Preparation of films based on reticulated fish gelatin containing garlic essential oil.

Agro-industrial co-products, such as fish gelatin, stand out for their capacity in forming biopolymeric films, being biocompatible and non-toxic; however, its hydrophilicity poses a challenge. Essential oils, rich in bioactives, attract research interest aiming to enhance the protective barrier of films and enable their application in packaging. This study produced films based on cross-linked Nile tilapia skin gelatin, incorporating garlic essential oil. Gelatin obtained through partial collagen hydrolysis from the fish skin and cross-linked with gallic acid had hydroxyproline content of 10.02 g 100 g-1 and gel strength of 287 g, which were consistent with other studies. Oil extraction used supercritical CO2 as a solvent and ethanol as a cosolvent, following a factorial experimental design, evaluating the extraction temperature (40 °C and 70 °C) and cosolvent ratio (1:1 and 1:3), with three central points. Extraction was successful, with higher yields on a dry basis at 70 °C (88.35 %), using a 1:1 cosolvent ratio. Films incorporated with oil exhibited lower water vapor permeability (WVP) than those with only cross-linked gelatin (1.59 (g m-1 s-1 Pa-1) 1011). The film with the most suitable tensile strength (19.07 MPa), elongation (120.91 %), and WVP (1.09 (g m-1 s-1 Pa-1) 1011) properties contained garlic oil extracted at the central point (55 °C and 1:2). Thermal analysis indicated increased melting temperatures in films with added oil, suggesting low thermal degradation. These results suggest that garlic oil addition can improve the properties of fish gelatin-based films, making them promising for biodegradable packaging.

Advanced Microfluidic Technologies for Lipid Nano-Microsystems from Synthesis to Biological Application.

Microfluidics is an emerging technology that can be employed as a powerful tool for designing lipid nano-microsized structures for biological applications. Those lipid structures can be used as carrying vehicles for a wide range of drugs and genetic materials. Microfluidic technology also allows the design of sustainable processes with less financial demand, while it can be scaled up using parallelization to increase production. From this perspective, this article reviews the recent advances in the synthesis of lipid-based nanostructures through microfluidics (liposomes, lipoplexes, lipid nanoparticles, core-shell nanoparticles, and biomimetic nanovesicles). Besides that, this review describes the recent microfluidic approaches to produce lipid micro-sized structures as giant unilamellar vesicles. New strategies are also described for the controlled release of the lipid payloads using microgels and droplet-based microfluidics. To address the importance of microfluidics for lipid-nanoparticle screening, an overview of how microfluidic systems can be used to mimic the cellular environment is also presented. Future trends and perspectives in designing novel nano and micro scales are also discussed herein.

Deformation and rupture of microcapsules flowing through constricted capillary.

The dynamics of deformable microcapsules flowing through constricted channels is relevant in target delivery of chemicals in physiological systems, porous media, microfluidic medical diagnostic devices and many other applications. In some situations, the microcapsules need to sustain the stress they are subjected to as they flow through constricted channels and in others, the stress may be the rupture trigger used to release the internal content. We experimentally investigate the flow of monodispersed gellan gum microcapsules through a constricted capillary tube by measuring the evolution of the pressure difference and flow visualization. The maximum pressure difference and capsule deformation is obtained for capsules with different diameter and shell thickness. We map the conditions, e.g. diameter and shell thickness, at which the capsule membrane ruptures during the flow, releasing its internal phase.

High-throughput continuous production of liposomes using hydrodynamic flow-focusing microfluidic devices.

The microfluidic hydrodynamic flow-focusing is a simple technique for nanoscale liposome formation that provides several advantages compared to the traditional manufacturing techniques. This work aimed to perform a systematic study of the liposome formation using planar microfluidic devices with different channel aspect-ratios, as an alternative to enhance the throughput of liposome synthesis. In general, liposomes with a low polydispersity and a precise control of the size were successfully produced from alteration of the flow rate ratio and channel aspect-ratio. The higher aspect-ratio enabled the most rapid generation of liposomes with similar diameter and significant lower polydispersity index than the obtained by other batch technique. Besides, ß-carotene was successfully incorporated into liposomes with efficiency of approximately 60% and the incorporation ability was not specific to a choice of microfluidic device aspect-ratio. The results suggest that the use of microfluidic devices could be employed for liposome production with a possible advantage to minimize the degree of parallelization of processes. These results demonstrate the potential technical feasibility of microfluidic processes for future industrial applications.

