|dc.description.abstract||Essential oils and extracts of various species of edible and medicinal plants, herbs, and spices constitute very potent biological active agents. They have a complex composition, containing from a few to several hundred constituents, mainly hydrocarbons and oxygenated compounds. Both, hydrocarbons and oxygenated compounds are responsible for odors and flavors, generated by aromatic plants as secondary metabolites (Ebrahimi et al., 2008).
Clove oil (CO) is an essential oil contained in the dried flower buds, leaves and stem of the tree Syzygiu aromaticum (Eastern Hemisphere) or Eugenia caryophyllata and Eugenia aromaticum (Western hemisphere) (Schmid, 1972). It has been used for centuries as an anesthetic for toothaches, headaches and joint pain (Shelef, 1983; Soto et al., 1995). Clove has received attention as an ideal fish anesthetic (Ackerman et al., 2002; Wagner et al., 2003; Hoskonen and Pirhonen, 2004; Roubach et al, 2005) and it has been used as a fragrant and flavoring agent in a variety of food and cosmetic products (Atsumi et al., 2001; Fujisawa et al., 2002., Ito et al., 2005).
Eugenol (EG) (4-allyl-2-methoxyphenol) is the principal constituent of the essential CO, accounting for 90-95% of the total oil amount (Briozzo et al., 1989; Gulcin et al., 2010). It has a strong phenolic smell and sharp acrid taste (Mouchreck, 2000; Ozturz et al., 2005). This phenolic compound has shown several biological activities such as anti-inflammatory activity, analgesic activity, anti-oxidative activity and anti-bacterial activity.
In the food industry, clove is often used in the form of ground, extracted essential oil or oleoresin, but always in a small amount due to its intense flavour. However, the use of CO could be a problem in industrial applications due to its high volatility and low stability. Hence, irritation the mucosa and skin, pungent taste, volatility, light sensitivity and poor water solubility make it unsuitable to use as such.
Considering the effectiveness and convenience of the application of essential CO and its main compound EG, the introduction of these compounds into food and cosmetic products has many challenges. These food ingredients are susceptible of degradation due to environmental stress conditions such as temperature, humidity, light, oxygen, interaction with other food ingredients and volatility of the aromatic compounds.
Encapsulation is the technique by which one material or a mixture of materials is coated with or entrapped within another material or system. The coated material is called active or core material, and the coating material is called shell, wall material, carrier or encapsulant. The development of microencapsulation products started in the 1950s with the research on pressure-sensitive coatings for the manufacture of carbonless copying paper (Green and Scheicher, 1955). Encapsulation technology is now well developed and accepted within the pharmaceutical, chemical, cosmetic, foods and printing industries (Augustin et al., 2001; Heinzen, 2002). In food products, fats and oils, aromatic compounds and oleoresins, vitamins, minerals, colorants and enzymes have been encapsulated (Dziezak, 1988; Jackson and Lee, 1991; Shahidi and Han, 1993).
The simplest form of microcapsules may consist of a core surrounded by a wall of uniform or non-uniform thickness. The core material may be composed of just one or several distinct types of ingredients whereas the carrier could be single or multilayered. The microcapsules are generally additives to a larger system and must be adapted to that system. Consequently, there are a number of performance requirements placed on microcapsules. A limited number of encapsulating methods exist (Versic, 1988) (Figure VI.1.1), but an enormous range of di¿erent materials can be used including proteins, carbohydrates (CDs, MDs, gums) and lipids (Brazel, 1999). The choice of wall materials depends upon a number of factors including: expected product objectives and requirements; nature of the core material; process of encapsulation; economics and whether the coating material is approved by the Food and Drug Administration (US) or European Food Safety Authority (Europe) (Amrita et al., 1991)
Being aware of the problems associated with the use of essential CO and its main compound EG, the aim of this study was using encapsulation as a tool in order to protect these sensitive bioactive compounds from degradation, eliminating unwanted effects and improving the effectiveness of their use in the industry.||es