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Effect of porous structure and spreading pressure on the storage stability of red onion microcapsules produced by spray freezing into liquid cryogenic and spray drying

L.A. Pascual-Pineda, M.P. Rascón, M.X. Quintanilla-Carvajal, M. Castillo-Morales, U.R. Marín, E. Flores-Andrade

Abstract

Red onion microcapsules were produced by spray freezing into liquid cryogenic (SFLC) and spray drying (SD) and their anthocyanin contents were evaluated kinetically at different water activities () at 35 °C. The spreading pressure-area isotherms were determined at 35 °C. These isotherms provide important information about the different phases of adsorbed water present in SD and SFLC capsules, which can be related to minimal integral entropy and to chemical stability during storage. The porosity of the microcapsules was examined using low-temperature adsorption of nitrogen. The maximum anthocyanin stability occurred at from 0.108 to 0.318, and 0.108 to 0.515, for SD and SFLC, respectively. SD products were nonporous whereas SFLC were mesoporous. The tendency to contraction of the adsorbed water film was compared with the minimum integral entropy and was proposed as a new stability criterion to predict suitable storage conditions of dehydrated foods.

Keywords

Minimum integral entropy, Monolayer, Spreading pressure, Spray freezing into liquid nitrogen

Freeze Granulation for the Processing of Silicon Nitride Ceramics

Ola Lyckfeldt, Kent Rundgren, M. Sjöstedt

Abstract

Freeze granulation (LS-2, PowderPro HB, Sweden) has been demonstrated as a favourable alternative to conventional granulation methods (spray drying, sieve granulation etc) in the production of granules for the pressing of high-performance ceramic powders. Freeze granulation/freeze drying prevents the migration of pressing aids or particle fines to the granule surface, as is the case in spray drying. This ensures granule homogeneity and an easy breakdown of granules during pressing. This, in turn, results in defect minimisation and optimal conditions for the sintering and the development of the desired material properties. In this study silicon nitride materials have been produced using freeze granulation, pressing and sintering to validate the performance. Materials with competitive properties were manufactured based on medium-cost, direct-nitrided powders (SicoNide P95, Permascand AB, Sweden), various pressing and sintering aid compositions as well as various pressing and sintering schedules. MgO vs Fe2O3 as sintering aid, PEG vs PVA as binder and higher pressure at the initial uniaxial pressing were found to promote the sintering performance.

Selective Oxidation of HMF via Catalytic and Photocatalytic Processes Using Metal-Supported Catalysts

Lolli A, Maslova V, Bonincontro D, Basile F, Ortelli S, Albonetti S

Abstract

In this study, 5-hydroxymethylfurfural (HMF) oxidation was carried out via both the catalytic and the photocatalytic approach. Special attention was devoted to the preparation of the TiO₂-based catalysts, since this oxide has been widely used for catalytic and photocatalytic application in alcohol oxidation reactions. Thus, in the catalytic process, the colloidal heterocoagulation of very stable sols, followed by the spray-freeze-drying (SFD) approach, was successfully applied for the preparation of nanostructured porous TiO₂-SiO₂ mixed-oxides with high surface areas. The versatility of the process made it possible to encapsulate Pt particles and use this material in the liquid-phase oxidation of HMF. The photocatalytic activity of a commercial titania and a homemade oxide prepared with the microemulsion technique was then compared. The influence of gold, base addition, and oxygen content on product distribution in the photocatalytic process was evaluated.

Keywords

5-hydroxymethyl furfural; TiO2; microemulsion; photocatalysis; spray-freeze drying

Modern frontiers and applications of spray-freeze-drying in design of food and biological supplements

Sayantani Dutta, J. A. Moses, C. Anandharamakrishnan

Abstract

Spray‐freeze‐drying (SFD) is a unique tandem technique combining spray drying (SD) and freeze drying (FD), and exploiting the advantages of both. SFD is particularly suitable for volatiles, biologicals, and food supplements that are sensitive to process extremities of temperature (SD) and time and cost (FD). Although SFD has been an area of interest to scientists for some time, there have been few very interesting investigations in food science in the recent past, which highlight the versatility and utility of this method, and been discussed in this review. The sources for SFD range from flavor ingredients to vegetables, lipids, enzymes, vitamins, and proteins. The extensive research findings in this domain have been collated in this focused review with the objective of providing the readers an essence of the forays made in this technology and the future possibilities it promises.

Passive inhalation of dry powder influenza vaccine formulations completely protects chickens against H5N1 lethal viral challenge.

