Controlling Solvent Polarity to Regulate Protein Self-Assembly Morphology and Its Universal Insight for Fibrillation Mechanism.

The mechanism of ethanol-induced fibrillation of ß-lactoglobulin (ß-lg) in the acidic aqueous solution upon heating was investigated using various techniques, mainly thioflavin T fluorescence, atomic force microscopy, nonreducing electrophoresis, mass spectrometry, Fourier transform infrared spectroscopy, and circular dichroism spectroscopy. The results showed that fibrillation occurred with a heating time increase, but high ethanol content slowed down the process. At a low ethanol volume fraction, peptides existed after heating for 2 h, with long and straight fibrils formed after 4-6 h, while at a high ethanol volume fraction, the proteins aggregated with very few peptides appeared at the early stage of heating, and short and curved fibrils formed after heating for 8 h. Ethanol weakened the hydrophobic interactions between proteins in the aqueous solution; therefore the latter could not completely balance the electrostatic repulsion, and thus suppressing the fibrillation process. It is believed that the fibrillation of ß-lg in the acidic solution upon heating is mainly dominated by the polypeptide model; however, ethanol inhibited the hydrolysis of proteins, and the self-assembly mechanism changed to the monomer model.

Development of halochromic electrospun labels for non-invasive shelf life assessment of rainbow trout (Oncorhynchus mykiss): Incorporation of barberry anthocyanin extract in protein-based smart packaging.

Using barberry (Berberis vulgaris L.) as a natural dye in combination with electrospinning technology represents a promising approach for the development of intelligent packaging systems. In this study, the influence of different concentrations of zein (16, 18, and 20%) and barberry anthocyanin-rich powder (BARP) (16, 18, and 20%) on the surface tension and rheological properties of the solution were evaluated. The most favorable nanofibers (NFs) were obtained from a solution containing 18% (w/w) zein under constant voltage. The surface morphology, size, and color-changing properties of electrospun NFs derived from zein polymers containing different concentrations of BARP (16, 18, and 20%) under various electrical fields (20, 22, and 24 kV) were evaluated. The Fourier-transform infrared spectroscopy analysis confirmed the interaction of BARP within the zein-based NFs. The results indicated that the concentration of BARP had a noticeable impact on the physicochemical properties of the NFs. Furthermore, efficacy of the appropriately fabricated halochromic label was evaluated for monitoring the packed rainbow trout fillet during refrigerated storage. On the 10th day, a noticeable visual color turned from pink to pale yellow was observed in response to pH variations. Additionally, the TVN value confirmed the effectiveness of halochromic electrospun labels for non-invasive assessment of fish fillet quality.

Recent advances in iron encapsulation and its application in food fortification.

Iron (Fe) is an important element for our body since it takes part in a huge variety of metabolic processes. However, the direct incorporation of Fe into food fortification causes a number of problems along with undesirable organoleptic properties. Thus, encapsulation has been suggested to alleviate this problem. This study first sheds more light on the Fe encapsulation strategies and comprehensively explains the results of Fe encapsulation studies in the last decade. Then, the latest attempts to use Fe (in free or encapsulated forms) to fortify foods such as bakery products, dairy products, rice, lipid-containing foods, salt, fruit/vegetable-based products, and infant formula are presented. Double emulsions are highly effective at keeping their Fe content and display encapsulation efficiency (EE) > 88% although it decreases upon storage. The encapsulation by gel beads possesses several advantages including high EE, as well as reduced and great Fe release in gastric and duodenal conditions, respectively. Cereals, particularly bread and wheat, are common staple foods globally; they are very suitable for food fortification by Fe derivatives. Nevertheless, the majority of Fe in flour is available as salts of phytic acid (IP6) and phytates, reducing Fe bioavailability in the human body. The sourdough process degrades IP6 completely while Chorleywood Bread Making Process and conventional processes decrease it by 75% in comparison with whole meal flour.

Electrospun plant protein-based nanofibers loaded with sakacin as a promising bacteriocin source for active packaging against Listeria monocytogenes in quail breast.

