Applications of Spray-drying in Microencapsulation of Food Ingredients- An Overview

www.elsevier.com/locate/foodres

Food Research International 40 (2007) 1107–1121

Review

Applications of spray-drying in microencapsulation of foodingredients: An overview

Adem Gharsallaoui *, Gaelle Roudaut, Odile Chambin, Andree Voilley, Remi Saurel

Eau, Molecules Actives, Macromolecules, Activite (EMMA), ENSBANA, Universite de Bourgogne, 1 Esplanade Erasme, 21000 Dijon, France

Received 2 March 2007; accepted 21 July 2007

Abstract

Spray-drying process has been used for decades to encapsulate food ingredients such as flavors, lipids, and carotenoids. During thisdrying process, the evaporation of solvent, that is most often water, is rapid and the entrapment of the interest compound occurs quasi-instantaneously. This required property imposes a strict screening of the encapsulating materials to be used in addition to an optimiza-tion of the operating conditions. Likewise, if the encapsulated compound is of hydrophobic nature, the stability of the feed emulsionbefore drying should also be considered. Thus, spray-drying microencapsulation process must rather be considered as an art than a sci-ence because of the many factors to optimize and the complexity of the heat and mass transfer phenomena that take place during themicrocapsule formation. This paper reports the main process engineering information that are considered useful to the success of amicroencapsulation operation by spray-drying. Besides, a summary of the most commonly used wall materials and the main encapsu-lated food compounds are presented.� 2007 Elsevier Ltd. All rights reserved.

Keywords: Spray-drying; Microencapsulation; Core; Wall material; Food applications

Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11082. Spray-drying: summary of some technical considerations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1109

0963-9doi:10.

* CoE-m

2.1. Atomization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11092.2. Droplet – hot air contact . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11092.3. Evaporation of droplet water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11092.4. Dry product-humid air separation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1110

3. Spray-drying as a process for microencapsulation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1110
3.1. Microencapsulation process steps. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11113.2. Operating conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1111
4. Microencapsulation by spray-drying: which wall must be used? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1112
4.1. Wall material required properties. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11124.2. Wall material selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11134.3. Most commonly used wall materials. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1113
4.3.1. Carbohydrates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11144.3.2. Gums . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11154.3.3. Proteins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1115

969/$ - see front matter � 2007 Elsevier Ltd. All rights reserved.1016/j.foodres.2007.07.004

rresponding author.ail address: [email protected] (A. Gharsallaoui).

mailto:[email protected]

1108 A. Gharsallaoui et al. / Food Research International 40 (2007) 1107–1121

5. Some examples of food ingredients microencapsulated by spray-drying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1116
5.1. Flavors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11165.2. Lipids and oleoresins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11175.3. Other food ingredients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1117
6. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1118Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1118References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1118

Fig. 1. Morphology of different types of microcapsules (Gibbs et al.,1999).

1. Introduction

Thanks to microencapsulated ingredients, many prod-ucts that were considered technically unfeasible are nowpossible. Such ingredients are totally enveloped in a coat-ing material, thereby conferring useful or eliminating use-less properties to or from the original ingredient.Microencapsulation is defined as a process in which tinyparticles or droplets are surrounded by a coating, orembedded in a homogeneous or heterogeneous matrix, togive small capsules with many useful properties. Microen-capsulation can provide a physical barrier between the corecompound and the other components of the product. Moreespecially, in the food field, microencapsulation is a tech-nique by which liquid droplets, solid particles or gas com-pounds are entrapped into thin films of a food grademicroencapsulating agent. The core may be composed ofjust one or several ingredients and the wall may be singleor double-layered. The retention of these cores is governedby their chemical functionality, solubility, polarity and vol-atility. Shahidi and Han (1993) proposed six reasons forapplying microencapsulation in food industry: to reducethe core reactivity with environmental factors; to decreasethe transfer rate of the core material to the outside environ-ment; to promote easier handling; to control the release ofthe core material; to mask the core taste; and finally todilute the core material when it should be used in only verysmall amounts.

In its simplest form, a microcapsule is a small spherewith a uniform wall around it. The material inside themicrocapsule is referred to as the core, internal phase, orfill, whereas the wall is sometimes called shell, coating, wall

material, or membrane. Practically, the core may be a crys-talline material, a jagged adsorbent particle, an emulsion, asuspension of solids, or a suspension of smaller microcap-sules. The microcapsule may even have multiple walls. Inthis review, only ‘‘core’’ and ‘‘wall’’ will be used to referto the encapsulated ingredient and encapsulating agent,respectively.

Most microcapsules are small spheres with diameterscomprised between a few micrometers and a few millime-ters. However many of these microcapsules bear littleresemblance to these simple spheres. In fact, both the sizeand shape of formed microparticles depend on the materi-als and methods used to prepare them. The different typesof microcapsules and microspheres are produced from awide range of wall materials (monomers and/or polymers)

and by a large number of different microencapsulation pro-cesses such as: spray-drying, spray-cooling, spray-chilling,air suspension coating, extrusion, centrifugal extrusion,freeze-drying, coacervation, rotational suspension separa-tion, co-crystallization, liposome entrapment, interfacialpolymerization, molecular inclusion, etc. (Desai & Park,2005; Gibbs, Kermasha, Alli, & Mulligan, 1999; Gouin,2004; King, 1995; Shahidi & Han, 1993). Depending onthe physico-chemical properties of the core, the wall com-position, and the used microencapsulation technique, dif-ferent types of particles can be obtained (Fig. 1): simplesphere surrounded by a coating of uniform thickness; par-ticle containing an irregular shape core; several core parti-cles embedded in a continuous matrix of wall material;several distinct cores within the same capsule and multi-walled microcapsules.

Although most often considered as a dehydration pro-cess, spray-drying can be used to encapsulate active mate-rial within a protective matrix formed from a polymer ormelt (Dziezak, 1988). Although many techniques have beendeveloped to microencapsulate food ingredients, spray-dry-ing is the most common technology used in food industrydue to low cost and available equipment. Microencapsula-tion by spray-drying has been successfully used in the food

A. Gharsallaoui et al. / Food Research International 40 (2007) 1107–1121 1109

industry for several decades (Gouin, 2004), and this processis one of the oldest encapsulation methods used since the1930s to prepare the first encapsulated flavors using gumacacia as wall material (Shahidi & Han, 1993).

The objective of this paper is to review the state of theart of microencapsulation of food ingredients by spray-dry-ing and present necessary theoretical and practical infor-mation on this process. Thus, the present paper discussesthe uses of spray-drying for microencapsulation ends fromfour perspectives. First, it focuses on some theoreticalaspects of the spray-drying process. Next, the paper dis-cusses the application of spray-drying in microencapsula-tion of food ingredients. The third section presentscriteria required for encapsulating agents and describesseveral wall materials that have proved good encapsulationefficiency. The final part summarizes important recentapplications concerning the microencapsulation of foodingredients by spray-drying.

2. Spray-drying: summary of some technical considerations

Spray-drying is a unit operation by which a liquid prod-uct is atomized in a hot gas current to instantaneouslyobtain a powder. The gas generally used is air or morerarely an inert gas as nitrogen. The initial liquid feedingthe sprayer can be a solution, an emulsion or a suspension.Spray-drying produces, depending on the starting feedmaterial and operating conditions, a very fine powder(10–50 lm) or large size particles (2–3 mm).

Water removal by spray-drying solutions is a commonengineering practice. By decreasing water content andwater activity, spray-drying is generally used in food indus-try to ensure a microbiological stability of products, avoidthe risk of chemical and/or biological degradations, reducethe storage and transport costs, and finally obtain a prod-uct with specific properties like instantaneous solubility forexample. The spray-drying process has been developed inconnection with the manufacture of dried milk. However,when milk is spray-dried, the process can be consideredas a microencapsulation one; milk fat is being the corematerial that is protected against oxidation by a wall mate-rial consisting of a mix of lactose and milk proteins. In thismix, the carbohydrates provide structure through glass for-mation whereas the proteins provide emulsification andfilm forming properties.

We present in this part some fundamental informationconcerning the process of spray-drying and we stronglythink that the knowledge of these considerations is veryimportant to carry out the process of microencapsulationby spray-drying.

2.1. Atomization

Liquid atomization in small droplets can be carried outby pressure or centrifugal energy. Used atomizers includepneumatic atomizer, pressure nozzle, spinning disk config-urations and recently two fluid nozzle and sonic nozzle

(Masters, 1968). The goal of this stage is to create a maxi-mum heat-transferring surface between the dry air and theliquid in order to optimize heat and mass transfers. Thechoice upon the atomizer configuration depends on thenature and viscosity of feed and the desired characteristicsof dried product. The higher the provided energy is, thefiner are the formed droplets. For the same energy amount,the size of formed particles increases with increasing feedrate. However, the size of particles increases when both vis-cosity and surface tension of the initial liquid are high. Sev-eral types of atomizers such as centrifugal, steam, andhomogenizing ones have been described by Bowen (1938).

2.2. Droplet – hot air contact

This contact takes place during atomization and initiatesthe drying stage. According to the atomizer emplacementcompared to the hot air spreader, one can distinguish co-current drying and counter-current one. In co-current pro-cess the liquid is sprayed in the same direction as the flowof hot air through the apparatus, hot air inlet temperatureis typically 150–220 �C, evaporation occurs instanta-neously (Fleming, 1921) and for which dry powders willbe exposed to moderate temperatures (typically 50–80 �C)which limits thermal degradations. Whereas, during coun-ter-current drying, the liquid is sprayed in the oppositedirection of the flow of hot air and for which the dry prod-uct is exposed to high temperatures which limits the appli-cations of this process to thermo-sensitive products.However, the main advantage of the counter-current pro-cess is that it is considered as more economic in term ofconsumed energy.