Tomar J, Biel C, de Haan CAM, Rottier PJM, Petrovsky N, Frijlink HW, Huckriede A, Hinrichs WLJ, Peeters B

Abstract

Bird to human transmission of high pathogenicity avian influenza virus (HPAIV) poses a significant risk of triggering a flu pandemic in the human population. Therefore, vaccination of susceptible poultry during an HPAIV outbreak might be the best remedy to prevent such transmissions. To this end, suitable formulations and an effective mass vaccination method that can be translated to field settings needs to be developed. Our previous study in chickens has shown that inhalation of a non-adjuvanted dry powder influenza vaccine formulation during normal breathing results in partial protection against lethal influenza challenge. The aim of the present study was to improve the effectiveness of pulmonary vaccination by increasing the vaccine dose deposited in the lungs and by the use of suitable adjuvants. Two adjuvants, namely, Bacterium-like Particles (BLP) and Advax, were spray freeze dried with influenza vaccine into dry powder formulations. Delivery of dry formulations directly at the syrinx revealed that BLP and Advax had the potential to boost either systemic or mucosal immune responses or both. Upon passive inhalation of dry influenza vaccine formulations in an optimized set-up, BLP and Advax/BLP adjuvanted formulations induced significantly higher systemic immune responses than the non-adjuvanted formulation. Remarkably, all vaccinated animals not only survived a lethal influenza challenge, but also did not show any shedding of challenge virus except for two out of six animals in the Advax group. Overall, our results indicate that passive inhalation is feasible, effective and suitable for mass vaccination of chickens if it can be adapted to field settings.

Keywords

Passive; adjuvants; challenge; influenza; inhalation; powders; protection; pulmonary

Effect of Drying Methods of Alumina Powder and Graphene Oxide Mixture on the Mechanical and Electrical Properties of Sintered Composites Fabricated by Spark Plasma Sintering

P. V. Fokin, Nestor Washington Solis Pinargote, E. V. Kuznetsova, Pavel Peretyagin

Abstract

This paper presents a study on graphene-reinforced alumina ceramic composites and the resulting mechanical and electrical properties. Three drying methods were chosen for the fabrication of the initial mixtures: spray, freeze, and vacuum. Spark plasma sintering was chosen as a method of consolidating mixtures. A combination of spray drying and spark plasma sintering makes it possible to produce a high-density (99%) ceramic nanocomposite with improved mechanical properties. The hardness and crack resistance values were increased by 6 and 28%, respectively, compared to other materials studied in this work. This improvement is due to an extremely good dispersion of graphene in the composite, which leads to the decrease in the grain size of the ceramic matrix and consequently reduces the probability of crack occurrence. In addition to these exceptional mechanical properties, the sintered composites also showed high electrical conductivity, which allows the compacts to be machined using electrical discharge machining and thus facilitates the fabrication of ceramic components with sophisticated shapes while reducing machining costs.

Application of disaccharides alone and in combination, for the improvement of stability and particle properties of spray-freeze dried IgG

Daneshmand B, Faghihi H, Amini Pouya M, Aghababaie S, Darabi M, Vatanara A

Abstract

Spray-freeze drying (SFD) is a recently applied method to develop pharmaceutical powders. This study aimed to analyze the competence of Trehalose, Mannitol, Lactose, and Sorbitol instability and aerosolization of Immunoglobulin G (IgG) via SFD.

METHODS:

Induced soluble aggregates were quantified at 0 and 3 months, and 45 °C using size-exclusion chromatography. Conformation and thermogravimetric assessments were done by Fourier transform infrared spectroscopy and differential scanning calorimetry. Laser light scattering was performed to determine the particle sizes. Aerodynamic features were characterized by twin stage impinger and scanning electron microscopy.

RESULTS:

Although sugars/polyols preferably stabilized IgG following the process, storage stabilization was achieved in Trehalose, Trehalose-Lactose, Lactose, and Trehalose-Mannitol-based powders with soluble aggregates <5%. The conformation of antibody was preserved with β sheet content from 66.28% to 76.37%. Particle sizes ranged from 5.23 to 8.12 µm. Mannitol exhibited the best aerodynamic behavior, fine particle fraction (FPF: 70%) but high degree of protein aggregation during storage.

CONCLUSIONS:

SFD could favorably stabilize antibody using Trehalose and its combination with Lactose and Mannitol, and also, Lactose alone. Sorbitol disturbed IgG powder recovery. Incorporation of other types of excipient is required for efficient respiratory delivery of IgG molecules.