Heteroaggregation of lipid droplets coated with sodium caseinate and lactoferrin.

Formation and characterization of droplet heteroaggregates were investigated by mixing two emulsions previously stabilized by proteins oppositely charged. Emulsions were composed of 5vol.% of sunflower oil and 95vol.% of sodium caseinate or lactoferrin aqueous dispersions. They were produced using ultrasound with fixed power (300W) and sonication time (6min). Different volume ratios (0-100%) of sodium caseinate-stabilized emulsion (droplet diameter around 1.75µm) to lactoferrin-stabilized emulsion (droplet diameter around 1.55µm) were mixed under conditions that both proteins showed opposite charges (pH7). Influence of ionic strength (0-400mM NaCl) on the heteroaggregates stability was also evaluated. Creaming stability, zeta potential, microstructure, mean particle diameter and rheological properties of the heteroaggregates were measured. These properties depended on the volume ratio (0-100%) of sodium caseinate to lactoferrin-stabilized emulsion (C:L) and the ionic strength. In the absence of salt, different zeta potential values were obtained, rheological properties (viscosity and elastic moduli) were improved and the largest heteroaggregates were formed at higher content of lactoferrin-stabilized emulsion (60-80%). The system containing 40 and 60vol.% of sodium caseinate and lactoferrin stabilized emulsion, respectively, presented good stability against phase separation besides showing enhanced rheological and size properties due to extensive droplets aggregation. Phase separation was observed only in the absence of sodium caseinate, demonstrating the higher susceptibility of lactoferrin to NaCl. The heteroaggregates produced may be useful functional agents for texture modification and controlled release since different rheological properties and sizes can be achieved depending on protein concentrations.

ß-Carotene-loaded nanostructured lipid carriers produced by solvent displacement method.

Tristearin solid lipid nanoparticles and tristearin/high oleic sunflower oil nanostructured lipid carriers were produced by solvent displacement method. All conditions allowed forming polydisperse particles within nanometric range and the presence of high oleic sunflower oil did not affect the particles mean size. Nevertheless, incorporation of ß-carotene reduced the particles polydispersity. Thermograms of solid lipid nanoparticles and nanostructured lipid carriers showed that sunflower oil generated a crystal order disturbance, since nanoparticles with less-organized lipid matrix were produced. Nanostructured lipid carriers exhibited an improvement of ß-carotene loading capacity when compared with solid lipid nanoparticles, which enhanced with the increasing of high oleic sunflower oil content. Although total ß-carotene degradation was similar for all systems, color analysis showed that the degradation of encapsulated ß-carotene was lower for high sunflower oil content. Nanostructured lipid carriers exhibited advantages over the solid lipid nanoparticles, such as enhanced drug loading capacity and prevention of drug expulsion, which makes this a versatile delivery system for food applications.

Evaluation of the composition of culture medium for yeast biomass production using raw glycerol from biodiesel synthesis

The work herewith investigated the production of yeast biomass as a source of protein, using Yarrowia lipolytica NRRL YB-423 and raw glycerol from biodiesel synthesis as the main carbon source. A significant influence of glycerol concentration, initial pH and yeast extract concentration on biomass and protein content was observed according to the 2v5-1 fractional design. These factors were further evaluated using a central composite design and response surface methodology, and an empirical model for protein content was established and validated. The biomass of Yarrowia lipolytica NRRL YB-423 reached 19.5 ± 1.0 g/L in shaken flasks cultivation, with a protein content of 20.1 ± 0.6% (w/w).

Evaluation of the composition of culture medium for yeast biomass production using raw glycerol from biodiesel synthesis.

The work herewith investigated the production of yeast biomass as a source of protein, using Yarrowia lipolytica NRRL YB-423 and raw glycerol from biodiesel synthesis as the main carbon source. A significant influence of glycerol concentration, initial pH and yeast extract concentration on biomass and protein content was observed according to the 2v (5-1) fractional design. These factors were further evaluated using a central composite design and response surface methodology, and an empirical model for protein content was established and validated. The biomass of Yarrowia lipolytica NRRL YB-423 reached 19.5 ± 1.0 g/L in shaken flasks cultivation, with a protein content of 20.1 ± 0.6% (w/w).