**1. CDs in food science and food technology**

There is much interest in manipulating the complex-forming ability of cyclodextrins (CDs) with a view to developing applications [1–10]. In the last years, several reviews describing the use of CDs in food and flavor applications have been published [5, 6, 11–16]). CDs have been recommended for applications in food processing and as food additives with a variety of aims: (i) to protect lipophilic food components that are sensitive to oxygen and light- or heatinduced degradation; (ii) to solubilize food colorings and vitamins; (iii) to stabilize fragrances, flavors, vitamins, and essential oils against unwanted changes; (iv) to suppress unpleasant odors or tastes and (v) to achieve a controlled release of certain food constituents.

Indeed, CDs form inclusion complexes with a variety of molecules including fats, flavors and colors. For instance, they are used for the removal and masking of undesirable components and

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

controlled release of desired food constituents [17]. Moreover, CDs are used in food formulations for flavor protection or flavor delivery [18]. Most natural and artificial flavors are volatile oils or liquids, and complexation with CDs provides a promising alternative to the conventional encapsulation technologies for flavor protection. CDs act as molecular encapsulants, protecting the flavor throughout many rigorous food-processing methods such as freezing, thawing and microwaving. β-CD as a molecular encapsulant allows the flavor quality and quantity to be preserved to a greater extent and longer period compared to other encapsulants and provides longevity to the food item [19]. In Japan, CDs have been approved as "modified starch" for food applications for more than two decades, serving to mask odors in fresh food and to stabilize fish oils. One or two European countries—for example, Hungary—have approved γ-CD for use in certain applications because of its low toxicity. It was proved that CDs may alter the sensory profile of a food and the flavor release depends of the CD type [20], the temperature [21] and may depend the solvent nature that is, water, water/alcohol mixtures, etc. [22]. Their beneficial effects essentially derive from the ability to form stable inclusion complexes with sensitive lipophilic nutrients and constituents of flavor and taste, making easy to prepare powdered flavor materials [23–25] and even to release such flavors during cooking [26]. Toxicological data are examined and an assessment of CDs from the standpoint of safety for human consumption is made [27]. Regulations are covered, showing a general trend toward a wider acceptance of CDs as food additives. The growing health consciousness of consumers and expanding market for functional foods and nutraceutical products are opening up to CDs a promising future in food industry [11].

[36, 37], but also olfactometry can be used for detection to have extra information about flavors [38]. The ability to separate and quantitate enantiomers at low levels should be useful for detecting adulterated products, for evaluating fermentation processes and for the accurate characterization of enantiomeric flavor components, growth regulators, pesticides, and herbicides as well as their chiral environmental degradation products and metabolites [39].

Encapsulation of Essential Oils by Cyclodextrins: Characterization and Evaluation

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Flavonoids and terpenoids are good for human health because of their antioxidative and antimicrobial properties but they cannot be utilized as foodstuff owing to their very low aqueous solubility and bitter taste. Sumiyoshi [40] discussed the improvement of the properties of these plant components (flavonoids and terpenoids) with CD complexation. CDs are used in preparation of foodstuffs in different ways. For example, highly branched CDs are used in flour-based items like noodles, pie dough, pizza sheets and rice cakes to impart elasticity and flexibility to dough [41]. They are also used in the preparation of antimicrobial food preservatives containing trans-2-hexanalin in apple juice preparation [42] and in the processing of medicinal mushrooms for the preparation of crude drugs and health foods. CDs are used in the preparation of controlled release powdered flavors and confectionery items and are also used in chewing gum to retain its flavor for longer duration, a property highly valued by cus-

tomers [43]. CDs are also used in the detection of aflatoxin in food samples [44].

**2. Essential oils**

properties both antioxidants and antibiotics (**Figure 1**).

A large variety of commercial encapsulation practices are currently followed, however, those involving the formation of flavor/CD molecular-inclusion complexes offer great potential for protection of volatile and labile flavoring materials present in a multicomponent food system throughout many rigorous food-processing methods (cooking, pasteurization, etc.) [14, 45–47]. In the same way, CDs can eliminate some taste. In fact, a bitter taste is the main reason for the rejection of various food products although exceptions to this rule are rooted in many cultures: in some foods and beverages, such as coffee, beer, and wine, a certain degree of bitterness is expected [2, 48–51]. Bitterness, however, has proved a major limitation in the acceptance of commercial citrus juices. A commercial process is needed that removes bitter components without adding anything to the juice, while still maintaining the expected flavor and nutritional value of the product. CDs can be used for the removal or masking of undesirable components. Some foods have a peculiar smell, but, when CDs are added in their manufacture, these components form CD-inclusion complexes deodorizing the result product. For instance, this process is used for deodorizing soybean milk and soy protein, and also for removing the peculiar fish odors, seafood and meat products [52–54]. On the other hand, the formation of inclusion complexes with CDs can protect some lipophilic food components that are sensitive to oxygen and heat- or light-induced degradation [55]. In addition, CDs protected phenolic compounds from enzymatic oxidation by forming inclusion complexes [56–59].