The main objective of this study was to fabricate nanofibers from zein incorporated with two concentrations of sakacin (9 and 18 AU/mL) with anti-Listeria properties by electrospinning technique. The efficacies of the resulting active nanofibers against L. innocua, in quail breast during 24 days of refrigerated storage (4 ± 1 °C) were evaluated. The minimum inhibitory concentration (MIC) of bacteriocin against L. innocua was approximate 9 AU/mL. Fourier-transform infrared spectra of bacteriocin-loaded nanofibers indicated characteristic peaks of zein and sakacin and that the nanofibers showed an encapsulation efficiency close to 91.5 %. The thermal stability of sakacin increased by electrospinning. Scanning electron microscopy images showed that nanofibers prepared from electrospinning zein/sakacin solutions exhibited smooth and continuous nanofibers with no defects with an average diameter between 236 and 275 nm. The presence of sakacin led to decreased contact angle properties. Nanofibers with 18 AU/mL sakacin exhibited the highest zone of inhibition of 226.14 ± 8.05 mm. The lowest L. innocua (6.1 logs CFU/cm2) growth after 24 days at 4 °C were obtained in quail breast wrapped with zein containing 18 AU/mL sakacin. The results demonstrate an outlook for the potential use of zein nanofibers containing sakacin to reduce L. innocua contamination in ready-to-eat (RTE) products.

Nano-vesicular carriers for bioactive compounds and their applications in food formulations.

The most commonly used vesicular systems in the food industry include liposomes, niosomes, phytosomes, or transfersomes. This review focuses on showing how nano-vesicular carriers (NVCs) amend the properties of bioactive compounds (bioactives), making them suitable for food applications, especially functional foods. In this research, we elaborate on the question of whether bioactive-loaded NVCs affect various food aspects such as their antioxidant capacity, or sensory properties. This review also shows how NVCs improve the long-term release profile of bioactives during storage and at different pH values. Besides, the refinement of digestibility and bioaccessibility of diverse bioactives through NVCs in the gastrointestinal tract is elucidated. NVCs allow for stable vesicle formation (e.g. from anthocyanins) which reduces their cytotoxicity and proliferation of cancer cells, prolongs the release bioactives (e.g. d-limonene) with no critical burst, reduces the biofilm formation capacity of both Gram-positive/negative strains and their biofilm gene expression is down-regulated (in the case of tannic acid), low oxidation (e.g. iron) is endured when exposed to simulated gastric fluid, and unpleasant smell and taste are masked (in case of omega-3 fatty acids). After the incorporation of bioactive-loaded NVCs into food products, their antioxidant capacity is enhanced, maintaining high encapsulation efficiency and enduring pasteurization conditions, and they are not distinguished from control samples in sensory evaluation despite the reverse situation about free bioactives.

Millifluidic-assisted ionic gelation technique for encapsulation of probiotics in double-layered polysaccharide structure.

A unique double-layered vehicle was fabricated for the first time based on a millifluidic/direct gelation to encapsulate probiotics. Free probiotic bacteria are usually very sensitive to severe gastrointestinal conditions and maintaining their survival when passing through the digestive tract is essential. The effects of alginate concentration (20-30 g/L), flow rates of alginate (0.8-1.2 mL/min), and W/O emulsion (0.5-0.7 mL/min) on encapsulation efficiency (EE), size, and sphericity of core-shell millicapsules were optimized for encapsulation of Bifidobacterium animalis subsp. lactis and Lactobacillus plantarum. The optimized calcium-alginate millicapsule was spherical (0.97 ± 0.01 SF), with an average diameter of 4.49 ± 0.19 mm, and encapsulation efficiency of 98.17 ± 0.5 %. Two strains were encapsulated separately in W/O emulsion as a core of the millicapsule. After coating with chitosan, the encapsulation yield of the bacteria, survival rates under simulated gastrointestinal (GI) conditions, and viability during storage were determined. Survival efficiency of B. animalis subsp. lactis and L. plantarum after millifluidic encapsulation were found to be 92.33 and 90.81 %, respectively. Cell viability of encapsulated probiotics after passing through the GI system was improved (7.5 log CFU mL-1 for both strains). Although the viability of the encapsulated probiotics stored at -18 °C for five months significantly decreased (p<0.05), the number of live cells was approximately in accordance with the standard definition of long-term probiotic survival (6 log CFU/g). This work provides a pathway for the construction of an innovative delivery system with high efficiency and protective effects for probiotics.

