Stability Of Β-carotene Emulsions Research Articles

Physicochemical stability and in vitro bioaccessibility of β-carotene emulsions stabilized with arabinoxylan hydrolysates-soy protein isolate conjugates

The physicochemical stability of β-carotene emulsions and the bioaccessibility of β-carotene stabilized by arabinoxylan hydrolysate (AXH)-soy protein isolate (SPI) conjugates (formed by dry heating) was evaluated. β-Carotene emulsions were prepared using SPI, AXH/SPI mixtures and AXH-SPI conjugates separately. Results of mean droplet size and zeta potential indicated that AXH-SPI conjugates-stabilized emulsions are less sensitive to environmental stress, and exhibit better stability during long time storage and simulated gastrointestinal digestion, as compared with emulsions stabilized with AXH/SPI mixtures or SPI alone. In addition, emulsions stabilized by AXH-SPI conjugates exhibited higher chemical stability and bioaccessibility of β-carotene. These results suggested that AXH-SPI conjugates-stabilized emulsions developed in this study have potential applications as protectors and carriers of liposoluble active ingredients.

Enhancing the stabilization of β-carotene emulsion using ovalbumin-dextran conjugates as emulsifier

A simple reliable way of improving the emulsifying behaviour of a protein is through covalent binding with a polysaccharide. Thus the effects of ovalbumin (OVA) after modified by dextran (Dex) under traditional wet heating (WH) or microwave heating (MH) on stabilisation and digestion of β-carotene emulsions were comprehensively studied. The emulsifying activity and emulsion stability of OVA were improved significantly after Dex covalent modification under WH or MH condition. OVA–Dex–MH conjugates performed better than OVA and OVA–Dex–WH conjugates in producing an extremely narrow size distribution and high encapsulation rate of β-carotene in emulsion. In addition, OVA–Dex–MH conjugates were considerably more effective in oil droplet stabilization against acidic/alkaline conditions (pH 3.0–10.0), high ionic strength (150 mM NaCl) and high temperature (90 °C for 30 min), consistent with the results of apparent viscosity analysis that the flow behavior index of β-carotene emulsions stabilized by OVA–Dex conjugates decreased compared with that of OVA-stabilized emulsion. Moreover, in the first 30 min of digestion, the degrees of lipolysis in emulsions stabilized by OVA, OVA–Dex–MH, and OVA–Dex–WH conjugates were 60.88%, 80.77%, and 75.32%. However, no significant difference was observed in the protein digestion and bio-accessibility of β-carotene. These results proved that OVA–Dex–MH conjugates have the potential to form stable, food-grade emulsion-based delivery systems against environmental stresses. • EAI and ESI of OVA were improved remarkably after Dex covalent modification. • OVA–Dex–MH conjugates has advantage in producing a narrow size distribution emulsion. • OVA–Dex conjugates can improve the ability of emulsion to resist external environment. • Emulsion resistance to environmental stress was match with apparent viscosity results. • OVA–Dex conjugates were better than OVA in accelerating the release rate of lipids.

Enhanced Physicochemical Stability of β-Carotene Emulsions Stabilized by β-Lactoglobulin-Ferulic Acid-Chitosan Ternary Conjugate.

The purpose of the present work is to fabricate emulsions with excellent stability to deliver β-carotene using a novel biomacromolecule. β-Lactoglobulin-ferulic acid-chitosan ternary conjugate (BFCC), which was synthesized based on the carbodiimide-mediated coupling reaction and laccase induction, was confirmed by Fourier transform infrared (FTIR) and proton nuclear magnetic resonance (1H NMR) spectra. Also, BFCC was used to stabilize β-carotene emulsions. The results indicated that the concentration of BFCC affected the physical stability of β-carotene emulsions. Compared with the emulsions stabilized by β-lactoglobulin (β-LG), chitosan-ferulic acid conjugate (CFC), and β-LG-CFC mixture (BFCM), the emulsion stabilized by BFCC exhibited better stability under various environmental stresses. Moreover, the emulsion stabilized by BFCC had higher β-carotene retention during storage at 25 and 55 °C or under ultraviolet (UV) light exposure. The knowledge acquired in the current research offered an effective way to develop novel biomacromolecular emulsifiers and could find potential in fabricating delivery systems for bioactive compounds with markedly enhanced physiochemical properties.

Emulsion design for the delivery of β-carotene in complex food systems

ABSTRACTβ-Carotene has been widely investigated both in the industry and academia, due to its unique bioactive attributes as an antioxidant and pro-vitamin A. Many attempts were made to design delivery systems for β-carotene to improve its dispersant state and chemical stability, and finally to enhance the functionality. Different types of oil-in-water emulsions were proved to be effective delivery systems for lipophilic bioactive ingredients, and intensive studies were performed on β-carotene emulsions in the last decade. Emulsions are thermodynamically unstable, and emulsions with intact structures are preferable in delivering β-carotene during processing and storage. β-Carotene in emulsions with smaller particle size has poor stability, and protein-type emulsifiers and additional antioxidants are effective in protecting β-carotene from degradation. Recent development in the design of protein-polyphenol conjugates has provided a novel approach to improve the stability of β-carotene emulsions. When β-carotene is consumed, its bioaccessibility is highly influenced by the digestion of lipids, and β-carotene in smaller oil droplets containing long-chain fatty acids has a higher bioaccessibility. In order to better deliver β-carotene in complex food products, some novel emulsions with tailor-made structures have been developed, e.g., multilayer emulsions, solid lipid particles, Pickering emulsions. This review summarizes the updated understanding of emulsion-based delivery systems for β-carotene, and how emulsions can be better designed to fulfill the benefits of β-carotene in functional foods.

