.

Improved physicochemical stability and bioaccessibility of astaxanthin-loaded oil-in-water emulsions by a casein-caffeic acid-glucose ternary conjugate

In this study, the influence of casein-caffeic acid-glucose ternary conjugate (CSC) on the physicochemical properties and bioaccessibility of astaxanthin-loaded emulsion was investigated and compared with sodium caseinate (CSN), a synthetic emulsifier commonly used in the food industry. The CSC-stabilized emulsion exhibits droplet characteristics similar to CSN-stabilized emulsion, and can effectively resist the external forces that lead to the phase separation of the emulsion. Although phase separation also occurred at pH 4.0, CSC emulsion had a wider range of pH stability (pH 3.0, 5.0-8.0) and higher salt ion stability than CSN emulsion. Furthermore, CSC-stabilized astaxanthin emulsions showed better astaxanthin protection under different heat treatment conditions and storage temperatures compared with CSN. After 28 days of storage at 4 °C, astaxanthin residues in the CSC-stabilized emulsion reached 92.37 %. The bioaccessibility of astaxanthin in CSC-stabilized emulsion was 26.21 %, much higher than that in CSN (6.47 %). This research study provides a platform for designing astaxanthin-fortified food or beverage systems to achieve better stability and delivery to target sites.

Enhancing the Gastrointestinal Stability of Curcumin by Using Sodium Alginate-Based Nanoemulsions Containing Natural Emulsifiers

Curcumin presents interesting biological activities but low chemical stability, so it has been incorporated into different emulsion-based systems in order to increase its bioaccessibility. Many strategies are being investigated to increase the stability of these systems. Among them, the use of polysaccharides has been seen to highly improve the emulsion stability but also to modulate their digestibility and the release of the encapsulated compounds. However, the effect of these polysaccharides on nanoemulsions depends on the presence of other components. Then, this work aimed to study the effect of alginate addition at different concentrations (0-1.5%) on the gastrointestinal fate and stability of curcumin-loaded nanoemulsions formulated using soybean lecithin or whey protein as emulsifiers. Results showed that, in the absence of polysaccharides, whey protein was more effective than lecithin in preventing curcumin degradation during digestion and its use also provided greater lipid digestibility and higher curcumin bioaccessibility. The addition of alginate, especially at ≥1%, greatly prevented curcumin degradation during digestion up to 23% and improved the stability of nanoemulsions over time. However, it reduced lipid digestibility and curcumin bioaccessibility. Our results provide relevant information on the use of alginate on different emulsifier-based nanoemulsions to act as carriers of curcumin.

Intake of Sugar Substitute Gummy Candies Benefits the Glycemic Response in Healthy Adults: A Prospective Crossover Clinical Trial

Sugar reduction in food has attracted great health concerns worldwide. Gummies have been one of the most popular and highly favored candies due to their chewable properties, simplicity to swallow, and delicious taste. The general perception is that gummies raise blood sugar levels, but the truth is that gummies with the right formula can control glycemic response. The purpose of this study is to investigate the effects of the gummy dosage form and sugar types on the glycemic response control. Maltitol and erythritol as sweetener alternatives were applied in gummy candies (total and partial sugar substitutes gummy, T-SG and P-SG), with sucrose-based gummies used as comparisons (CG). A prospective crossover study was then conducted on 17 healthy adults. The effects of different types of gummies on glycemic response in healthy adults were evaluated on the basis of the participants’ glycemic index (GI) and glycemic load (GL) values. Every three-day interval, participants took CG, P-SG, T-SG, and glucose solution, respectively, and the theoretical glucose conversion content was kept the same in all groups for each trial. Each participant performed four tests with each sample and recorded the changes in blood glucose after food consumption. It was found that all three types of gummies slowed down subjects’ glycemic response when not taken in excess, and the improvement effect was in the trend of T-SG > P-SG > CG. Both P-SG and T-SG were low-GI candies (54.1 and 49.9). CG that was not consumed in excess of 17.2 g had a high GI (81.9) but a low GL (<10). Texture analysis and in vitro digestion were used to explore the effect of gummy matrix on glucose release. T-SG and P-SG retained a higher hardness and were less hydrolyzed to release glucose during digestion compared with CG. Additionally, experiments have revealed that gummies can reverse the poor glucose tolerance in women. In conclusion, gummies are a good carrier for dietary supplements due to their sustained-release characteristic of available carbohydrates and provide healthier options for people in control of glucose homeostasis.

