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Physicochemical changes of MTGase cross-linked surimi gels subjected to liquid nitrogen spray freezing

Xiaoying Luo, Jinling Li, Wenli Yan, Ru Liu, Tao Yin, Juan You, Hongying Du, Shanbai Xiong, Yang Hu

Abstract

Physicochemical properties of microbial transglutaminase (MTGase) cross-linked surimi gels subjected to liquid nitrogen (LN) spray freezing with different temperatures and cross-linking degrees were investigated. Gels with lower LN spray temperature (−90 °C) were found taking less time in cooling down themselves to maximum-ice-crystal generating temperature. Microstructure images showed the pores of gels became smaller and the structure gradually became denser, as freezing temperature decreased and cross-linking degree increased. It also revealed T₂₂ relaxation time of gels decreased significantly with surimi gels cross-linking degree increasing, indicating the binding ability of gels to moisture was enhanced accordingly. Meanwhile, the proton density weighted image brightness declined along with the LN spray temperature decreasing, and the image brightness showed a decreasing trend from outside to inside, indicating that water migrated and permeated easier from the inside of the gel network to the outside undergone higher LN temperature and lower cross-linking degree. Besides, the L^⁎ and W values of LN groups decreased along with LN spray temperature and cross-linking degree increasing. Moreover, −90 °C LN group with 46.70% cross-linking degree presented the highest breaking force which ascribed to their synergistic efforts in maintaining a stable and dense structure of gels via controlling ice crystals and cross-linkages’ generation.

Keywords

Surimi gel, Cross-linking degree, Liquid nitrogen spray freezing

Effect of formulation and inhaler parameters on the dispersion of spray freeze dried voriconazole particles

Qiuying Liao, Ivan C.H. Lam, Hinson H.S. Lin, Leon T.L. Wan, Jason C.K. Lo, Waiting Tai, Philip C.L. Kwok, Jenny K.W. Lam

Abstract

Spray freeze drying is a particle engineering technique that allows the production of porous particles of low density with excellent aerosol performance for inhalation. There are a number of operating parameters that can be manipulated in order to optimise the powder properties. In this study, a two-fluid nozzle was used to prepare spray freeze dried formulation of voriconazole, a triazole antifungal agent for the treatment of pulmonary aspergillosis. A full factorial design approach was adopted to explore the effects of drug concentration, atomisation gas flow rate and primary drying temperature. The aerosol performance of the spray freeze dried powder was evaluated using the next generation impactor (NGI) operated with different inhaler devices and flow rates. The results showed that the primary drying temperature played an important role in determining the aerosol properties of the powder. In general, the higher the primary drying temperature, the lower the emitted fraction (EF) and the higher the fine particle fraction (FPF). Formulations that contained the highest voriconazole concentration (80% w/w) and prepared at a high primary drying temperature (−10 °C) exhibited the best aerosol performance under different experimental conditions. The high concentration of the hydrophobic voriconazole reduced surface energy and cohesion, hence better powder dispersibility. The powders produced with higher primary drying temperature had a smaller particle size after dispersion and improved aerosol property, possibly due to the faster sublimation rate in the freeze-drying step that led to the formation of less aggregating or more fragile particles. Moreover, Breezhaler®, which has a low intrinsic resistance, was able to generate the best aerosol performance of the spray freeze dried voriconazole powders in terms of FPF.

Keywords

Aerosol performance, Antifungal agent, Factorial design, Freeze drying, Inhalation, Pulmonary delivery, Spray freeze drying

Evaluation of Process Conditions for Ultrasonic Spray-Freeze Drying of Transglutaminase

Hilal İşleroğlu, Izzet Turker

Abstract

In this study, a commercial transglutaminase enzyme was dried using an ultrasonic spray freeze drying method and the effects of the process conditions were optimized to maximize the final transglutaminase activity. Accordingly, process parameters affecting enzyme activity were selected, such as nozzle frequency (48 and 120 kHz), flow rate (2, 5 and 8 mL/min) and plate temperature for secondary drying (25, 35 and 45 °C). Moreover, the effects of different pH values (pH=2.0 and 9.0) and high temperature (80 °C) on enzyme activity, physical properties and particle morphology of transglutaminase were discussed. According to the results, transglutaminase preserved its activity despite ultrasonic spray freeze drying. Sonication enhanced the enzyme activity. Using the desirability function method, the optimum process conditions were determined to be flow rate 3.10 mL/min, plate temperature 45 °C and nozzle frequency 120 kHz. The predicted activity ratio was 1.17, and experimentally obtained ratio was 1.14±0.02. Furthermore, enzyme produced by ultrasonic spray freeze drying had low moisture values (2.92-4.36 %) at 8 h of drying. When the morphological structure of the transglutaminase particles produced by ultrasonic spray freeze drying under the optimum conditions was examined, spherical particles with pores on their surfaces were observed. In addition, flow properties of the transglutaminase powders were considered as fair under most conditions according to the Carr index.

