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•Numerous techniques developed for particle formation, encapsulation, impregnation and drying.•Food ingredients based on proteins, lipids, carbohydrates and minor components ...processed.•Proper characterization of properties and functionality of particles is essential.•Correlation of product functionality and processing parameters is needed.•Processing of functional food ingredients using SC-CO2 technologies shows great potential.
Numerous techniques have been developed for particle formation, encapsulation, impregnation and drying using supercritical carbon dioxide (SC-CO2), demonstrating the flexibility in such technologies while offering advantages in terms of the control of particle size, size distribution and morphology that cannot be matched by conventional technologies. A variety of food ingredients based on proteins, lipids, carbohydrates and minor components have been processed using SC-CO2 technologies and characterized in terms of their properties and functionality. Delivery of health benefiting food bioactives and their controlled release have been a major focus. It is important to better understand the relationships between product functionality and processing parameters so that optimal processes can be designed to produce ingredients with maximum functionality and bioavailability. Considering the growing demand for functional food ingredients, ingredients produced using SC-CO2 particle formation technologies show great potential for further development, targeting food and natural health product applications.
Relatively hydrophobic polyamide (PA) membranes exhibit lower flux rates during aqueous separations but can accommodate different solvents for various separation applications. Since most of the ...information on commercial reverse osmosis (RO) membranes is proprietary, further investigation on their structure would be beneficial for selection of the proper membranes especially for processes involving different solvents. Four commercially available RO membranes, AK, AG, SE and SG, were characterized using contact angle, XPS, ATR-FTIR, FE-SEM and AFM measurements. All membranes were found to be relatively hydrophobic with contact angles greater than 60°. The findings suggest that hydrophobicity of AK and AG were due to close intermolecular chain distances providing intermolecular hydrogen bonds while hindering water–polymer interactions. In the case of SE and SG membranes, an additional polymer, PVA, was probably involved during polymerization forming a polyesteramide structure resulting in reduced number of sites for water to interact with. Understanding the chemical structure associated with the hydrophobic network of the PA membranes is necessary to achieve the targeted separation without sacrificing membrane efficiency.
► AK, AG, SE and SG are commercial RO membranes with contact angles higher than 60°. ► AK, AG have rougher surfaces while SE, SG have thinner and smoother top layer. ► AK, AG exhibit peaks at 1541
cm
−1 and 1609
cm
−1 while SE, SG have peaks at 1730
cm
−1. ► AG has lower O/N ratio than AK whereas SE has lower C/N ratio than SG. ► Advanced analysis provided insight into structures of these polyamide membranes.
•Anthocyanin-loaded liposomes were yielded by supercritical carbon dioxide (SC-CO2).•Liposomes had a particle size of 159.3±0.16nm, PdI of 0.244±0.02 and EE of 50.6%.•Increased anthocyanin level led ...to a structural change in the liposomal bilayers.•Increased cholesterol level led to a reduced surface charge of liposomes.•Liposomes demonstrated great protection of anthocyanin in simulated gastric fluid.
Anthocyanin-loaded liposomes were prepared via an improved supercritical carbon dioxide (SC-CO2) method. The effects of anthocyanin and cholesterol concentrations were studied in terms of the particle size distribution, encapsulation efficiency (EE), bioactive loading, morphology, zeta potential, anthocyanin-phospholipid interaction and in vitro release profiles. Anthocyanin-loaded liposomes had a particle size of 159±0.2nm, polydispersity index of 0.244±0.02, EE of 50.6% and zeta potential of −40.2mV. Elevated anthocyanin concentration increased the particle size with reduced uniformity due to enhanced electrostatic interactions and hydrogen bonding between anthocyanin and phospholipids. Liposomes exhibited unilamellar, spherical and near-spherical shapes with increased asymmetry and heterogeneity in the bilayer packing upon increased anthocyanin and cholesterol addition. The anthocyanin release from liposomes was slow (≤35.9%) in the simulated gastric fluid but rapid in the simulated intestinal fluid, induced by the degradation of the vesicles by pancreatin. Anthocyanin-loaded liposomes show great potential for functional food and nutraceutical applications.
Anthocyanin-loaded liposomes were prepared via a single step supercritical carbon dioxide (SC-CO2) process. Phospholipid/anthocyanin suspension equilibrated with CO2 was depressurized at a constant ...pressure and rate. The effects of pressure, depressurization rate and temperature on the characteristics of liposomes were investigated. Liposomes obtained had a mean diameter of 160±2nm, polydispersity index of 0.26±0.01, encapsulation efficiency of 52.2±2.1% and zeta potential of −44.3±2.9mV. Elevated pressure and depressurization rate generated smaller particles with higher uniformity while high temperature led to reduced sphericity. The SC-CO2 method produced liposomes with enhanced intactness, sphericity and uniformity compared to the thin film hydration method. This method offers the possibility to utilize dense phase CO2 to process the phospholipid aggregates into nano/micro particles and control their characteristics via tuning of processing parameters. SC-CO2 method shows promise in scalable production of liposomes loaded with a variety of bioactives, targeting food applications.
