Encapsulation Of Active Compounds Research Articles

Operating limits and parametric sensitivity of laboratory device for continuous production of liquid marbles

Encapsulation of active compounds into liquid marbles (LMs) represents an emerging technology with potential applications in several fields including food, cosmetics and pharmaceutics. However, existing methods for the preparation of LMs are either based on manual one-by-one fabrication or on batch processes such as high-shear granulation, which lack the required precision in LM size distribution. We present a device capable of continuous LM production with high reproducibility, control over the LM properties and production rate flexibility. The device utilizes droplet impact onto a continuously moving powder bed on a belt conveyor with subsequent product separation by sieving. The device has been applied for fabricating LMs from various combinations of coating powders and core liquids including water- and oil-based systems as well as melts. Monodisperse populations of all three LM types were obtained in the range of 2.0–3.5 mm depending on the nozzle setting, and the maximum productivity of the device was up to 50 LMs per second. The effect of process parameters was investigated and guidelines for defect-free production were obtained. We 0.5 Re 0.25 above a critical value was found to indicate the onset of undesirable satellite droplet generation or interface jamming upon the droplet impact; the critical value was also found to depend on the thickness of the moving powder bed. Surprisingly, the minimum safe interval between consecutive LMs that was necessary to avoid coalescence was found to be invariable with respect to both LM type and diameter. The device was capable of laboratory-scale LM production for a range of product testing and prototyping purposes and provided useful data for subsequent process scale-up. • New device for continuous fabrication of liquid marbles was construced • Aqueous, oil- and melt-based liquid marbles were successfully produced • Feasible regions of opearing parameters for defect-free operation were determined • Criteria for trouble-shooting and scale-up were established

Encapsulation of Active Compounds in Fruit and Vegetable Juice Processing: Current State and Perspectives

The production of value-added and/or functional juices has increased significantly in recent years, following an increased consumer demand to promote health and/or prevent disease through diet and nutrition. Micro and nano-encapsulation are promising technologies to protect and deliver sensitive compounds, allowing a controlled release in the target sites. This paper offers an overview of current applications, limits and challenges of encapsulation technologies in the production of fruit and vegetable juices, with a particular emphasis on products derived from different botanical sources.

Nanostructured bioactive compounds for ecological food packaging

Plastics have been successfully used as packaging materials, but environmental pollution by plastics is inducing a growing interest for alternative, biocompatible plastics. In this context, bionanocomposites are developed for application in the food packaging sector. This article reviews methods for encapsulation of bioactive compounds into nanostructures, which can be further incorporated into packaging materials to improve food quality and safety. Encapsulation of active compounds in bionanocomposites is done using various methods such as spray drying, spray cooling and chilling, fluidized bed coating, coacervation, liposome entrapment, co-crystallization, nanoemulsion, air suspension, freeze-drying, interfacial polymerization, molecular inclusion and sol–gel. Nonetheless, none of these methods are universally applicable for a bioactive or food component. Alternatively, lipid-based nanostructures such as liposomes and solid lipid nanoparticles have been effectively used for the delivery of bioactive molecules showing antimicrobial and antioxidant activities. Fat-soluble vitamins can be incorporated in nanoemulsions, which in addition to polymeric nanoparticles are suitable vehicles to phytochemicals like quercetin and curcumin. Nanofibers are also promising materials to incorporate bioactive substances in food packaging.

Protein Nanocage as a pH-Switchable Pickering Emulsifier.

Encapsulation of active compounds in Pickering emulsions using bioderived protein-based stabilizers holds potential for the development of novel formulations in the fields of foods and cosmetics. We employ a dodecahedron hollow protein nanocage as a pH-switchable Pickering emulsifier. E2 protein nanocages are derived from pyruvate dehydrogenase multienzyme complex from Geobacillus stearothermophilus which adsorb at the oil/water interface at neutral and basic pH's and stabilize the Pickering emulsions, while in the acidic range, at pH ∼4, the emulsion separates into emulsion and serum phases due to flocculation. The observed process is reversible for at least five cycles. Optimal formulation of a Pickering emulsion composed of rosemary oil, an essential oil, and water has been achieved by ultrasonication and results in droplets of approximately 300 nm in diameter with an oil/water ratio of 0.11 (v/v) and 0.30-0.35% (wt %). Ionic stabilization is observed for concentrations up to 250 mM NaCl and pH values from 7 to 11. The emulsions are stable for at least 10 days when stored at different temperatures up to 50 °C. The resulting Pickering emulsions of different compositions also form a gel-like structure and show shear thinning behavior under shear stress at a higher oil/water ratio.

Controlled Release Properties of Zein–Fatty Acid Blend Films for Multiple Bioactive Compounds

To develop edible films having controlled release properties for multiple bioactive compounds, hydrophobicity and morphology of zein films were modified by blending zein with oleic (C18:1)Δ⁹, linoleic (C18:2)Δ(9,12), or lauric (C₁₂) acids in the presence of lecithin. The blend zein films showed 2-8.5- and 1.6-2.9-fold lower initial release rates for the model active compounds, lysozyme (LYS) and (+)-catechin (CAT), than the zein control films, respectively. The change of fatty acid chain length affected both CAT and LYS release rates while the change of fatty acid double bond number affected only the CAT release rate. The film morphologies suggested that the blend films owe their controlled release properties mainly to the microspheres formed within their matrix and encapsulation of active compounds. The blend films showed antilisterial activity and antioxidant activity up to 81 μmol Trolox/cm². The controlled release of multiple bioactive compounds from a single film showed the possibility of combining application of active and bioactive packaging technologies and improving not only safety and quality but also health benefits of packed food.

Precipitation of Hemicelluloses from DMSO/Water Mixtures Using Carbon Dioxide as an Antisolvent

Supercritical antisolvent precipitation is a relatively recent technology which can be used for controlled preparation of polymer particles from solutions. This is done by the addition of an antisolvent to a polymer solution causing supersaturation of the polymer, especially under supercritical conditions. The particle size of the precipitates can be adjusted mainly by the rate of supersaturation. Spherical xylan or mannan particles having a narrow particle size distribution were precipitated from hemicellulose solutions in dimethyl‐sulfoxide (DMSO) or DMSO/water mixtures by carbon dioxide as an antisolvent. By depending on the type of hemicellulose, the DMSO/H2O ratio, and the precipitation conditions such as pressure and temperature, the resulting particle size can be adjusted within a wide range from less than 0.1 to more than 5 μm. Nano‐ and microstructured native xylans and mannans as obtained can be used in many applications such as encapsulation of active compounds, slow release agents, or chromatographic separation materials.