Both *in vitro* and *in vivo* studies have demonstrated the important applications of essential oils, such an antioxidant or antibacterial activity, even antitumor or anti-inflammatory, with important technological applications in food science and pharmacology [60–64]. Indeed the presence of eugenol, carvacrol or thymol as main component of these oils guarantee their

The complexation of CDs with sweetening agents such as aspartame stabilizes and improves the taste. It also eliminates the bitter aftertaste of other sweeteners such as stevioside, glycyrrhizin and rubusoside. CD itself is a promising new sweetener. Enhancement of flavor by CDs has been also claimed for alcoholic beverages such as whisky and beer [28]. The bitterness of citrus fruit juices is a major problem in the industry caused by the presence of limonoids (mainly limonin) and flavonoids (mainly naringin). Cross-linked CD polymers are useful to remove these bitter components by inclusion complexation [29]. CDs are also used to control bitterness in tannins, plant and fungal extracts; skim milk hydrolyses and overcooked tea and coffee [30]. They can also be used to keep the profile of oil volatiles in paste samples that were vacuum- or spray-dried [31, 32], due to their high encapsulation efficiency. The most prevalent use of CD in process aids is the removal of cholesterol from animal products such as eggs or dairy products, like cheese [33]. CD-treated material shows 80% removal of cholesterol. Free fatty acids can also be removed from fats using CDs, thus improving the frying property of fat (e.g., reduced smoke formation, less foaming, less browning and deposition of oil residues on surfaces) [30]. Fruits and vegetable juices are also treated with CD to remove phenolic compounds, which cause enzymatic browning. In juices, polyphenol oxidase converts the colorless polyphenols to colored compounds and addition of CDs removes polyphenoloxidase from juices by complexation. Sojo et al. [34] studied the effect of CDs on the oxidation of *o*-diphenol by banana polyphenoloxidase and found that CDs act as activator as well as inhibitor. By combining 1–4% CD with chopped ginger root, Sung [35] established that it could be stored in vacuum at cold temperature for 4 weeks or longer without browning or rotting.

Other studies describes the development of a gas chromatography-mass spectrometry (GC-MS) library to identify optically active compounds in the flavor and fragrance field using enantioselective GC with CD derivatives (CDs) as chiral selectors in combination with MS [36, 37], but also olfactometry can be used for detection to have extra information about flavors [38]. The ability to separate and quantitate enantiomers at low levels should be useful for detecting adulterated products, for evaluating fermentation processes and for the accurate characterization of enantiomeric flavor components, growth regulators, pesticides, and herbicides as well as their chiral environmental degradation products and metabolites [39].

Flavonoids and terpenoids are good for human health because of their antioxidative and antimicrobial properties but they cannot be utilized as foodstuff owing to their very low aqueous solubility and bitter taste. Sumiyoshi [40] discussed the improvement of the properties of these plant components (flavonoids and terpenoids) with CD complexation. CDs are used in preparation of foodstuffs in different ways. For example, highly branched CDs are used in flour-based items like noodles, pie dough, pizza sheets and rice cakes to impart elasticity and flexibility to dough [41]. They are also used in the preparation of antimicrobial food preservatives containing trans-2-hexanalin in apple juice preparation [42] and in the processing of medicinal mushrooms for the preparation of crude drugs and health foods. CDs are used in the preparation of controlled release powdered flavors and confectionery items and are also used in chewing gum to retain its flavor for longer duration, a property highly valued by customers [43]. CDs are also used in the detection of aflatoxin in food samples [44].

A large variety of commercial encapsulation practices are currently followed, however, those involving the formation of flavor/CD molecular-inclusion complexes offer great potential for protection of volatile and labile flavoring materials present in a multicomponent food system throughout many rigorous food-processing methods (cooking, pasteurization, etc.) [14, 45–47]. In the same way, CDs can eliminate some taste. In fact, a bitter taste is the main reason for the rejection of various food products although exceptions to this rule are rooted in many cultures: in some foods and beverages, such as coffee, beer, and wine, a certain degree of bitterness is expected [2, 48–51]. Bitterness, however, has proved a major limitation in the acceptance of commercial citrus juices. A commercial process is needed that removes bitter components without adding anything to the juice, while still maintaining the expected flavor and nutritional value of the product. CDs can be used for the removal or masking of undesirable components. Some foods have a peculiar smell, but, when CDs are added in their manufacture, these components form CD-inclusion complexes deodorizing the result product. For instance, this process is used for deodorizing soybean milk and soy protein, and also for removing the peculiar fish odors, seafood and meat products [52–54]. On the other hand, the formation of inclusion complexes with CDs can protect some lipophilic food components that are sensitive to oxygen and heat- or light-induced degradation [55]. In addition, CDs protected phenolic compounds from enzymatic oxidation by forming inclusion complexes [56–59].