2.3. Evaporation of droplet water

At the time of droplets – hot air contact, balances oftemperature and vapor partial pressure are establishedbetween liquid and gas phases. Thus, heat transfer is car-ried out from air towards the product as a result of temper-ature difference whereas water transfer is carried out in theopposite direction due to the vapor pressure difference.

Based on the fundamental theory of drying, three suc-cessive steps can be distinguished. Just after the hot air –liquid contact, heat transfer principally causes the increaseof the droplets temperature up to a constant value. Thisvalue is defined as the air drying humid thermometer tem-perature; after that, the evaporation of droplets water iscarried out at constant temperature and water vapor par-tial pressure. The rate of water diffusion from the dropletcore to its surface is usually considered constant and equalto the surface evaporation rate. Finally, when the dropletwater content reaches a critical value, a dry crust is formedat the droplet surface and the drying rate rapidly decreaseswith the drying front progression and becomes dependenton the water diffusion rate through this crust. Drying istheoretically finished when the particle temperaturebecomes equal to that of the air.


These three steps have different durations depending onboth product nature and air inlet temperature. In fact, ifthe air inlet temperature is high, the dry crust is rapidlyformed because of the high water evaporation rate. Dueto the large surface to volume ratio of the atomized drop-lets, drying of formed droplets in the hot atmosphere is avery rapid process.

In a first stage, the hot gas causes an increase of thedroplet temperature, which promotes liquid evaporationfrom the droplet surface and a corresponding shrinkageof the droplet. The rapid migration of the water to thedroplet surface maintains a constant evaporation rate.At some point the suspended particles form a continuousnetwork. Originally the use of spray-drying was advo-cated as a rapid method for drying compounds whichshowed unacceptable levels of degradation when driedin the slower classic drying processes. Usually, dryingtimes are of the order of 5–100 s (Corrigan, 1995). How-ever, in a well-designed system 15–30 s is a fair time forthe passage of the sprayed particle through the dryingzone (Fogler & Kleinschmidt, 1938). The general spray-drying process mechanism description proposed by Flem-ing (1921) is still valid. In fact, at the moment of themixing of the air with the atomized liquid, the dryingtakes place almost instantaneously and an intensive evap-oration is taking place at the surface of each droplet. Theevaporation is so rapid that the droplet remains kept cooluntil the dry state is reached; this is due to the absorptionof heat in vaporizing the liquid. After the evaporation hasceased, the temperature of the particle rises to the generaltemperature of the drying chamber (Papadakis & King,1988a).

2.4. Dry product-humid air separation

This separation is often done through a cycloneplaced outside the dryer which reduces product lossesin the atmosphere: most dense particles are recoveredat the base of the drying chamber while the finest onespass through the cyclone to be separated from the humidair. In addition to cyclones, spray-dryers are commonlyequipped with both filters, called ‘‘bag houses’’ that areused to remove the finest powder, and chemical scrub-bers to remove the remaining powder or any volatilepollutants (e.g. flavorings). The obtained powder is madeof particles which originate from spherical drops aftershrinking. Depending on the composition, the waterand gas content of the drop, these particles can becompact or hollow (Bimbenet, Bonazzi, & Dumoulin,2002).

The use of multi-stage spray-dryers makes it possible toincrease the residence time and to decrease the drying tem-perature limiting thus thermal denaturation and improvingthermal effectiveness (kJ needed per kg of dry product)(Schuck, 2002). Moreover, integration of a fluidized bedon the drier outlet side makes it possible to better controlparticle size and to manufacture powders with very low

water contents (Turchiuli et al., 2005). Mass and heat bal-ances of a multistage spray-dryer were experimentallyestablished and the energy specific consumption was stud-ied (Bimbenet et al., 2002).

The morphological modifications of the particles duringspray-drying were described by Alamilla-Beltran, Chano-na-Perez, Jimenez-Aparicio, and Guiterrez-Lopez (2005).Changes of particle size and morphology during spray-dry-ing are related to moisture content and drying temperature.These changes are usually described by classical theory ofdrying. However, a method based on image analysis ofmaltodextrin particles at various vertical distances fromthe atomizing nozzle has been proposed (Alamilla-Beltranet al., 2005). Technical properties of spray-dried microcap-sules depend mainly on particle– particle interactions forflowability, and particle–liquid interactions for wettabilityand re-dispersibility.

Because of the complexity of the various spray-dryingsteps, spray-drier design has traditionally been based onexperience, trial-and-error, and pilot scale work. However,new development in Computational Fluid Dynamics(CFD) and drop size measurement have important effectson device design as well as residence-time distribution func-tion method (Paris, Ross, Dastur, & Morris, 1971). CFDwas applied in spray-drying of food ingredients (Langrish& Fletcher, 2001; Straatsma, Van Houwelingen, Steenber-gen, & De Jong, 1999) in order to predict thermal degrada-tion, aroma loss, wall deposition, and particle stickiness.Moreover, modeling of droplet morphology (Lin & Gen-try, 1999), particle formation (Lin & Gentry, 1997; Teunou& Poncelet, 2005), droplet shell formation (Lin, Zhang, &Gentry, 2000), as well as air temperature and humidity pro-files (Papadakis & King, 1988b) during spray-drying werereported. Mathematical modeling of spray-drying processis difficult because of the great number of parameters thatintervene during the process such as, droplets exhibitingevaporation, collision, breakups, agglomeration, heat andmass exchange between the droplets and the drying med-ium, among other factors (Negiz, Lagergren, & Cinar,1995).

3. Spray-drying as a process for microencapsulation

Spray-drying is the most common and cheapest tech-nique to produce microencapsulated food materials.Equipment is readily available and production costs arelower than most other methods. Compared to freeze-dry-ing, the cost of spray-drying method is 30–50 times cheaper(Desobry, Netto, & Labuza, 1997). Spray-drying has beenconsidered as a solution for conventional drying problemsbecause the process has usually proved not only efficientbut also economic (Masters, 1968). The economics ofspray-drying were discussed by Quinn (1965). However,Spray-drying is considered as an energy wasting operationbecause it is impossible to utilize all the heat going throughthe drying chamber.


3.1. Microencapsulation process steps

The application of spray-drying process in microencap-sulation involves three basic steps (Dziezak, 1988): prepa-ration of the dispersion or emulsion to be processed;homogenization of the dispersion; and atomization of themass into the drying chamber. However, and more detail-ing the third stage of the process, Shahidi and Han(1993) suggested that the microencapsulation by spray-dry-ing involves four stages: preparation of the dispersion oremulsion; homogenization of the dispersion; atomizationof the infeed emulsion; and dehydration of the atomizedparticles.

The first stage is the formation of a fine and stable emul-sion of the core material in the wall solution. The mixtureto be atomized is prepared by dispersing the core material,which is usually of hydrophobic nature, into a solution ofthe coating agent with which it is immiscible. The disper-sion must be heated and homogenized, with or withoutthe addition of an emulsifier depending on the emulsifyingproperties of the coating materials because some of themhave themselves interfacial activities. In the spray-dryingprocess, the initial emulsion droplets are in the order ofdiameter 1–100 lm. Before the spray-drying step, theformed emulsion must be stable over a certain period oftime (Liu et al., 2001), oil droplets should be rather smalland viscosity should be low enough to prevent air inclusionin the particle (Drusch, 2006). Emulsion viscosity and par-ticle size distribution have significant effects on microen-capsulation by spray-drying. High viscosities interferewith the atomization process and lead to the formationof elongated and large droplets that adversely affect thedrying rate (Rosenberg, Kopelman, & Talmon, 1990).The core material retention during microencapsulation byspray-drying is affected by the composition and the proper-ties of the emulsion and by the drying conditions.

The obtained oil-in-water emulsion is then atomizedinto a heated air stream supplied to the drying chamberand the evaporation of the solvent, usually water, conse-quently leads to the formation of microcapsules. As thesprayed particles fall through the gaseous medium, theyassume a spherical shape with the oil encased in the aque-ous phase (Dziezak, 1988). The short time exposition andthe rapid evaporation of water keep the core temperaturebelow 40 �C, in spite of the high temperatures generallyused in the process (Dubernet & Benoit, 1986).

3.2. Operating conditions

In order to obtain good microencapsulation efficiencyand even if the wall material is suitable, optimal spray-dry-ing conditions must be used. The main factors in spray-dry-ing that must be optimized are feed temperature, air inlettemperature, and air outlet temperature (Liu, Zhou, Zeng,& Ouyang, 2004). In fact, feed temperature modifies theviscosity of the emulsion, its fluidity and thus, its capacityto be homogenously sprayed. When the feed temperature is

increased, viscosity and droplets size should be decreasedbut high temperatures can cause volatilization or degrada-tion of some heat-sensitive ingredients. The rate of feeddelivered to the atomizer is adjusted to ensure that eachsprayed droplet reaches the desired drying level before itcomes in contact with the surface of the drying chamber.Moreover, appropriate adjustment of the air inlet temper-ature and flow rate is important (Zbicinski, Delag, Stru-millo, & Adamiec, 2002). In fact, air inlet temperature isdirectly proportional to the microcapsule drying rate andthe final water content. When the air inlet temperature islow, the low evaporation rate causes the formation ofmicrocapsules with high density membranes, high watercontent, poor fluidity, and easiness of agglomeration.However, a high air inlet temperature causes an excessiveevaporation and results in cracks in the membrane induc-ing subsequent premature release and a degradation ofencapsulated ingredient or also a loss of volatiles (Zakarian& King, 1982). The air inlet temperature is usually deter-mined by two factors: the temperature which can safelybe used without damaging the product or creating operat-ing hazards and the comparative cost of heat sources (Fog-ler & Kleinschmidt, 1938).

