lable at ScienceDirect

Food Hydrocolloids 51 (2015) 327e337

Contents lists avai

Food Hydrocolloids

journal homepage: www.elsevier .com/locate/ foodhyd

Retention of saffron bioactive components by spray dryingencapsulation using maltodextrin, gum Arabic and gelatin as wallmaterials

Hamid Rajabi a, Mohammad Ghorbani a, Seid Mahdi Jafari a, *,Alireza Sadeghi Mahoonak a, Ghadir Rajabzadeh b

a Department of Food Materials and Process Design Engineering, University of Agricultural Sciences and Natural Resources, Gorgan, Iranb Research Institute of Food Science and Technology, Mashhad, Iran

a r t i c l e i n f o

Article history:Received 22 February 2015Received in revised form25 May 2015Accepted 27 May 2015Available online 5 June 2015

Keywords:SaffronEncapsulationSpray dryingActive componentsBiopolymers

* Corresponding author. Pishro Food Technology Res32426 432.

E-mail address: smjafari@gau.ac.ir (S.M. Jafari).

http://dx.doi.org/10.1016/j.foodhyd.2015.05.0330268-005X/© 2015 Elsevier Ltd. All rights reserved.

a b s t r a c t

Saffron as the world's most expensive spice is very sensitive and loses its active compounds in exposureto environmental conditions. In this work, microencapsulation of saffron extract by various biopolymerswas studied as an effective way to preserve its active compounds. Emulsions with a constant ratio ofsaffron extract/wall material of 1:20 and two levels of total solids (TS of 30 and 40%), were preparedusing a homogenizer, and then spray dried. Powders were characterized in terms of powder yield,encapsulation efficiency, and retention of saffron active components, microstructure, and moisturecontent. Retention of picrocrocin, safranal and crocin after spray drying was analyzed by measuringabsorbance at 257, 330 and 440 nm, respectively. It was observed that a mixture with 40% TS consistingof maltodextrin, gum Arabic and gelatin in the weight ratio of 0.94:0.05:0.01 retained the highestamount of picrocrocin, safranal and crocin, by retention values of 90.06, 80.37, and 91.03%, respectively.Both encapsulation efficiency and powder yield were positively influenced by total solids content, whichcould be related to the emulsion viscosity and droplet size. To conclude, a mixture of maltodextrin, gumArabic and gelatin was efficient for saffron extract encapsulation by spray drying.

© 2015 Elsevier Ltd. All rights reserved.

1. Introduction

Saffron from about 3000 years ago has been cultivated and usedbecause of its unique features (Deo, 2003). Saffron, the dried andcolored-red stigma of Crocus sativus L., belongs to the Iridaceaefamily, and is produced largely in Asia (particularly Iran)(Fern�andez & Pandalai, 2004; Kafi, Koocheki, Rashed, & Nassiri,2006; Khazaei, Jafari, Ghorbani, & Kakhki, 2014; Xuabin, 1992).Today, saffron has foundmany uses ranging from fragrances to dyesand medicines (Melnyk, Wang, & Marcone, 2010). In recent years,despite of its high price, the use of saffron is steadily increasing, dueto changes of consumer preference towards natural products hav-ing functional properties (Knewstaubb & Henry, 1988).

Three main active compounds identified in saffron are crocin,picrocrocin and safranal (Carmona, Zalacain, S�anchez, Novella, &Alonso, 2006; Nassiri-Asl & Hosseinzadeh, 2014; Tarantilis,

earch Group. Tel./fax: þ98 17

Polissiou, & Manfait, 1994) which lose their nature when exposedto light, heat and oxygen. Crocin and picrocrocin undergo tooxidation and hydrolysis reactions; meanwhile safranal, whichcauses the fragrance in saffron, is volatile at ambient temperatures.Therefore, encapsulation of saffron extract could result in a powderwith a longer shelf life.