A comprehensive parametric study for understanding the combined millifluidic and dripping encapsulation process and characterisation of oil-loaded capsules.

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.

Prolonged-release of menthol through a superhydrophilic multilayered structure of balangu (Lallemantia royleana)-gelatin nanofibers.

This study aimed to develop a sandwich structure based on electrospun mats derived from gelatin (central layer) and Balangu seed gum (outer layers) and to compare its capability for prolonging the menthol release in the oral phase compared to the gelatin monolayer mat. The mesh-like structure and the smooth and uniform surface of the electrospun mats designed in this study were authenticated by Atomic Force Microscopy (AFM). By designing the sandwich structure, the dissolution time and contact angle of the mats were increased and their bioadhesive strength decreased. The swelling degree of the gelatin mat (453.25 ± 32.56%) was significantly higher than that of the sandwich mat (297.71 ± 22.68%) (p < 0.05). Successful entrapment and the thermal stability of the produced mats were proved by X-ray diffraction (XRD), differential scanning calorimetry (DSC), and Fourier-transform infrared spectroscopy (FTIR) tests. The release kinetics in the human simulated saliva showed that the burst release of menthol from the structure of electrospun gelatin mats, due to its fast-dissolving nature, was well prolonged by the designed sandwich system. The Fickian Case-I release was the main mechanism in the menthol release and the Peppas-Sahlin was the most suitable model governing the release of menthol from these structures.

Food-grade gliadin microstructures obtained by electrohydrodynamic processing.

This paper presents a comprehensive study on the electrohydrodynamic processing of gliadin to develop food-grade delivery systems with different morphologies. The effects of biopolymer concentration, applied voltage and solution flow-rate on particle morphology, molecular organisation, crystallinity and thermal properties were investigated. Gliadin concentration influenced the apparent viscosity and conductivity of the solutions, giving raise to particle morphologies at 10 wt% gliadin and beaded-free fibers above 25 wt% gliadin. In general, increasing the voltage resulted in smaller average sizes of the obtained structures, while no significant differences in morphology were observed among the tested flow rates. Interestingly, the amide I position in the FTIR reflected changes in protein conformation which could be correlated with the final morphology attained. Moreover, the acetic acid used for solution preparation disrupted the original amino acid chain packing of the gliadin fraction, being the electrospun/electrosprayed samples amorphous. These gliadin-based microparticles and microfibers obtained could serve as food-grade delivery vehicles.

Active Food Packaging Coatings Based on Hybrid Electrospun Gliadin Nanofibers Containing Ferulic Acid/Hydroxypropyl-Beta-Cyclodextrin Inclusion Complexes.

In this work, hybrid gliadin electrospun fibers containing inclusion complexes of ferulic acid (FA) with hydroxypropyl-beta-cyclodextrins (FA/HP-ß-CD-IC) were prepared as a strategy to increase the stability and solubility of the antioxidant FA. Inclusion complex formation between FA and HP-ß-CD was confirmed by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimeter (DSC), and X-ray diffraction (XRD). After adjusting the electrospinning conditions, beaded-free fibers of gliadin incorporating FA/HP-ß-CD-IC with average fiber diameters ranging from 269.91 ± 73.53 to 271.68 ± 72.76 nm were obtained. Control gliadin fibers containing free FA were also produced for comparison purposes. The incorporation of FA within the cyclodextrin molecules resulted in increased thermal stability of the antioxidant compound. Moreover, formation of the inclusion complexes also enhanced the FA photostability, as after exposing the electrospun fibers to UV light during 60 min, photodegradation of the compound was reduced in more than 30%. Moreover, a slower degradation rate was also observed when compared to the fibers containing the free FA. Results from the release into two food simulants (ethanol 10% and acetic acid 3%) and PBS also demonstrated that the formation of the inclusion complexes successfully resulted in improved solubility, as reflected from the faster and greater release of the compounds in the three assayed media. Moreover, in both types of hybrid fibers, the antioxidant capacity of FA was kept, thus confirming the suitability of electrospinning for the encapsulation of sensitive compounds, giving raise to nanostructures with potential as active packaging structures or delivery systems of use in pharmaceutical or biomedical applications.

Preparation and Characterization of Herbicide Mecoprop Imprinted Polymer and Its Application as a Selective Sorbent in Water Sample.

