Authorea

Karina edited sectionMicroencapsul.tex about 9 years ago

Commit id: 51384b5b503ff539fdb7ff709f536435335fcdae

deletions | additions

Microencapsulation has been widely used to protect materials encapsulated the adverse conditions of processing and storage food. It is technology consists in packaging of active substances using thin polymer coating that act as a protective film applied the liquid, solid or gaseous material (Anal & Singh, 2007; Shoji et al., 2013). In the food science this technology has been seen as a promising method to overcome limitations related to instability of several incorporated substances in food, such as micronutrients (Nesterenko, Alric, Silvestre, & Durrieu, 2014; H. Wang, Shi, Cheung, & Xin, 2011), enzymes (Anjani, Kailasapathy, & Phillips, 2007), flavor (J. Wang, Cao, Sun, & Wang, 2011), probiotics (Gebara et al., 2013; Maciel, Chaves, Grosso, & Gigante, 2014), antioxidants and antimicrobial agents (Betz & Kulozik, 2011; Betz et al., 2012) reducing their interaction with the product, in addition, increasing its bioavailability after ingestion. The choice wall material and encapsulation technique is important factors for ensure protective effect encapsulated substance during processing, storage and ingestion of food. The wall material should be capable of forming a cohesive layer with the encapsulating agent (food ingredient), as well as being compatible, but immiscible with encapsulated agent, and provide resistance, impermeability, flexibility and stability. For its application in the food industry, the carrier material must be food grade, such as alginate, chitosan, carboxymethyl cellulose, carrageenan, gelatin and pectin, and they must be able to maintain the bioavailability of the compounds. (Anal & Singh, 2007; Joye, Davidov-pardo, & Julian, 2014). Differents techniques can be applied, such as spray drying, spray cooling, spray chilling, extrusion, freezing drying, cocristalization, simple and complex coacervation, liposomes and others (Gouin, 2004; Iris Julie Joye & McClements, 2014). However, the choice is depending of the encapsulated substance, characteristics desired in the final product and release mechanism. Once, the incorporation of particle in product can not be negatively affected sensory properties (Betz et al., 2012; Iris J Joye et al., 2014). This topic will be discussed the preparation, characterization and application of the microparticles in the food industry. \subsection{3.1 Microparticule preparation} Currently, there are lot of techniques for the production of microparticles. This The encapsulation techniques are divide in physical, (spray drying, spray chilling, spray cooling, fluid bed coating, extrusion, freeze drying and cocristalization), chemical (interfacial polymerisation) and physical chemical physicochemical (simple and complex coacervation, organic phase separation, ionotropic gelation and liposomes) methods. Before selection one them, industry should have taken into account, the following points: processing and storage conditions, density type of microcapsule desired (size and size particle, shape), properties of the carrier material, triggers and mechanisms of release and release, cost and scale of production (Shahidi and Han, 1993; Nedovic et al., 2011; Martín et al., 2015). Spray drying, spray cooling, spray chilling, extrusion, emulsion, freezing drying,cocristalization, simple and complex coacervation, liposomes are the principal same techniques described for encapsulation of food ingredients. Spray Drying drying is one of the oldest of the encapsulation technique and commonly applied in the food industry that has great potential for being economical, flexible, using equipment that is readily available and produces morphologically homogeneous microparticles. In this technique, the drying involves the use of a solution in a hot air stream to evaporate the solvent, which in the case of applications in food is water, followed by separation of the dried particles (Gharsallaoui et al., 2007; Shewan and Stokes, 2013, Martín et al., 2015). The parameter selection such as types atomizers (single-fluid, high-pressure spray nozzle or spinning disc), concentration and viscosity of the feed and feed flow rate rate, can be used for control the particles size, which size ranging between 5 a 80 μm (Shahidi and Han, 1993; Gharsallaoui et al., 2007; Nazzaro et al., 2012; Shewan and Stokes, 2013). Spray driyng It is most widely used for encapsulation flavors, lipids, carotenoids and heat sensitive compounds due to the very short exposure of the particle to hot air (Gharsallaoui et al., 2007; Jones and McClements, 2010).The limitation this technique is the use of the biopolymers high viscosity or non-water soluble and short-term protection linked to particle during rehydration (Champagne and Fustier, 2007; Shewan and Stokes, 2013). Other encapsulation technique similar spray drying are spray cooling and spray chilling that involving also the dispersion of encapsulating material in a liquid and sprayed coating material from a nozzle in a controlled environment, with produce of small droplets. The difference between these techniques and spray drying is the temperature drying of the coating wall material using cold air, which enables the solidification of the particle (Poshadri and Kuna, 2010; Shewan and Stokes, 2013; Martín et al., 2015). Lipids are commonlyused commonly used as carrier material in these techniques for encapsulating hydrophilic ingredients, as well as water-soluble vitamins, enzymes, acidifiers, vitamins (referencia), enzymes (referencia), acidifiers (referencia), and some flavors. flavors (referencia). Extrusion technique is the most popular method for encapsulation probiotic bacteria, because particle production is simple, use relatively low temperature and does not need organic solvents. It involves preparation a hydrocolloid solution, adding food ingredient or probiotic, then the solution is dripped through a syringe needle or nozzle, which influences the nozzle into a solution that promotes gelation. The size of particles is influenced by the diameter of the needle or nozzle, the flow rate and viscosity of the solution, and the properties of the gelling environment (Nazarro et al., 2012; Martíns et al., 2015). Another commonly used technique is the emulsion. It is the food ingredient (discontinuous phase) is added in an oil (continuous phase), then, the mixture is homogenized to form two combination of emulsion: water/oil or oil/water and water/oil/water. Once the emulsion formed, this, then broken by adding CaCl2 to form the particles within the oil phase (Heindebach et al., 2012; Nazzaro et al., 2012). The particles are collected by centrifugation or filtration. The size of particles can be vary between 25 μm and 2 mm, due the speed agitation which controlled the size of the beads (Martíns et al., 2015). Freeze drying method is the dehydration simple process based upon sublimation. It sublimation, where the whole dehydration process is completed under low temperature and low pressure. This technique has been used for encapsulation heat sensitive compounds, as well as nature aromas, water-soluble essences and probiotics, probiotics. The major disadvantages of method are the long processing time and poor protection due whole dehydration process high-porous wall. Coacervation is completed under low a physicochemical method also called phase separation. This technique involves the fluid-fluid phase separation of an aqueous polymeric solution, where a changes in characteristics of the medium (temperature, ionic strength, pH and polarity), resulting in a precipitation of wall material and a continuous coating of wall polymer around the core droplets. There are two types of coacervation, simple and complex. Simple coacervation involve only one polymer and separation phase occurs by salt addition or pH and temperature changes. Complex coacervation involve two polymers and phase separation occurring due interation anion-cation. This encapsulation process is very efficient, relatively simple and low pressure. cost process. \subsection{3.2 Microparticle characterization} \subsection{3.3 Application}