Encapsulation is defined as a protective method for activecompounds which are sensitive to environmental conditions(Ahmed, Akter, Lee,& Eun, 2010; Borgogna, Bellich, Zorzin, Lapasin,& Ces�aro, 2010; Jafari, Assadpoor, He, & Bhandari, 2008; Medina-Torres et al., 2013; Sa�enz, Tapia, Ch�avez, & Robert, 2009). On theother hand, during encapsulation, active compounds are packagedwithin a matrix or membrane (Akhavan, Jafari, Ghorbani, &Assadpoor, 2014). Encapsulation of herbal products couldimprove process capability, easy maintenance and low cost de-livery, protect against environmental conditions and improve finalproduct qualities (Deladino, Anbinder, Navarro, & Martino, 2008;Shu, Yu, Zhao, & Liu, 2006).

Among several encapsulation techniques, spray drying is theeffective and most common one in the food industry (Jafari et al.,

H. Rajabi et al. / Food Hydrocolloids 51 (2015) 327e337328

2008; Pang, Yusoff, & Gimbun, 2014; R�e, 1998; Reineccius, 2001,2004; Shahidi & Han, 1993), and one of the oldest encapsulationmethods. The method consists of liquid atomization into smalldroplets, a drying step carried out using a warmed gas andcollection of the solid particles (Beck-Broichsitter, Schmehl, Seeger,& Gessler, 2011). Selection of appropriate wall materials is one ofthe main steps in microencapsulation process (Pang et al., 2014).Common microencapsulation agents such as gum Arabic (GA) andmaltodextrin (MD) are often used for herbal or plant-relatedproducts (Bhusari, Muzaffar, & Kumar, 2014; Fazaeli, Emam-Djomeh, Ashtari, & Omid, 2012; Janiszewska, 2014; Sahin-Nadeem, Dinçer, Torun, Topuz, & €Ozdemir, 2013; Silva, Vieira, &Hubinger, 2014; Turchiuli, Munguia, Sanchez, Ferre, & Dumoulin,2014). For instance, Khazaei et al. (2014) employed two bio-polymers, namely MD and GA to microencapsulate the anthocya-nins of saffron petals. Furthermore, Castro-Mu~noz, Barrag�an-Huerta, and Y�a~nez-Fern�andez (2014) investigated the spray dry-ing microencapsulation of clarified juice extracted from purplecactus pear using gelatin (GE) and MD.

There is no information available on microencapsulation ofsaffron extract by spray drying. Most of the works in literature dealwith microencapsulation of colorants (Barbosa, Borsarelli, &Mercadante, 2005; Rocha, F�avaro-Trindade, & Grosso, 2012; Shuet al., 2006), flavors (Baranauskien _e, Venskutonis, Dewettinck, &Verh�e, 2006; Bayram, Bayram, & Tekin, 2005; Liu, Zhou, Zeng, &Ouyang, 2004; Reineccius, 1988; Reineccius, Ward, Whorton, &Andon, 1995) or essential oils (Kanakdande, Bhosale, & Singhal,2007; Rosenberg, Kopelman, & Talmon, 1990; Soottitantawatet al., 2004, 2005; Soottitantawat, Yoshii, Furuta, Ohkawara, &Linko, 2003) alone, but saffron stigma has all three type of theseingredients and therefore, microencapsulation of its extract, is acomplex process. Crocin is a water-soluble glycosidic carotenoidresponsible for color, picrocrocin causes a bitter-taste and safranalis the main volatile oil present in saffron (Caballero-Ortega, Pereda-Miranda, & Abdullaev, 2007).

The objective of this work was to study the microencapsulationof saffron extract by spray drying with binary and ternary blends ofMD, GA, and GE as wall materials. The microcapsules were evalu-ated for the retention of saffron active components, moisturecontent and encapsulation efficiency. Scanning electron micro-scopy was also used to observe the microstructural characteristicsof encapsulated powders.

