**2. Microencapsulation**

Microencapsulation (ME) is a technique in which solid, or liquid, gaseous active is coated by a coating material to give small capsules aiming to obtain some physical or chemical properties, which can be applied in a food system. The terminology used to describe "microparticle" refers to a particle with diameter from 1 to 1000 μm, irrespective of the interior or exteriors structure. Generally, nanocapsule refers to a particle range from 10 to 1000 nm [13]. Microspheres refer to spherical microparticles, and subcategory of microcapsules applies to microparticles, which have a core surrounded by materials. "Microcapsule" is defined as a spherical particle size that ranges 50–2 mm including a core material where microspheres are spherically empty particles. However, both microcapsules and microspheres are often used synonymously [13]. In addition, some related terms are used alternatively called "microbeads" and "beads." Moreover, some particles greater than 1000 μm can be termed microgranules or macrocapsules.

Encapsulated material located inside small capsules is known as core materials or internal phase or active ingredient, whereas the outer or protective materials are called as wall material, carrier, shell, or encapsulation matrix (**Figure 1**). The wall protects the core materials from environment such as light, oxygen, moisture, etc. Wall materials can be commonly used as both synthetic polymers and biomaterials (carbohydrates and proteins or combination materials). Therefore, the purposes of encapsulation technique are (1) protection of core material from environmental conditions such as oxygen, temperature, moisture, RH, light; (2) masking of odor, taste, and activity of encapsulated materials; (3) controlled release of active compounds (sustained or delayed release); (4) separation of incompatible components;

**25**

**Figure 2.**

**Figure 1.**

*of Food Technologists).*

*Microencapsulated Vegetable Oil Powder DOI: http://dx.doi.org/10.5772/intechopen.85351*

**Table 1** [16].

ity and targeted release of encapsulated materials [14].

(5) conversion of liquids to free-flowing solids; (6) increasing the oxidation stabil-

microcapsule, and (vi) assembly of microcapsule are shown in **Figure 3** [4].

It has been reported that the size and shape of microcapsules depend on wall materials and the methods used during preparation. The selection of wall materials relies on the properties of core materials, final products, and characteristics such as food-grade product, production cost, low viscosity property at high solid content, emulsifying properties and emulsion stability, ability of holding core materials in their structure without any reactivity during processing or storage, control release of core material, and protecting core materials from environmental conditions [15, 16]. The common wall materials of microencapsulated oil can be classified into three groups including carbohydrate, protein, and lipids and wax as summarized in

An emulsion technique has been widely used for the preparation of encapsulation. Oil-in-water emulsions (O/W) are commonly used in cosmetics, pharmaceutical, and food industries for encapsulation by using different core materials.

*Schematic diagram of microencapsulated material structure (adapted from [4]. Copyright 2015 by © Institute* 

*Schematic diagram of microcapsules model (adapted from [14]. Copyright 2009 by DESIDOC.*

Microcapsule models can be classified into three basic categories as monocored, polycored, and matrix types (**Figure 2**) [14]. Monocored microcapsule contains a single hollow chamber within a capsule; however, the polycore microcapsule includes a number of different size chambers within the shell. On the hand, the matrix type of microparticle refers to active ingredients integrated within the matrix of the shell material [14]. Different types of microcapsules such as (i) simple microcapsule, (ii) matrix, (iii) irregular microcapsule, (iv) multicore microcapsule, (v) multiwall

#### *Microencapsulated Vegetable Oil Powder DOI: http://dx.doi.org/10.5772/intechopen.85351*

*Microencapsulation - Processes, Technologies and Industrial Applications*

application is finally discussed.