High quality anthocyanin-loaded liposomes were prepared using SC-CO2. In this process, heterogenous phospholipid aggregates suspended in an aqueous medium are transformed into unilamellar and spherical liposomes with a narrow size distribution and other characteristics that can be regulated via tuning of the processing parameters (pressure, depressurization rate and temperature). The SC-CO2 method resulted in superior particle characteristics over those prepared via the traditional thin film hydration method and also overcame some drawbacks like organic solvent residue and vesicle leakage associated with the traditional method. Anthocyanin encapsulated into liposomes can be protected from adverse external conditions with potential benefits in food and nutraceutical formulations for improved efficacy and health benefits. This improved SC–CO2 process shows great promise for potential scale up of liposome production in the industry to encapsulate a variety of bioactives, targeting food and nutraceutical applications.
•Liposomes were prepared using a supercritical carbon dioxide (SC-CO2) method.•The SC-CO2 method yielded liposomes with small particle size and high uniformity.•High pressure and depressurization rate yielded smaller and more uniform vesicles.•Liposomes were stable for 3weeks, maintaining unimodal size distribution.•The SC-CO2 method shows great promise to produce liposomes to deliver bioactives.
Liposomes loaded with lutein were prepared utilizing supercritical carbon dioxide (SC-CO2). The effects of pressure, depressurization rate, temperature and lutein-to-lipid ratio on particle size ...distribution, zeta potential, encapsulation efficiency (EE), bioactive loading, morphology, phase transition and crystallinity were investigated. Liposomes prepared by the SC-CO2 method had a particle size of 147.6±1.9nm–195.4±2.3nm, an encapsulation efficiency of 56.7±0.7%–97.0±0.8% and a zeta potential of −54.5±1.2mV to −61.7±0.6mV. A higher pressure (200–300bar) and depressurization rate (90–200bar/min) promoted a higher encapsulation of lutein whereas the lutein-to-lipid ratio had the dominant effect on the morphology of vesicles along with size distribution and EE. X-ray diffraction data implied a substantial drop in the crystallinity of lutein upon its redistribution in the liposome membranes. Differential scanning calorimetry indicated a broadened phase transition upon the simultaneous rearrangement of lutein and phospholipid molecules into liposomal vesicles. The SC-CO2 method resulted in particle characteristics highly associated with the ability of CO2 to disperse phospholipids and lutein molecules. It offers a promising approach to use dense phase CO2 to homogenize hydrophobic or amphiphilic aggregates suspended in an aqueous medium and regulate the vesicular characteristics via pressure and depressurization rate. The SC-CO2 method has potential for scalable production of liposomal nanovesicles with desirable characteristics and free of organic solvents.
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•Lutein-loaded liposomes were prepared using supercritical carbon dioxide (SC-CO2).•Liposomes have a small particle size and high encapsulation efficiency (EE).•High pressure and depressurization rate increase the EE and uniformity of liposomes.•Amphiphiles may be uniformly dispersed in an aqueous phase upon depressurization.•The SC-CO2 method showed great promise to produce liposomes to deliver bioactives.
•Liposomes were prepared from soy lecithin using SC–CO2 method via depressurization of supercritical phase.•Volumetric expansion of water was 10–14% at 60–40°C upon reaching equilibrium with high ...pressure CO2.•At 300bar, particle size of liposomes was 523±2nm with a PdI of 0.226±0.009.•Depressurization rate of 120bar/min lowered PdI to 0.198±0.016 for a relatively high homogeneity.•Spherical liposomes with good uniformity and stability over 4weeks were obtained.
Liposomes were produced utilizing the supercritical carbon dioxide technology via depressurization of the supercritical phase and the effects of pressure, depressurization rate and temperature on liposome characteristics were investigated. The relative volumetric expansion of water upon equilibration with high pressure CO2 reached a plateau at 14.4%, 12.3% and 10.2% at 40°C, 50°C and 60°C, respectively. With an increase in pressure to 300bar, the liposomes obtained had a relatively large particle size of 523±2nm and a small polydispersity index (PdI) of 0.226±0.009. Increasing depressurization rate up to 120bar/min lowered PdI to 0.198±0.016 for a relatively high homogeneity. Pressures over 200bar yielded spherical vesicles with good uniformity and liposomes could be stored for up to 4weeks with limited change in size (below 5%). Supercritical CO2 method displayed advantages of high stability and homogeneity for liposome preparation over conventional thin film hydration method.