2. Materials and methods

2.1. Saffron powder preparation

Saffronwas picked before sunlight from a farm around Torbat-E-Heydariyeh (Iran). Stigmas were separated from the other part offlowers. In order to determine the optimal drying method, threemethods were pre-investigated considering drying at room tem-perature (25 �C ± 1), dehydration with electrical oven (60 �C ± 1),and microwave drying (1000 W). Our results showed (data notgiven) that the highest content of saffron active components (SAC)was obtained when saffron treated at higher temperatures andlower times. Among the mentioned methods, drying with micro-wave at 1000 W resulted in the least SAC degradation during theprocess. Dried stigmas were crashed and sieved (0.421 mmmeshes). Prior to use, the saffron powder was kept in an air-tightplastic bag within a desiccator at room temperature to preventmoisture absorption.

GA was provided by SD Fine Chemical Co. Limited, Mumbai(India). MD with a dextrose equivalent (DE) of 16.5e19 was pur-chased from Aldrich (USA). GE (Bovine, Art., 4078) and Ethanolwere supplied by Merck (Germany).

2.2. Preparation of saffron extract

Saffron extract was prepared by extraction of dried powderedstigmas in water: 50 %v/v ethanol for 2 h. The proportion of solventto saffron powder was kept at weight ratio of 100:1. The extract wasfiltrated (Whatman filter paper No. 42) and then concentrated in arotary evaporator (BUCHI Rotaevaporator R114, Germany) for about30 min until 90% of the solvent was removed and stored at 4e5 �Cprior to the next stage. Picrocrocin, safranal and crocin content ofsaffron extract was determined using a UVeVis spectrophotometer(DR5000, Hach-Lange, Germany) by measuring the absorbance at257, 330 and 440 nm, respectively, as described by Orfanou andTsimidou (1996).

2.3. Preparation of feed composition

Different amounts of MD, GA and GE were used as carriers sothat the resulted emulsion total solids were equal to either 30 or40% (w/w). Compositions of MD, GA and GE mixtures at differentdesign points are listed in Table 1. Each formulation was preparedby blending and rehydrating the carriers in distilled water (40 �C)by magnetic stirrer (IKA® C-MAG HS 7) at 350 rpm for 2 h. Afterdissolution, the mixture was placed overnight in the refrigerator(5 ± 1 �C) to obtain full hydration. The next day, concentratedsaffron extract was added to the feed at proportion of 1:20(saffron extract:carrier, mass/mass) and homogenized by arotorestator homogenizer (Ultra-Turrax IKA® T25) at 13,600 rpmfor 2 min.

2.4. Measurement of viscosity

A rotational programmable viscometer (DV III Ultra, BrookfieldEngineering Laboratories, USA) at 25 �C using the SC4-18 and SC4-31 spindles was used for viscosity measurement. The temperatureof emulsions was brought to equilibrium and maintained constantthroughout experiments by means of a thermostat tank. Themeasurements recorded at shear rate of 50 s�1 were considered asemulsion viscosity.

2.5. Measurement of surface tension

Surface tension was determined by the Du Nouy ring method(Kruss K100 Tensiometer, Germany) at 25 �C. Deionized water wasused to calibrate the tension meter for surface tensionmeasurements.

2.6. Microencapsulation by spray drying

Spray drying process was performed in a BUCHI mini spraydryer (B-191, Switzerland). The emulsions were fed into the dryingchamber through a peristaltic pump. The inlet and outlet air tem-perature were maintained at 180 ± 5 �C and 90 ± 5 �C, respectively.The air flow, rate of feeding and atomization pressure were 600 l/h,5 ml/min and 20 psi, respectively, for both total solids content. Thepowders obtained were stored to exclude light and were keptat �20 �C until analyzed.

2.7. Powder yield determination

Powder yield was measured through determination of recov-ered product given by the ratio between the total recoveredproduct mass and the mass of extract initially fed into the spraydryer, and it was expressed by the following equation (Le�on-Martínez, M�endez-Lagunas, & Rodríguez-Ramírez, 2010):

Table 1Proportions of maltodextrin (MD), gum Arabic (GA) and gelatin (GE) as per mixture design.