**2. Microencapsulation**

of triacylglycerols (TAG) (>90–95%) with minor diacylglycerols, tocopherols/ tocotrienols, and phytosterol ester (<5–10%). Several health benefits of vegetable oils are gastronomic, nutritional, organoleptic, antioxidant, anti-inflammatory, anti-vasoconstrictive, antiarrhythmic, antithrombotic, antimicrobial, antihypertension, antiaging, etc. [4]. The vegetable oils and their components have been growing of interest in food, cosmetics, and pharmaceutical industries as of their natural and safety produce, and the acceptance by the consumer has been found increasingly. Although vegetable oils have gained popularity and interest, they are sensitive to oxidative deterioration and generate several degradation products such as aldehyde, ketones, epoxides, hydroxyl compounds, etc. These changes occurring in vegetable oil affect shelf life, sensory properties, and overall acceptability of products. Microencapsulation technique has been applied as it has the potential to delay lipid oxidation rate of vegetable oils. Several studied have shown that vegetable oil can play an important role in protection against oxidation using microencapsulation technique [5–10]. Microencapsulation (ME) is the technique in which small particle or liquid droplets are coated or are embedded in a homogenous or heterogonous matrix to form small capsules in both dry form and wet form products [11]. However, there are several methods of encapsulated vegetable oil powder include emulsification, spray drying, freeze drying, fluidized bed coating, extrusion, cocrystallization, molecular inclusion, coaxial electrospray system, and coacervation [4, 12]. Therefore, the objective of this chapter is conveying an overview of the microencapsulated vegetable oil powder method and technique. This chapter summarizes the preparation of vegetable oil-in-water emulsion stabilized by proteins and other wall materials, providing information on microencapsulated powder using spray drying, and characterization of microencapsulated powder and

Microencapsulation (ME) is a technique in which solid, or liquid, gaseous active is coated by a coating material to give small capsules aiming to obtain some physical or chemical properties, which can be applied in a food system. The terminology used to describe "microparticle" refers to a particle with diameter from 1 to 1000 μm, irrespective of the interior or exteriors structure. Generally, nanocapsule refers to a particle range from 10 to 1000 nm [13]. Microspheres refer to spherical microparticles, and subcategory of microcapsules applies to microparticles, which have a core surrounded by materials. "Microcapsule" is defined as a spherical particle size that ranges 50–2 mm including a core material where microspheres are spherically empty particles. However, both microcapsules and microspheres are often used synonymously [13]. In addition, some related terms are used alternatively called "microbeads" and "beads." Moreover, some particles greater than

Encapsulated material located inside small capsules is known as core materials or internal phase or active ingredient, whereas the outer or protective materials are called as wall material, carrier, shell, or encapsulation matrix (**Figure 1**). The wall protects the core materials from environment such as light, oxygen, moisture, etc. Wall materials can be commonly used as both synthetic polymers and biomaterials (carbohydrates and proteins or combination materials). Therefore, the purposes of encapsulation technique are (1) protection of core material from environmental conditions such as oxygen, temperature, moisture, RH, light; (2) masking of odor, taste, and activity of encapsulated materials; (3) controlled release of active compounds (sustained or delayed release); (4) separation of incompatible components;

1000 μm can be termed microgranules or macrocapsules.

**24**

(5) conversion of liquids to free-flowing solids; (6) increasing the oxidation stability and targeted release of encapsulated materials [14].

Microcapsule models can be classified into three basic categories as monocored, polycored, and matrix types (**Figure 2**) [14]. Monocored microcapsule contains a single hollow chamber within a capsule; however, the polycore microcapsule includes a number of different size chambers within the shell. On the hand, the matrix type of microparticle refers to active ingredients integrated within the matrix of the shell material [14]. Different types of microcapsules such as (i) simple microcapsule, (ii) matrix, (iii) irregular microcapsule, (iv) multicore microcapsule, (v) multiwall microcapsule, and (vi) assembly of microcapsule are shown in **Figure 3** [4].

It has been reported that the size and shape of microcapsules depend on wall materials and the methods used during preparation. The selection of wall materials relies on the properties of core materials, final products, and characteristics such as food-grade product, production cost, low viscosity property at high solid content, emulsifying properties and emulsion stability, ability of holding core materials in their structure without any reactivity during processing or storage, control release of core material, and protecting core materials from environmental conditions [15, 16]. The common wall materials of microencapsulated oil can be classified into three groups including carbohydrate, protein, and lipids and wax as summarized in **Table 1** [16].