Progress in the Application of Food-Grade Emulsions

The detailed investigation of food-grade emulsions, which possess considerable structural and functional advantages, remains ongoing to enhance our understanding of these dispersion systems and to expand their application scope. This work reviews the applications of food-grade emulsions on the dispersed phase, interface structure, and macroscopic scales; further, it discusses the corresponding factors of influence, the selection and design of food dispersion systems, and the expansion of their application scope. Specifically, applications on the dispersed-phase scale mainly include delivery by soft matter carriers and auxiliary extraction/separation, while applications on the scale of the interface structure involve biphasic systems for enzymatic catalysis and systems that can influence substance digestion/absorption, washing, and disinfection. Future research on these scales should therefore focus on surface-active substances, real interface structure compositions, and the design of interface layers with antioxidant properties. By contrast, applications on the macroscopic scale mainly include the design of soft materials for structured food, in addition to various material applications and other emerging uses. In this case, future research should focus on the interactions between emulsion systems and food ingredients, the effects of food process engineering, safety, nutrition, and metabolism. Considering the ongoing research in this field, we believe that this review will be useful for researchers aiming to explore the applications of food-grade emulsions.

Recent progresses in the delivery of β-carotene: From nano/microencapsulation to bioaccessibility

Beta-carotene (BC) as an efficient pro-vitamin is effective in improving vision, immune system and cognitive function as well as preventing coronary diseases and cancer. However, besides its poor chemical stability, the high lipophilic nature of BC reduces its dispersibility and consequently bioavailability which limits its application into food, pharmaceutical and nutraceuticals. Different carriers with vesicular or particulate structures have been studied and utilized for promoting BC solubility, dispersibility, and protection against diverse operational or environmental stresses and also controlling BC release and subsequent bioaccessibility. The current study, therefore reviews different micro/nanocarriers reported on BC encapsulation with special focusing on its bioavailability. Liposomal structures have been successfully used for enhancing BC stability and bioavailability. Besides, emulsion-based carriers including Pickering emulsions, nanoemulsions and microemulsions have been widely evaluated for BC encapsulation and protection. In addition, lipid-based nanoparticles and nanostructural carriers have also been applied successfully for this context. Moreover, gel structures including emulgels, hydrogels and oleogels are studied in some researches. Most of these delivery systems led to higher hydro-solubility and dispersibility of BC which consequently increased its bioavailability; thereupon could promote its application into food, cosmetic and nutraceutical products. However, for remarkable incorporation of BC and other bioactive compounds into edible products, the safety and toxicological aspects of these delivery system especially those designed in nano scale should be addressed in the further researches.

A review of recent progress in improving the bioavailability of nutraceutical-loaded emulsions after oral intake

Increasing awareness of the health benefits of specific constituents in fruits, vegetables, cereals, and other whole foods has sparked a broader interest in the potential health benefits of nutraceuticals. Many nutraceuticals are hydrophobic substances, which means they must be encapsulated in colloidal delivery systems. Oil-in-water emulsions are one of the most widely used delivery systems for improving the bioavailability and bioactivity of these nutraceuticals. The composition and structure of emulsions can be designed to improve the water dispersibility, physicochemical stability, and bioavailability of the encapsulated nutraceuticals. The nature of the emulsion used influences the interfacial area and properties of the nutraceutical-loaded oil droplets in the gastrointestinal tract, which influences their digestion, as well as the bioaccessibility, metabolism, and absorption of the nutraceuticals. In this article, we review recent in vitro and in vivo studies on the utilization of emulsions to improve the bioavailability of nutraceuticals. The findings from this review should facilitate the design of more efficacious nutraceutical-loaded emulsions with increased bioactivity.

