Physical and chemical properties of α-CD, β-CD, and γ-CD.
Many scientific studies have made advances in the ability to encapsulate natural extracts by cyclodextrins. These studies have addressed the physical and chemical conditions of the encapsulation reactions, employed several types of essential oils and characterized the microcapsules as to their ability to release encapsulated active principles. The essential oils studies with cyclodextrin encapsulation processes have been highly varied. However, the most studied are the essential oils with antimicrobial and antioxidant capacities. The essential antimicrobial and antioxidant oils are easily degraded. In the presence of oxygen, they are oxidized, and at low temperatures, they are volatilized and decomposed. Thus, cyclodextrins are coatings capable of protecting these essential oils from environmental conditions and agents capable of promoting oil degradation, in addition to controlling their release. In this chapter of the book, we review scientific papers that examine the encapsulation of antimicrobial essential oils and antioxidant essential oils with β-cyclodextrins.
- essential oil
- microencapsulation techniques
- inclusion complex
Essential oils are complex and multicomponent mixtures produced from plant secondary metabolites and it can be extracted from different parts of the plants. Its composition depends on factors such as harvest season, part of the plant where the oil was extracted, geographic origin, and extraction method. They are used in the most diverse areas such as pharmaceuticals, cosmetics, agriculture, food, and textiles, among others.
Essential oils’ antimicrobial activity has been extensively studied, succeeding both against Gram-positive bacteria and Gram-negative bacteria, as well against fungi. They also exhibit antiparasitic, antiviral, and antioxidant properties. However, its use is conditioned to processes and/or products that do not undergo thermal processing, as these essential oils are largely volatile, oxidizable, and thermosensitive.
Thus, the encapsulation techniques present themselves as an effective alternative in the protection of essential oils, releasing them at the desired time and place. There are several encapsulation techniques, among which we can highlight spray drying, spray cooling, extrusion, solvent evaporation, coacervation, and the use of supercritical fluids. What differs them from each other are the equipment used and the process conditions, the encapsulation efficiency, the particle size obtained, and the cost.
One of the key factors to be considered in the encapsulation process is the coating material. This determines the particles stability, the efficiency, and the degree of the core protection. Examples of coating materials are synthetic and biodegradable polymers, inorganic materials such as clays and silicates, proteins such as gelatin and casein, polysaccharides, and sugars, with emphasis on cyclodextrins. These are widely used in the industry due to properties such as inertia and toxicity.
The encapsulation process can form macroparticles, microparticles, and nanoparticles, and obtaining them is dependent on the choice of techniques and parameters involved in the process. In general, the compound to be encapsulated is suspended in a solution, and then the coating material is dissolved and precipitated by overlaying the core.
Therefore, encapsulating an essential oil ensures that it maintains its properties of interest while being protected from external factors such as mechanical stress, temperature, and oxidation. In the case of thermal protection, this is an extremely important advantage in which the inclusion complex can be used in processes and/or products that make use of thermal sources.
2. Essential oils
The use of plants in daily life has been a constant throughout all stages of evolution. They have been used as an unlimited source of food for humans and animals, fibers for clothing, and as useful medicines. Among the compounds obtained from vegetal material, the essential oils stand out and deserve particular attention due to their peculiar characteristics [1, 2].
Essential oils are oily aromatic liquid compounds containing complex mixtures of volatile compounds, which are the secondary metabolites of plants and play an important role in their defense. They are extracted from the vegetal material (flowers, shoots, seeds, leaves, branches, peels, fruits, and roots) of a large number of plants, usually representing only a small fraction of the plant composition (less than 5% of dry material) [2, 3, 4, 5].
These bioactive compounds have promising potential to maintain and promote health and to prevent microbial growth, and have been applied in diverse areas, such as in pharmaceuticals, food, textiles, biomedical applications, cosmetics, and agriculture industries. They usually possess low solubility and absorption and are chemically unstable and susceptible to oxidative deterioration and loss of volatile compounds, especially when exposed to oxygen, light, moisture, and heat, resulting in decreased bioavailability and efficacy [6, 7, 8].
The essential oil constituents are a family of organic compounds with a low molecular weight, and they can be divided into four groups according to their chemical structures: terpenes, terpenoids, phenylpropenes, and “others.” Terpenes are hydrocarbons produced from the combination of several isoprene units (C5H8), and they are synthesized in the cytoplasm of vegetal cells. The main representatives of this group are the monoterpenes (C10H16) and sesquiterpenes (C15H24), but longer chains, such as diterpenes (C20H32) and triterpenes (C30H40), are also part of this group. Limonene is a classic example of a terpene. Terpenoids are terpenes that undergo biochemical modifications through enzymes that add oxygen molecules and move or remove methyl groups. Terpenoids can be subdivided into alcohols, esters, aldehydes, ketones, ethers, phenols, and epoxides. Examples of terpenoids are thymol, carvacrol, linalool, menthol, and geraniol [4, 9]. Phenylpropenes constitute a subfamily among the various groups of organic compounds called phenylpropanoids that are synthesized in plants from the amino acid precursor phenylalanine. Phenylpropenes constitute a relatively small part of essential oils, and those that have been more carefully studied are eugenol, vanillin, and cinnamaldehyde .
The proportion of these constituents is different in each essential oil and is a function of several factors, including the species, the part of the plant from which the oil was extracted, the harvesting season, geographical origin, and the method of extraction. All these factors directly influence the oil composition and, consequently, the bioactive properties, conferring different biological functionalities to them [10, 11, 12, 13, 14, 15, 16, 17, 18].
2.2. Antimicrobial activity and mechanism of action
Antimicrobial activity can be considered the most investigated activity of essential oils, especially when associated with food preservation and the consequent increase in shelf life, because these bioactive compounds have the capacity to slow down growth and even eliminate contaminating pathogens from food products. Therefore, essential oils meet the current requirements of more concerned and demanding consumers who prefer to consume food without synthetic preservatives, expanding their application in this segment of the population .
In addition, foodborne illness is a growing public health problem throughout the world; only in the United States, 31 species of pathogens are estimated to cause 9.4 million cases of foodborne illness per year . This demands new strategies and more effective control and has motivated several studies with essential oils. Another characteristic of these compounds is the safety of their use in food. Many essential oils are considered by the Food and Drug Administration (FDA) as Generally Recognized as Safe (GRAS), meaning that they can be used in food products without the need for approval via technical analysis .
Some investigations have confirmed the antimicrobial activity of several essential oils. Teixeira et al.  studied the antimicrobial activity of 17 different essential oils against 7 different types of bacterial strains. All essential oils inhibited the growth of at least four of the bacteria tested. Pesavento et al.  tested the antimicrobial activity of the essential oils of oregano, rosemary, and thymol against
According to studies presented by Affonso et al. , clove oil presents pronounced antimicrobial activity when tested against
Knezevic et al.  confirmed the antimicrobial activity of essential oils of
The antimicrobial activity of essential oils is related to their hydrophobicity, a characteristic that favors interaction with the lipids of the cell membranes and with the mitochondria of the microbial cells. These interactions generally alter the permeability of bacterial cells, causing disturbances in the structures and resulting in coarse fractures that cause ion, molecule, and cellular content leakage, leading to microorganism death or inhibition of their growth .
In general, essential oils act to inhibit bacterial cell growth and the production of toxic bacterial metabolites. Most essential oils have a more pronounced effect on Gram-positive bacteria than on Gram-negative species, and this effect is likely due to differences in the cell wall composition of these bacteria [9, 26, 27].
According to Muñoz-Bonilla and Fernández-García , Gram-positive bacteria have only one outer layer, which facilitates penetration of external molecules, promoting interaction with the cytoplasmic membrane and making them more fragile compared with Gram-negative bacteria. Gram-negative bacteria have an additional membrane with a phospholipid bilayer structure responsible for protection of the inner cytoplasmic membrane, which confers greater resistance to this class of bacteria. The hydrophilic wall hinders the penetration of hydrophobic compounds, for example, essential oils, into the cell [29, 30].
Mechanisms that explain the action of essential oils on bacterial cells have been studied, but it is still not possible to say with certainty how the essential oils act on a microbial cell. These bioactive compounds have many components, and the antimicrobial action cannot be confirmed by the action of only a single component or by the activity on a single cell site .
The typical hydrophobic characteristic of essential oils is responsible for the breakdown of bacterial structures, which leads to increased permeability due to the inability of separation between the essential oils and the bacterial cell membrane. This fact alters cellular functions, making it difficult to maintain the energetic state, altering solute transport, promoting cellular component leakage, and deregulating cellular metabolism . Furthermore, because they contain phenolic compounds, the essential oils can disturb the cell membrane and inhibit the cell functional properties and are even capable of spilling cellular materials. The chemical composition of essential oils and/or their volatile compounds has a major impact on their antimicrobial mechanism, because phenolic compounds contain hydroxyl groups, which operate effectively against foodborne pathogenic bacteria .
2.3. Miscellaneous properties
Essential oils or their components not only have antibacterial properties [22, 23, 25, 32, 33] but also have antiparasitic [34, 35], antiviral [36, 37], antifungal [38, 39, 40], and antioxidant properties [32, 41, 42].
Alves-Silva et al.  determined the chemical composition and antimicrobial, antifungal, and antioxidant activities through four different antioxidant tests of three aromatic herb essential oils, coriander (
Even with so many well-researched studies, the application of essential oils still has some limitations. When used as a food preservative, the problem of essential oil constituents is that they often cause negative organoleptic changes if added in amounts sufficient to provide an antimicrobial effect, which generally requires high concentrations . Additionally, in many foods, the hydrophobicity of essential oil constituents is detrimental due to interactions with fat-containing foods .
There is also another aggravating factor which makes impossible for these compounds to be used in other products that wish to make use of its main characteristic. The compounds that promote antimicrobial and antioxidant activity in the essential oils are highly volatile, thermally unstable, and photodegradable, and in the presence of oxygen, they undergo oxidation. Thus, when they are not protected by a barrier are not very stable and at high temperatures they lose their biological activity and their applications can be compromised [45, 46, 47, 48].