Keywords

IgG; Spray-freeze drying; aerodynamic behavior; disaccharides; stability

Advax augments B and T cell responses upon influenza vaccination via the respiratory tract and enables complete protection of mice against lethal influenza virus challenge

Tomar J, Patil HP, Bracho G, Tonnis WF, Frijlink HW, Petrovsky N, Vanbever R, Huckriede A, Hinrichs WLJ

Abstract

Administration of influenza vaccines via the respiratory tract has potential benefits over conventional parenteral administration, inducing immunity directly at the site of influenza exposure as well as being needle free. In this study, we investigated the suitability of Advax™, a stable particulate polymorph of inulin, also referred to as delta inulin, as a mucosal adjuvant for whole inactivated influenza vaccine (WIV) administered either as a liquid or dry powder formulation. Spray freeze-drying produced Advax-adjuvanted WIV powder particles in a size range (1-5 μm) suitable for inhalation. The physical and biological characteristics of both WIV and Advax remained unaltered both by admixing WIV with Advax and by spray freeze drying. Upon intranasal or pulmonary immunization, both liquid and dry powder formulations containing Advax induced significantly higher systemic, mucosal and cellular immune responses than non-adjuvanted WIV formulations. Furthermore, pulmonary immunization with Advax-adjuvanted WIV led to robust memory B cell responses along with an increase of lung localization factors i.e. CXCR3, CD69, and CD103. A less pronounced but still positive effect of Advax was seen on memory T cell responses. In contrast to animals immunized with WIV alone, all animals pulmonary immunized with a single dose of Advax-adjuvanted WIV were fully protected with no visible clinical symptoms against a lethal dose of influenza virus. These data confirm that Advax is a potent mucosal adjuvant that boosts vaccine-induced humoral and cellular immune responses both in the lung and systemically with major positive effects on B-cell memory and complete protection against live virus. Hence, respiratory tract immunization, particularly via the lungs, with Advax-adjuvanted WIV formulation as a liquid or dry powder is a promising alternative to parenteral influenza vaccination.

Keywords

Advax; Immune mechanisms; Inhalation; Mucosal; Powders; Protection; Whole inactivated influenza vaccine

Using two-fluid nozzle for spray freeze drying to produce porous powder formulation of naked siRNA for inhalation

Liang W, Chow MYT, Chow SF, Chan HK, Kwok PCL, Lam JKW

Abstract

Spray freeze drying is an attractive technology to produce powder formulation for inhalation. It can be used to generate large porous particles which tend to aerosolize efficiently and do not aggregate readily. It also avoids material to be exposed to elevated temperature. In this study, we reported the use of two-fluid nozzle to produce spray freeze dried powder of small interfering RNA (siRNA). The effect of atomization gas flow rate and liquid feed rate were inspected initially using herring sperm DNA (hsDNA) as nucleic acid model. The atomization gas flow rate was found to have a major impact on the aerosol properties. The higher the atomization gas flow rate, the smaller the particle size, the higher the fine particle fraction (FPF). In contrast, the liquid feed rate had very minor effect. Subsequently, spray freeze dried siRNA powder was produced at various atomization gas flow rates. The particles produced were highly porous as examined with the scanning electron microscopy, and the structural integrity of the siRNA was demonstrated with gel electrophoresis. The gene-silencing effect of the siRNA was also successfully preserved in vitro. The best performing siRNA formulation was prepared at the highest atomization gas flow rate investigated with a moderate FPF of 30%. However, this was significantly lower than that obtained with the corresponding hsDNA counterparts (FPF ∼57%). A direct comparison between the hsDNA and siRNA formulations revealed that the former exhibited a lower density, hence a smaller aerodynamic diameter despite similar geometric size.

Keywords

Gene silencing; Next generation impactor; Pulmonary delivery; Spray freeze drying; siRNA

Processing of sintered and CVD coated SiC/CNFs thin composite tubes

Mubina Shaik, Asit Kumar Khanra, Bhaskar Prasad Saha

Abstract

Silicon carbide (SiC) and its composite powders dispersed with 1–3 wt% carbon nano-fibres (CNFs) were spray freeze granulated to produce spherical granules with uniform composition. Powders were shaped to thin dense tubes for use in a harsh environment by cold isostatic pressing followed by pressureless sintering at 2150 °C for 1 h in argon and SiC coating by chemical vapour deposition (CVD) technique. The physical, microstructural and thermo – mechanical properties of the composite tubes were evaluated and compared with bare SiC tubes. Good dispersibility of CNFs and sintering additives in the matrix by spray freeze granulation processing technique resulted in more than 98.5% theoretical density of the composite tubes with superior mechanical properties. SEM & EBSD analysis show grains are platy and equiaxed in nature with many CNFs trapped at the triple points hindering the SiC grain growth which is also confirmed by TEM analysis. The thermal conductivity value of the composite was also found higher than bare SiC at all temperatures when measured up to 1000 °C due to uniform distribution of CNFs in the matrix.

Keywords

SiC composites, Spray freeze granulation, Cold isostatic pressing, Sintering, CVD