GE (g) GA (g) MD (g) Amount (g) Formulation GE (g) GA (g) MD (g) Amount (g) Formulation

1.5 2 36.5 40 14 1.5 6 22.5 30 11.125 4.5 24.375 30 15 0.75 0 29.25 30 20.5 6 33.5 40 16 0 4 36 40 30.75 6 23.25 30 17 0.5 2 37.5 40 41.5 0 28.5 30 18 0 6 24 30 50 0 40 40 19 1.125 1.5 27.375 30 62 4 34 40 20 1 0 39 40 70 0 30 30 21 1.5 3 25.5 30 81 8 31 40 22 1.5 6 32.5 40 92 0 38 40 23 0 8 32 40 100.75 3 26.25 30 24 2 8 30 40 110.375 4.5 25.125 30 25 1 4 35 40 120 3 27 30 26 0.375 1.5 28.125 30 13

H. Rajabi et al. / Food Hydrocolloids 51 (2015) 327e337 329

y ¼ ðW2 �W1Þ � XwbðW2 �W1ÞMVTS

� 100 (1)

where y is the powder yield (%), Xwb is the moisture content in wetbasis (wb), MV is the volume of extract feed (L), Ts is the content oftotal solids (g dry matter/L), while W1 andW2 are the weight (g) ofthe powder receptacle before and after spray drying, respectively.

2.8. Encapsulation efficiency (EE)

In order to determine encapsulation efficiency of saffron com-ponents, 100 mg of each powder (containing 5 mg of initially addedsaffron) was dissolved in 100 ml distilled water. On the other hand,saffron extract with concentration equivalent to 100 mg encapsu-lated powder was prepared by dissolving 5 mg of saffron powder in100 ml distillated water followed by filtration. The absorbance ofthese solutions was measured at 275, 330 and 440 nm. EE of eachcomponent was calculated through the following equations(Sarfarazi, Jafari, & Rajabzadeh, 2015):

EE ¼ A1%1cmM$P

A1%1cmS$P

� 100 (2)

A1%1cmðlmaxÞ ¼ A� 10;000=mð100� HÞ (3)

where EE is the encapsulation efficiency, A1%1cmðlmaxÞ is the absor-

bance at the respective wavelength (maximum absorbance of thecorresponding compound), A is the specific absorbance, m is thesample weight (g), H is the moisture and volatile matter content,A1%1cmM$P is the absorbance at the respective wavelength in

microencapsulated powder, and A1%1cmS$P is the absorbance at the

respective wavelength in saffron extract.

2.9. Moisture content

Powders' moisture content (MC, % w.b.) was determined bydrying in a vacuum oven at 70 �C until constant weight. Sampleswere allowed to cool to room temperature in desiccators containingsilica gel (Jayasundera, Adhikari, Adhikari, & Aldred, 2011).

Fig. 1. The average value of encapsulation efficiency for saffron main components inmicroencapsulated powders with different TS (30 and 40%).

2.10. Scanning electron microscopy (SEM)

Microencapsulated saffron powders were observed under ascanning electron microscope (S-360, Cambridge, England). Pow-ders were attached to specimen stubs using a 2-sided adhesive tapeand left in desiccators containing phosphorous pentoxide for 48 h.

Samples were coated with a thin layer of gold under vacuum andwere examined at an accelerating voltage of 8.80 kV.

2.11. Statistical analysis

Extreme vertices designwith augmented axial points in mixturedesigns was used to obtain various proportions of MD, GA and GEfor saffron extract microencapsulation by spray drying. The entiretriangular region consisting of 26 design points was covered forexperiments. MINITAB Release 16 (Minitab Inc., PA, USA) softwarewas used for data analysis. All experiments were done in triplicateand average values were reported.