Chemical component groups of essential oils are readily converted by oxidation, isomerization, cyclization, or dehydrogenation, which are reactions that can be enzymatically or chemically triggered, and these processes are usually associated with a loss of quality. For example, terpenoids tend to be volatile and thermolabile and can be readily oxidized or hydrolyzed, depending on their structure. Further, the maintenance of essential oil composition depends strongly on the conditions under which it is processed and how it is handled and stored upon production. Certain factors are crucial for maintaining the stability of essential oils, such as temperature, light, and oxygen availability. Therefore, these factors need to be carefully considered .
In this way, it is possible to infer that the conditions in which these essential oils are kept are fundamental to their characteristics. Rowshan et al.  studied the thermal stability of the
Turek and Stintzing  evaluated the impact of different storage conditions on four essential oils (lavender, pine, rosemary, and thyme) to verify the influence of light and temperature on their composition. The authors obtained interesting results, stating that parameters such as pH, conductivity, and the chemical profile of the essential oils are severely altered when exposed to light and temperature, which modifies their quality. Their work also reinforced that each essential oil responds differently to these external parameters.
One option for minimizing the exposure problems of essential oils is to make use of these compounds in encapsulated form, by means of a protective shell, to limit the degradation/loss of biological activity during processing and storage and to control compound release at the time and site desired [52, 53, 54].
Microencapsulation presents a great potential for improvement and development of structures for the conservation of natural products. In the last decade, there has been great progress in the development of microencapsulated compounds in the food and pharmaceutical industries, as they offer greater degradation resistance and compound stability [53, 55, 56, 57, 58, 59].
Encapsulation is the process of constructing a functional barrier between the core and the coating material to avoid chemical and physical reactions and to maintain the biological, functional, and physico-chemical properties of the core materials. The proper choice of encapsulation technique and the coating material depends on the end use of the product and the processing conditions involved. The coating material determines the stability of the particles, the process efficiency, and the degree of core protection .
Since bioactive compounds has some limitations in their use, for example, induce negative organoleptic change, are highly volatile, thermally unstable, photodegradable, and therefore, they can be easily deteriorated, the use of a barrier that limits these exchanges is interesting. When encapsulated, these compounds are protected against a number of factors, such as temperature, moisture, light, oxidation, undesirable reactions with other compounds and mechanical stress during handling, processing, and storage of the final product. This leads to a prolonged shelf life and maintenance of metabolic activity for long periods of time during storage, which maintains the biological and functional characteristics of essential oils [60, 61, 62].
The encapsulation technique can be used for solid, liquid, or gaseous material packaging using fine polymer coatings to form macrocapsules (>5000 μm), microcapsules (0.2–5000 μm), or nanocapsules (<0.2 μm) [63, 64]. Nanoencapsulation is the coating of one or more substances within another material at the nanoscale. Microencapsulation is similar to nanoencapsulation, but it involves larger particles and is an already consolidated technique, with a longer study time compared to the nanoencapsulation process. On the other hand, macroencapsulation involves a larger scale than microencapsulation .
In general, the compound to be encapsulated is suspended in a solution containing the encapsulating agent, and then, this agent is dissolved and precipitated by coating the suspended material, or the compound to be encapsulated and the encapsulating agent are dissolved in a single solvent and simultaneously precipitated (coprecipitation). In this situation, various particles of the compound are within the layer of the encapsulating agent, with the capsule formation, which may be microcapsules and/or microspheres, for example . The encapsulating agent protects the core by isolating it and allows release through a specific stimulus at the time and place desired . Figure 1 shows a schematic picture of microcapsules and microspheres.
Microcapsules are particles consisting of a substantial central inner core containing the active substance covered by a layer of the encapsulating agent, constituting the capsule membrane, while microspheres are matrix systems in which the nucleus is uniformly dispersed and/or dissolved in a polymer network. The microspheres may be homogeneous or heterogeneous depending on whether the core is in the molecular state (dissolved) or in particle form (suspended), respectively [64, 68].
The encapsulating agent should not react with the core, and it should have the ability to seal and hold the core within the capsule, protecting it from adverse conditions. Interactions between the wall material and the core can affect the release rate as well as the core volatility and particle size [63, 69].
The mechanisms involved in the core release are diffusion, where the active compound is released slowly by permeating the wall of the coating without compromising its physical integrity, or through a release trigger, which involves a change in pH, mechanical stress, temperature, enzymatic activity, time, or osmotic force, among other triggers, that promotes capsule breakdown and instantly releases the active compound .
The selection of the encapsulation technique and the coating material depends on the final application of the product, considering the physical and chemical stability, the concentration of the compounds in the encapsulation process, the required particle size, the release mechanism and the manufacturing costs [62, 64].
The encapsulation technique efficiency depends on several parameters. Retention of the active agent within the membrane shell is regulated by factors related to the chemical nature of the core, including its molecular weight, chemical functionality, polarity, and volatility, and by the properties of the coating material and the chosen encapsulation technique .
The key steps in an encapsulation method are incorporation of the bioactive compounds; droplet formation; removal of the solvent; collection of the capsules, and drying . Different encapsulation methods have been developed to meet different types of core and shell materials, as well as to generate particles with various sizes, thickness, and shell permeability, thus adjusting the active principle release rate . Some of the main encapsulation methods are spray drying, coacervation, solvent evaporation, extrusion, lyophilization, and encapsulation using supercritical fluids . These methods are described in the following sections.
3.3.1. Spray drying
Very simply, this process consists of (i) preparing, (ii) homogenizing, and (iii) atomizing the suspension and (iv) drying the atomized particles . The encapsulation efficiency using the spray drying technique is dependent on the preparation of a stable emulsion/suspension of oil in water and spraying it into small droplets on the drying bed . Therefore, the bulk ratio of hydrophilic and lipophilic phases, the oil droplet size distribution, the dry matter content, and the emulsion viscosity need to be optimized prior to use in this technique. The emulsions must have sufficient viscosity to be pumped and sprayed, and they should not be sticky and hygroscopic after drying, which will ensure particle stability during storage .
This technique requires well-adjusted operating conditions as well as a suitable composition of the solution containing the bioactive compounds. The first includes factors such as inlet air temperature, atomizing air flow, liquid flow rate, vacuum aspirator velocity, and solid concentration, among others . The success in obtaining particles using the spray drying method depends on factors such as the choice of polymer and the size distribution of the oil droplets in the emulsion [74, 75].
The main advantages of the spray drying technique are the combination of particle formation and drying in a single step, the possibility of using a wide variety of encapsulating agents, potentially large-scale production, simple equipment, low operating costs, high quality capsules with good yield, quick solubility of the capsules, small size, high capsule stability, and continuous operation [61, 64, 73, 76, 77]. The disadvantages are variations in the particle size and shape distribution, high temperatures, and rapid drying rates that normally do not allow encapsulation of thermosensitive compounds [61, 64, 73, 77].
Gallo et al.  studied the influence of the operation conditions of the spray drying method on the physical properties of
Coacervation is one of the oldest and most widely used encapsulation techniques, and it involves electrostatic attraction between two oppositely charged polymers and the formation of coacervates over a narrow pH range. This technique involves the addition of a coacervating agent to a homogeneous polymer solution. The coacervation agent desolvates the polymer solution in a coacervate (polymer rich phase) and coacervation medium (poor polymer phase). During the encapsulation process, the bioactive compound is encapsulated within the polymer rich phase [7, 8].
The coacervation technique may be simple or complex. What differentiates them is the method of phase separation. In simple coacervation, the polymer is salted by the action of electrolytes, such as sodium sulfate, or desolvated by the addition of a water-miscible nonsolvent, such as ethanol, or by increasing/decreasing the temperature. These conditions promote macromolecule-macromolecule interactions, allowing the production of microcapsules containing hydrophobic substances, such as essential oils. Simple coacervation offers important advantages over complex coacervation in terms of cost savings and flexible operations. To induce phase separation, simple coacervation uses cheap inorganic salts, while complex coacervation is more sensitive even at small pH changes. In addition, complex coacervation uses expensive hydrocolloids [8, 82].
On the other hand, complex coacervation involves complexation between two oppositely charged polymers (commonly a polysaccharide and a protein). Complex coacervation involves three basic steps. The first step consists of the formation of an oil/water (o/w) emulsion, and the second step consists of separation of the liquid phase rich in the insoluble polymer; this phase results from the electrostatic attraction between opposing charges of the polymers caused by a reduction in the pH of the solution. The last step is coating stabilization (coating hardening, using thermal, cross-linking or desolvation techniques, to form self-sustained microcapsules). The formation of the coacervation coating is conducted by the difference in surface tension between the coacervation phase, the water and the hydrophobic material [7, 8, 62].
The main advantage of complex coacervation is that it has a high level payload (up to 99%). In addition, this method is simple, low cost, and solvent free. Therefore, complex coacervation can be used to manufacture microcapsules at an industrial scale .
Several investigations have utilized the coacervation method to microencapsulate bioactive compounds, such as propolis extract, sweet orange oil, essential oil of mustard seeds (
3.3.3. Solvent evaporation
This technique is based on the evaporation of the internal phase of an emulsion by shaking. Generally, the coating material is dissolved in a volatile organic solvent. The core material is then dissolved or dispersed in the encapsulating agent solution to form a suspension, an emulsion, or a solution. Thereafter, the organic phase is emulsified under agitation in a dispersion phase consisting of a nonsolvent of the encapsulant, which is immiscible with the organic solvent and contains an appropriate emulsifying agent. Once the emulsion is stabilized, the shaking is maintained, and the solvent evaporates after diffusing through the continuous phase, resulting in solid microspheres. The microspheres are recovered by filtration or centrifugation, and washed and dried [87, 7]. Patil et al.  encapsulated clove oil in methylcellulose microcapsules using the solvent evaporation method.