The temperature at the end of the drying zone, alsocalled in literature exhaust temperature or air outlet tem-perature, obtained under given conditions can be consid-ered as the control index of the dryer. It is quite difficultto predict this outlet temperature in advance for a givenproduct, since it depends on the drying characteristics ofthe material. Contrary to the air inlet temperature, theair outlet one cannot be directly controlled since it dependson the air inlet temperature, and the ideal air outlet temper-ature for the microencapsulation of food ingredients suchas flavors has been reported to be 50–80 �C. Table 1 sum-marizes experimental conditions that have been recentlyoptimized for the encapsulation of different food ingredi-ents by spray-drying. The best spray-drying conditionsare a compromise between high air temperature, high solidconcentration of the solution, and easy pulverization anddrying without expansion and cracks of final particles(Bimbenet et al., 2002).

Reineccius (1988) reported that the greatest loss of thevolatiles during microencapsulation by spray-drying takesplace at early stages of drying, prior to the formation ofa dry crust at the surface of the drying particles. However,the use of some specific compounds can modify the dryingproperties of microcapsules. Indeed, the addition of lactoseto the whey protein-based system appeared to enhancecrust formation by improving the drying properties of thewall. This positive effect of lactose has been attributed tothe formation of a continuous glass phase of lactose inwhich the protein chains are dispersed (Rosenberg & Sheu,1996). In addition, the lactose glass phase increases thehydrophilic nature of the wall matrix and limits the diffu-sion of the solvent through the wall (Moreau & Rosenberg,1996). It was expected also that heat denaturation of wheyproteins influences emulsification characteristics and thus

Table 1Experimental conditions recently optimized for the encapsulation of some different food ingredients by spray-drying

Encapsulated ingredient Wall material Feedtemperature(�C)

Air inlettemperature (�C)

Air outlettemperature (�C)

References

Anhydrous milk fat Whey proteins/lactose 50 160 80 Young et al. (1993)Ethyl butyrate ethyl caprylate Whey proteins/lactose 5 160 80 Rosenberg and Sheu

(1996)Oregano, citronella and

marjoram flavorsWhey proteins/milk proteins NR 185–195 85–95 Baranauskiene et al.

(2006)Soya oil Sodium caseinate/carbohydrates NR 180 95 Hogan et al. (2001)Calcium citrate calcium

lactateCellulose derivatives/polymethacrylic acid

NR 120–170 91–95 Oneda and Re(2003)

Lycopene Gelatin/sucrose 55 190 52 Shu et al. (2006)Fish oil Starch derivatives/glucose syrup NR 170 70 Drusch et al. (2006)Cardamom essential oil Mesquite gum Room T 195–205 105–115 Beristain et al.

(2001)Arachidonyl L-ascorbate Maltodextrin/gum arabic/soybean

polysaccharidesNR 200 100–110 Watanabe et al.

(2004)Cardamom oleoresin Gum arabic/modified starch/

maltodextrinNR 176–180 115–125 Krishnan et al.

(2005)Bixin Gum arabic/maltodextrin/sucrose Room T 180 130 Barbosa et al. (2005)D-Limonene Gum arabic/maltodextrin/modified

starchNR 200 100–120 Soottitantawat et al.

(2005a)L-Menthol Gum arabic/modified starch NR 180 95–105 Soottitantawat et al.

(2005b)Black pepper oleoresin Gum arabic/modified starch NR 176–180 105–115 Shaikh et al. (2006)Cumin oleoresin Gum arabic/maltodextrin/modified

starchNR 158–162 115–125 Kanakdande et al.

(2007)Fish oil Sugar beet pectin/glucose syrup NR 170 70 Drusch (2006)Caraway essential oil Milk proteins/whey proteins/

maltodextrinNR 175–185 85–95 Bylaite et al. (2001)

Short chain fatty acid Maltodextrin/gum arabic NR 180 90 Teixeira et al. (2004)

NR: not reported.


microencapsulating properties (Rosenberg & Sheu, 1996).Microencapsulation efficiency can be increased by increas-ing wall solution solids concentration which can be relatedto the effect of wall solids concentration on the formationof surface core prior to the formation of crust around thedrying droplets (Young, Sarda, & Rosenberg, 1993).

The main limitation of the spray-drying technique inmicroencapsulation is the limited number of wall materialsavailable and that must have a good solubility in water.Another disadvantage for spray-drying that should be con-sidered is that it produces a fine microcapsules powderwhich needs further processing such as agglomeration.

4. Microencapsulation by spray-drying: which wall must beused?

The choice of a wall material for microencapsulation byspray-drying is very important for encapsulation efficiencyand microcapsule stability. The criteria for selecting a wallmaterial are mainly based on the physico-chemical proper-ties such as solubility; molecular weight; glass/melting tran-sition; crystallinity; diffusibility; film forming andemulsifying properties. Moreover, the costs should be alsoconsidered. Thus, judicious choice of encapsulating mate-

rial according to the desired application is an importanttask.

4.1. Wall material required properties

The wall system is designed to protect core materialfrom factors that may cause its deterioration, to preventa premature interaction between the core material andother ingredients, to limit volatile losses, and also to allowcontrolled or sustained release under desired conditions(Shahidi & Han, 1993).

Depending on the core material and the characteristicsdesired in the final product, wall materials can be selectedfrom a wide variety of natural and synthetic polymers.Since almost all spray-drying processes in the food industryare carried out from aqueous feed formulation, the wallmaterial must be soluble in water at an acceptable level(Gouin, 2004). In addition to its high solubility, a wallmaterial for microencapsulation by spray-drying shouldpossess good properties of emulsification, film forming,and drying and the wall concentrated solutions should havelow viscosity (Reineccius, 1988). Many available wall mate-rials possess these properties but the number of materialsapproved for food uses is limited (Dziezak, 1988). Manybiopolymers have been used in microencapsulation of var-

Fig. 2. Schematic characteristic isothermal drying curves of various wallmaterials. See text for details. (Matsuno & Adachi, 1993).


ious food ingredients by spray-drying. The microencapsu-lation of food ingredients is often achieved with biopoly-mers of various sources, such as natural gums (gumarabic, alginates, carragenans, etc.), proteins (milk or wheyproteins, gelatin, etc.), maltodextrins with different dex-trose equivalence, waxes and their blends. However, typicalwall materials for microencapsulation by spray-drying arelow molecular weight carbohydrates, milk or soy proteins,gelatin and hydrocolloids like acacia gum (Reineccius,Ward, Whorten, & Andon, 1995; Thevenet, 1995) andmore recently local materials, such as mesquite gum (Beri-stain & Vernon-Carter, 1994; Beristain, Garcıa, & Vernon-Carter, 2001) have been used to overcome the expensivecost of some commonly used materials. Unusual novelmicroencapsulation methods based on interfacial engineer-ing technology have recently been developed in order toimprove quality of manufactured powder. Among thesemethods, a process of electrostatic layer-by-layer deposi-tion was successfully developed to prepare spray-driedmicrocapsules containing tuna oil (Klinkesorn, Sophano-dora, Chinachoti, Decker, & McClements, 2006). Thesemicrocapsules were reported to be unaffected by air inlettemperature probably because of the robustness of the wallbarrier.

4.2. Wall material selection

An important step in developing microcapsules is theselection of a wall material that meets required criteria(mechanical strength, compatibility with the food product,appropriate thermal or dissolution release, appropriateparticle size, etc. (Brazel, 1999). The selection of wall mate-rials for microencapsulation by spray-drying has tradition-ally involved trial-and-error procedures in which themicrocapsules are formed. The latter are then evaluatedfor encapsulation efficiency, stability under different stor-age conditions, degree of protection provided to the corematerial, surface observation by scanning microscopy,among other evaluations (Perez-Alonso, Baez-Gonzalez,Beristain, Vernon-Carter, & Vizcarra-Mendoza, 2003).

An important method that can be useful to determinesuitable composition of a wall material blend for lipidencapsulation has been proposed by Matsuno & Adachi(1993). A suitable material that can be used in this methodshould possess a high emulsifying activity, a high stability,a tendency to form a fine and dense network during dryingand should not permit lipid separation from the emulsionduring dehydration. This method is based on the measure-ment of the drying rate of an emulsion as a function ofmoisture content. Because the isothermal drying rate isgoverned by the diffusion rate of water during drying, thedrying rate may reflect the characteristics of the samplematrix: the finer and denser the matrix, the lower the dry-ing rate (Imagi, Yamanouchi, Okada, Tanimoto, & Mat-suno, 1992). A characteristic curve of drying rate hasbeen presented as a function of moisture content for fourgroups of wall materials (Fig. 2) (Matsuno & Adachi,

1993). This figure has been interpreted in term of abilityof the wall material to form a dense network. In fact, dry-ing rate of materials that gives type 1 curves decreases rap-idly as the water content decreases, that means a rapidformation of a dense skin and a good protection of coreingredient against oxygen transfer and possible deteriora-tion. Such a curve corresponds to maltodextrin, pullulan,gum arabic and gelatin. These materials were thus consid-ered as the most suitable for microencapsulation using adrying process. Characteristic type 2 materials are sub-stances of high molecular weight and with a three-dimen-sional structure such as sodium caseinate and albumin,type 3 materials are low molecular weight saccharides likeglucose, and type 4 materials are those that easily crystal-lize upon dehydration such as mannitol (Matsuno & Ada-chi, 1993). According to this interpretation, type 2, 3, and 4materials cannot efficiently protect encapsulated lipidsbecause they do not form a dense skin at an early stageof drying, and consequently are not suitable for this pur-pose. This method has been criticized for its lack of preci-sion and no-discrimination between materials showingsimilarly shaped drying curves (Perez-Alonso et al.,2003). Moreover, in order to screen the most suitable wallmaterial for lipid encapsulation, these authors proposed aquantitative method based on estimation of the activationenergy of carbohydrate polymers blends dried isother-mally. This method provides a quantitative discriminatingparameter and requires the knowledge of the drop volumeshrinkage of every conceivable blend.