A simple and green process based on supercritical carbon dioxide (SC–CO2) technology was used to produce solid lipid microparticles from fully hydrogenated canola oil (FHCO). The effects of pressure ...(122, 211 and 300 bar) and nozzle diameter (0.1, 0.3 and 14.3 mm) on the particle size, morphology, thermal properties and polymorphism were investigated. Then, the essential oil loading capacity of the particles obtained under optimum conditions was evaluated. Smaller nozzle diameter (0.1 mm) and lower pressure (122 bar) produced spherical particles with narrower particle size distribution and a mean diameter of 1.27 μm. Melting point of all particles decreased to 65 °C from 69 °C for the FHCO. The main polymorphic form of the particles obtained at lower pressures and larger nozzle diameters was α, whereas it was β at higher pressures and smaller nozzle diameters. Essential oil loading efficiency of 96% was achieved when FHCO blended with 40% essential oil was used as the feed material. SC-CO2 process is a promising technology for solid lipid particle formation as delivery vehicles for bioactives.
•A simple and green solid lipid micronization method is reported.•Supercritical carbon dioxide process is able to produce hollow spherical solid lipids.•Melting point of the particles decreased by 4 °C after the process.•Higher pressures and smaller nozzle diameters changed polymorphic form of the solid lipid microparticles from α to β.•Bulk density of the particles decreased 10-fold compared to the starting material.
•Liposomes were produced using a modified supercritical process via two protocols.•Liquid phase was depressurized at constant rate in protocol (I) and constant rate and pressure in (II).•Pressures ...>100bar, 40bar/min and 50°C were selected for small particle size and uniformity.•Liposomes were stable for 8 and 6 weeks for protocols (I) and (II) with a high zeta potential.•Modified process was superior over thin film hydration method.
Liposomes were prepared utilizing a modified supercritical process. In this method, phospholipid suspension in water was equilibrated with high pressure CO2 and the CO2-expanded liquid phase was depressurized via two protocols. In protocol (I), depressurization rate was kept constant while in protocol (II), both the depressurization rate and the pressure inside the vessel were constant. Pressure, depressurization rate and temperature were the processing parameters evaluated in terms of their effect on the properties of the liposomes obtained. Particle size of liposomes prepared by the modified supercritical method was as small as 265±4nm and 214±3nm for protocols (I) and (II), respectively. Elevated pressure contributed to a smaller size while higher depressurization rates resulted in enhanced uniformity. Amount of unhydrated CO2 dissolved in the phospholipid bilayer seems to be important for a small particle size while release rate from between the bilayers may affect size distribution. Liposomes prepared by the modified supercritical method were stable for up to 8 and 6 weeks for protocols (I) and (II), respectively, with a high zeta potential. Protocol (II) yielded smaller and more uniform particles while protocol (I) gave higher storage stability. The modified supercritical method is more effective in liposome preparation than conventional thin film hydration method for a reduced size and enhanced stability.
The “natural” food colorants, carotenoids, are of great importance to human health. In an effort to enhance the efficiency of SC-CO
2 extraction of carotenoids from carrots, canola oil was ...investigated as a continuous co-solvent. The carotenoid content of the starting material was determined by traditional solvent extraction (TSE). Carrot samples with different particle size and moisture content were extracted with SC-CO
2 at different temperature, pressure, canola oil concentration and CO
2 flow rate for 4
h. Carotenoids were identified and quantified by HPLC analysis. α-Carotene, β-carotene, and lutein were the main carotenoids in the extracts. When canola oil was added as a co-solvent, the α- and β-carotene yields were improved more than twice and lutein yield was more than four times higher compared to those obtained with SC-CO
2 extraction alone. Both increasing temperature and increasing pressure had significant positive effects on the carotene yields except for that of lutein. Larger particle size had a negative effect on carotenoid yields. The α- and β-carotene yields decreased with moisture while the lutein yield increased. Higher carotenoid yields were achieved after 4
h of extraction at higher flow rate, while more carotenoids were solubilized in SC-CO
2 at lower flow rate. The highest carotenoid yields were obtained at 70
°C, 55.1
MPa, 5% canola oil concentration (w/w of CO
2), 0.25–0.5
mm particle size, 0.8% moisture content of feed material, and 2
L/min CO
2 flow rate. Employing canola oil as a continuous co-solvent in SC-CO
2 extraction is a novel and efficient technique for the recovery of carotenoids from natural materials.