3.3.4. Extrusion technique
Oil encapsulation by extrusion consists basically of (i) injection and (ii) melt extrusion, followed by (iii) centrifugal extrusion (coextrusion). The main advantages of the encapsulation of essential oils by extrusion are stability against oxidation, prolonged shelf life, and lower rates of essential oil evaporation. However, this is an expensive process, and the particles do not have a uniform distribution . Soliman et al.  microencapsulated essential oils of clove (
3.3.5. Freeze drying
Freeze drying is a method that involves dehydration of the frozen material under a vacuum sublimation process; the removal of water occurs without subjecting the sample to high temperatures. This method provides products of excellent quality because it minimizes the changes associated with high temperature. However, its high cost and long process time reduce its applicability . Examples of studies that used this technique include Calvo et al.  who microencapsulated extra virgin olive oil in the presence of maltodextrin, carboxymethylcellulose, and lecithin; Ezhilarasi et al. , who studied microencapsulation of garcinia fruit extract by spray drying and its effect on bread quality; Piletti et al. , who encapsulated eugenol essential oil into β-cyclodextrin molecules through lyophilization; and Hill et al. , who encapsulated cinnamon bark extract, trans-cinnamaldehyde, clove extract, eugenol, and a 2:1 mixture (trans-cinnamaldehyde: eugenol) with β-cyclodextrin using the lyophilization method.
3.3.6. Technology employing supercritical fluids
The encapsulation technology employing supercritical fluids has been developed to minimize the disadvantages associated with traditional encapsulation methods, and it has a great relevance for the pharmaceutical, cosmetic, and food industries. It has several inherent advantages: non-toxicity and easy removal of the solvent without degradation of the product, and the process uses a wide variety of materials that produce controlled particle sizes and morphologies. Generally, it is preferred for essential oils that are sensitive to high temperatures, oxygen, and chemicals. Technology using supercritical fluids is considered a green technology because of the use of supercritical carbon dioxide in most cases. Supercritical carbon dioxide (CO2) has properties that are ideal for bioactive compound encapsulation. The characteristic properties of supercritical CO2 are lower viscosity, higher diffusivity, lower surface tension, faster process, and high solubility of the active compound [7, 8].
The supercritical apparatus consists of a high pressure stainless steel impregnation cell, a magnetic stirrer plate, a temperature controlled water bath, a high pressure CO2 pump, and a pressure transducer. The impregnation cell contains two chambers separated by a mesh. The lower chamber is filled with essential oil, and the upper chamber is filled with microparticles or matrices in which the oil needs to be impregnated . The essential oils of lavandin, oregano, canola, and passion fruit seed oil have been encapsulated using this method [80, 92, 93, 94].
For the encapsulation process, selection of the encapsulating material is a very important step. This material should be chosen according to its bioactivity, non-toxicity, intended application, and method of particle formation . Biodegradable polymers, such as PLA, PLGA, and PCL, have primarily been used as a coating in the medical field, especially in tissue engineering and drug release. To a lesser extent, inorganic materials such as silicates, clays, and polyphosphates can also be used. Further, proteins (gelatin, casein, and soy proteins), lipids (waxes, paraffin, and oils), and synthetic polymers (acrylic polymers, polyvinylpyrrolidone) may be used. However, the most widespread materials used as encapsulating agents are polysaccharides and sugars (gums, starches, and celluloses), especially cyclodextrins, which are widely used mainly in the food industry due to their interesting properties; specifically, they are inert and non-toxic [7, 62].
Cyclodextrin had its origin around 1981, when Villier discovered a new starch derivative obtained from bacterial degradation, which presented properties similar to those of cellulose, and distinguished two types of crystals of cellulosin: the cyclodextrins α and β . Twelve years later, when studying the bacterial digestion of starch, Szejtli  identified two crystalline products with the same characteristics as Villier’s cellulosins. Deepening his studies, he perfected the process of obtaining these crystals and isolated the bacterium that produced them, deeming it
Cyclodextrins (CD’s) are cyclic oligosaccharides consisting of glucose units linked by α-(1,4) glycosidic bonds derived from the enzymatic degradation of starch by certain bacteria, and they are chemically and physically stable molecules [95, 97]. The most common natural CDs have six, seven, and eight d-glucopyranose units and are named α, β, and γ cyclodextrin, respectively, and they differ from each other by virtue of ring size and solubility . While the central cavity of CDs has a hydrophobic character, the surrounding walls are hydrophilic, and this feature allows CDs to form capsules, acting as a host for lipophilic compounds in their cavities and forming inclusion complexes [97, 99, 100, 101].
The binding of bioactive compounds within the host cyclodextrin is not fixed or permanent, but rather a dynamic equilibrium. This way, the formation of inclusion complexes is result of an equilibrium between the free and CD molecules and the bioactive compounds—CD complex . Therefore, some factors may affect inclusion complex formation, such as type of cyclodextrin, cavity size, pH and ionization state, temperature, and method of preparation .
CD molecules are cone-like in shape with a cavity 7.9 Å deep. The upper and lower diameters of the CD wells are 4.7 and 5.3 Å, 6.0 and 6.5 Å, and 7.5 and 8.3 Å for α-CD, β-CD, and γ-CD, respectively .
Among the CDs, β-CD is the most used, because its apolar cavity can host molecules of molecular masses between 100 and 400 g mol−1, which is the molecular mass range of most molecules of interest. β-CD is also easy to recover industrially through the crystallization process , and it has the lowest solubility and an intermediate size (Table 1). In addition, β-CD production is the most economically viable, with an industrial cost per kilogram approximately 20 times lower than that of the other CD types .
|Aqueous solution (g 100 mL−1|
|Cavity diameter (Â)||4.7–5.3||6.0–6.5||1.5–8.3|
|Cavity volume (Â3)||174||262||427|
|Crystal form||Hexagonal blades||Monoclinic parallelograms||Quadratic prisms|
|Melting point (°C)||275||280||275|
|Surface tension (nM/m)||73||73||73|
|Rate of acid hydrolysis (h−1)||0.11||0.13||0.23|
These inclusion complexes are important because they improve the chemical and physical stability and solubility of the compounds encapsulated in water. Due to the solubility of CDs in water and because they have the ability to form reversible inclusion complexes with non-polar molecules in aqueous solution, the water molecules inside the ring are easily replaced by non-polar molecules or molecules with less polarity than water, forming structures that are energetically more stable .
The encapsulation can reduce volatilization rates, and promote the gradual release of the encapsulated molecules, which improves their efficacy and bioavailability. Furthermore, they act as protectors against oxidative damage, light degradation, and heat, and other adverse effects linked to the medium in which they are inserted and maintain the initial characteristics of the compound for a long period. These inclusion complexes are relatively more hydrophilic and larger in size than the non-associated active compound, which helps to increase the retention of the encapsulated substance. They are also very interesting because they can mask undesirable flavors and odors that the encapsulated compounds may present [21, 56, 72, 101, 102, 106, 107, 108, 109, 110].
Marques  notes that the goal of encapsulation using cyclodextrin is to reduce the volatility and toxicity of the encapsulated compounds, provide protection of compounds that are sensitive to factors that promote their degradation, and alter the kinetics of migration and release of the encapsulated active components into the external environment.
The use of cyclodextrins is verified in diverse industrial products, such as pharmaceuticals [107, 111, 112], agrochemicals [113, 114, 115], and foods [116, 117, 118, 119]. In the food area, cyclodextrins are nontoxic and considered GRAS, and thus are used for several purposes [120, 121]. These structures offer increased resistance to degradation of the active compounds and make the host-microcapsule complex more stable [53, 56, 57, 122, 123].
Szente and Szejtli  studied the toxicity of CDs and demonstrated that oral administration of high doses of CDs does not cause any harm. Several studies have shown that CDs are nontoxic and do not present intoxication risks, because they are not absorbed in the gastrointestinal tract or through lipophilic biological membranes, and the same results have been obtained with regard to teratogenicity and mutagenicity [124, 125, 126, 127, 128]. Antisperger  also evaluated the toxicity of CDs when introduced in an amount equivalent to 20% in the diet of rats and dogs and found no toxicity.
5. Cyclodextrins in thermal protection
The thermal degradation is one of the main natural compounds’ degradation forms. In most cases, the increase in temperature is undesirable, as it favors the volatilization of less stable compounds, which are responsible for the biological activity. Therefore, the thermal degradation makes it impossible to apply many of the natural compounds studied, due to the alteration of their characteristics when exposed to high temperatures. Due to this situation, several authors have studied the encapsulation of these bioactive compounds with cyclodextrin, in order to provide a barrier, aiming the thermal protection of these natural compounds and preventing bioactive compounds from being lost and thus ensuring the application of these products in different situations.
Abarca et al.  prepared an inclusion complex of 2-nonanone (2-NN) with β-cyclodextrin by a co-precipitation method. 2-Nonanone are aliphatic hydrocarbons, aromatic volatiles commonly found in plant tissues, presenting antifungal behavior with low mammalian toxicity, a pleasant fruity/floral odor, resistance to rapid decomposition, adequate volatility, environmental acceptability, and a high potential for commercial development. The TGA and DSC analyses showed that thermal stability increased when 2-NN was encapsulated with β-CD. The antifungal activity of the inclusion complex was tested against
Babaoglu et al.  encapsulated clove essential oil in hydroxypropyl-beta-cyclodextrin using the kneading method (a low-cost and easy-to-operate encapsulation technique) with hydroxypropyl beta-cyclodextrin and oil at a molar ratio of 1:1. The study demonstrated that the stability of the inclusion complex formed was greater and that the encapsulation process also increased the total phenolic content and antioxidant properties compared with the essential oil in free form. The authors indicate that this increase is due to an increase in the solubility of the essential oil molecules in water as a result of inclusion complex formation. Furthermore, the release rate of the essential oil was controlled with encapsulation. However, the authors concluded that this rate could be improved with the use of different proportions of essential oils. With this study, the potential for the use of microencapsulated clove oil in the pharmaceutical and food industries is evident, because this formulation keeps the oil constituents active and avoids losses and degradation.
