ter, organic solvents, or mixtures thereof, is quickly removed by the ... particles, the better is the solubility of the encapsulated nutraceuticals. ...... Ciprofloxacin.
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Nanocapsules formation by nano spray drying Cordin Arpagaus*, Philipp John**, Andreas Collenberg**, David Rütti** *NTB University of Applied Sciences of Technology Buchs, Institute for Energy Systems, Buchs, Switzerland; **BÜCHI Labortechnik AG, Flawil, Switzerland
10.1
Introduction
Spray drying is defined as the transformation of a fluid from a liquid state into a dried particulate form by spraying the fluid into a hot drying medium (Masters, 1991). It is a suitable one-step process for the conversion of various liquid formulations (e.g., aqueous and organic solutions, emulsions, and suspensions) into dry powders. Spray drying is a simple, fast, and scalable drying technology (Arpagaus and Schwartzbach, 2008) that is well-established in the chemical, food, and pharmaceutical industries (Wang et al., 2005). Spray drying equipment is commercially available and the production cost is lower compared to that of other drying technologies, such as freeze drying (Gharsallaoui et al., 2007). The powders produced are high in quality and have low moisture content, resulting in high shelf stability (Anandharamakrishnan and Padma Ishwarya, 2015). The cooling effect of the evaporating solvent conserves the droplet temperature relatively low; therefore heat-sensitive products can be dried with negligible degradation (Masters, 1991). Spray drying offers high flexibility to control particle size and morphology by optimizing the process parameters and feed formulation (Nandiyanto and Okuyama, 2011). The dried powder form has higher stability, better protection from the environment (e.g., oxidation, light, and temperature), easier handling and storage, and redispersibility in aqueous solutions (Murugesan and Orsat, 2012; Okuyama et al., 2006). Spray drying is able to result in several types of particle shapes, such as smooth and spherical, collapsed, dimpled, wrinkled, raisin-like, and highly crumpled or folded particles (Nandiyanto and Okuyama, 2011). Fig. 10.1 shows a traditional laboratory-scale spray dryer. The spray drying process consists of three fundamental steps, s atomization of the liquid feed, s drying of the sprayed droplets in the drying gas and formation of dry particles, and s separation and collection of the dry product from the drying gas.
The nozzle atomizes the feed into droplets. The reduction in particle size leads to a large increase in the surface area. In the drying chamber, the solvent, which can be water, organic solvents, or mixtures thereof, is quickly removed by the continuous flow of the hot drying gas (usually air or inert gas). The dried solid particles are separated from the gas stream by a cyclone and collected in a collection vessel. Nanoencapsulation Technologies for the Food and Nutraceutical Industries Copyright © 2017 Elsevier Inc. All rights reserved.
Nanocapsules formation by nano spray drying
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Spray drying is the most frequently used encapsulation technique for food products (Jafari et al., 2008b; Mahdavi et al., 2014). It is applied for food materials, such as flavors (Esfanjani et al., 2015; Gharsallaoui et al., 2007; Rajabi et al., 2015), vitamins, minerals, salts, colorants (Assadpour and Jafari, 2017; Assadpour et al., 2017; Mahdavee Khazaei et al., 2014), oils, lipids, spices (Jafari et al., 2007a), polyphenols, proteins, carotenoids, antioxidants, probiotic living cells (Celli et al., 2015), probiotic bacteria, enzymes (Bürki et al., 2011; Dahili and Feczkó, 2015), peptides, and many more. Encapsulation is accomplished by dissolving, emulsifying, or dispersing the core substance in a solution of the carrier material and then spraying the mixture into the hot drying chamber. The encapsulated material may be present in either liquid or solid form. Encapsulation protects the bioactive compound from the surrounding environment, increases the product storage stability (Anandharamakrishnan, 2014; Celli et al., 2015) and preserves their health-promoting properties (Quintanilla-Carvajal et al., 2010). Moreover, encapsulation is applied to regulate the release of the bioactive compound, to target to specific sites, to mask the taste of an ingredient, and to improve bioavailability (Whelehan, 2014). Choosing the right material for the encapsulating wall is very important to reach high encapsulation efficiency and capsule stability (Estevinho et al., 2013). Wall materials can be selected from a wide variety of natural (Mahdavi et al., 2014) and synthetic polymers (Gharsallaoui et al., 2007). Natural food-grade compounds are are frequently used to minimize the potential toxic effects associated with ingestion. Some examples of common natural polymers are, s gums (e.g., arabic gum, guar gum, and carrageenans), s carbohydrates (e.g., lactose, maltodextrins, cyclodextrins, dextrose, sodium alginate, cel-
lulose derivatives, chitosan, and starches), and s proteins (e.g., whey, egg, soy, casein, gelatine, collagen, and albumin).
The addition of surfactants is often required to stabilize the polymer particles. Further details about the selection of appropriate wall materials can be found in several other works (Ezhilarasi et al., 2013; Fathi et al., 2014; Ngan et al., 2014; Rajabi et al., 2015; Sabliov and Astete, 2015). Furthermore, excellent studies on the microencapsulation of food ingredients by spray drying exist in the scientific literature (Gharsallaoui et al., 2007; Mahdavi et al., 2014). The sizes of the particles formed through encapsulation are classified into macro (>5 mm), micro (1 μm to 5 mm), and nano (