Effects of different surfactants on the conjugates of soybean protein-polyphenols for the preparation of β-carotene microcapsules

In this study, we investigated the spray-drying microencapsulation of β-carotene in oil co-stabilized by soy protein isolate-epigallocatechin-3-gallate conjugate (SPE) and small molecule surfactants [sodium dodecyl sulfate (SDS), hexadecyl trimethyl ammonium bromide (CTAB), and tea saponin (TS)] of different concentrations [0.1, 0.5, and 1.0% (w/v)], as a prospective approach to stabilize β-carotene. The results show that different surfactant types and concentrations significantly affect the encapsulation efficiency, water dispersibility, microstructure, and digestion of the microcapsules. Interactions between the surfactants and the SPE at the interface were found to include both synergistic and competitive effects, and they depended on the surfactant type and concentration. Moreover, the addition of SDS and TS before spray drying significantly improved the microencapsulation performance of the microcapsules and the water dispersion behavior of the corresponding spray-dried powders. The highest encapsulation efficiency was achieved for the SPE-0.1TS-encapsulated β-carotene microcapsules. In contrast, the addition of CTAB was not conducive to microcapsule formation, resulting in poor encapsulation efficiency, water dispersibility, thermal stability, β-carotene retention rate, and oxidation stability. In vitro gastrointestinal digestion results revealed that the addition of CTAB promotes the release of β-carotene and improves the bioaccessibility of β-carotene. In contrast, except for SPE-1.0SDS, the addition of SDS and TS inhibited β-carotene release and reduced β-carotene bioaccessibility. This study demonstrated that this novel β-carotene encapsulation formulation can overcome stability limitations for the development of β-carotene supplements with a high bioaccessibility.

Ultrasonic-assisted preparation of eucalyptus oil nanoemulsion: Process optimization, in vitro digestive stability, and anti-Escherichia coli activity

Eucalyptus oil (EO) is a natural and effective antimicrobial agent; however, it has disadvantages such as poor water solubility and instability. The aim of this study was to investigate the effect of process vessels and preparation process parameters on the particle size of the emulsion droplets using ultrasonic technique and response surface methodology to prepare eucalyptus oil nanoemulsion (EONE). The optimal sonication process parameters in conical centrifuge tubes were confirmed: sonication distance of 0.9 cm, sonication amplitude of 18%, and sonication time of 2 min. Under these conditions, the particle size of EONE was 18.96 ± 4.66 nm, the polydispersity index was 0.39 ± 0.09, and the zeta potential was -31.17 ± 2.15 mV. In addition, the changes in particle size, potential, micromorphology, and anti-Escherichia coli activity of EONE during digestion were investigated by in vitro simulated digestion. The emulsion was stable in simulated salivary fluid, tended to aggregate in simulated gastric fluid, and increased in particle size and potential value in simulated intestinal fluid. EONE showed higher anti-E. coli activity than EO by simulated digestion. These results provide a useful reference for the in vivo antimicrobial application of the essential oil.

Comparison of bioaccessibility of astaxanthin encapsulated in starch-based double emulsion with different structures

In this study, different types of starch-based double emulsion (SDE) structures were developed to improve the bioavailability of astaxanthin (AST). Droplet size, microstructure, zeta potential of the AST-loaded SDEs were measured during in vitro digestion model. Compared with the C-type SDEs prepared with high amylose starch (HAS), the AST-loaded SDEs prepared using native corn starch of 5 wt% (B-type structure) and 7 wt% (A-type structure) presented small mean droplet diameters (MA = 11.18 ± 0.40 μm and 8.23 ± 0.37 μm, respectively) and were more stable after simulated gastric digestion. Furthermore, the lipid digestion products (free fatty acids) were studied after simulated intestinal digestion. Interestingly, the bioaccessibility (57.54 ± 1.88%) of AST-loaded SDEs prepared by HAS was six times higher than that of digested unencapsulated AST. Thus, SDEs were found to be suitable carriers for liposoluble nutrient delivery and bioavailability in foods, beverages, and nutraceuticals.

Improved stability and aqueous solubility of β-carotene via encapsulation in self-assembled bioactive oleanolic acid nanoparticles

Poor water solubility and stability of β-carotene (Car) greatly hinder its application in foods. Herein, naturally occurring bioactive oleanolic acid (OA) was used as a nanocarrier to overcome these shortcomings by fabricating Car-loaded OA nanoparticles (Car/OA NPs). Through optimization, the encapsulation efficiency and loading capacity reached 80.7% and 32.6%, respectively. Systematic characterization suggested that Car was successfully encapsulated, and hydrogen bonding and hydrophobic interactions are the main forces facilitating the self-assembly and encapsulation. Compared with free Car, Car/OA NPs exhibited significantly improved water dispersibility and enhanced stability against UV radiation, heat, ionic strength, and acidic conditions. Further, Car/OA NPs provided gastric protection, delayed-release in simulated gastric fluid (SGF) and controlled release in simulated intestinal fluid (SIF). Additionally, both OA NPs and Car/OA NPs showed markedly inherent hepatoprotective effects. This work demonstrates that OA NPs can be used as inherent bioactive nanocarriers to deliver hydrophobic nutrients and bioactive food components.