Inclusion complexes formed with cyclodextrin are already being used as additives in final products, as reported by Wang et al. , that performed a work demonstrating this possibility when preparing cyclodextrin microencapsulated ammonium polyphosphate (MCAPP), with the goal of improving the water durability of APP and making a novel functional flame retardants. One of the interesting results found by the authors was that cyclodextrin resulted in the transformation of hydrophilic to hydrophobic of the flame retardant surface. Then, MCAPP was incorporated into the ethylene vinyl acetate copolymer (EVA), extensively used for the several applications like electrical insulation, cable jacketing and repair, water proofing, and corrosion protection, in order to improve flame retardancy of the EVA. The results showed that after the incorporation, the EVA composites presented improvements in mechanical, thermal stability, combustion properties, and flame-retardant properties, mainly because cyclodextrin shell improves the compatibility of the composites and the dispersion of APP in the EVA matrix evidencing that the microencapsulation technology with cyclodextrin contributes to obtain products with better characteristics and greater applicability. This study showed that cyclodextrin encapsulation is not only limited to natural products, but can also act as an encapsulating agent for other products as well, increasing its stability.
Another study that inserted the inclusion complex obtained in a final product was done by Kayaci et al. . Geraniol is a natural component of plant essential oils, generally used as a fragrance/flavor in food industry to treat infectious diseases and/or preserve the food. The authors studied solid inclusion complexes of geraniol/cyclodextrins (α-CD, β-CD, and γ-CD). The results showed that the complexation efficiency between geraniol and γ-CD was higher. After this verification, the authors incorporated this inclusion complex into polyvinyl alcohol (PVA) nanofibers (NF) via electrospinning. The SEM analysis showed a homogeneous distribution of the inclusion complex (geraniol/γ-CD) to the PVA nanofibers. PVA/inclusion complex (geraniol/γ-CD) nanofibers presented higher thermal stability when compared to PVA/geraniol nanofibers only. Geraniol is easily volatilized, a fact that can be observed during electrospinning or during storage. When the PVA/geraniol nanofibers are evaluated, it was verified that after one day of its production, the geraniol had already evaporated completely. In contrast, PVA/inclusion complex (geraniol/γ-CD) nanofibers lost only about 10% of geraniol after two years of manufacturing. This result led the authors to conclude that PVA/inclusion complex (geraniol/γ-CD) nanofibers have potential application in the food packaging sector due to the high surface area and nanoporous structure of nanofibers and also due to the high thermal stability and longer durability of the agent active because it is encapsulated.
Hădărugă et al.  studied
Kalogeropoulos et al.  performed a thermal study of
Hill et al.  investigated the complexes formed by oils encapsulated in β-cyclodextrin (BCD) and their antimicrobial activity. The natural products studied were cinnamon bark extract, trans-cinnamaldehyde, clove bud extract, eugenol, and a 2:1 (trans-cinnamaldehyde:eugenol) mixture microencapsulated with the freeze-drying method. The oils and their BCD complexes were analyzed for their antimicrobial activity against
The antimicrobial analysis showed that all the antimicrobials effectively inhibited bacterial growth within the tested concentration range except for free eugenol. The EO-BCD complexes inhibited both bacterial strains at lower active compound concentrations than free oils, likely due to increased solubility in water that led to greater contact between the pathogens and essential oils. Moreover, the results showed that in addition to masking the sensory effect of the attributes of antimicrobial agents, complexation may potentiate their activity.
Wang et al.  studied the encapsulation of garlic oil (GO) and obtained an inclusion complex with GO encpasulated by the β-cyclodextrin using the co-precipitation method. The authors also used DSC to evaluate the thermal stability of the complex. The garlic oil is rich in organosulphur compounds that have a variety of antimicrobial and antioxidant activities but are very volatile and have low physicochemical stability.
The BCD thermogram showed a large endothermic peak at approximately 127°C that, according to the authors, is related to elimination of water molecules that are bound to the cyclodextrin molecules. For GO in its free form, the authors verified the existence of two peaks at approximately 186° and 223°C and associated the peaks with GO oxidation. These two exothermic peaks were not found in the GO-BCD complex thermogram, indicating that the biological compound is protected from oxidation within the BCD cavity.
Hădărugă et al.  studied the thermal and oxidative stability of Atlantic salmon oil (
Li et al.  also prepared an inclusion complex of benzyl isothiocyanate (BITC) extracted from papaya seeds with β-cyclodextrin. The thermal properties of BCD, BITC and its inclusion complex (BITC-BCD) were investigated using DSC and TG techniques. The DSC curve of BITC-BCD shows that volatilization of uncoated BITC occurred. The TG curve of BCD showed a slope close to 300°C, which was generally attributed to the onset of BCD decomposition. The BITC is a volatile material and quickly loses mass at 80–165°C. The inclusion complex showed volatility between 140°C and 300°C, indicating that the BCD cavity provides protection against BITC volatilization.
Zhou et al.  studied the Baicalein (Ba) encapsulation, an active ingredient extracted from a medicinal herb
Vilanova and Solans  studied the inclusion complexes of Vitamin A Palmitate with β-cyclodextrins, without the use of organic solvents. The low stability and low water solubility of some vitamins limit its use as a food additive, so the authors’ interest was to use cyclodextrin as an encapsulating agent to overcome these deficiencies, making possible the production of foods enriched with vitamins, in order to prevent diseases related to their deficiency. All results showed a notably increase of Vitamin A Palmitate water solubility and stability in front of temperature, oxygen, and UV light when encapsulated. This works showed that the formation of inclusion complexes is a potential strategy to not only enrich but also to provide stability in surfactant-free food emulsion formulations, which seem to be a promising vehicle to increase the bioavailability of Vitamin A Palmitate in food.
Fernandes et al.  evaluated the thermal stability of cyanidin-3-O-glucoside (cy3glc) (major blackberry anthocyanin) and blackberry purees through molecular inclusion with β-cyclodextrin (β-CD). This work evidenced the thermal protection provided by the encapsulating agent, which showed a thermal stabilization of cy3glc, resulting in a decrease of the degradation rate constant (k) and in several alterations in the cy3glc-β-CD DSC thermogram. According to the authors, anthocyanin-loaded β-CD could potentially carry and stabilize anthocyanins, improving their bioavailability, which could be an advantage for efficient utilization in food systems.
All the showed works evidenced the importance of encapsulation to maintain the properties of the studied compounds, allowing their application in different situations. It is evident that cyclodextrin is the most widely used encapsulating agent, as it provides the formation of inclusion complexes with interesting properties.
6. A case study
Eugenol is an essential oil with excellent antimicrobial properties. However, because it is thermosensitive, it has restricted the applicability in processes that require high temperatures. Piletti et al.  proposed a method for protecting this oil by encapsulating it in β-cyclodextrin. The authors evaluated the encapsulation of eugenol molecules by means of lyophilization and later evaluated the antimicrobial activity of the complex (eugenol-β-cyclodextrin) against the bacteria
However, when using cyclodextrin as an encapsulating agent, the idea was that there would be thermal protection of the essential oil, ensuring that the compound property of interest (antimicrobial activity) was not altered. This was confirmed by the heat treatment of the eugenol-β-cyclodextrin complex in a furnace maintained at 80°C (temperature approximately twice the temperature of free eugenol volatilization) for 2 h and subsequent re-evaluation of antimicrobial activity. Figures 2 and 3 illustrate the antimicrobial capacity of the complex after the heat treatment against
The encapsulated eugenol molecules were thermally protected, remained in the complexes after heat treatment and manifested the antimicrobial activity of this essential oil. Therefore, encapsulation using β-cyclodextrin is a promising method to protect eugenol, preserving its antibacterial action when it is used under conditions higher than its volatilization temperature.
All these studies show the efficiency of β-cyclodextrin as an encapsulating agent and demonstrate its high thermal protection capacity for bioactive natural compounds, which are highly unstable, without damaging the biological property of interest in these compounds.
Thus, the encapsulation of essential oils using β-cyclodextrin is an alternative to promote the use of these biocomposites as additives, boosting the development of functional materials, providing new applications for them in the diverse areas, such as medical, pharmaceutical, cosmetic, and food, combining the use of technology with the appreciation of natural raw materials.