3. Results and discussion

3.1. Effect of TS on the retention of saffron bioactive componentsduring encapsulation

The average values of encapsulation efficiency for SAC areshown in Fig.1.With respect to the total solids content, this variablehad a positive effect on the encapsulation efficiency, i.e., highersolids content resulted in higher encapsulation efficiencies. It isshown that the most important factor determining the retention ofvolatiles and encapsulation efficiency of food oils during spraydrying is the dissolved solids content in the feed (Jafari, He, &Bhandari, 2007a, 2007b). Our results revealed that encapsulationefficiency of threemajor components of saffron increased by higherTS. This result can be attributed to the emulsion droplet size, whichdecreases when total solids content is increased (Jafari et al., 2008).Many studies have shown that lower emulsion droplet size leads tohigher encapsulation efficiency of oils and flavors (Jafari et al.,

Fig. 2. The average powder yield of microencapsulated saffron at two levels of TS.

H. Rajabi et al. / Food Hydrocolloids 51 (2015) 327e337330

2008; Liu et al., 2001; Soottitantawat et al., 2005). Tonon, Grosso,and Hubinger (2011), studying the microencapsulation of flaxseedoil using gum Arabic as wall material, also verified that theencapsulation efficiency directly was influenced by the total solidscontent.

These results also can be related to the emulsion properties.Emulsion viscosity is increased as a function of total solids con-centration, thus, is required shorter time to form a crust andreducing the circulation movements inside the droplets andresulting in higher retention (Jafari et al., 2008). It was observedthat a mixture with 40% TS consisting MD, GA and GE in the weightratio of 0.94:0.05:0.01 retained the highest amounts of picrocrocin,safranal and crocin, by retention values of 90.06, 80.37 and 91.03%,respectively. Liu et al. (2001) found that addition of GE at 1% (w/w)in combination with GA as the emulsifier noticeably increased theencapsulation efficiency of ethyl butyrate, due to faster formationof crust on the surface of droplets.

One reason for decreased SAC retention at 30% TSmay be bubbleinflation-bursting phenomenon. Reducing the soluble solids con-tent in the feed results in an increase in the amount of wateravailable to evaporate which leads to a decrease in solution vis-cosity followed by a softer surface to allow the particle to expand;this phenomenon becomes more prevalent at lower TS (30%). Liu,Furuta, Yoshii, and Linko (2000) found that the plausible break-down of flavor emulsions on inflation of the droplets, and sur-passing the droplet temperature higher than its boiling pointcauses a rapid decrease in flavor retention during microencapsu-lation by spray drying. Also, Pang et al. (2014) reported similarresults in spray drying of Orthosiphon stamineus extracts.

3.1.1. Picrocrocin retentionEncapsulation efficiency of picrocrocin varied from 54.57 to

90.06%. As shown in Fig. 1, picrocrocin retention was significantlyaffected by the total solids content. A lot of researches have beenperformed on the influence of different carriers alone or in com-binations on the encapsulation efficiency of flavors (Madene,Jacquot, Scher, & Desobry, 2006). Optimum operating conditionsand emulsion properties could minimize the loss of flavor in-gredients. Also, wall material properties have a significant effect onthe stability of oxygen-sensitive flavors (Reineccius, 1988). Bayramet al. (2005) studied spray drying of sumac flavor and found thatencapsulation efficiency increased with increase in soluble solidscontent.

Microencapsulation of other flavor compounds has also beenstudied (Balassa, Fanger,&Wurzburg, 1971; Brenner, 1983; Schultz,Dimick, & Makower, 1956; Szente & Szejtli, 1986; Taylor, 1983;Zilberboim, Kopelman, & Talmon, 1986). It should be noted thatincrease in the emulsion viscosity could act effectively in protectingflavoring ingredients against thermal degradation and otherdestructive agents during drying stage by increasing the surface tovolume ratio due to decrease in the size of atomized droplets. Also,increasing the soluble solids content could increase the encapsu-lation efficiency of flavoring compounds at the early stage of drying(Bayram et al., 2005).

