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Spray-freeze-drying for the Encapsulation of Food Ingredients and Biologicals
Published in S. Padma Ishwarya, Spray-Freeze-Drying of Foods and Bioproducts, 2022
IgG was converted into solid particles using spray-freeze-drying. Different excipients such as mannitol, trehalose and zinc acetate dehydrate were included in the feed formulation to protect the protein against denaturation during ultrasonic atomization by SFV/L method. The particle size was controlled by regulating the frequency of ultrasonic atomizer and the feed flow rate of IgG solution through the ultrasonic nozzle. SFD of IgG solution without any excipients resulted in agglomerated particles with many pores and channels on the surface. Addition of zinc acetate as excipient was found to reduce the particle size to around 10 μm. Further, the formation of complex conjugates between IgG and zinc acetate followed by its precipitation promoted the formation of separated and smaller microparticles of IgG–zinc acetate with reduced specific surface area and prevented particle agglomeration (Costantino et al., 2000; Lam, Duenas & Cleland, 2001). Moreover, instead of becoming more concentrated after ice crystallization and being exposed to ice-water interface, the protein complex separated from the bulk water phase before any damage was caused by the subsequent freeze-drying stage of SFD process (Costantino et al., 2000; Wang, Chua, & Wang, 2004).
Piezoelectrical Materials for Biomedical Applications
Published in Jince Thomas, Sabu Thomas, Nandakumar Kalarikkal, Jiya Jose, Nanoparticles in Polymer Systems for Biomedical Applications, 2019
M. S. Neelakandan, V. K. Yadu Nath, Bilahari Aryat, K. A. Vishnu, Jiya Jose, Nandakumar Kalarikkal, Sabu Thomas
Piezoelectricity is found in utilizable applications, such as the engendering and detection of sound, generation of high voltages, electronic frequency generation, microbalances, to drive an ultrasonic nozzle, and ultrafine focusing of optical assemblies. It is withal the substratum of a number of scientific instrumental techniques with atomic resolution, the scanning probe microscopies, such as STM, AFM, scanning Near-field Optical microscopy SNOM, etc., and everyday uses, such as acting as the ignition source for cigarette lighters, and push-start propane barbecues, as well as the time reference source in quartz watches.
Novel approaches based on ultrasound for spray drying of food and bioactive compounds
Published in Drying Technology, 2021
Rajeshree A. Khaire, Parag R. Gogate
Ultrasonic nozzle produces low velocity and uniform spray, thus the spray trajectory is smaller compared to the conventional nozzle spray. This reduces the wall deposition and facilitates the design of low diameter drying chamber for the spray drying operation. Also, the smaller sized particles produced allow faster evaporation due to increased surface area contributing to the requirement of shorter dryer design. Further, the ultrasonic nozzle can be operated in horizontal and vertically downward or upward direction which increases the possible configurations of drying chambers suitable for the operation.[33] Additionally, the use of ultrasonic nozzle evades the requirement of compressed air and thus, the gradient between atomized droplets and hot air in the chamber is maintained that results in better evaporation. It has also been reported that, the small droplets may bounce off the chamber wall, while the large droplets may stick to the wall and increase the deposition on the wall contributing to losses. Similarly, it has also been observed that smaller particles are less prone to wall deposition due to low inertia and greater impact of air flow on small sized particles compared to larger particles.[34] Thus, ultrasonic nozzles could be an effective solution to the wall deposition problem. However, it was observed by Lebedev et al.[35] that the low velocity spray in the range of 1–4 m/s, produced using ultrasonic atomization is not enough to dry all the particles in the chamber leading to agglomeration in the collection flask. The drying air used was at 80 °C with relative humidity of 0.2% and the moisture content of particle reduced with increased spray velocity. Therefore, large velocities of drying air was needed in the case of ultrasonic nozzle to produce particles with negligible moisture content which would in turn affect the drying chamber design to some extent. A detailed comparison of different nozzles with ultrasonic nozzle is provided in Table 1.[8,12,18,19,36,37]