An emulsion technique has been widely used for the preparation of encapsulation. Oil-in-water emulsions (O/W) are commonly used in cosmetics, pharmaceutical, and food industries for encapsulation by using different core materials.

**Figure 1.**

*Schematic diagram of microencapsulated material structure (adapted from [4]. Copyright 2015 by © Institute of Food Technologists).*

**Figure 2.** *Schematic diagram of microcapsules model (adapted from [14]. Copyright 2009 by DESIDOC.*

#### **Figure 3.**

*Different types of microcapsules: (i) simple microcapsule, (ii) matrix, (iii) irregular microcapsule, (iv) multicore microcapsule, (v) multiwall microcapsule, and (vi) assembly of microcapsule (adapted from [4]. Copyright 2015 by © Institute of Food Technologists).*

Traditionally, O/W emulsions are prepared by oil homogenization with an aqueous phase containing one or more emulsifiers. However, the achievement of emulsion forming is limited depending on emulsifier properties such as on ionic strength, pH, and temperature, affecting emulsion stability and encapsulated compound [17, 18]. Guzey and McClements [17] indicated that one strategy to improve protection against environmental stresses is to create covalent protein-polysaccharide complexes and another strategy is to create multiple layers of emulsifiers and/or polyelectrolytes using a layer-by-layer (LBL) electrostatic deposition technique. According to LBL technique, it is based on LBL deposition of polyelectrolytes onto oppositely charged surfaces due to electrostatic attraction. Firstly, a primary emulsion containing an ionic emulsifier has produced a small oil droplet during homogenization. Thereafter, a secondary emulsion containing droplets coated with a two-layer interface is created using opposite charge polyelectrolytes with the primary emulsion. Finally, the secondary emulsion is mixed with another oppositely charge polyelectrolytes to create a tertiary emulsion. The procedure can be repeated to form oil droplet coated by interfaces containing more layer (**Figure 4**). The multilayer emulsions were reported having better stability to environmental stress than O/W emulsion with single-layer interfaces [3, 17, 19].

It has been found that LBL technique provides a multilayer emulsion with satisfying properties. However, the stable multilayer emulsions using an LBL technique depend on biopolymer properties, for example, charge density, molecular weight, conformation, emulsifier layer thickness, and bulk physicochemical condition. In addition, there have been several techniques applied for microencapsulation of vegetable oil powder. Drying process is the method commonly used for microencapsulation of vegetable oil, which changes liquid into powder. Spray drying is the most widely used

**27**

**Figure 4.**

*permission from [17].*

encapsulation technique in the food industry that is a relatively simple, continuous, and low-cost commercial process [4]. The microencapsulation using spray drying involves atomization and drying of solution, emulsion, suspension, slurry, and paste to produce solid material. It contains (1) preparation of emulsion sample, (2) atomization of the emulsion into fine droplets, (3) droplet-hot-air contact, (4) evaporation of droplet water, and (5) recovery of powder (**Figure 5**) [20]. Generally, the spray drying

*Schematic representation of layer-by-layer technique producing multilayer emulsions (reproduced with* 

*Microencapsulated Vegetable Oil Powder DOI: http://dx.doi.org/10.5772/intechopen.85351*

Plant-based carbohydrate:

• Maltodextrin • Starch • Cellulose • Gum arabic • Guar gum • Pectin

• Galactomannans • Cyclodextrin • Mesquite gum etc. Marine-based carbohydrate:

• Carrageenan • Alginate

• Xanthan • Chitosan • Dextran • Gellan

*Source: [16].*

**Table 1.**

Microbial- or animal-based carbohydrate:

*Different wall materials used for microencapsulation.*

**Carbohydrate Proteins Lipids and wax**

• Zein • Gluten

• Casein • Whey protein • Gelatin

Plant-based protein: • Soy protein • Pea protein • Barley protein

• Milk fat • Phospholipid • Beeswax • Carnauba wax

Animal-based protein:

#### *Microencapsulated Vegetable Oil Powder DOI: http://dx.doi.org/10.5772/intechopen.85351*


#### **Table 1.**

*Microencapsulation - Processes, Technologies and Industrial Applications*

Traditionally, O/W emulsions are prepared by oil homogenization with an aqueous phase containing one or more emulsifiers. However, the achievement of emulsion forming is limited depending on emulsifier properties such as on ionic strength, pH, and temperature, affecting emulsion stability and encapsulated compound [17, 18].