Exploration of the Microstructure and Rheological Properties of Sodium Alginate-Pectin-Whey Protein Isolate Stabilized Β-Carotene Emulsions: To Improve Stability and Achieve Gastrointestinal Sustained Release

Sodium alginate (SA)-pectin (PEC)-whey protein isolate (WPI) complexes were used as an emulsifier to prepare β-carotene emulsions, and the encapsulation efficiency for β-carotene was up to 93.08%. The confocal laser scanning microscope (CLSM) and scanning electron microscope (SEM) images showed that the SA-PEC-WPI emulsion had a compact network structure. The SA-PEC-WPI emulsion exhibited shear-thinning behavior and was in a semi-dilute or weak network state. The SA-PEC-WPI stabilized β-carotene emulsion had better thermal, physical and chemical stability. A small amount of β-carotene (19.46 ± 1.33%) was released from SA-PEC-WPI stabilized β-carotene emulsion in simulated gastric digestion, while a large amount of β-carotene (90.33 ± 1.58%) was released in simulated intestinal digestion. Fourier transform infrared (FTIR) experiments indicated that the formation of SA-PEC-WPI stabilized β-carotene emulsion was attributed to the electrostatic and hydrogen bonding interactions between WPI and SA or PEC, and the hydrophobic interactions between β-carotene and WPI. These results can facilitate the design of polysaccharide-protein stabilized emulsions with high encapsulation efficiency and stability for nutraceutical delivery in food and supplement products.

Evaluation of Cellular Absorption and Metabolism of β-Carotene Loaded in Nanocarriers after In Vitro Digestion

Three protein emulsifiers encapsulating β-carotene (BC) with accompanying lipids into nanoemulsions (NEs) or without lipids into nanoparticles (NPs) were fabricated to study the effect of the type of interfacial protein on carrier design and the structure remodeling during digestion on the overall uptake and metabolism of BC in Caco-2 cells. BC-loaded micelles and micellar-like aggregates were collected after in vitro digestion and applied to Caco-2 cell monolayers. The digestion process significantly enhanced the cellular uptake of BC by 1.2-2.2 times and 4.1-8.2 times loaded in NEs and NPs, respectively. Whey protein isolate-based carriers improved the absorption but decreased the metabolism of BC to retinyl palmitate. The presence of lipids was found to improve metabolism and aid the transport of retinoids to the basolateral side of Caco-2 monolayers. Understanding the transportation behavior of the protein-based nanocarries after digestion may contribute to the design of biosafe carriers with higher bioavailability to deliver lipophilic nutrients.

Carboxymethyl cellulose/okara protein influencing microstructure, rheological properties and stability of O/W emulsions

BACKGROUND

The role of protein-polysaccharide interactions and their mixtures has been a vital factor affecting the formation and stability of food emulsions. Okara protein (OP), which is extracted from the by-product of soybean processing, has received much attention because of its abundant sources and potential attributes with respect to food formulation. Carboxymethyl cellulose (CMC), a well-known food-grade polysaccharide additive, has been widely utilized in the protein-polysaccharide system, whereas, among the proteins, the role of OP has not yet been explored.

RESULTS

The present study first assessed the ζ-potential and hydrodynamic diameter of aqueous mixtures containing OP (1.0 wt%) and CMC (0-0.5 wt%), followed by the investigation of OP-CMC mixtures stabilized O/W emulsions. As CMC increased, oil droplet size, surface protein adsorption, apparent viscosity and storage modulus increased, whereas the loss tangent decreased.

CONCLUSION

CMC resulted in emulsion destabilization compared to emulsions without CMC, whereas a higher concentration of CMC promoted emulsion stability against creaming for emulsions in the presence of CMC. The results provide information with respect to OP and CMC being incorporated into food formulations and also strengthen our understanding of the related mechanism, in addition to facilitating the further utilization of OP. © 2020 Society of Chemical Industry.