Ayala-Zavala JF, Soto-Valdez H, González-León A, Álvarez-Parrilla E, Martıín-Belloso O, González-Aguilar GA. Microencapsulation of cinnamon leaf ( Cinnamomum zeylanicum) and garlic ( Allium sativum) oils in b-cyclodextrin. Journal of Inclusion Phenomena and Macrocyclic Chemistry. 2008; 60:359-368. DOI: 10.1007/s10847-007-9385-1
Sharifi-Rad J, Sureda A, Tenore GC, Daglia M, Sharifi-Rad M, Valussi M, Tundis R, Sharifi-Rad M, Loizzo MR, Ademiluyi AO, Sharifi-Rad R, Ayatollahi SA, Iriti M. Biological activities of essential oils: from plant chemoecology to traditional healing systems. Molecules. 2017; 22:1-55. DOI: 10.3390/molecules22010070
Burt S. Essential oils: Their antibacterial properties and potential applications in foods—A review. International Journal of Food Microbiology. 2004; 94:223-253. DOI: 10.1016/j.ijfoodmicro.2004.03.022
Hyldgaard M, Mygind T, Meyer RL. Essential oils in food preservation: mode of action, synergies, and interactions with food matrix components. Frontiers in Microbiology. 2012; 3:1-24. DOI: 10.3389/fmicb.2012.00012
El Asbahani A, Miladi K, Badri W, Sala M, Aït Addi EH, Casabianca H, El Mousadik A, Hartmann D, Jilale A, Renaud FNR, Elaissari A. Essential oils: From extraction to encapsulation. International Journal of Pharmaceutics. 2015; 483(1-2):220-243. DOI: 10.1016/j.ijpharm.2014.12.069
Codevilla CF, Bazana MT, Silva CB, Barin JS, Menezes CR. Nanoestruturas contendo compostos bioativos extraídos de plantas. Ciência e Natura. 2015; 37:142-151. DOI: 10.5902/2179-460X19743
Sagiri SS, Anis A, Pal K. A review on encapsulation of vegetable oils: Strategies, preparation methods and applications. Polymer-Plastics Technology and Engineering. 2016; 55(3):291-311. DOI: 10.1080/03602559.2015.1050521
Bakry AM, Abbas S, Ali B, Majeed H, Abouelwafa MY, Mousa A, Liang L. Microencap-sulation of oils: A comprehensive review of benefits, techniques, and applications. Comprehensive Reviews in Food Science and Food Safety. 2016; 15:143-182. DOI: 10.1111/1541-4337.12179
Nazzaro F, Fratianni F, De Martino L, Coppola R, De Feo V. Effect of essential oils on pathogenic bacteria. Pharmaceuticals. 2013; 6:1451-1474. DOI: 10.3390/ph6121451
Mejri J, Abderrabba M, Mejri M. Chemical composition of the essential oil of Ruta chalepensisL: Influence of drying, hydro-distillation duration and plant parts. Industrial Crops and Products. 2010; 32(3):671-673. DOI: 10.1016/j.indcrop.2010.05.002
Haddouchi F, Chaouche TM, Zaouali Y, Ksouri R, Attou A, Benmansour A. Chemical composition and antimicrobial activity of the essential oils from four Ruta species growing in Algeria. Food Chemistry. 2013; 141(1):253-258. DOI: 10.1016/j.foodchem.2013.03.007
Ehlert PAD, Ming LC, Marques MOM, Fenandes DM, Rocha WA, Luz JMQ, Silva RF. Influência do horário de colheita sobre o rendimento e composição do óleo essencial de erva-cidreira brasileira [Lippia alba (Mill.) N. E. Br.]. Revista Brasileira de Plantas Medicinais. 2013; 15:72-77. DOI: 10.1590/S1516-05722013000100010
Russo A, Formisano C, Rigano D, Senatore F, Sebastiano D, Cardile V, Rossellie S, Bruno M. Chemical composition and anticancer activity of essential oils of Mediterranean sage ( Salvia officinalisL.) grown in different environmental conditions. Food and Chemical Toxicology. 2013; 55:42-47. DOI: 10.1016/j.fct.2012.12.036
Jordán MJ, Lax V, Rota MC, Loráns S, Sotomayor JA. Effect of bioclimatic area on the essential oil composition and antibacterial activity of Rosmarinus officinalisL. Food Control. 2013; 30(2):463-468. DOI: 10.1016/j.foodcont.2012.07.029
Veloso RA, Castro HG, Barbosa LCA, Cardoso DP, Chagas Júnior AF, Scheidt GN. Teor e composição do óleo essencial de quatro acessos e duas cultivares de manjericão ( Ocimum basilicumL.). Revista Brasileira de Plantas Medicinais. 2014; 16:364-371. DOI: 10.1590/1983-084X/12_180
Luz JMQ, Silva SM, Habber LL, Marquez MOM. Essential oil of Melissa officinalisL. at differents seasons, systems of planting and fertilizations. Revista Brasileira de Plantas Medicinais. 2014; 16:552-560. DOI: 10.1590/1983-084X/11_130
López-Mejía OA, López-Malo A, Palou E. Antioxidant capacity of extracts from amaranth ( Amaranthus hypochondriacusL.) seeds or leaves. Industrial Crops and Products. 2014; 53:55-59. DOI: 10.1016/j.indcrop.2013.12.017
Jiang H, Wang J, Song L, Cao X, Yao X, Tang F, Yue Y. GC×GC-TOFMS analysis of essential Ooils composition from leaves, twigs and deeds of Cinnamomum camphoraL. Presl and their insecticidal and repellent activities. Molecules. 2016; 21:423. DOI: 10.3390/molecules21040423
Piletti R, Bugiereck AM, Pereira AT, Gussati E, Dal Magro J, Mello JMM, Dalcanton F, Ternus RZ, Soares C, Riella HG, Fiori MA. Microencapsulation of eugenol molecules by β-cyclodextrine as a thermal protection method of antibacterial action. Materials Science and Engineering C. 2017; 75:259-271. DOI: 10.1016/j.msec.2017.02.075
Scallan E, Hoekstra RM, Angulo FJ, Tauxe RV, Widdowson MA, Roy SL, Jones JL, Griffin PM. Foodborne illness acquired in the United States-major pathogens. Emerging Infectious Diseases. 2011; 17:7-15. DOI: 10.3201/eid1701.P11101
Hill LE, Gomes C, Taylor TM. Characterization of beta-cyclodextrin inclusion complexes containing essential oils (trans-cinnamaldehyde, eugenol, cinnamon bark, and clove bud extracts) for antimicrobial delivery applications. LWT—Food Science and Technology. 2013; 51(1):86-93. DOI: 10.1016/j.lwt.2012.11.011
Teixeira B, Marques A, Ramos C, Neng NR, Nogueira JMF, Saraiva JA, Nunes ML. Chemical composition and antibacterial and antioxidant properties of commercial essential oils. Industrial Crops and Products. 2013; 43:587-595. DOI: 10.1016/j.indcrop.2012.07.069
Pesavento G, Calonico C, Bilia AR, Barnabei M, Calesini F, Addona R, Mencarelli L, Carmagnini L, Di Martino MC, Lo Nostro A. Antibacterial activity of Oregano, Rosmarinus and Thymus essential oils against Staphylococcus aureus and Listeria monocytogenes in beef meatballs. Food Control. 2015; 54:188-199. DOI: 10.1016/j.foodcont.2015.01.045
Affonso RS, Rennó MN, GBCA S, TCC F. Aspectos químicos e biológicos do óleo essencial de Cravo da Índia. Revista Virtual de Química. 2012; 4:46-161. ISSN: 1984-6835
Knezevic P, Aleksic V, Simin N, Svircev E, Petrovic A, Mimica-Dukic N. Antimicrobial activity of Eucalyptus camaldulensisessential oils and their interactions with conventional antimicrobial agents against multi-drug resistant Acinetobacter baumannii. Journal of Ethnopharmacology. 2016; 178:125-136. DOI: 10.1016/j.jep.2015.12.008
Chorianopoulos N, Kalpoutzakis E, Aligiannis N, Mitaku S, Nychas G-J, Haroutounian SA. Essential oils of Satureja, Origanum, and Thymus species: Chemical composition and antibacterial activities against foodborne pathogens. Journal of Agricultural of Food Chemistry. 2004; 52:8261-8267. DOI: 10.1021/jf049113i
Kim SI, Yoon JS, Jung JW, Hong K, Ahn YJ, Kwon HW. Toxicity and repellency of origanum essential oil and its components against Tribolium castaneum(Coleoptera: Tenebrionidae) adults. Journal of Asia Pacific Entomology. 2010; 13(4):369-373. DOI: 10.1016/j.aspen.2010.06.011
Muñoz-Bonilla A, Fernández-García M. Polymeric materials with antimicrobial activity. Progress in Polymer Science. 2012; 37(2):281-339. DOI: 10.1016/j.progpolymsci.2011.08.005
Calsamiglia S, Busquet M, Cardozo PW, Castillejos L, Ferret A. Invited review: Essential oils as modifiers of rumen microbial fermentation. Journal of Dairy Science. 2007; 90(6):2580-2595. DOI: 10.3168/jds.2006-644
Ravichandran M, Hettiarachchy NS, Ganesh V, Ricke SC, Singh S. Enhancement of antimicrobial activities of naturally occurring phenolic compounds by nanoscale delivery against Listeria monocytogenes, Escherichia coli O157:H7 and Salmonella Typhimurium in broth and chicken meat system. Journal of Food Safety. 2011; 31:462-471. DOI: 10.1111/j.1745-4565.2011.00322.x
Bajpai VK, Baek KH, Kang SC. Control of Salmonella in foods by using essential oils: A review. Food Research International. 2012; 45(2):722-734. DOI: 10.1016/j.foodres.2011.04.052
Nikolic M, Glamoclija J, Ferreira ICFR, Calhelha RC, Fernandes A, Markovic T, Markovic D, Giweli A, Sokovic M. Chemical composition, antimicrobial, antioxidant and antitumor activity of Thymus serpyllumL., Thymus algeriensis Boiss. and Reut and Thymus vulgarisL. essential oils. Industrial Crops and Products. 2014; 52:183-190. DOI: 10.1016/j.indcrop.2013.10.006