4.3. Most commonly used wall materials

It is obvious that the chemical functionality, the solubil-ity and the diffusion through the forming matrix determinethe retention degree of core compounds during the prepa-ration of microcapsules by spray-drying. Therefore,


microencapsulation efficiency and microcapsules stabilityduring storage are largely dependent on wall material com-position. Carbohydrates such as starches, maltodextrinsand corn syrup solids are usually used in microencapsula-tion of food ingredients. However, wall materials that arebased on these compounds have poor interfacial propertiesand must be chemically modified in order to improve theirsurface activity. In contrast, proteins have an amphiphiliccharacter that offer physicochemical and functional proper-ties required to encapsulate hydrophobic core materials.Moreover, protein compounds such as sodium caseinate,soy protein isolate, and whey protein concentrates and iso-lates, could also be expected to have good microencapsu-lating properties.

4.3.1. Carbohydrates

Carbohydrates such as starches, corn syrup solids andmaltodextrins have been usually used as encapsulatingagents (DeZarn, 1995; Kenyon, 1995). These materialsare considered as good encapsulating agents because theyexhibit low viscosities at high solids contents and good sol-ubility, but most of them lack the interfacial propertiesrequired for high microencapsulation efficiency and gener-ally associated with other encapsulating materials such asproteins or gums. Soybean soluble polysaccharide was alsofound to be a superior emulsifier over gum arabic to retainmicroencapsulated ethyl butyrate during spray-drying(Yoshii et al., 2001). In addition, it is known that polysac-charides having gelling properties could stabilize emulsionstowards flocculation and coalescence (Dalgleish, 2006). Anovel approach to improve encapsulating properties ofcommon wall materials consists on chemical modificationsof carbohydrates. For example, some modified starcheshave surface active properties and are widely used in theprocess of microencapsulation by spray-drying. Hydro-lyzed starch products are hydrophilic compounds, thushave little affinity for hydrophobic flavors (Shaikh, Bho-sale, & Singhal, 2006). Their hydrophilic nature can bemodified by linking hydrophobic side chains like octenylones (Drusch & Schwarz, 2006).

Maltodextrins provide good oxidative stability to encap-sulated oil but exhibit poor emulsifying capacity, emulsionstability and low oil retention (Kenyon, 1995). However,the retention of emulsified ethyl butyrate during spray-dry-ing was shown to be dependent on the maltodextrin con-centration and the type of emulsifier (Yoshii et al., 2001).A maltodextrins characterization study published by Raja,Sankarikutty, Sreekumar, Jayalekshmy, & Narayanan(1989) showed that maltodextrins with dextrose equiva-lence between 10 and 20 fit in for using as wall material.Those maltodextrin samples show the highest retention offlavor because they could be dispersed in water up to35.5% of the solution without haze formation.

Sucrose, glucose and starch were reported to be notsuitable for spray-drying of sumac flavor due to theircaramelization properties, adherence to the surface of thespray-dryer, and heterogeneous form that caused the clog-

ging of the nozzle (Bayram, Bayram, & Tekin, 2005). Asfor trehalose, in its glassy state this disaccharide decreaseslipid oxidation and is therefore a suitable wall material formicroencapsulation purposes. However, a rapid oxidationof microencapsulated fish oil was observed upon crystalli-zation of trehalose, which limits the range of applicationsto products to be stored at low humidity (Drusch, Serfert,Van Den Heuvel, & Schwarz, 2006). These same authorsproposed to use polymers, mixtures of carbohydrates andsalts that are known to modify the kinetics of sugar crystal-lization in order to improve stability of microencapsulatedoils.

Pectin is a polymer able to produce stable emulsions atlow concentration. The emulsifying properties of pectin aredue to the protein residues present within the pectin chainand its chemical composition characterized by a highercontent of acetyl groups (Leroux, Langendorff, Schick,Vaishnav, & Mazoyer, 2003). A pectin content of 1–2% isconsidered to be sufficient for the preparation of a stableemulsion for spray-drying (Drusch, 2006). Sugar beet pec-tin could be considered as a suitable wall material formicroencapsulation of lipophilic food ingredients byspray-drying. Fish oil was successfully encapsulated in awall system containing sugar beet pectin as coating agentand glucose syrup as bulk one (Drusch, 2006). It was alsoshown that spray-drying had no effect on the majority offunctional properties of pectin (Monsoor, 2005).

Likewise, dry emulsions of oil dispersed in aqueoussolution of hydroxypropylmethyl-cellulose (HPMC) wereprepared by spray-drying (Christensen, Pedersen, & Kris-tensen, 2001a). The obtained powders were cohesive, butthe flow properties were improved by adding sucrose(Christensen, Pedersen, & Kristensen, 2001b). In anotherresearch paper, the same authors suggested that the re-crys-tallization of amorphous sucrose obtained by spray-dryingcould be avoided by storage below the glass transitiontemperature under dry conditions (Christensen, Pedersen,& Kristensen, 2002).

The use of low molecular weight carbohydrates inmicroencapsulation is usually associated with problems ofcaking, collapse and re-crystallization of the amorphouscarbohydrate upon storage. Caking can be explained bythe formation of inter-particle bonds between adjacent par-ticles when surface viscosity reached a critical value (LeMeste, Champion, & Roudaut, 2002). In addition, thepresence of fine particles and the distribution of grain sizeare particularly important for control and prevention ofsugar caking (Mathlouthi & Roge, 2003). Spray-dryingtechnique is known to be unsuitable for producing powdersof sugar and acid-rich foods due to their stickiness. In fact,the process of spray-drying may result in: disordering thesugar crystal lattice, formation of polymorphic orpseudo-polymorphic phase, elimination of crystallinity,and general in alteration in the energy of the dried solids(Corrigan, 1995). The rapid removal of water that occursby spray-drying produces amorphous materials and in thiscontext surface stickiness of droplet could be predicted


during spray-drying by many approaches such as glasstransition temperature (Adhikari, Howes, Lecomte, &Bhandari, 2005).

4.3.2. Gums

Gums are used in microencapsulation for both their filmforming and emulsion stabilization properties. Among allgums, acacia gum, generally called gum arabic, standsout due to its excellent emulsification properties and thusis widely used. Gum arabic is a polymer consisting of D-glu-curonic acid, L-rhamnose, D-galactose, and L-arabinose,with approximately 2% protein (Dickinson, 2003). Theemulsification properties of the gum arabic are attributedto the presence of this protein fraction (Dickinson, 2003).Gum arabic was found to be a better wall material forencapsulation of cardamom oleoresin than maltodextrinsand modified starch and the obtained microcapsules exhib-ited a free flowing character (Krishnan et al., 2005). It wasalso recently reported that gum arabic is good wall materialfor encapsulation of cumin oleoresin by spray-drying(Kanakdande, Bhosale, & Singhal, 2007). Gum arabic isusually preferred because it produces stable emulsions withmost oils over a wide pH range, and it also forms a visiblefilm at the oil interface. Because of this emulsifying effi-ciency, gum arabic has been usually used to encapsulatelipids (Kenyon, 1995). Typically the ratio of oil/wall mate-rial, when gum arabic is used, is lower than 0.15. Gum ara-bic is ideally suitable for the microencapsulation of lipidsbecause of both its surface activity and its film formingproperties. The partial replacement (50%) of gum arabicwith glucose was reported to increase microencapsulationefficiency of soy oil from 74% to 92% (McNamee, White,O’Riordan, & O’Sullivan, 2001). However maltodextrinDE 18.5 was considered as the most suitable partial repla-cer for gum arabic because the obtained wall material pre-sents a good solubility and a rapid reconstitution of theemulsion in water.

However, another study showed that gum arabic wasnot efficient as a wall material for the encapsulation of fivedifferent monoterpenes (citral, linalool, b-myrcene, limo-nene, and b-pinene) (Bertolini, Siani, & Grosso, 2001).Indeed, gum arabic-based obtained capsules show a limitedbarrier capacity against oxidation because they act as semi-permeable membranes and their permeability to oxygen isa preponderant factor in the shelf life of the core material.It was reported also that gum arabic is not effective asorange oil microencapsulant when it is compared to wheyand soy protein isolates. Moreover, this gum producedthe smallest orange oil encapsulating particles and the leaststable ones (Kim & Morr, 1996). Properties of gum arabicand other hydrocolloids at interfaces were well reviewed byDickinson (2003).

Likewise, expensive cost, limited supply, and qualityvariations have restricted the use of gum arabic for encap-sulation purpose and turned researchers to seek alternativemicroencapsulating materials. Since Beristain & Vernon-Carter (1994) reported that mesquite gum can be consid-

ered as an alternative inexpensive encapsulating polymerthat could entrap orange peel oil with a high efficiency.Later, this research group suggested that mesquite gumcan be used in the preparation of oil-in-water emulsions,over a wide range of pH values. Cardamom-based oilmicrocapsules were also successfully produced by spray-drying, and high efficiency (83.6%) was reached when mes-quite gum/oil ratio equal to 4 was used (Beristain et al.,2001).