Developing spray-freeze-dried particles containing a hyaluronic acid-coated liposome–protamine–DNA complex for pulmonary inhalation

Kaori Fukushige, Tatsuaki Tagami, Munekazu Naito, Eiichi Goto, Shuichi Hirai, Naoyuki Hatayama, Hiroki Yokota, Takao Yasui, Yoshinobu Baba, Tetsuya Ozeki

Abstract

The liposome–protamine–DNA complex (LPD) is an effective cationic carrier of various nucleic acid constructs such as plasmid DNA and small interfering RNA (siRNA). Hyaluronic acid coated on LPD (LPDH) reduces cytotoxicity and maintains the silencing effect of LPD-encapsulated siRNA. Herein, we aim to develop LPD- or LPDH-containing spray-freeze-dried particles (SFDPs) for therapeutic delivery of siRNA to the lungs. LPD- or LPDH-containing SFDPs (LPD- or LPDH-SFDPs) were synthesized and their structure and function as gene carriers were evaluated using physical and biological methods. The particle size of LPDH, but not of LPD, was constant after re-dispersal from the SFDPs and the amount of siRNA encapsulated in LPDH was larger than that in LPD after re-dispersal from the SFDPs. The in vitro pulmonary inhalation properties of LPDH-SFDPs and LPD-SFDPs were almost the same. The cytotoxicity of LPDH-SFDPs in human umbilical vein endothelial cells (HUVEC) was greatly decreased compared with that of LPD-SFDPs. In addition, Bcl-2 siRNA in LPDH-SFDPs had a significant gene silencing effect in human lung cancer cells (A549), whereas Bcl-2 siRNA in LPD-SFDPs had little effect. These results indicate that compared with LPD, LPDH is more useful for developing SFDPs for siRNA pulmonary inhalation.

Influences of drying methods on the structural, physicochemical and antioxidant properties of exopolysaccharide from Lactobacillus helveticus MB2-1

Luyao Xiao, Yingying Li, Juanjuan Tian, Jianzhong Zhou, Qian Xu, Li Feng, Xin Rui, Xia Fan, Qiuqin Zhang, Xiaohong Chen, Mingsheng Dong, Wei Li

Abstract

In this study, in order to evaluate influences of different drying methods on the structural characteristics, physicochemical properties and antioxidant activities of exopolysaccharides (EPS) from Lactobacillus helveticus MB2-1, three drying methods, including spray-drying (SD), freeze-drying (FD) and spray freeze-drying (SFD), were applied to dry EPS. Results showed that different drying procedures had no significant influence on the primary structure and constituent monosaccharides of EPSs. However, the surface morphology of the three dried EPSs varied greatly in size and shape due to different drying processes. Among three dried EPSs, the particle size distribution of spray freeze-dried EPS (SF-EPS) was relatively narrower and uniform. Additionally, SF-EPS behaved better apparent viscosity and emulsifying property than spray-dried EPS (S-EPS) and freeze-dried EPS (F-EPS). SF-EPS exhibited stronger antioxidant activities when compared with S-EPS and F-EPS, according to the results of scavenging activities on different radicals and chelating activity on ferrous ion. Overall, SFD was the appropriate method for industrial production of EPS from Lactobacillus helveticus MB2-1 with better physicochemical properties and antioxidant activities.

Spray-freeze-drying of coffee

S. Padma Ishwarya, C. Anandharamakrishnan

Abstract

The suitability of Spray-Freeze-Drying (SFD) technique for soluble coffee processing was evaluated. The resultant product characteristics were compared against its spray-dried (SD) and freeze-dried (FD) counterparts. SFD and FD coffee powders exhibited a comparable aroma profile as indicated by the electronic nose analysis. SFD resulted in higher volatile retention (93%) than FD (77%) and SD (57%), as inferred from GC–MS analysis. SFD coffee showed instantaneous solubility due to its highly porous nature as observed in morphology studies. SFD coffee depicted monomodal particle size distribution with mean diameter (91.1 μm) ranging between SD (50.41 μm) and FD (636.8 μm) particles. SFD resulted in higher free (ρB, 0.612 g/mL) and tapped (ρT, 0.679 g/mL) bulk densities of the product against SD (ρB: 0.328 g/mL; ρT: 0.388 g/mL) and FD (ρB: 0.345 g/mL; ρT: 0.361 g/mL). SFD coffee exhibited free flowing characteristics as indicated by its Hausner ratio (1.11) and Carr index (10%).

Keywords

Soluble coffee, Spray-Freeze-Drying, Volatile retention, Morphology, Bulk density, Tap density

Freeze Granulated Zeolites X and A for Biogas Upgrading

Kritika Narang, Farid Akhtar

Abstract

Biogas is a potential renewable energy resource that can reduce the current energy dependency on fossil fuels. The major limitation of utilizing biogas fully in the various applications is the presence of a significant volume fraction of carbon dioxide in biogas. Here, we used adsorption-driven CO2 separation using the most prominent adsorbents, NaX (faujasite) and CaA (Linde Type A) zeolites. The NaX and CaA zeolites were structured into hierarchically porous granules using a low-cost freeze granulation technique to achieve better mass transfer kinetics. The freeze granulation processing parameters and the rheological properties of suspensions were optimized to obtain homogenous granules of NaX and CaA zeolites 2–3 mm in diameter with macroporosity of 77.9% and 68.6%, respectively. The NaX and CaA granules kept their individual morphologies, crystallinities with a CO2 uptake of 5.8 mmol/g and 4 mmol/g, respectively. The CO2 separation performance and the kinetic behavior were estimated by breakthrough experiments, where the NaX zeolite showed a 16% higher CO2 uptake rate than CaA granules with a high mass transfer coefficient, 1.3 m/s, compared to commercial granules, suggesting that freeze-granulated zeolites could be used to improve adsorption kinetics and reduce cycle time for biogas upgrading in the adsorption swing technology.