Abdollahzadeh E, Rezaei M, Hosseini H. Antibacterial activity of plant essential oils and extracts: the role of thyme essential oil, nisin, and their combination to control Listeria monocytogenes inoculated in minced fish meat. Food Control. 2014; 35(1):177-183. DOI: 10.1016/j.foodcont.2013.07.004
Soares BV, Neves LR, Oliveira MSB, Chaves FCM, Dias MKR, Chagas EC, Tavares-Dias M. Antiparasitic activity of the essential oil of Lippia alba on ectoparasites of Colossoma macropomum (tambaqui) and its physiological and histopathological effects. Aquaculture. 2016; 452:107-114. DOI: 10.1016/j.aquaculture.2015.10.029
Meira CS, Menezes LRA, Santos TB, Macedo TS, Fontes JEN, Costa EV, Pinheiro MLB, Silva TB, Guimarães ET, Soares MBP. Chemical composition and antiparasitic activity of essential oils from leaves of Guatteria friesianaand Guatteria pogonopus(Annonaceae). Journal of Essential Oil Research. 2017; 29(2):156-162. DOI: 10.1080/10412905.2016.1210041
Pilau MR, Alves SH, Weiblen R, Arenhart S, Cueto AP, Lovato LT. Antiviral activity of the Lippia graveolens (Mexican oregano) essential oil and its main compound carvacrol against human and animal viruses. Brazilian Journal of Microbiology. 2011; 42(4):1616-1624. DOI: 10.1590/S1517-838220110004000049
Dunkic V, Vuko E, Bezic N, Kremer D, Ruscic M. Composition and antiviral activity of the essential oils of Eryngium alpinumand E. amethystinum. Chemistry & Biodiversity. 2013; 10(10):1894-1902. DOI: 10.1002/cbdv.201300061
Mota KSL, Pereira FO, Oliveira WA, Lima IO, Lima EO. Antifungal activity of Thymus vulgarisL. essential Ooil and its constituent phytochemicals against Rhizopus oryzae: Interaction with Ergosterol. Molecules. 2012; 17(12):14418-14433. DOI: 10.3390/molecules171214418
Zeng H, Chen X, Liang J. In vitro antifungal activity and mechanism of essential oil from fennel ( Foeniculum vulgareL.) on dermatophyte species. Journal of Medical Microbiology. 2015; 64:93-103. DOI: 10.1099/jmm.0.077768-0
Gakuubi MM, Maina AW, Wagacha JM. Antifungal activity of essential oil of Eucalyptus camaldulensisDehnh. against selected Fusariumspp. International Journal of Microbiology. 2017; 2017:1-7. DOI: 10.1155/2017/8761610
Cherrat L, Espina L, Bakkali M, García-Gonzalo D, Pagán R, LaglaouiA. Chemical composition and antioxidant properties of Laurus nobilisL. and Myrtus communisL. essential oils from Morocco and evaluation of their antimicrobial activity acting alone or in combined processes for food preservation. Journal of the Science of Food and Agriculture. 2014; 94(6):1197-1204. DOI: 10.1002/jsfa.6397
Aleksic V, Knezevic P. Antimicrobial and antioxidative activity of extracts and essential oils of Myrtus communisL. Microbiological Research. 2014; 169(4):240-254. DOI: 10.1016/j.micres.2013.10.003
Alves-Silva JM, Santos SMD, Pintado ME, Pérez-Álvarez JA, Fernández-López JL, Viuda-Martos M. Chemical composition and in vitro antimicrobial, antifungal and antioxidant properties of essential oils obtained from some herbs widely used in Portugal. Food Control. 2013; 32(2):371-378. DOI: 10.1016/j.foodcont.2012.12.022
Emiroglu ZK, Yemis GP, Skun BK, Candogan K. Antimicrobial activity of soy edible films incorporated with thyme and oregano essential oils on fresh ground beef patties. Meat Science. 2010; 86:283-288. DOI: 10.1016/j.meatsci.2010.04.016
Venturini CG, JNC M, Machado G. Propriedades e aplicações recentes das ciclodextrinas. Química Nova. 2008; 31:360-368. DOI: 10.3109/02652041003681398
Seo EJ, Min SG, Choi MJ. Release characteristics of freeze-dried eugenol encapsulated with beta-cyclodextrin by molecular inclusion method. Journal of Microencapsulation. 2010; 27:496-505. DOI: 10.3109/02652041003681398
Turasan H, Sarin S, Sumnu G. Encapsulation of rosemary essential oil. LWT—Food Science and Technology. 2015; 64(1):112-119. DOI: 10.1016/j.lwt.2015.05.036
Calo JR, Crandall PG, O’Bryan CA, Ricke SC. Essential oils as antimicrobials in food systems—A review. Food Control. 2015; 54:111-119. DOI: 10.1016/j.foodcont.2014.12.040
Turek C, Stintzing FC. Stability of essential oils: A review. Comprehensive Reviews in Food Science and Food Safety. 2013; 12:40-53. DOI: 10.1111/1541-4337.12006
Rowshan V, Bahmanzadegan A, Saharkhiz MJ. Influence of storage conditions on the essential oil composition of Thymus daenensisCelak. Industrial Crops and Products. 2013; 49:97-101. DOI: 10.1016/j.indcrop.2013.04.029
Turek C, Stintzing FC. Impact of different storage conditions on the quality of selected essential oils. Food Research International. 2012; 46:341-353. DOI: 10.1016/j.foodres.2011.12.028
Nori MP, Favaro-Trindade CS, Alencar SM, Thomazini M, Balieiro JCC, Castillo CJC. Microencapsulation of propolis extract by complex coacervation. LWT—Food Science and Technology. 2011; 44(2):429-435. DOI: 10.1016/j.lwt.2010.09.010
Hosseini SF, Zandi M, Rezaei M, Farahmangdghavi F. Two-step method for encapsulation of oregano essential oil in chitosan nanoparticles: Preparation, characterization and in vitro release study. Carbohydrate Polymers. 2013; 95:50-56. DOI: 10.1016/j.carbpol.2013.02.031
Beirão-Da-Costa S, Duarte C, Bourbon AI, Pinheiro NC, Januário MIN, Vicente AA, Beirão-Da-Costa ML, Delgadillo I. Inulin potential for encapsulation and controlled delivery of Oregano essential oil. Food Hydrocolloids. 2013; 33(2):199-206. DOI: 10.1016/j.foodhyd.2013.03.009
Choi MJ, Soottitantawat A, Nuchuchua O, Min SG, Ruktanonchai U. Physical and light oxidative properties of eugenol encapsulated by molecular inclusion and emulsion–diffusion method. Food Research International. 2009; 42(1):148-156. DOI: 10.1016/j.foodres.2008.09.011
Singh M, Dua JS, Menra M, Soni M, Prasad DN. Microencapsulation and its various aspects: a review. International Journal of Advanced Research. 2016; 4:2094-2108
Wu Y, Luo Y, Wang Q. Antioxidant and antimicrobial properties of essential oils encapsulated in zein nanoparticles prepared by liquid-liquid dispersion method. LWT—Food Science and Technology. 2012; 48(2):283-290. DOI: 10.1016/j.lwt.2012.03.027
Kamimura JA, Santos EH, Hill LE, Gomes CL. Antimicrobial and antioxidant activities of carvacrol microencapsulated in hidroxypropyl-beta-ciclodextryn. LWT—Food Science and Technology. 2014; 57:701-709. DOI: 10.1016/j.lwt.2014.02.014
Pinho E, Grootveld M, Soares G, Henriques M. Cyclodextrins as encapsulation agents for plant bioactive compounds. Carbohydrate Polymers. 2014; 101:121-135. DOI: 10.1016/j.carbpol.2013.08.078
Wang S, Marcone MF, Barbut S, Lim LT. Fortification of dietary biopolymers-based packaging material with bioactive plant extracts. Food Research International. 2012; 49(1):80-91. DOI: 10.1016/j.foodres.2012.07.023
Vemmer M, Patel AV. Review of encapsulation methods suitable for microbial biological control agents. Biological Control. 2013; 67(3):380-389. DOI: 10.1016/j.biocontrol.2013.09.003
Martins IM, Barreiro MF, Coelho M, Rodrigues AE. Microencapsulation of essential oils with biodegradable polymeric carriers for cosmetic applications. Chemical Engineering Journal. 2014; 245:191-200. DOI: 10.1016/j.cej.2014.02.024
Gharsallaoui A, Roudaut G, Chambin O, Voilley A, Saurel R. Applications of spray-drying in microencapsulation of food ingredients: An overview. Food Research International. 2007; 40(9):1107-1121. DOI: 10.1016/j.foodres.2007.07.004
Silva PT, Fries LCM, Menezes CR, Holkem AT, Schwan CL, Wigmann EF, Bastos JO, Silva CB. Microencapsulation: concepts, mechanisms, methods and some applications in food technology. Ciência Rural. 2014; 44:1304-1311. DOI: 10.1590/0103-8478cr20130971
Suganya V, Anuradha V. Microencapsulation and Nanoencapsulation: A review. International Journal of Pharmaceutical and Clinical Research. 2017; 9:233-239. DOI: 10.25258/ijpcr.v9i3.8324
Jyothi NVN, Prasanna PM, Sakarkar SN, Prabha KS, Ramaiah PS, Srawan GY. Microen-capsulation techniques, factors influencing encapsulation efficiency. Journal of Microen-capsulation. 2010; 27(3):187-197. DOI: 10.3109/02652040903131301
Nesterenko A, Alric I, Silvestre F, Durrieu V. Vegetable proteins in microencapsulation: A review of recent interventions and their effectiveness. Industrial Crops and Products. 2013; 42:469-479. DOI: 10.1016/j.indcrop.2012.06.035
Gaonkar A, Niraj V, Khare A, Sobel R, editors. Microencapsulation in the Food Industry: A Practical Implementation Guide. 1st ed. USA: Elsevier; 2014. 590 p
Nazzaro F, Orlando P, Fratianni F, Coppola R. Microencapsulation in food science and biotechnology. Current Opinion in Biotechnology. 2012; 23(2):182-186. DOI: 10.1016/j.copbio.2011.10.001