4.3.3. Proteins

The excellent functional properties of proteins allowthem to be a good coating material for the microencapsu-lation by spray-drying. In addition, proteins possess highbinding properties for the flavor compounds (Landy, Dru-aux, & Voilley, 1995). The most commonly used proteinsfor encapsulating food ingredients by spray-drying are milk(or whey) proteins and gelatin.

Because they possess functional properties required formicrocapsule forming wall material (Rosenberg & Sheu,1996), whey proteins have been successfully used as a wallsystem to encapsulate anhydrous milk fat by spray-dryingand encapsulation yield greater than 90% was obtained(Young et al., 1993). According to the same authors,microencapsulation efficiency can be improved by partial(50%) replacement of whey proteins by lactose. In fact,the incorporation of lactose in the whey protein-based wallsystem can limit the diffusion of apolar substances throughthis wall. Lactose in its amorphous state acts as a hydro-philic sealant that significantly limits diffusion of thehydrophobic core through the wall and thus leads to highmicroencapsulation efficiency values. Spray-drying wasused to study microencapsulation of ethyl butyrate andethyl caprylate in wall systems consisting of whey proteinisolate or a mixture of whey protein isolate and lactose(ratio 1:1) (Rosenberg & Sheu, 1996). The authors reportedthat retention of these two volatiles was affected by wallsolids concentration, initial ester load, and by ester andwall type. It has later been shown that caraway essentialoil could be encapsulated in a wall system consisting ofmilk proteins which should provide it an effective protec-tion against oxidation (Bylaite, Nylander, Venskutonis, &Jonsson, 2001; Bylaite, Venskutonis, & Mapdbieriene,2001).

It has been shown that sodium caseinate has betterencapsulation properties than micellar casein (Vega, Kim,Chen, & Roos, 2005). This result was explained accordingto the molecular conformation, the high diffusivity, and thestrong amphiphilic characteristics of the individual caseinsthat allow for a better distribution around the encapsulatedfat globule surface than micellar caseins. The reversibledepletion–flocculation of emulsions stabilized with casei-nate and containing excess protein can be inhibited bythe addition of calcium ions concentration well below thatrequired to precipitate the protein (Dickinson, Radford, &Golding, 2003). Microencapsulation by spray-drying of soyoil in sodium caseinate as wall material has been studied


(Hogan et al., 2001). It was shown that oil/protein ratioshould not exceed 1 or the formed emulsion could be desta-bilized during spray-drying. The effect of spray-drying onthe physico-chemical properties of oil-in-water emulsionsstabilized by milk proteins was studied (Sliwinski et al.,2003). It was shown that spray-drying resulted in a dena-turation and aggregation of b-lactoglobulin. Heat-treat-ments of whey proteins were shown to affect thefunctional properties of spray-dried powder probably byprotein denaturation (Millqvist-Fureby, Elofsson, & Ber-genstahl, 2001). During spray-drying the temperature ofthe drying droplet increases slightly, while its water contentdecreases at the same time. Protein denaturation, especiallyglobular proteins, can occur only when two parameters arecombined: high temperature and high water activity of thedrying droplet. As a result, it is very difficult to predict theeffect of spray-drying process on the stability of wallproteins.

Gelatin is a water-soluble material with wall-formingability in spray-drying (Lee, Kim, & Kim, 1999) and itwas reported that the characteristics and morphology ofgelatin microparticles could be improved by addition ofmannitol (Bruschi, Cardoso, Lucchesi, & Gremiao, 2003).While based on the drying characteristic curves, Imagiet al. (1992) had showed that, compared to maltodextrin,pullulan, glucose, maltose and mannitol, gelatin had allthe properties of an effective entrapping agent: high emul-sifying activity, high stabilizing activity, and a tendencyto form a fine dense network upon drying. The additionof a small amount (1% (w/w)) of gelatin could increasethe retention of ethyl butyrate when gum arabic is usedas emulsifier and according to Yoshii et al. (2001), the earlyformation of the surface crust due to the presence of gela-tin, prevented the loss of ethyl butyrate emerged from theunstable ethyl butyrate emulsion.

In Iwami, Hattori, Yasumi, & Ibuki (1988) obtainedspherical microcapsules of gliadin containing polyunsatu-rated lipid. It was reported that these spray-dried micro-particles were resistant to oxidative deterioration during along-term storage at various water activity values. In thisstudy spray-drying has proven to raise the antioxidanteffect of gliadin without impairing its digestibility. Spray-drying is known to induce protein denaturation as shownabove, but in the case of gluten hydrolysates, it wasreported that spray-drying process can only modify interfa-cial protein properties (Linares, Larre, & Popineau, 2001).Recently, Pierucci, Andrade, Baptista, Volpato, & Rocha-Leao (2006) reported that pea protein can be considered asa good coating agent for the microencapsulation of ascor-bic acid. In all cases, it should be noticed that there aresometimes some issues in the use of proteins as encapsulat-ing agents. For example, losses of aldehyde based flavorcomponent, labelling, allergy and precipitation when pro-tein based microcapsules are added to food products hav-ing pH near their isoelectric point. In addition, somereligious and social (halal, kosher, vegetarian food choices)issues must be considered.

5. Some examples of food ingredients microencapsulated by

spray-drying

Actually, essential interests are attributed to encapsula-tion of flavors, lipids, and carotenoids among other ingredi-ents. Because a single encapsulating agent can not possessall ideal wall material properties, recent researches havefocused on mixtures of carbohydrates, gums, and proteins.This section focuses on the most important food ingredientsthat were recently encapsulated by spray-drying.

5.1. Flavors

Most of the flavoring compounds which give foods theircharacteristic aroma are highly volatile with respect towater. Therefore they are easily lost during spray-dryingoperation. Several methods have been reported for micro-encapsulation of flavors, but the most common techniqueemployed is spray-drying. Microencapsulation of hydro-phobic flavors is of great importance in the flavoring andfood industries, since solid or liquid microencapsulatedfood flavor exhibit a good chemical stability and a con-trolled release. Spray-drying is generally used to produceflavor powders in a short time. Many studies have been car-ried out on the influence of wall materials compositions andthe operating conditions on the retention and controlledrelease of encapsulated flavors (Madene, Jacquot, Scher,& Desobry, 2006). L-Menthol, a cyclic terpene alcohol nor-mally available in the form of crystals or granules with amelting point 41-43 �C presents a high volatility and a whis-ker growth (Soottitantawat et al., 2005b). These two prob-lems that limit its application and shelf life storage wereovercome by spray-drying microencapsulation and it wasreported that the high retention of L-menthol in a wall sys-tem of maltodextrin and gum arabic was observed only athigh solid content. Thus, it was shown that the optimal L-menthol concentration in the feed emulsion, which shouldhave a high retention of flavor and low flavor residue onthe surface, was L-menthol/wall materials of 1/4. Recently,flavors of oregano, citronella and marjoram were success-fully encapsulated by spray-drying in wall systems ofskimmed milk powder and whey protein concentrate (Bar-anauskiene, Venskutonis, Dewettinck, & Verhe, 2006).The major problem reported during the microencapsulationof these flavors is that the global molecular composition ofmicroencapsulated flavors can be modified by drying. Oxi-dative stability of encapsulated D-Limonene in a matrix ofgum arabic, soybean water-soluble polysaccharides andmodified starch, blended with maltodextrin, and preparedby spray-drying, was also studied (Soottitantawat et al.,2005a, 2004).

Essential oils, especially those rich in monoterpenes areusually used as flavor ingredients. The greater polarity, thatleads to a greater solubility of the encapsulated compoundin an aqueous medium, results in a greater capacity of diffu-sion through the matrix during spray-drying, and conse-quently to greater losses during the formation of the


capsules (Rosenberg et al., 1990; Voilley, 1995). Diffusion ofvolatiles through the wall matrix during spray-drying can beexplained by a mechanism of selective permeability. Thisassumes mainly that the retention of the compound is afunction of the core molar volume. It was shown later, thatit could be the ‘‘molecular diameter’’ and not the molar vol-ume that determines the diffusion of the compoundsthrough the matrix during the drying process (Bertoliniet al., 2001). In fact, monoterpenic molecules having thesame molecular weight (C10H16) and similar solubilitiesshowed different retention yields in the drying process.These differences were explained by the molecular structuresof the monoterpenes isomers (Bertolini et al., 2001). Inanother study, sumac flavor has been successfully encapsu-lated by spray-drying in sodium chloride as wall material(Bayram et al., 2005) but the salty property of this carrierand the acidic property of sumac limit the applications ofthe obtained particles to salted cookies, salads, crackers, etc.

5.2. Lipids and oleoresins

In general, lipids are difficult to disperse in food prod-ucts, in addition and especially polyunsaturated fatty acidsare susceptible to auto-oxidation, which results in off-fla-vors and toxic compounds. Lipids can be used as solventsin which one can solubilize hydrophobic substances suchas volatile aromatic compounds. Matsuno & Adachi(1993) enumerated five advantages of lipid encapsulation:retarding auto-oxidation; enhancing stability; controllinglipid-soluble flavor release; masking bitter taste of lipid-sol-uble substances; and protecting dissolved substancesagainst enzyme hydrolysis. Spray-drying is quite suitablein the encapsulation of oils and oleoresins. Microencapsula-tion of cardamom oleoresin by spray-drying using gum ara-bic, maltodextrin, and modified starch as wall materials hasbeen reported (Krishnan et al., 2005). This study showedthat the stability of cardamom oleoresin decreased as thequantity of gum arabic decreased in its blends with malto-dextrin and modified starch, and the blend (gum arabic:maltodextrin: modified starch) of (4/6:1/6:1/6) was consid-ered as suitable. This ternary blend proved to be alsoefficient for the encapsulation of cumin oleoresin (Kanak-dande et al., 2007). Stability of black pepper oleoresinencapsulated in gum arabic and emulsifying modifiedstarches by spray-drying has been reported (Shaikh et al.,2006). Sodium caseinate/carbohydrate blends were used toencapsulate soya oil by spray-drying and the obtainedresults showed that microencapsulation efficiency can beimproved by increasing the dextrose equivalence of the car-bohydrates (Hogan et al., 2001).