Physical and chemical stabilities of β-carotene emulsions stabilized by Ulva fasciata polysaccharide

The objectives of this study were to investigate the effect of Ulva fasciata polysaccharide (UFP) on the physical and chemical characteristics of β-carotene oil-in-water (O/W) emulsions. The β-carotene (O/W) emulsions were prepared by combining 95 wt% UFP (1–5%, wt/wt) solutions with 5 wt% soybean oil containing β-carotene (0.05 wt% in the final emulsion). The stability of β-carotene emulsions was evaluated by droplet size and distribution, viscosity, zeta-potential, visual phase separation, light microscopy imaging and β-carotene degradation of the emulsions during storage. In addition, the influences of ionic strength and pH on physical stabilities of emulsions were characterized. Emulsions stabilized with high concentration (>2% wt/wt) of UFP had an average droplet size (D [3, 2]) less than 1.0 μm, and the average droplet size significantly decreased until the polysaccharide concentration reached 3%. Light microscopy images and emulsion zeta-potentials demonstrated 3% (wt/wt) UFP to be the optimum emulsifying agent concentration. UFP revealed better emulsifying properties and improved physical stabilities of β-carotene emulsions when compared to other commercial polysaccharides, including gum Arabic and beet pectin.

Utilization of interfacial engineering to improve physicochemical stability of β-carotene emulsions: Multilayer coatings formed using protein and protein–polyphenol conjugates

The impact of lactoferrin (LF)–chlorogenic acid (CA) and (−)-Epigallocatechin-3-gallate (EGCG) conjugates on the physicochemical properties of β-carotene emulsions was investigated. Formation of lactoferrin–polyphenol conjugates, which was confirmed by SDS–PAGE, caused changes in the structure and nature of lactoferrin. Based on layer-by-layer electrostatic deposition, β-carotene bilayer emulsions were prepared by lactoferrin and lactoferrin–polyphenol conjugates at pH 7.0. The physicochemical properties of primary and secondary emulsions were evaluated and the results suggested that LF–polyphenol conjugates-stabilized primary and secondary emulsions exhibited better emulsifying properties and improved physical stability of β-carotene bilayer emulsions under freeze–thaw, ionic strength and thermal treatments. In addition, the lactoferrin–polyphenol conjugates could effectively enhance chemical stability of β-carotene in oil-in-water emulsions against heat treatment and ultraviolet light exposure, and the least degradation of β-carotene occurred in LF–EGCG conjugate-stabilized primary emulsion. The interfacial engineering technology utilized in this study may lead to the formation of emulsions with improved physicochemical and functional performance.

Physicochemical properties of β-carotene emulsions stabilized by chlorogenic acid–lactoferrin–glucose/polydextrose conjugates

In this study, the influence of chlorogenic acid (CA)–lactoferrin (LF)–glucose (Glc) conjugate and CA-LF-polydextrose (PD) conjugate on the physicochemical characteristics of β-carotene emulsions was investigated. Novel emulsifiers were formed during Maillard reaction between CA–LF conjugate and Glc/PD. The physicochemical properties of β-carotene emulsions were characterized by droplet size, ζ-potential, rheological behavior, transmission changes during centrifugal sedimentation and β-carotene degradation. Results showed that the covalent attachment of Glc or PD to CA–LF conjugate effectively increased the hydrophilicity of the oil droplets surfaces and strengthened the steric repulsion between the oil droplets. Glucose was better than polydextrose for the conjugation with CA–LF conjugate to stabilize β-carotene emulsions. In comparison with LF and CA–LF–Glc/PD mixtures, CA–LF–Glc/PD ternary conjugates exhibited better emulsifying properties and improved physical stability of β-carotene emulsions during the freeze–thaw treatment. In addition, CA–LF–Glc/PD conjugates significantly enhanced chemical stability of β-carotene in the emulsions against ultraviolet light exposure.

Impact of chitosan–EGCG conjugates on physicochemical stability of β-carotene emulsion

The aim of the present study was to investigate the effects of low-molecular-weight chitosan (LC)–(−)-epigallocatechin-3-gallate (EGCG) conjugates on the physicochemical properties of oil-in-water emulsions incorporating β-carotene within the oil droplets. Covalent coupling of LC to EGCG was achieved by hydroxyl-free radical grafting. The physicochemical stability of β-carotene emulsions was characterized by droplet size and distribution, rheological behavior, transmission profiles using novel centrifugal sedimentation and β-carotene degradation in the emulsion during storage. β-Carotene emulsions stabilized by LC–EGCG conjugates had relatively smaller mean droplet size, more homogenous droplet size distribution and less change in centrifugal transmission profiles, indicating a substantial improvement in physical stability. Degradation of β-carotene in emulsions during storage was significantly retarded by LC–EGCG conjugates than native LC (formed without the redox pair and without EGCG) and control LC (formed with redox pair and without EGCG). These results implied that LC–EGCG conjugates were able to improve the physical stability of β-carotene emulsion and inhibit the deterioration of β-carotene in oil-in-water emulsions.

