Search

Aim: This study aimed to utilise and optimise the millifluidic and dripping encapsulation technique to develop and characterise the oil-core capsules., Methods: Sodium alginate with Tween-20 (continuous phase) and sunflower oil (dispersed phase) were used in millifluidic system. After determining the surface and interfacial tensions and flow behaviour parameters, flow rates of phases and concentrations of alginate and Tween were optimised by the Taguchi method. The flow regime of droplets was also evaluated. Optimised millicapsules were characterised concerning morphology, dimension, encapsulation efficiency, SEM, FTIR and, DSC results., Results: Dripping flow regime during droplet formation was observed. Reducing the interfacial tension between the continuous and dispersed phases resulted in about a 10.18% reduction in diameter. Optimised millicapsules depicted spherical shape (0.03 ± 0.01) with 3.95 ± 0.05 mm size and 97.5 ± 0.2% encapsulation efficiency. The FTIR and DSC results confirmed the entrapment of oil., Conclusion: Millifluidic and dripping method effectively encapsulated sunflower oil in core-shell capsules.

One of the major challenges with microencapsulation and delivery of low molecular weight bioactive compounds is their diffusional loss during storage and process conditions as well as under gastric conditions. In an attempt to slow down the release rate of core material, electrospray fabricated calcium alginate microhydrogels were coated with low molecular weight and high molecular weight chitosans. Caffeine as a hydrophilic model compound was used due to its several advantages on human behavior especially increasing consciousness. Mathematical modeling of the caffeine release by fitting the data with Korsmeyer-Peppas model showed that Fick's diffusion law could be the prevalent mechanism of the release. Electrostatic interaction between alginate and chitosan (particularly in the presence of 1% low molecular weight chitosan) provided an effective barrier against caffeine release and significantly reduced swelling of particles compared to control samples. The results of this study demonstrated that calcium alginate microhydrogels coated by chitosan could be used for encapsulation of low molecular compounds. However, more complementary research must be done in this field. In addition, electrospray, by producing monodisperse particles, would be as an alternative method for fabrication of microparticles based on natural polymers., (Copyright © 2018. Published by Elsevier B.V.)

Electrospraying nano- and micro-particle fabrication is a one-step, non-invasive process, which has application in encapsulating of thermosensitive functional, bioactive materials and cells and making microhydrogels. This study investigates the effect of various electrospraying process parameters on the characteristics of calcium alginate microhydrogel particles. The alginate solution concentration, CaCl 2 coagulation bath concentration, voltage, nozzle diameter, distance between nozzle and collecting bath (D), alginate delivery pressure (∼H) were examined. The best droplet formation rate, in non-disperse dripping mode, was obtained at 8 kV using a 500 μm inner diameter nozzle tip, D = 8 cm, H = 20 cm. Morphology, swelling behaviour and texture analysis of the particles which were followed by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) confirmed that 1.5-2% (w/v) CaCl 2 was the desirable concentration for hydrogels formation. Particle size range between 267 and 1500 μm could be obtained by the drip feed mode compared with 2.3-6 μm by the pressure-assisted electrospray through a coaxial head.

This study aimed to evaluate hydrogel properties produced by electrospraying alginate/AHSG (Alyssum homolocarpum seed gum) dispersions at different mixing ratios (0:100, 25:75, 50:50, 75:25, and 100:0). The results revealed that the ζ-potential and electrical conductivity of dispersions decreased with increasing the alginate to AHSG ratio. The dispersions were able to be atomized from the tip of the nozzle without the need for surfactant addition. The apparent viscosity increased with increasing alginate to AHSG ratio. The size of particles decreased, and their sphericity increased when the alginate to AHSG ratio increased. Intermolecular hydrogen bonds were formed between alginate and AHSG. The thermal stability of hydrogel increased as the alginate to AHSG ratio increased. At a mixing ratio of 75 alginate:25 AHSG, the porous structure of alginate hydrogel beads reduced. The XRD spectrum indicated that the crystalline structure of gums transformed into the amorphous state after the electrospraying. [ABSTRACT FROM AUTHOR]

Abstract This work reports on a simple, fast and food-grade encapsulation approach with potential for probiotic protection, which consists on the formation of agarose-based hydrogel particles. These were generated by the supramolecular self-assembly of the probiotic-containing carbohydrate solutions by dripping them into a biphasic bath with an upper oil layer, which acted as the particle-forming antisolvent, and a lower aqueous layer, where the hydrogel particles were collected. This technique, which we have named "oil-induced biphasic hydrogel particle formation", has been used to encapsulate the sensitive strain Bifidobacterium pseudocatenulatum CECT 7765. In order to avoid agarose gelling at 40 °C before the encapsulation process, this seaweed-derived carbohydrate was combined with other hydrocolloids (alginate, whey protein concentrate, and gelatin), and the obtained probiotic-containing hydrogel particles were subsequently freeze-dried. The protection ability of this method versus directly freeze-drying the probiotic-containing solutions was demonstrated during storage and simulated in-vitro digestion. Both the formation of a continuous layer surrounding the bacteria and the optimal combination of materials (agarose providing suitable oxygen barrier and WPC with proven probiotic affinity) rendered encapsulation systems keeping viability levels required for commercial applications. Graphical abstract Image 1 Highlights • Agarose-based blends were developed as encapsulating systems for probiotics. • Hydrogel particles were formed through a newly developed process. • Encapsulation prior to freeze-drying resulted in improved probiotic protection. • This strategy efficiently protected the sensitive bacteria through in-vitro digestion. [ABSTRACT FROM AUTHOR]