Study of spray-dried powders with 50% butteroil encap-sulated in sucrose and double encapsulated in a matrix ofvegetable waxes shows that double encapsulation methodcould improve capsule resistance to moisture sorption, butalso decreases powder flow properties (Onwulata, Kon-stance, & Holsinger, 1998). In a previous study, this researchgroup suggested that encapsulated spray-dried powders con-

taining 40% butteroil had shown lower flow characteristicsand where highly cohesive. These results had been explainedby the fat content and the propensity of bridging, but flowproperties were enhanced by adding a commercial anti-cak-ing flow agent (Konstance, Onwulata, & Holsinger, 1995).

The oxidative and thermal stabilities of crude squid oilhave been effectively enhanced by spray-drying microencap-sulation (Lin, Lin, & Hwang, 1995). Used wall materialswere gelatin, sodium caseinate, and maltodextrin. The addi-tion of lecithin and carboxymethyl cellulose was reported toimprove encapsulating effectiveness and oxidative and ther-mal stabilities. The most effective formulation that showsthe best thermal stability was (oil/gelatin/caseinate/malto-dextrin/lecithin/carboxymethyl cellulose) of (30/20/20/20/4/1). In general, microencapsulation of polyunsaturatedacids or their acylglycerols limits or delays its oxidation.In fact, the esterification of polyunsaturated fatty acids withL-ascorbic acid and subsequent microencapsulation of theester would be a useful technology for suppressing orretarding the oxidation of the polyunsaturated fatty acid.So that, 6-O-arachidonoyl L-ascorbate was microencapsu-lated in various wall materials by spray-drying and the oxi-dation of arachidonic acid under 37 �C and 12% relativehumidity was well retarded by its microencapsulation ingum arabic or a soluble soybean polysaccharide (Watana-be, Fang, Adachi, Fukami, & Matsuno, 2004). Morover,it was reported that saturated acyl L-ascorbate can be usedto stabilize against oxidation linoleic acid encapsulatedusing whey protein concentrate (Jimenez, Garcia, & Beri-stain, 2004), maltodextrin or gum arabic by spray-drying(Watanabe, Fang, Minemoto, Adachi, & Matsuno, 2002).Fat properties, such as crystal forms and habit, in spray-dried microcapsules were also investigated as a functionof storage time (Millqvist-Fureby, 2003).

5.3. Other food ingredients

Spray-drying was used in formulating calcium micropar-ticles using cellulose derivatives and polymethacrylic acidas wall systems (Oneda & Re, 2003). Results showed thatthe size and morphology of spray dried microparticles werefound to be affected by the type of polymer and its initialconcentration. Lycopene was successfully microencapsulat-ed by spray-drying using a wall system consisting of gelatinand sucrose. The optimal ratio of gelatin/sucrose was 3/7and that of core/wall material was 1/4 (Shu, Yu, Zhao, &Liu, 2006). In this work, and although lycopene is athermo-sensitive compound, feed temperature was 55 �C,inlet temperature was 190 �C, homogenization pressurewas 40 MPa, and lycopene purity was more than 52%.Spray-drying was also considered as the most effective tech-nique for encapsulating iodine and the best results wereobtained with dextrin as an encapsulating agent (Diosady,Alberti, & Venkatesh Mannar, 2002). The obtained micro-particles containing up to 1% iodine were stable for periodsup to 12 months under a temperature of 40 �C and a highrelative humidity. The stabilization of carotenoids in foods


and foodstuffs against isomerization or oxidation is veryimportant because their degradation lowers the final prod-uct quality in terms of nutritional properties as well as col-oration. Maltodextrins were found to be effective inprotecting the carotenoids of paprika oleoresin (Beatus,Raziel, Rosenberg, & Kopelman, 1985). Light stability ofspray-dried bixin encapsulated with gum arabic andmaltodextrin was studied, and results prove that bixinmicroencapsulated in gum arabic was more stable tophoto-degradation than that in maltodextrin + Tween 80(Barbosa, Borsarelli, & Mercadante, 2005). This resultwas interpreted by the highly branched structure of thegum arabic that is a film-forming and acts as an excellentemulsifier for non-polar substances (Dickinson, 2003).Spray-drying has been considered as an excellent meansof preservation of nutritive value of vitamins (Hartman,Akeson, & Stahmann, 1967) and this technique could con-sequently be suitable to encapsulate all vitamin groups.

6. Conclusion

In spite of the recent developments of the spray-dryingtechnique, the process remains far from completely beingcontrolled. Especially, the use of spray-drying for microen-capsulation ends is complex because of the multitude of fac-tors to optimize. The drying step in itself is not difficult tosucceed and can be optimized by trial-and-error procedurebut distinct improvements should be made on the choice ofencapsulation materials as well as the study of the varioustypes of molecular interactions: water/wall, water/core,and wall/core. The majority of current studies relate tothe formulation of emulsions before drying, the microcap-sules size distribution, their morphology, as well as therelease rate measurements of the encapsulated compound.However, a great work remains to be made concerningthe choice of encapsulating materials according to the phys-ico-chemical properties of food ingredient to encapsulateand the desired properties of microcapsules. In the sameway, it is necessary to characterize the various encapsula-tion polymers especially from emulsifying ability, viscosityin aqueous solutions, and drying properties in order toimplement new efficient encapsulating blends. Also, thescreening of new wall materials which could ensure bothgood encapsulation effectiveness and modulated release ofthe core ingredient becomes essential to overcome expensivecosts and unavailability of some commonly materials.

Acknowledgement

The authors gratefully acknowledge the technical andfinancial support of the ‘‘Conseil Regional de Bourgogne’’during the research of this subject which led to this paper.

References

Adhikari, B., Howes, T., Lecomte, D., & Bhandari, B. R. (2005). A glasstransition temperature approach for the prediction of the surface

stickiness of a drying droplet during spray-drying. Powder Technology,

149, 168–179.Alamilla-Beltran, L., Chanona-Perez, J. J., Jimenez-Aparicio, A. R., &

Guiterrez-Lopez, G. F. (2005). Description of morpholoigical changesof particles along spray drying. Journal of Food Engineering, 67,179–184.

Baranauskiene, R., Venskutonis, P. R., Dewettinck, K., & Verhe, R.(2006). Properties of oregano (Origanum vulgare L.), citronella(Cymbopogon nardus G.) and marjoram (Majorana hortensis L.)flavors encapsulated into milk protein-based matrices. Food Research

International, 39, 413–425.Barbosa, M. I. M. J., Borsarelli, C. D., & Mercadante, A. Z. (2005). Light

stability of spray-dried bixin encapsulated with different ediblepolysaccharide preparations. Food Research International, 38, 989–994.

Bayram, O. A., Bayram, M., & Tekin, A. R. (2005). Spray drying ofsumac flavour using sodium chloride, sucrose, glucose and starch ascarriers. Journal of Food Engineering, 69, 253–269.

Beatus, Y., Raziel, A., Rosenberg, M., & Kopelman, I. J. (1985). Spray-drying microencapsulation of paprika oleoresin. Lebensmittel-Wis-

senschaft und-Technologie, 18, 28–34.Beristain, C. I., & Vernon-Carter, E. J. (1994). Utilization of mes-

quite (Prosopis juliflora) gum as emulsion stabilizing agent for spraydried encapsulated orange peel oil. Drying Technology, 12,1727–1733.

Beristain, C. I., Garcıa, H. S., & Vernon-Carter, E. J. (2001). Spray-driedencapsulation of cardamom (Elettaria cardamomum) essential oil withmesquite (Prosopis juliflora) gum. Lebensmittel-Wissenschaft und-

Technologie, 34, 398–401.Bertolini, A. C., Siani, A. C., & Grosso, C. R. F. (2001). Stability of

monoterpenes encapsulated in gum arabic by spray-drying. Journal of

Agriculture and Food Chemistry, 49, 780–785.Bimbenet, J. J., Bonazzi, C., Dumoulin, E. (2002). Drying of foodstuffs.

Drying’2002 – In: Proceeding of the 13th international drying sympo-

sium (pp. 64–80).Bowen, W. S. (1938). Spray drying. Industrial and Engineering Chemistry,

30, 1001–1002.Brazel, C. S. (1999). Microencapsulation: Offering solutions for the food

industry. Cereal Foods World, 44, 388–393.Bruschi, M. L., Cardoso, M. L. C., Lucchesi, M. B., & Gremiao, M. P. D.

(2003). Gelatin microparticles containing propolis obtained by spray-drying technique: Preparation and characterization. International

Journal of Pharmaceutics, 264, 45–55.Bylaite, E., Nylander, T., Venskutonis, R., & Jonsson, B. (2001).

Emulsification of caraway essential oil in water by lecithin and b-lactoglobulin: Emulsion stability and properties of the formed oil-aqueous interface. Colloids and Surfaces B: Biointerfaces, 20, 327–340.

Bylaite, E., Venskutonis, P. R., & Mapdbieriene, R. (2001). Properties ofcaraway (Carum carvi L.) essential oil encapsulated into milk protein-based matrices. European Food Research and Technology, 212,661–670.