Keywords

freeze granulation, zeolite NaX, zeolite CaA, gas separation, carbon dioxide capture

Effect of encapsulation methods on the physicochemical properties and the stability of Lactobacillus plantarum (NCIM 2083) in synbiotic powders and in-vitro digestion conditions

K.S. Yoha, J.A. Moses, C. Anandharamakrishnan

Abstract

Encapsulation of probiotic bacteria requires precise control over a range of process parameters, all of which are technique-specific. The technology of encapsulation has received considerable attention in recent years, owing to the numerous ranges of benefits it offers, particularly in terms of quality retention, storage stability, and targeted delivery. In this research, spray-drying (SD) and spray-freeze-drying (SFD) techniques were used to encapsulate Lactobacillus plantarum (NCIM 2083). Fructo-oligosaccharide (FOS), whey protein (WP) and maltodextrin (MD) were used as encapsulating agents at different formulations. Changes in physicochemical properties were evaluated. FOS:WP:MD (2:0.5:0.5) gave higher encapsulation efficiencies of around 89.21% and 96.16% for SD and SFD, respectively. Probiotic stability was studied under simulated in-vitro digestion conditions and over the storage period of 60 days. SFD synbiotics showed better survivability during digestion; whereas, storage studies indicated around 0.95 fold increased retention of cell viability in SD synbiotics as compared to SFD.

Keywords

Synbiotics, Drying, Encapsulation, Microbial stability, Cell viability

Spray-freezing induced multidimensional morphology tuning of assembled spherical carbon for solar-driven steam generation

Da Li, Ang Li, Yaxin Chen, Guanyu Chen, Xiaohong Chen, Dexu Zhang, Haitao Zhu, Imran Ahmed Samo, Huaihe Song

Abstract

Carbon materials have been extensively researched as solar absorbers in the field of solar steam generation (SSG) for their full spectrum absorption, non-biotoxicity, and excellent photothermal properties. In this work, we provide a general ice-templating method for obtaining multidimensional carbon materials controlled by regulating the surface tension during the phase separation of phenolic resin solution. Through spraying the atomized droplets into liquid nitrogen, freeze drying, and carbonization, a type of spherical carbon material assembled with carbon nanosheets with a thickness of about 3 nm can be obtained. With the enhancement of the surface tension by spray and the adjustment of the concentration of phenolic resin, a series of morphologies of carbon materials can be obtained from nanowires to nanosheets and further to spherical assemblies. In addition, an efficient SSG system was designed by combining the carbon material with polyurethane foam as matrix, notably showing good evaporation efficiency of 81.7% with a solar flux of 500 W/m2. This work provides a new idea for the morphology control of assembled carbon materials and has achieved excellent performance in the field of photothermal conversion.

Hydroxypropyl beta cyclodextrin: a water-replacement agent or a surfactant upon spray freeze-drying of IgG with enhanced stability and aerosolization

Shahriar Milani, Homa Faghihi, Abdolhosein Roulholamini Najafabadi, Mohsen Amini, Hamed Montazeri, Alireza Vatanara

Abstract

The great potential of hydroxypropyl beta-cyclodextrin (HPßCD), as a dried-protein stabilizer, has been attributed to various mechanisms namely water-replacement, vitrification and surfactant-like effects. Highlighting the best result in our previous study (weight ratio IgG: HPßCD of 1:0.4), herein we designed to evaluate the efficacy of upper (1:2) and lower (1:0.05) ratios of HPßCD in stabilization and aerosol properties of spray freeze-dried IgG. The protective effect of HPβCD, as measured by size exclusion chromatography (SEC-HPLC) was most pronounced at C3′ and C3″, IgG:trehalose:HPβCD ratios of 1:2:0.25 and 1:2:0.05 with aggregation rate constants of 0.46 ± 0.02 and 0.58 ± 0.01 (1/month), respectively. The secondary conformations were analyzed through Fourier transform infrared spectroscopy (FTIR) and all powders well-preserved with the lack of any visible fragments qualified through sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PPAGE). Scanning electron microscopy (SEM) and twin stage impinger (TSI) were employed to characterize the suitability of particles for further inhalation therapy of antibodies and the highest values of fine particle fraction (FPF) were achieved by C3′ and C3″, 56.43 and 48.12%. The powders produced at the current ratio 1:2:0.25 and 1:2:0.05 are superior to our previous examination with regards to manifesting lower aggregation and comparable FPF values.