Impact of Protein-Enriched Plant Food Items on the Bioaccessibility and Cellular Uptake of Carotenoids

Carotenoids are lipophilic pigments which have been associated with a number of health benefits, partly related to antioxidant effects. However, due to their poor solubility during digestion, carotenoid bioavailability is low and variable. In this study, we investigated the effect of frequently consumed proteins on carotenoid bioaccessibility and cellular uptake. Whey protein isolate (WPI), soy protein isolate (SPI), sodium caseinate (SC), gelatin (GEL), turkey and cod, equivalent to 0/10/25/50% of the recommended dietary allowance (RDA, approx. 60g/d), were co-digested gastro-intestinally with carotenoid-rich food matrices (tomato and carrot juice, spinach), and digesta further studied in Caco-2 cell models. Lipid digestion, surface tension and microscopic visualization were also carried out. Co-digested proteins positively influenced the micellization of carotenes (up to 3-fold, depending on type and concentration), especially in the presence of SPI (p < 0.001). An increased cellular uptake was observed for xanthophylls/carotenes (up to 12/33%, p < 0.001), which was stronger for matrices with an initially poor carotenoid micellization (i.e., tomato juice, p < 0.001), similar to what was encountered for bioaccessibility. Turkey and cod had a weaker impact. Significant interactions between carotenoids, lipids and proteins were observed during digestion. Co-digested proteins generally improved lipid digestion in all matrices (p < 0.001), especially for carrot juice, though slight decreases were observed for GEL. Protein impact on the surface tension was limited. In conclusion, proteins generally improved both carotenoid bioaccessibility and cellular uptake, depending on the matrices and carotenoid-type (i.e., carotene vs. xanthophylls), which may be relevant under specific circumstances, such as intake of carotenoid-rich food items low in lipids.

Astaxanthin-loaded emulsion gels stabilized by Maillard reaction products of whey protein and flaxseed gum: Physicochemical characterization and in vitro digestibility

In order to evaluate the effect of ultrasound and Maillard reaction on the physicochemical properties and gastrointestinal fate of astaxanthin-loaded emulsion gels, the Maillard reaction products (MRPs) of whey protein and flaxseed gum (FG) were prepared by traditional or ultrasonic assisted wet-heating. The MRPs obtained by ultrasonic assisted wet-heating had higher grafting degree and more expanded structures evidenced by the browning intensity, fluorescence intensity and circular dichroism (CD) analysis, thus enhancing its functional properties like solubility and emulsifying capacity. The MRPs improved the water holding capacity, encapsulation efficiency, stability of emulsion gels, in which astaxanthin was wrapped as a model bioactive compound. During the simulated digestion process, the bioaccessibility of loaded astaxanthin reached 72.08% for the emulsion gels stabilized by MRPs. The results highlighted the potential of MRPs in improving functionality of protein and as a delivery carrier of bioactive compounds in food industry.

Mild Enzyme-Induced Gelation Method for Nanoparticle Stabilization: Effect of Transglutaminase and Laccase Cross-Linking

Low-environment-sensitive nanoparticles were prepared by enzymatic cross-linking of electrostatic complexes of dextran-grafted whey protein isolate (WPI-Dextran) and chondroitin sulfate (ChS). The effect of transglutaminase (TG) and laccase cross-linking on nanoparticle stability was investigated. Covalent TG cross-linking and grafted dextran cooperatively contributed to the stability of nanoparticles against dissociation and aggregation under various harsh environmental conditions (sharply varying pH, high ionic strength, high temperature, and their combined effects). However, fragmentation induced by laccase treatment did not promote nanoparticle stability. Structural characterization showed that the compact structure promoted by TG-induced covalent isopeptide bonds repressed dissociation against varying environmental conditions and thermal-induced aggregation. Furthermore, the increasing α-helix and decreasing random coil contents benefited the formation of disulfide bonds, further contributing to the enhanced stability of nanoparticles cross-linked by TG, whereas weak hydrophobic interactions and hydrogen bonding as evidenced by the increase in β-sheet and microenvironmental changes were not able to maintain the stability of nanoparticles treated with laccase. Encapsulated cinnamaldehyde presented sustained release from TG-cross-linked nanoparticles, and the bioaccessibility was considerably enhanced to 50.7%. This research developed a novel mild strategy to enhance nanoparticle stability in harsh environments and digestive conditions, which could be an effective delivery vehicle for hydrophobic nutrients and drug applications in food and pharmaceutical industries.