Christensen, K. L., Pedersen, G. P., & Kristensen, H. G. (2001a).Preparation of redispersible dry emulsions by spray drying. Interna-

tional Journal of Pharmaceutics, 212, 187–194.Christensen, K. L., Pedersen, G. P., & Kristensen, H. G. (2001b).

Technical optimisation of redispersible dry emulsions. International

Journal of Pharmaceutics, 212, 195–202.Christensen, K. L., Pedersen, G. P., & Kristensen, H. G. (2002). Physical

stability of redispersible dry emulsions containing amorphous sucrose.European Journal of Pharmaceutics and Biopharmaceutics, 53, 147–153.

Corrigan, O. I. (1995). Thermal analysis of spray dried products.Thermochimica Acta, 248, 245–258.

Dalgleish, D. G. (2006). Food emulsions–Their structures and structure-forming properties. Food Hydrocolloids, 20, 415–422.

Desai, K. G. H., & Park, H. J. (2005). Recent developments inmicroencapsulation of food ingredients. Drying Technology, 23,1361–1394.

Desobry, S. A., Netto, F. M., & Labuza, T. B. (1997). Comparison ofspray-drying, drum drying and freeze-drying for (1! 3, 1! 4)-b-


carotene encapsulation and preservation. Journal of Food Science, 62,1158–1162.

DeZarn, T. G. (1995). Food ingredients encapsulation: An overview. In S.J. Risch & G. A. Reineccius (Eds.), Encapsulation and controlled

release of food ingredients. ACS symposium series (Vol. 590, pp. 74–86).Washington, DC: American Chemical Society.

Dickinson, E. (2003). Hydrocolloids at interfaces and the influence on theproperties of dispersed systems. Food Hydrocolloids, 17, 25–39.

Dickinson, E., Radford, S. J., & Golding, M. (2003). Stability andrheology of emulsions containing sodium caseinate: Combined effectsof ionic calcium and non-ionic surfactant. Food Hydrocolloids, 17,211–220.

Diosady, L. L., Alberti, J. O., & Venkatesh Mannar, M. G. (2002).Microencapsulation for iodine stability in salt fortified with ferrousfumarate and potassium iodide. Food Research International, 35,635–642.

Drusch, S., (2006). Sugar beet pectin: A novel emulsifying wall componentfor microencapsulation of lipophilic food ingredients by spray-drying.Food Hydrocolloids. doi:10.1016/j.foodhyd.2006.08.007.

Drusch, S., & Schwarz, K. (2006). Microencapsulation properties of twodifferent types of n-octenylsuccinate-derivatised starch. European Food

Research Technology, 222, 155–164.Drusch, S., Serfert, Y., Van Den Heuvel, A., & Schwarz, K. (2006).

Physicochemical characterization and oxidative stability of fish oilencapsulated in an amorphous matrix containing trehalose. Food

Research International, 39, 807–815.Dubernet, C., & Benoit, J. P. (1986). La microencapsulation: Ses

techniques et ses applications en biologie. L’actualite chimique.(Decem-bre), 19–28.

Dziezak, J. D. (1988). Microencapsulation and encapsulated ingredients.Food Technology(April), 136–151.

Fleming, R. S. (1921). The spray process of drying. The Journal of

Industrial and Engineering Chemistry, 13, 447–449.Fogler, B. B., & Kleinschmidt, R. V. (1938). Spray drying. Industrial and

Engineering Chemistry, 30, 1372–1384.Gibbs, B. F., Kermasha, S., Alli, I., & Mulligan, C. N. (1999).

Encapsulation in the food industry: A review. Internatioanl Journal

of Food Sciences and Nutrition, 50, 213–224.Gouin, S. (2004). Micro-encapsulation: Industrial appraisal of existing

technologies and trends. Trends in Food Science and Technology, 15,330–347.

Hartman, G. H., Akeson, J. W. R., & Stahmann, M. A. (1967). Leafprotein concentrate prepared by spray-drying. Journal of Agricultural

and Food Chemistry, 15, 74–79.Hogan, S. A., McNamee, B. F., O’Riordan, E. D., & O’Sullivan, M.

(2001a). Microencapsulation properties of sodium caseinate. Journal of

Agricultural and Food Chemistry, 49, 1934–1938.Hogan, S. A., McNamee, N. F., O’Riordan, E. D., & O’Sullivan, M.

(2001b). Emulsification and microencapsulation properties of sodiumcaseinate/carbohydrate blends. International Dairy Journal, 11,137–144.

Imagi, J., Yamanouchi, T., Okada, K., Tanimoto, M., & Matsuno, R.(1992). Properties of agents that effectively entrap liquid lipids.Bioscience Biotechnology and, Biochemistry, 56, 477–480.

Iwami, K., Hattori, M., Yasumi, T., & Ibuki, F. (1988). Stability ofgliadin-encapsulated unsaturated fatty acids against autoxidation.Journal of Agriculture and Food Chemistry, 36, 160–164.

Jimenez, M., Garcia, H. S., & Beristain, C. I. (2004). Spray-dryingmicroencapsulation and oxidative stability of conjugated linoleic acid.European Food Research and Technology, 219, 588–592.

Kanakdande, D., Bhosale, R., & Singhal, R. S. (2007). Stability of cuminoleoresin microencapsulated in different combination of gum arabic,maltodextrin and modified starch. Carbohydrate Polymers, 67,536–541.

Kenyon, M. M. (1995). Modified starch, maltodextrin, and corn syrupsolids as wall materials for food encapsulation. In S. J. Risch & G. A.Reineccius (Eds.), Encapsulation and controlled release of food ingre-

dients. ACS symposium series (Vol. 590, pp. 42–50). Washington, DC:American Chemical Society.

Kim, Y. D., & Morr, C. V. (1996). Microencapsulation properties ofgum arabic and several food proteins: Spray-dried orange oil emul-sion particles. Journal of Agricultural and Food Chemistry, 44,1314–1320.

King, A. H. (1995). Encapsulation of food ingredients: A review ofavailable technology, focusing on hydrocolloids. In S. J. Risch & G. A.Reineccius (Eds.), Encapsulation and controlled release of food ingre-

dients. ACS symposium series (Vol. 590, pp. 26–39). Washington, DC:American Chemical Society.

Klinkesorn, U., Sophanodora, P., Chinachoti, P., Decker, E. A., &McClements, D. J. (2006). Characterization of spray-dried tuna oilemulsified in two-layered interfacial membranes prepared usingelectrostatic layer-by-layer deposition. Food Research International,

39, 449–457.Konstance, R. P., Onwulata, C. I., & Holsinger, V. H. (1995). Flow

properties of spray-dried encapsulated butteroil. Journal of Food

Science, 60, 841–844.Krishnan, S., Bhosale, R., & Singhal, R. S. (2005). Microencapsulation of

cardamom oleoresin: Evaluation of blends of gum arabic, maltodextrinand a modified starch as wall materials. Carbohydrate Polymers, 61,95–102.

Krishnan, S., Kshirsagar, A. C., & Singhal, R. S. (2005). The use of gumarabic and modified starch in the microencapsulation of a foodflavoring agent. Carbohydrate Polymers, 62, 309–315.

Landy, P., Druaux, C., & Voilley, A. (1995). Retention of aromacompounds by proteins in aqueous solution. Food Chemistry, 54,387–392.

Langrish, T. A. G., & Fletcher, D. F. (2001). Spray-drying of foodingredients and applications of CFD in spray-drying. Chemical

Engineering and Processing, 40, 345–354.Lee, S.-W., Kim, M.-H., & Kim, C.-K. (1999). Encapsulation of ethanol

by spray drying technique: Effects of sodium lauryl sulfate. Interna-

tional Journal of Pharmaceutics, 187, 193–198.Le Meste, M., Champion, D., Roudaut, G., et al. (2002). Glass transition

and food technology: A critical appraisal. Journal of Food Science, 67,2444–2458.

Leroux, J., Langendorff, V., Schick, G., Vaishnav, V., & Mazoyer, J.(2003). Emulsion stabilizing properties of pectin. Food Hydrocolloids,

17, 455–462.Lin, C. C., Lin, S. Y., & Hwang, L. S. (1995). Microencapsulation of squid

oil with hydrophilic macromolecules for oxidative and thermalstabilization. Journal of Food Science, 60, 36–39.

Lin, J-C., & Gentry, J. W. (1997). Modeling of particle formation by spraydrying process. Journal of Aerosol Science, 28, S477–S478.

Lin, J-C., & Gentry, J. W. (1999). Spray drying droplet morphology:Theoretical model. Journal of Aerosol Science, 30, S545–S546.

Lin, J-C., Zhang, H-J, & Gentry, J. W. (2000). Spray drying dropletmorphology: Formation of shell. Journal of Aerosol Science, 31,S797–S798.

Linares, E., Larre, C., & Popineau, Y. (2001). Freeze- or spray-driedgluten hydrolysates. 1. Biochemical and emulsifying properties as afunction of drying process. Journal of Food Engineering, 48, 127–135.

Liu, X-D., Atarashi, T., Furuta, T., Yoshii, H., Aishima, S., Ohkawara,M., et al. (2001). Microencapsulation of emulsified hydrophobicflavours by spray drying. Drying Technology, 19, 1361–1374.

Liu, Z., Zhou, J., Zeng, Y., & Ouyang, X. (2004). The enhancement andencapsulation of Agaricus bisporus flavor. Journal of Food Engineering,

65, 391–396.Madene, A., Jacquot, M., Scher, J., & Desobry, S. (2006). Flavour

encapsulation and controlled release – A review. International Journal

of Food Science and Technology, 41, 1–21.Masters, K. (1968). Spray drying: The unit operation today. Industry

Engineering and Engineering Chemistry, 60, 53–63.Mathlouthi, M., & Roge, B. (2003). Water vapour sorption isotherms and

the caking of food powders. Food Chemistry, 82, 61–71.

http://dx.doi.org/10.1016/j.foodhyd.2006.08.007


Matsuno, R., & Adachi, S. (1993). Lipid encapsulation technology –Techniques and applications to food. Trends in Food Science and

Technology, 4, 256–261.McNamee, B. F., White, L. E., O’Riordan, E. D., & O’Sullivan, M.