Fathi M, Mozafari MR, Mohebbi M. Nanoencapsulation of food ingredients using lipid based delivery systems. Trends in Food Science & Technology. 2012; 23(1):13-27. DOI: 10.1016/j.tifs.2011.08.003
Dalmoro A, Barba AA, Lamberti G, D’Amore M. Intensifying the microencapsulation process: Ultrasonic atomization as an innovative approach. European Journal of Pharmaceutics and Biopharmaceutics. 2012; 80(3):471-477. DOI: 10.1016/j.ejpb.2012.01.006
Risch SJ, Reineccius GA. Encapsulation and Controlled Release of Food Ingredients. Washington, DC: American Chemical Society (ACS); 1995. 214 p. DOI: 10.1021/bk-1995-0590
Roccia P, Martínez ML, Llabot JM, Ribotta PD. Influence of spray-drying operating conditions on sunflower oil powder qualities. Powder Technology. 2014; 254:307-313. DOI: 10.1016/j.powtec.2014.01.044
Turchiuli C, Munguia MTJ, Sanchez MH, Ferre HC, Dumoulin E. Use of different supports for oil encapsulation in powder by spray drying. Powder Technology. 2014; 255:103-108. DOI: 10.1016/j.powtec.2013.08.026
Carneiro HCF, Tonon RV, Grosso CRF, Hubinger MD. Encapsulation efficiency and oxidative stability of flaxseed oil microencapsulated by spray drying using different combinations of wall materials. Journal of Food Engineering. 2013; 115(4):443-451. DOI: 10.1016/j.jfoodeng.2012.03.033
Gallo L, Llabot JM, Allemandi D, Bucalá V, Piña J. Influence of spray-drying operating conditions on Rhamnus purshiana( Cáscara sagrada) extract powder physical properties. Powder Technology. 2011; 208(1):205-214. DOI: 10.1016/j.powtec.2010.12.021
Mahdavi SA, Jafari SM, Ghorbani M, Assadpoor E. Spray-drying microencapsulation of anthocyanins by natural biopolymers: A review. Drying Technology. 2014; 32(5):509-518. DOI: 10.1080/07373937.2013.839562
Fernandes RVB, Carmo EL, Borges SV, Botrel DA, Silva YF, Souza HJB. Comportamento de óleo essencial de alecrim microencapsulado por spray drying em diferentes umidades relativas. Ciência Agrícola. 2016; 14(1):73-82. DOI: 0103-8699
Goñi ML, Gañán NA, Strumia MC, Martini RE. Eugenol-loaded LLDPE films with antioxidant activity by supercritical carbon dioxide impregnation. Journal of Supercritical Fluids. 2016; 111:28-35. DOI: 10.1016/j.supflu.2016.01.012
Oliveira DA, Mezzomo N, Gomes C, Ferreira SRS. Encapsulation of passion fruit seed oil by means of supercritical antisolvent process. Journal of Supercritical Fluids. 2017; 129:96-105. DOI: 10.1016/j.supflu.2017.02.011
Gallardo G, Guida L, Martinez V, López MC, Bernhardt D, Blasco R, Pedroza-Islas R, Hermida LG. Microencapsulation of linseed oil by spray drying for functional food application. Food Research International. 2013; 52(2):473-482. DOI: 10.1016/j.foodres.2013.01.020
Sutaphanit P, Chitprasert P. Optimisation of microencapsulation of holy basil essential oil in gelatin by response surface methodology. Food Chemistry. 2014; 150:313-320. DOI: 10.1016/j.foodchem.2013.10.159
Xiao Z, Liu W, Zhu G, Zhou R, Niu Y. Production and characterization of multinuclear microcapsules encapsulating lavender oil by complex coacervation. Flavour and Fragrance Journal. 2013; 29(3):166-172. DOI: 10.1002/ffj.3192
Jun-Xia X, Hai-Yan Y, Jian Y. Microencapsulation of sweet orange oil by complex coacervation with soybean protein isolate/gum Arabic. Food Chemistry. 2011; 125(4):1267-1272. DOI: 10.1016/j.foodchem.2010.10.063
Peng C, Zhao S-Q, Zhang J, Huang G-Y, Chen L-Y, Zhao F-Y. Chemical composition, antimicrobial property and microencapsulation of Mustard ( Sinapis alba) seed essential oil by complex coacervation. Food Chemistry. 2014; 165:560-568. DOI: 10.1016/j.foodchem.2014.05.126
Dima C, Cotârlet M, Alexe P, Dima S. Microencapsulation of essential oil of pimento [ Pimenta dioica(L) Merr.] by chitosan/k-carrageenan complex coacervation method. Innovative Food Science and Emerging Technologies. 2014; 22:203-211. DOI: 10.1016/j.ifset.2013.12.020
Hwisa NT, Katakam P, Chandu BR, Adiki SK. Solvent evaporation techniques as promising advancement in microencapsulation. Vedic Research International Biological Medicinal Chemistry. 2013; 1(1):8-22. DOI: 10.14259/bmc.v1i1.29
Patil DK, Agrawal DS, Mahire RR, More DH. Synthesis, characterization and controlled release studies of ethyl cellulose microcapsules incorporating essential oil using an emulsion solvent evaporation method. American Journal of Essential Oils and Natural Products. 2016; 4(1):23-31. DOI: 2321 9114
Soliman EA, El-Moghazy AY, El-Din MSM, Massoud MA. Microencapsulation of essential oils within alginate: formulation and in vitro evaluation of antifungal activity. Journal of Encapsulation and Adsorption Sciences. 2013; 3(1):48-55. DOI: 10.4236/jeas.2013.31006
Calvo P, Castaño AL, Lozano M, González-Gómez D. Influence of the microencapsulation on the quality parameters and shelf-life of extra-virgin olive oil encapsulated in the presence of BHT and different capsule wall components. Food Research International. 2012; 45(1):256-261. DOI: 10.1016/j.foodres.2011.10.036
Ezhilarasi PN, Indrani D, Jena BS, Anandharamakrishnan C. Freeze drying technique for microencapsulation of Garcinia fruit extract and its effect on bread quality. Journal of Food Engineering. 2013; 117(4):513-520. DOI: 10.1016/j.jfoodeng.2013.01.009
Almeida AP, Rodríguez-Rojo S, Serra AT, Vila-Real H, Simplicio AL, Delgadilho I, Da Costa SB, Da Costa LB, Nogueira ID, Duarte CMM. Microencapsulation of oregano essential oil in starch-based materials using supercritical fluid technology. Innovative Food Science & Emerging Technologies. 2013; 20:140-145. DOI: 10.1016/j.ifset.2013.07.009
Varona S, Rodríguez-Rojo A, Martín A, Cocero MJ, Duarte CMM. Supercritical impregnation of lavandin ( Lavandula hybrida) essential oil in modified starch. The Journal of Supercritical Fluids. 2011; 58(2):313-319. DOI: 10.1016/j.supflu.2011.06.003
Ciftci ON, Temelli F. Formation of solid lipid microparticles from fully hydrogenated canola oil using supercritical carbon dioxide. Journal of Food Engineering. 2016; 178:137-144. DOI: 10.1016/j.jfoodeng.2016.01.014
Szejtli J. Introduction and general overview of cyclodextrin chemistry. Chemical Reviews. 1998; 98(5):1743-1753. DOI: 10.1021/cr970022c
Teixeira B, Marques A, Pires C, Ramos C, Batista I, Saraiva JA, Nunes ML. Characterization of fish protein films incorporated with essential oils of clove, garlic and origanum: Physical, antioxidant and antibacterial properties. LWT—Food Science and Technology. 2014; 59(1):533-539. DOI: 10.1016/j.lwt.2014.04.024
Aguiar UN, De Lima SG, Rocha MS, De Freitas RM, Oliveira TM, Silva RM, Moura LCB, De Almeida LTG. Preparação e caracterização do complexo de inclusão do óleo essencial de croton zehntneri com β-ciclodextrina. Química Nova. 2014; 37(1):50-55. DOI: 10.1590/S0100-40422014000100010
Lyra MAM, Alves LDS, Fontes DAF, Soares-Sobrinho JL, Rolim-Neto PJ. Ferramentas analíticas aplicadas à caracterização de complexos de inclusão fármacociclodextrina. Revista de Ciências Farmacêuticas Básica e Aplicada. 2010; 31(2):117-124. DOI: 1808-4532
Cevallos PAP, Buera MP, Elizalde BE. Encapsulation of cinnamon and thyme essential oils components (cinnamaldehyde and thymol) in β-cyclodextrin: Effect of interactions with water on complex stability. Journal of Food Engineering. 2010; 99(1):70-75. DOI: 10.1016/j.jfoodeng.2010.01.039
Rakmai J, Cheirsilp B, Mejuto JC, Torrado-Agrasar A, Simal-Gándara J. Physico-chemical characterization and evaluation of bio-efficacies of black pepper essential oil encapsulated in hydroxypropyl-betacyclodextrin. Food Hydrocolloids. 2017; 65:157-164. DOI: 10.1016/j.foodhyd.2016.11.014
Babaoglu HC, Bayrak A, Ozdemir N, Ozgun N. Encapsulation of clove essential oil in hydroxypropyl beta-cyclodextrin for characterization, controlled release, and antioxidant activity. Journal of Food Processing and Preservation. Forthcoming. DOI: 10.1111/jfpp.13202
Marques HMC. A review on cyclodextrin encapsulation of essential oils and volatiles. Flavour and Fragrance Journal. 2010; 25(5):313-326. DOI: 10.1002/ffj.2019
Wang J, Cao Y, Sun B, Wang C. Physicochemical and release characterisation of garlic oil-ß-cyclodextrin inclusion complexes. Food Chemistry. 2011; 127(4):1680-1685. DOI: 10.1016/j.foodchem.2011.02.036
Szente L, Szejtli J. Cyclodextrins as food ingredientes. Trends in Food Science and Technology. 2004; 15(3-4):137-142. DOI: 10.1016/j.tifs.2003.09.019