Impact of whey protein – Beet pectin conjugation on the physicochemical stability of β-carotene emulsions

The aim of the present study was to investigate the impact of whey protein isolate (WPI)-beet pectin conjugation on the physical and chemical properties of oil-in-water emulsions incorporating β-carotene within the oil droplets. Covalent coupling of WPI to beet pectin was achieved by dry heating of WPI-beet pectin mixtures of different weight ratios at 80, 90, 100 °C and 79% relative humidity for incubation times ranging from 1 to 9 h. It was confirmed by SDS-polyacrylamide gel electrophoresis that WPI covalently linked to beet pectin. The physical and chemical stability of β-carotene emulsions was characterized by droplet size and distribution, transmission profiles using novel centrifugal sedimentation technique, microstructure and β-carotene degradation during the storage. Compared with those stabilized by WPI alone and unheated WPI-beet pectin mixtures, β-carotene emulsions stabilized by WPI-beet pectin conjugates had much smaller droplet sizes, more homogenous droplet size distribution, less change in centrifugal transmission profiles and obviously improved freeze–thaw stability, indicating a very substantial improvement in the physical stability. Rheological analysis exhibited that emulsions stabilized by WPI-beet pectin conjugates changed from a shear thinning to more like Newtonian liquid compared those with WPI alone and unheated WPI-beet pectin mixtures. Degradation of β-carotene in emulsion during storage was more obviously retarded by WPI-beet pectin conjugate than WPI and unheated WPI-beet pectin mixture, probably due to a thicker and denser interfacial layer in emulsion droplets. These results implied that protein–polysaccharide conjugates were able to improve the physical stability of β-carotene emulsion and inhibit the deterioration of β-carotene in oil-in-water emulsions.

Effect of chitosan molecular weight on the stability and rheological properties of β-carotene emulsions stabilized by soybean soluble polysaccharides

In this study, β-carotene emulsions were prepared using a two-stage homogenization process and adsorption of chitosan to anionic droplets coated with soybean soluble polysaccharides (SSPS). Effects of the molecular weights of chitosan on the stability and rheological properties of β-carotene emulsions were investigated. Results demonstrated that the ζ-potential, particle size and rheological properties of emulsions were greatly dependent on the chitosan molecular weight. It was found that the particle size of SSPS-stabilized emulsions increased with the rise of chitosan molecular weight at higher chitosan concentrations (>0.2 wt%). Chitosan molecular weight had a significant impact on the heat and light stability of β-carotene in emulsions. SSPS-stabilized emulsion with the adsorption of medium molecular weight-chitosan (MM-chitosan) was more stable than those with the adsorption of low and high molecular weight-chitosan (LM-chitosan and HM-chitosan). Dynamic oscillatory shear tests indicated that the viscoelasticity could be enhanced by the adsorption of higher molecular weight of chitosan onto the SSPS-coated droplet surfaces.

Effect of Polyglycerol Esters of Fatty Acids on the Physicochemical Properties and Stability of β-Carotene Emulsions during Digestion in Simulated Gastric Fluid

The effects of six different polyglycerol esters of fatty acids (PGEs) and two different particle sizes produced using various processing parameters on the physicochemical properties and stability of the β-carotene emulsions during digestion in simulated gastric fluid (SGF) were investigated. β-Carotene emulsions were prepared by high-pressure homogenization using β-carotene (0.1% w/w) in soybean oil as the oil phase and 1% (w/w) PGE in Milli-Q water as the water phase. The particle size of β-carotene emulsions was measured by a laser diffraction technique, and the stability of emulsions was interpreted in terms of the increase in particle size and span value of emulsion droplets and the retention of β-carotene during digestion in SGF. The average particle size ranges of emulsions were 0.17 to 0.27 μm for fine emulsions and 1.16 to 1.59 μm for coarse emulsions. In the prepared β-carotene emulsions, the particle size decreased with increasing polymerization of the glycerol in PGEs, and the higher polymerization of the glycerol also increased the stability of emulsions during digestion in SGF. Although the β-carotene content in the emulsions significantly decreased with increasing digestion period, loss of β-carotene was more severe in unstable emulsions than in stable emulsions, suggesting that the particles incorporated into droplets could provide some protective barrier for decreasing the β-carotene degradation. Therefore, β-carotene emulsions stabilized by PGEs with high polymerization of the glycerol may be useful for further applications in food and drug formulations. Decaglycerol monooleate (MO750) was demonstrated to be the most effective emulsifier in stabilizing β-carotene emulsions in this study.