Bulk polymerization method was used to prepare a homogeneous molecularly imprinted polymer (MIP) for the specific extraction of herbicide mecoprop (MCPP). Thereafter, the binding performance of this functional polymer was evaluated under optimal condition, compared to a non-imprinted polymer. From the Scatchard plot analysis, two types of binding sites were detected in the MIP, the high affinity binding sites with a KD (equilibrium dissociation constant) of 6.4 µM and the low affinity ones with a KD of 55.9 µM. In addition, the possibility of using synthesized MIP for MCPP extraction from environmental aqueous samples was explored. The adsorption capacity of MIP in spiked bottled water and groundwater samples showed that the polymer could effectively extract MCPP from bottled water and groundwater (p < 0.05) with the recovery of 70.5% and 65.1%, respectively, demonstrating the potential of imprinted polymers for cost-effective and effective water treatment.

Electrospray-assisted encapsulation of caffeine in alginate microhydrogels.

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.

Electrospray-assisted drying of live probiotics in acacia gum microparticles matrix.

Acacia gum solution was employed as a carrier for electrospray-assisted drying of probiotic cells. To optimize the process, effect of gum concentration, thermal sterilization as a prerequisite for microbial studies, and surfactant addition on physical properties of feed solution was investigated. Increasing gum concentration from 20 to 40 wt.% led to a viscosity increase, whilst surface tension did not change meaningfully and electrical conductivity declined after an increasing trend up to 30 wt.% of the gum. Thermal sterilization increased the viscosity without any significant effect on the conductivity and surface tension. Surfactant addition reduced the surface tension and conductivity but the viscosity increased. Highly uniform particles were formed by electrospray-assisted drying of autoclaved 35 wt.% acacia gum solution containing 1 wt.% Tween 80. Thermal sterilization and surfactant addition improved electrospray-ability of acacia gum solution. Bacterial count showed that more than 96 percent of probiotic cells passed the process viably.

Enrichment of cellulose acetate nanofibre assemblies for therapeutic delivery of l-tryptophan.

The essential amino acid l-tryptophan is naturally present in the body, and is also available as a water soluble dietary supplement. The feasibility of preparing enriched cellulose acetate (CA)-based fibres as a vehicle for therapeutic delivery of such biomolecules was investigated. A new ternary solvent system consisting of acetone: N,N-dimethylacetamide: methanol (2:1:2) has been demonstrated to permit the solution blending of CA with the water soluble l-tryptophan. Nanofibrous webs substantially free of structural defects were continuously produced with mean fibre diameters in the range of 520-1010nm, dependent on process parameters. Morphology and diameter of fibres were influenced by concentration of CA spinning solution, applied voltage and flow rates. The kinetic release profile of l-tryptophan from electrospun CA nanofibres was described by the pseudo-second order kinetic model. Fibres with mean diameter of 720nm provide both the highest initial desorption rate and rate constant, which was partially attributed to the low fibre diameter and high relative surface area, but also the fact that the 720nm fibres produced were the most bead-free, providing diffusion advantages over the fibres with lowest mean diameter (520nm). The feasibility of combining l-tryptophan within fibres provides a promising route for manufacture of transdermal delivery devices.

Principles of electrospraying: A new approach in protection of bioactive compounds in foods.

Electrospraying is a potential answer to the demands of nanoparticle fabrication such as scalability, reproducibility, and effective encapsulation in food nanotechnology. Electrospraying (and the related process of electrospinning) both show promise as a novel delivery vehicle for supplementary food compounds since the process can be carried out from an aqueous solution, at room temperature and without coagulation chemistry to produce matrices or particulates in the micro- and nano-range. The presentation of core materials at the nanoscale improves target ability to specific areas of the digestive tract and gives improved control of release rate. Adoption of these electrohydrodynamic atomization technologies will allow the industry to develop a wide range of novel high added value functional foods. To optimize production conditions and maximize throughput, a clear understanding of the mechanism of electrospraying is essential. This article presents a comprehensive review of the principles of electrospraying to produce nanoparticles suitable for food technology application, particularly for use in encapsulation and as nanocarriers.

Controlling the morphology and material characteristics of electrospray generated calcium alginate microhydrogels.

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, CaCl2 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) CaCl2 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.