Bobbio PA, Bobbio FO. Química do processamento de alimentos. 2nd ed. São Paulo: Varela; 1995. 151 p. DOI: 8585519126
Antunes MD, Dannenberg GS, Fiorentini AM, Pinto VZ, Lim L-T, Zavareze ER, Dias ARG. Antimicrobial electrospun ultrafine fibers from zein containing eucalyptus essential oil/cyclodextrin inclusion complex. International Journal of Biological Macromolecules. 2017; 104:874-882. DOI: 10.1016/j.ijbiomac.2017.06.095
Hattrem MN, Kristiansen KA, Aachmann FL, Dille MJ, Draget KI. Ibuprofen-in-cyclodextrin-in-W/O/W emulsion—Improving the initial and long-term encapsulation efficiency of a model active ingredient. International Journal of Pharmaceutics. 2015; 487(1-2):1-7. DOI: 10.1016/j.ijpharm.2015.03.059
Khatibi SA, Misaghi A, Moosavy M, Basti AA, Koohi MK, Khosravi P, Haghirosada F. Encapsulation of Zataria Multiflora Bioss. essential oil into nanoliposomes and in vitro antibacterial activity against Escherichia coli O157:H7. Journal of Food Processing and Preservation. 2017; 41(3):1-10. DOI: 10.1111/jfpp.12955
Devi KP, Nisha SA, Sakthivel R, Pandian SK. Eugenol (an essencial oil of clove) acts as an antibacterial agent against Samonella typhi by disrupting the cellular membrane. Journal of Ethnopharmacology. 2010; 130(1):107-115. DOI: 10.1016/j.jep.2010.04.025
Chatterjee D, Bhattacharjee P. Comparative evaluation of the antioxidant efficacy of encapsulated and un-encapsulated eugenol-rich clove extracts in soybean oil: Shelf-life and frying stability of soybean oil. Jounal of Food Engineering. 2013; 117(4):545-550. DOI: 10.1016/j.jfoodeng.2012.11.016
Machín R, Isasi JR, Vélaz I. Cyclodextrin hydrogels as potential drug delivery systems. Carbohydrate Polymers. 2012; 87(3):2024-2030. DOI: 10.1016/j.carbpol.2011.10.024
Zhao Y, Sun C, Shi F, Firempong CK, Yu J, Xu X, Zhang W. Preparation, characterization, and pharmacokinetics study of capsaicin via hydroxypropyl-beta-cyclodextrin encapsulation. Pharmaceutical Biology. 2016; 54(1):130-138. DOI: 10.3109/13880209.2015.1021816
Liu H, Cai X, Wang Y, Chen J. Adsorption mechanism-based screening of cyclodextrin polymers for adsorption and separation of pesticides from water. Water Research. 2011; 45(11):3499-3511. DOI: 10.1016/j.watres.2011.04.004
Ge X, He J, Qi F, Yang Y, Huang Z, Lu R, Huang L. Inclusion complexation of chloropropham with -cyclodextrin: Preparation, characterization and molecular modeling. Spectrochimica Acta Part A. 2011; 81:397-403. DOI: 10.1016/j.saa.2011.06.028
Garrido J, Cagide F, Melle-Franco M, Borges F, Garrido EM. Microencapsulation of herbicide MCPA with native b-cyclodextrin and its methyl and hydroxypropyl derivatives: An experimental and theoretical investigation. Journal of Molecular Structure. 2014; 1061:76-81. DOI: 10.1016/j.molstruc.2013.12.067
Teixeira BN, Ozdemir N, Hill LE, Gomes CL. Synthesis and characterization of nano-encapsulated black pepper oleoresin using hydroxypropyl beta-cyclodextrin for antioxidant and antimicrobial applications. Journal of Food Science. 2013; 78(12):1913-1920. DOI: 10.1111/1750-3841.12312
Tao F, Hill LE, Peng Y, Gomes CL. Synthesis and characterization of ß-cyclodextrin inclusion complexes of thymol and thyme oil for antimicrobial delivery applications. LWT—Food Science and Technology. 2014; 59(1):247-255. DOI: 10.1016/j.lwt.2014.05.037
Shao P, Zhang J, Fang Z, Sun P. Complexing of chlorogenic acid with b-cyclodextrins: Inclusion effects, antioxidative properties and potential application in grape juice. Food Hydrocolloids. 2014; 41:132-139. DOI: 10.1016/j.foodhyd.2014.04.003
Gong L, Li T, Chen F, Duan X, Yuan Y, Zhang D, Jiang Y. An inclusion complex of eugenol into β-cyclodextrin: Preparation, and physicochemical and antifungal characterization. Food Chemistry. 2016; 196:324-330. DOI: 10.1016/j.foodchem.2015.09.052
Porte A, Porte LHM, De Oliveira LM. Cromatografia gasosa quiral na resolução de enantiômeros envolvidos em flavours de frutas. Química Nova. 2014; 37(10):1670-1679. DOI: 10.5935/0100-4042.20140262
Santos EH, Kamimura JA, Hill LE, Gomes CL. Characterization of carvacrol beta-cyclodextrin inclusion complexes as delivery systems for antibacterial and antioxidant applications. LWT—Food Science and Technology. 2015; 60(1):583-592. DOI: 10.1016/j.lwt.2014.08.046
De Souza RC, Valarini Júnior O, Pinheiro KH, Klososki SJ, Pimentel TC, Cardozo Filho L, Barão CE. Prebiotic green tea beverage added inclusion complexes of catechin and β-cyclodextrin: Physicochemical characteristics during storage. LWT—Food Science and Technology. 2017; 85:212-217. DOI: 10.1016/j.lwt.2017.07.022
Wei Y, Zhang J, Memon AH, Liang H. Molecular model and in vitro antioxidant activity of a water-soluble and stable phloretin/hydroxypropyl-β-cyclodextrin inclusion complex. Journal of Molecular Liquids. 2017; 236:68-75. DOI: 10.1016/j.molliq.2017.03.098
Thompson DO. Cyclodextrins—enabling excipients: Their present and future use in pharmaceuticals. Critical Reviews in Therapeutic Drug Carrier Systems. 1997; 14(1):101-104. DOI: 10.1615/CritRevTherDrugCarrierSyst.v14.i1.10
Hirayama F, Uekama K. Cyclodextrin-based controlled drug release system. Advanced Drug Delivery Reviews. 1999; 36(1):125-141. DOI: 10.1016/S0169-409X(98)00058-1
Rowe RC, Sheskey PJ, Owen SC. Handbook of Pharmaceutical Excipients. 50th ed. American Pharmaceutial Association: London, Chicago; 2006. 918 p
Cunha-Filho MSS, Sá-Barreto LCL. Utilização de ciclodextrinas na formação de complexos de inclusão de interesse farmacêutico. Revista de Ciências Farmacêuticas Básica e Aplicada. 2007; 28(1):1-9. DOI: 1808-4532
Liang H, Yuan Q, Vriesekoop F, Lv F. Effects of cyclodextrins on the antimicrobial activity of plant-derived essential oil compounds. Food Chemistry. 2012; 135(3):1020-1027. DOI: 10.1016/j.foodchem.2012.05.054
Antisperger G. New aspects in cyclodextrin toxicology. In: 6th International Symposium on Cyclodextrins; Abril; Chicago. Chicago: Editions de Santé; 1992. p. 227-283
Abarca RL, Rodríguez FJ, Guarda A, Galotto MJ, Bruna JE. Characterization of beta-cyclodextrin inclusion complexes containing an essential oil componente. Food Chemistry. 2016; 196:968-975. DOI: 10.1016/j.foodchem.2015.10.023
Wang B, Qian X, Shi Y, Yu B, Hong N, Song L, Hu Y. Cyclodextrin microencapsulated ammonium polyphosphate: Preparation and its performance on the thermal, flame retardancy and mechanical properties of ethylene vinyl acetate copolymer. Composites: Part B. 2015; 69:22-30. DOI: 10.1016/j.compositesb.2014.09.015
Kayaci F, Sen HS, Durgun E, Uyar T. Functional electrospun polymeric nanofibers incorporating geraniol–cyclodextrin inclusion complexes: High thermal stability and enhanced durability of geraniol. Food Research International. 2014; 62:424-431. DOI: 10.1016/j.foodres.2014.03.033
Hădărugă DI, Hădărugă NG, Costescu CI, David I, Gruia AT. Thermal and oxidative stability of the Ocimum basilicumL. essential oil/β-cyclodextrin supramolecular system. Beilstein Journal of Organic Chemistry. 2014; 10:2809-2820. DOI: 10.3762/bjoc.10.298
Kalogeropoulos N, Yannakopoulou K, Gioxari A, Chiou A, Makris DP. Polyphenol characterization and encapsulation in β-cyclodextrin of a flavonoid-rich Hypericum perforatum(St John’s wort) extract. LWT—Food Science and Technology. 2010; 43(6):882-889. DOI: 10.1016/j.lwt.2010.01.016
Hădărugă DI, Ünlüsayin M, Gruia AT, Birău C, Rusu G, Hădărugă NG. Thermal and oxidative stability of Atlantic salmon oil ( Salmo salarL.) and complexation with β-cyclodextrin. Beilstein Journal of Organic Chemistry. 2016; 12:179-191. DOI: 10.3762/bjoc.12.20
Li W, Liu X, Yang Q, Zhang N, Du Y, Zhu H. Preparation and characterization of inclusion complex of benzyl isothiocyanate extracted from papaya seed with β-cyclodextrin. Food Chemistry. 2015; 184:99-104. DOI: 10.1016/j.foodchem.2015.03.091
Zhou Q, Wei X, Dou W, Chou G, Wang Z. Preparation and characterization of inclusion complexes formed between baicalein and cyclodextrins. Carbohydrate Polymers. 2013; 95:733-739. DOI: 10.1016/j.carbpol.2013.02.038
Vilanova N, Solans C. Vitamin A Palmitate–b-cyclodextrin inclusion complexes: Characterization, protection and emulsification properties. Food Chemistry. 2015; 175:529-535. DOI: 10.1016/j.foodchem.2014.12.015
Fernandes A, Rocha MAA, LMNBF S, Brás J, Oliveira J, Mateus N, Freitas V. Blackberry anthocyanins: β-Cyclodextrin fortification for thermal and gastrointestinal stabilization. Food Chemistry. 2018; 245:426-431. DOI: 10.1016/j.foodchem.2017.10.109