It has been found that LBL technique provides a multilayer emulsion with satisfying properties. However, the stable multilayer emulsions using an LBL technique depend on biopolymer properties, for example, charge density, molecular weight, conformation, emulsifier layer thickness, and bulk physicochemical condition. In addition, there have been several techniques applied for microencapsulation of vegetable oil powder. Drying process is the method commonly used for microencapsulation of vegetable oil, which changes liquid into powder. Spray drying is the most widely used

Guzey and McClements [17] indicated that one strategy to improve protection against environmental stresses is to create covalent protein-polysaccharide complexes and another strategy is to create multiple layers of emulsifiers and/or polyelectrolytes using a layer-by-layer (LBL) electrostatic deposition technique. According to LBL technique, it is based on LBL deposition of polyelectrolytes onto oppositely charged surfaces due to electrostatic attraction. Firstly, a primary emulsion containing an ionic emulsifier has produced a small oil droplet during homogenization. Thereafter, a secondary emulsion containing droplets coated with a two-layer interface is created using opposite charge polyelectrolytes with the primary emulsion. Finally, the secondary emulsion is mixed with another oppositely charge polyelectrolytes to create a tertiary emulsion. The procedure can be repeated to form oil droplet coated by interfaces containing more layer (**Figure 4**). The multilayer emulsions were reported having better stability to environmental stress than

*Different types of microcapsules: (i) simple microcapsule, (ii) matrix, (iii) irregular microcapsule, (iv) multicore microcapsule, (v) multiwall microcapsule, and (vi) assembly of microcapsule (adapted from* 

O/W emulsion with single-layer interfaces [3, 17, 19].

*[4]. Copyright 2015 by © Institute of Food Technologists).*

**26**

**Figure 3.**

*Different wall materials used for microencapsulation.*

#### **Figure 4.**

*Schematic representation of layer-by-layer technique producing multilayer emulsions (reproduced with permission from [17].*

encapsulation technique in the food industry that is a relatively simple, continuous, and low-cost commercial process [4]. The microencapsulation using spray drying involves atomization and drying of solution, emulsion, suspension, slurry, and paste to produce solid material. It contains (1) preparation of emulsion sample, (2) atomization of the emulsion into fine droplets, (3) droplet-hot-air contact, (4) evaporation of droplet water, and (5) recovery of powder (**Figure 5**) [20]. Generally, the spray drying

**Figure 5.** *Schematic representation of spray dryer.*

has been used to produce the encapsulation of vegetable oil in the food industry [8, 9, 21–24]. The spray drying process conditions (inlet and outlet temperature, nozzle size, feed rate, etc.) have been found to affect the characteristics and properties of encapsulations. However, the optimum drying condition should obtain minimized fat-free surface powder. It was reported that low inlet and outlet temperatures can reduce the viscosity and the diffusivity of fat. Moreover, large emulsion droplet and nozzle size provide a large powder with low surface area and low fat-free surface [25–28]. The advantages of spray drying compose of simple process, fast and easy to scale up, availability of machinery, low production cost, varied particle sizes, and excellent dispersibility in media. However, some limitations of spray drying were stated such as loss of core material during processing and oxidation of flavoring compounds [29, 30]. In addition, not only spray drying technique was selected to apply for encapsulation process, but different drying techniques are also available for vegetable oil encapsulation such as freeze drying, fluidized bed spray drying, nozzleless electrostatic atomization spray drying, and supercritical carbon dioxide spray drying [25, 26, 31, 32].