(2001). Effect of partial replacement of gum arabic with carbohydrateson its microencapsulation properties. Journal of Agricultural and Food

Chemistry, 49, 3385–3388.Millqvist-Fureby, A. (2003). Characterisation of spray-dried emulsions

with mixed fat phases. Colloids and Surfaces B: Biointerfaces, 31,65–79.

Millqvist-Fureby, A., Elofsson, U., & Bergenstahl, B. (2001). Surfacecomposition of spray-dried milk protein-stabilised emulsions inrelation to pre-heat treatment of proteins. Colloids and Surfaces B:

Biointerfaces, 21, 47–58.Monsoor, M. A. (2005). Effect of drying methods on the functional

properties of soy hull pectin. Carbohydrate Polymers, 61, 362–367.

Moreau, D. L., & Rosenberg, M. (1996). Oxidative stability of anhydrousmilk fat microencapsulated in whey proteins. Journal of Food Science,

61, 39–43.Negiz, A., Lagergren, E. S., & Cinar, A. (1995). Mathematical models of

cocurrent spray drying. Industrial and Engineering Chemistry Research,

34, 3289–3302.Oneda, F., & Re, M. I. (2003). The effect of formulation variables on

the dissolution and physical properties of spray-dried micro-spheres containing organic salts. Powder Technology, 130,377–384.

Onwulata, C. I., Konstance, R. P., & Holsinger, V. H. (1998). Propertiesof single- and double- encapsulated butteroil powders. Journal of Food

Science, 63, 100–103.Papadakis, S. E., & King, C. J. (1988a). Air temperature and humidity

profiles in spray drying. 2. Experimental measurements. Industrial and

Engineering Chemistry Research, 27, 2116–2123.Papadakis, S. E., & King, C. J. (1988b). Air temperature and humidity

profiles in spray drying. 1. Features predicted by the particle source incell model. Industrial and Engineering Chemistry Research, 27,2111–2116.

Paris, J. R., Ross, P. N., Dastur, S. P., & Morris, L. (1971). Modelingof the air flow pattern in a countercurrent spray-dryingtower. Industrial Engineering Process Design Development, 10,157–164.

Perez-Alonso, C., Baez-Gonzalez, J. G., Beristain, C. I., Vernon-Carter, E.J., & Vizcarra-Mendoza, M. G. (2003). Estimation of the activationenergy of carbohydrate polymers blends as selection criteria for theiruse as wall material for spray-dried microcapsules. Carbohydrate

polymers, 53, 197–203.Pierucci, A. P. T. R., Andrade, L. R., Baptista, E. B., Volpato, N. M., &

Rocha-Leao, M. H. M. (2006). New Microencapsulation system forascorbic acid using pea protein concentrate as coat protector. Journal

of microencapsulation, 23, 654–662.Quinn, J. J. (1965). The economics of spray drying. Industrial and

Engineering Chemistry, 57, 35–37.Raja, K. C. M., Sankarikutty, B., Sreekumar, M., Jayalekshmy, A., &

Narayanan, C. S. (1989). Material characterization studies of malto-dextrin samples for the use of wall material. Starch/ starke, 41,298–303.

Reineccius, G. A. (1988). Spray-drying of food flavors. In G. A.Reineccius & S. J. Risch (Eds.), Flavor encapsulation (pp. 55–66).Washington, DC: Amercian Chemical Society.

Reineccius, G. A., Ward, F. M., Whorten, C., & Andon, S. A. (1995).Developments in gum acacias for the encapsulation of flavors. In S. J.Risch & G. A. Reineccius (Eds.), Encapsulation and controlled release

of food ingredients. ACS symposium series (Vol. 590, pp. 161–168).Washington, DC: American Chemical Society.

Rosenberg, M., & Sheu, T-Y. (1996). Microencapsulation of volatiles byspray-drying in whey protein-based wall systems. International Dairy

Journal, 6, 273–284.

Rosenberg, M., Kopelman, I. J., & Talmon, Y. (1990). Factors affectingretention in spray-drying microencapsulation of volatile materials.Journal of Agricultural and Food Chemistry, 38, 1288–1294.

Schuck, P. (2002). Spray drying of dairy products: State of the art. Lait,

82, 375–382.Shahidi, F., & Han, X. Q. (1993). Encapsulation of food ingredients.

Critical Review in Food Science and Nutrition, 33, 501–547.Shaikh, J., Bhosale, R., & Singhal, R. (2006). Microencapsulation of black

pepper oleoresin. Food Chemistry, 94, 105–110.Shu, B., Yu, W., Zhao, Y., & Liu, X. (2006). Study on microencapsu-

lation of lycopene by spray-drying. Journal of Food Engineering, 76,664–669.

Sliwinski, E. L., Lavrijsen, B. W. M., Vollenbroek, J. M., van derStege, H. J., van Boekel, M. A. J. S., & Wouters, J. T. M. (2003).Effects of spray drying on physicochemical properties of milk protein-stabilised emulsions. Colloids and Surfaces B: Biointerfaces, 31,219–229.

Soottitantawat, A., Bigeard, F., Yoshii, H., Furuta, T., Ohkawara, M., &Linko, P. (2005a). Influence of emulsion and powder size on thestability of encapsulated D-limonene by spray drying. Innovative Food

Science and Emerging Technologies, 6, 107–114.Soottitantawat, A., Takayama, K., Okamura, K., Muranaka, D., Yoshii,

H., & Furuta, T. (2005b). Microencapsulation of L-menthol by spraydrying and its release characteristics. Innovative Food Science and

Emerging Technologies, 6, 163–170.Soottitantawat, A., Yoshi, H., Furuta, T., Ohgawara, M., Forssell, P., &

Partanen, R. (2004). Effect of water activity on the releasecharacteristics and oxidative stability of D-limonene encapsulated byspray drying. Journal of Agriculture and Food Chemistry, 52,1269–1276.

Straatsma, J., Van Houwelingen, G., Steenbergen, A. E., & De Jong, P.(1999). Spray drying of food products: 2. Prediction of insolubilityindex. Journal of Food Engineering, 42, 73–77.

Teixeira, M. I., Andrade, L. R., Farina, M., & Rocha-Leao, M. H. M.(2004). Characterization of short chain fatty acid microcapsulesproduced by spray drying. Materials Science and Engineering, 24,653–658.

Teunou, E., & Poncelet, D. (2005). Rotary disc atomisation for micro-encapsulation applications – Prediction of the particle trajectories.Journal of Food Engineering, 71, 345–353.

Thevenet, F. (1995). Acacia gums: Natural encapsulation agent for foodproducts. In S. J. Risch & G. A. Reineccius (Eds.), Encapsulation and

controlled release of food ingredients. ACS symposium series (Vol. 590,pp. 51–59). Washington, DC: American Chemical Society.

Turchiuli, C., Fuchs, M., Bohin, M., Cuvelier, M. E., Ordonnaud, C.,Peyrat-Maillars, M. N., et al. (2005). Oil encapsulation by spraydrying and fluidised bed agglomeration. Innovative Food Science and

Emerging Technologies, 6, 29–35.Vega, C., Kim, E.-H.-J., Chen, X. D., & Roos, Y. H. (2005). Solid-state

characterization of spray-dried ice cream mixes. Colloids and Surfaces

B: Biointerfaces, 45, 66–75.Voilley, A. (1995). Flavor encapsulation influence of encapsulation media

on aroma retention during drying. In S. J. Risch & G. A. Reineccius(Eds.), Encapsulation and controlled release of food ingredients. ACS

symposium series (Vol. 590, pp. 169–179). Washington, DC: AmericanChemical Society.

Watanabe, Y., Fang, X., Adachi, S., Fukami, H., & Matsuno, R. (2004).Oxidation of 6-O-arachidonoyl -ascorbate microencapsulated with apolysaccharide by spray-drying. Lebensmittel-Wissenschaft und-Tech-

nologie, 37, 395–400.Watanabe, Y., Fang, X., Minemoto, Y., Adachi, S., & Matsuno, R.

(2002). Suppressive effect of saturated acyl L-ascorbate on theoxidation of linoleic acid encapsulated with maltodextrin or gumarabic by spray-drying. Journal of Agricultural and Food Chemistry, 50,3984–3987.

Yoshii, H., Soottitantawat, A., Liu, X.-D., Atarashi, T., Furuta, T.,Aishima, S., et al. (2001). Flavor release from spray-dried maltodex-


trin/gum arabic or soy matrices as a function of storage relativehumidity. Innovative Food Science and Emerging Technologies, 2,55–61.

Young, S. L., Sarda, X., & Rosenberg, M. (1993). Microencapsulationproperties of whey proteins. 1. Microencapsulation of anhydrous milkfat. Journal of Dairy Science, 76, 2868–2877.

Zakarian, A. J., & King, C. J. (1982). Volatiles loss in the zone duringspray drying of emulsions. Industrial Engineering Chemistry Process

Design and Development, 21, 107–113.Zbicinski, I., Delag, A., Strumillo, C., & Adamiec, J. (2002). Advanced

experimental analysis of drying kinetics in spray drying. Chemical

Engineering Journal, 86, 207–216.

Documents

Applications of Spray-drying in Microencapsulation of Food Ingredients- An Overview