Effect of ultrasound-assisted extraction on the structure and emulsifying properties of peanut protein isolate

BACKGROUND

With an increasing demand for edible protein, research on new extraction methods is attracting more attention. The effects of such methods on functional properties are important. The present study aimed to evaluate the effect of ultrasound-assisted extraction on the extraction efficiency, structure, and the emulsifying properties of peanut protein isolate (PPI).

RESULTS

Ultrasound-assisted extraction significantly improved extraction efficiency and shortened the processing time. The nanostructure, molecular weight distribution, and particle size of PPI were altered by ultrasound-assisted extraction. The emulsifying properties of the PPI from ultrasound-assisted extraction were significantly improved compared with alkaline extraction. Peanut protein isolate had lower molecular weight fractions, higher levels of hydrophobic amino acids, and the highest fluorescence intensity with ultrasound intensity, temperature, and time of 3.17 W cm^-3 , 35 °C, and 30 min, respectively. These contributed to the higher emulsifying activity index and emulsifying stability index of the PPI emulsions. The uniform distribution of droplets and smaller particle size of the PPI emulsions was also observed.

CONCLUSION

The results suggested that ultrasound can be used to induce the conformational changes to modify the interfacial association between protein-oil phases, thereby improving the emulsifying properties of peanut protein. © 2020 Society of Chemical Industry.

Comparison of Different Protein Emulsifiers on Physicochemical Properties of β-Carotene-Loaded Nanoemulsion: Effect on Formation, Stability, and In Vitro Digestion

In this study, β-carotene-loaded nanoemulsions are emulsified using four biomacromolecular proteins-peanut protein isolate (PPI), soy protein isolate (SPI), rice bran protein isolate (RBPI), and whey protein isolate (WPI)-in order to explore their emulsion stability and in vitro digestion characteristics. All four nanoemulsions attained high encapsulation levels (over 90%). During the three-stage in vitro digestion model (including oral, gastric, and small intestine digestion phases), the PPI-emulsified nanoemulsion showed the highest lipolysis rates (117.39%) and bioaccessibility (37.39%) among the four nanoemulsions. Moreover, the PPI-emulsified nanoemulsion (with the smallest droplet size) also demonstrated the highest stability during storage and centrifugation, while those for the RBPI-emulsified nanoemulsion (with the largest droplet size) were the lowest. In addition, all four nanoemulsions showed superior oxidation stability when compared with the blank control of corn oil. The oxidation rates of the PPI- and WPI-stabilized groups were slower than the other two groups.

Remodeling of β-Carotene-Encapsulated Protein-Stabilized Nanoparticles during Gastrointestinal Digestion In Vitro and in Mice

The remodeling of β-carotene-encapsulated protein nanoparticles (NPs) during digestion in vitro and in vivo was investigated. The NPs were formed using three different proteins. Hydrolysis of the surface protein during digestion resulted in structure remodeling of NPs and the formation of small-sized micellar-like aggregates below 100 nm, accelerating the release of β-carotene into the aqueous phase. However, the reduced surface ζ-potential in the intestinal fluid suggested the adsorption of bile salts, favoring the formation of small-sized micellar-like aggregates. A shifted peak of β-carotene in the micellar phase from 965 cm^-1 to about 855 cm^-1 in Fourier transform infrared spectroscopy analysis indicated that β-carotene existed in the amorphous state. Microstructure observation in vivo further confirmed that β-carotene was loaded in micellar-like aggregates and dispersed uniformly in water. The cellular uptake study showed that the absorption rate of digested NPs was significantly increased by 1.34- to 4.16-fold when compared with undigested NPs.

Comparison of protein hydrolysates against their native counterparts in terms of structural and antioxidant properties, and when used as emulsifiers for curcumin nanoemulsions

The stability and in vitro digestion of nanoemulsions stabilized by natural protein hydrolysates (PPI, SPI and WPI) are discussed.