Microencapsulation – A review

Thomas ZafiriadisFood Technologist MSc. – DVM,

Professor in Culinary Technicians’ and Chef’s Department Katerini Public Institution for Professional Training (IEK)

Director of ESTIA LAB

Abstract: The quest for new methods providing safer and healthier food products, which retain all the essential dietary components, such as vitamins, and their organoleptic properties, has led to the development of microencapsulation, i.e. the method of encapsulating active and sensitive to processing

compounds in food products in the form of micro - or nanoparticles. In order to achieve this, microencapsulation uses several techniques, such as spray drying and cooling, extrusion, fluidizing bed, coacervation, alginate beads formation, liposome formation, RESS/SAS and inclusion encapsulation. The

selection of appropriate method depends on the characteristics of the active ingredients, the wall material and the cost of application. In the near future, food industry will depend on microencapsulation and biotechnology for its development.

Key words: microencapsulation, spray drying, spray cooling, extrusion, co-acervation, fluidized bed, liposomes, ellagitannins, nanoparticles, biopolymers.

1. INTRODUCTION:

Since the appearance of human kind on earth, there is a constant effort for inventing new methods not only for better food preservation, but also forthe transfer of valuable nutrients and drugs with the food. Nowadays, the food industry is increasingly focusing on the incorporation of components thatprovide a health benefit to the customer in food products. Such valuable substances, which can be extremely vulnerable to low pH values, like the onesin stomach, are enzymes, flavors and oils. The most common and noninvasive mode of administration of these substances is via the oral route. Theintestinal delivery of such vulnerable substances deserves special attention, since the slightest change in conformation of the molecule can bedetrimental to its properties. However, the intestinal delivery is severely hampered due to the highly acidic environment in the stomach. One of themost significant methods that can be used in dealing with this problem is microencapsulation (Jafari et al, 2008, Lambert et al, 2008).

4. DISCUSSION:

Some of the technical difficulties encountered by industries - and solved by microencapsulation application - are:The loss of product functionality during processing, storage and/or commercialization.The lack of compatibility between functional substance and food matrix, something common in the case of fat soluble vitamins in aqueous foods.The development of undesirable flavors or strange odors due to added bioactive compound degradation. Marine oils, for instance, prone to undergooxidization.The control of the modification of food product texture as a consequence of the added compound, in order to achieve the manufacture of anacceptable product from a commercial point of view.The need for adapting the production line for the incorporation of a new substance which often implies the complete change of parameters involvedin the process.In the case of enzymes, the short operational life or the inactivation undergoing of the dissolved ones due to their sensitivity to processing or tracelevels of substances that can actuate as inhibitors (Lopez - Rubio et al, 2006).

Furthermore, certain components of food that are usually removed, discarded or destroyed during bleaching, refining and processing are essential for health promotionand disease prevention. Such components are phytochemicals, vitamins, dietary fiber, prebiotics and probiotics. Phytochemicals are non - nutritive plant chemicals thatcontain protective, disease - preventing compounds. More than 900 different compounds have been identified as components of food. They have been associated with theprevention and/or treatment of cancer, diabetes, cardiovascular disease and hypertension. As it is known vitamins are essential for a good health. However, the modernway of life has led to changes in food preparation and consumption habits resulting in unbalanced diets. In co - ordination with the fact that some vitamins destroy duringprocessing, created the need for food fortification with vitamins. Dietary fiber consists of structural and storage polysaccharides and lignin in plants that are not digested inthe human stomach and small intestine. These fibers have demonstrated benefits for health maintenance and disease prevention, as well as a component of medicalnutrition therapy. Finally, prebiotics are considered to be any food component that escapes digestion in small intestine and enters the colon, where it may serve as agrowth substrate for intestinal bacteria. This class includes non -digestible carbohydrates such as lactulose, inulin and a range of oligosaccharides that supply a source offermentable carbohydrate for the beneficial bacteria in the colon. Other biopolymers, such as chitosan and chitosan derivatives can also have a prebiotic character and canbe used as micro - or nanofibers or as encapsulating means of other components (Lopez - Rubio et al, 2006).

2. DEFINITIONS:

a process in which the cells are retained within anencapsulating matrix or membrane, i.e. the activeingredients (core materials) are packaged in a secondary(wall) material (Jafari et al, 2008; Hambleton et al, 2008;Hsieh et. al., 2009).

microsize particles that consist of capsule material anencapsulated component and can be prepared by methodssuch as freeze and spray drying, with the latter being themost commonly encapsulation technique used for foodproducts (Jafari et al, 2008, Laine et al, 2008).

3. METHODS AND MATERIALS:

Methods

Spray drying

Spray cooling/chilling

Fluidized bed

Spinningdiscco-

extrusion

Co-acervation

RESS/SAS

Inclusionen-

capsulation

MethodsEncapsulated

MaterialsEncapsulation Material Attributes Equipment

Spray drying encapsulation Flavor oils Liposomes

Protection against degradation/

oxidationSpray dryer

Spray cooling/chilling

Salts, textural ingredients, enzymes,

flavorsLiposomes and monoglycerides Stability improvement

and delay release Spray cooler

Fluidized bed

Polysaccharides, proteins, emulsifiers, fats, complex

formulations, ascorbicacid, acidulants

Alginates Protection and longer shelf life

Spinning disc co-extrusion

Polysaccharides, proteins, emulsifiers, fats Alginates Protection and longer

shelf lifeModified double fluid nozzle on

spray towers

Co-acervationFlavor oils, fish oilsnutrients, vitamins,

preservatives, enzymes

Gelatin/gum acacia system. gliadin, heparin/gelatin, carrageenan,

chitosan, soy protein, polyvinyl alcohol, gelatin/carboxymethyl-

cellulose, starch, – lactoglobulin/gum acacia, and guar/dextran

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