3.1.2. Safranal retentionSafranal is a volatile compound and unstable in ambient tem-

peratures. The microencapsulation procedure protects ingredientswhich are volatile or sensitive to heat, light, or oxidation (Jafariet al., 2008). Encapsulation efficiency of safranal varied from44.57 to 80.37%. As mentioned above for picrocrocin retention andshown in Fig. 1, safranal retention was significantly affected by thetotal solids content. A similar result was reported by Rosenberg andSheu (1996) in microencapsulation of ethyl butyrate and ethylcaprylate using whey protein as wall material. They found that

retention of these volatiles was significantly affected by wall solidsconcentration, i.e. retention increased at higher TS from 10 to 30%.Reineccius (1988) illustrated that after emulsion atomization in thedesiccation chamber, volatile compounds tend to evaporate withwater molecules which causes to volatile loss in early stage ofdrying, thus, facilitating crust formation around the atomizeddroplets which prevents the evaporation of volatile compounds,and increasing the efficiency.

The effect of wall material content in the emulsion on theencapsulation efficiency of volatile during spray drying was alsoinvestigated by others (King, 1988; Menting, Hoogstad, & Thijssen,1970; Reineccius, 1988; Rosenberg & Sheu, 1996) and all of themobtain similar results with ours.

3.1.3. Crocin retentionSometimes, the color changes of extracts is one result of

destructive reactions (Cort�es-Rojas, Souza,& Oliveira, 2014). Crocinretention ranged from 41.86 to 91.03 % and was significantlyinfluenced by the total solids content (Fig. 1). We found thatmicroencapsulated powder obtainedwith a 40% total solids contentand high-ratio of MD had significantly higher color strength thanothers. The lowest value of crocin retention was related toMD:GA:GE in a ratio of 24:4:2 for 30% TS. Other researchers haveobtained similar results in microencapsulation of color ingredientsby spray drying such as Rodríduez-Huezo et al. (2004) in caroten-oids encapsulation using GA, gellan gum and MD, Shu et al. (2006)in lycopene microencapsulation using GE and sucrose by spraydrying, and Chen and Tang (1998) in carrot pulp encapsulationusing spray-dryer, with sucrose and GE as wall materials.

3.2. Effect of TS on the powder yield

Powder yield varied from 60.48 to 87.03% and was significantlyinfluenced by the total solids content (Fig. 2). In contrast to resultsobtained for SAC retention, powder yield in some cases wasshowing a trend vice versa, i.e., decreased with increasing in thetotal solids content of the emulsions. Although the average powderyield for emulsions prepared with 40% TS was higher than otherones, but the maximumyield was obtained with 30% TS. In the caseof different wall materials, yield was maximized for MD:GA:GE inthe ratio of 77.5:20:2.5 (30% TS).

Different factors could affect the powder yield of spray driedherbal extracts such as operating conditions of spray dryer (Ersus&Yurdagel, 2007; Frascareli, Silva, Tonon, & Hubinger, 2012; Jangam& Thorat, 2010; Souza & Oliveira, 2006; Toneli, Park, Negreiros, &Murr, 2010), carrier type and its ratio in the emulsions (Barbosaet al., 2005; Bayram et al., 2005; Couto et al., 2011; Fernandes,

Fig. 3. The average moisture content of microencapsulated saffron powders at twolevels of TS.

H. Rajabi et al. / Food Hydrocolloids 51 (2015) 327e337 331

Candido, & Oliveira, 2012; Krishnan, Bhosale, & Singhal, 2005;Krishnan, Kshirsagar, & Singhal, 2005), and wall:core ratio(Frascareli et al., 2012; Hogan, McNamee, O'Riordan, & O'Sullivan,2001).

3.3. Effect of TS on powder moisture content

The moisture content (MC) of the powders was measured to bein the range of 2.705e5.33%. The powders produced by spraydrying method have a very lowMC, in the range between 2.9 ± 0.02to 4.66 ± 0.21% (w/w) (Couto et al., 2013). From the standpoint ofmedicinal usage of saffron, according to the literature (convention,2007), acceptable MC for spray dried pharmaceutical powders, islower than 5% (w/w). Therefore, it could be concluded that all of ourproducts had suitable levels of residual moisture content.

Fig. 4. Cox response trace plots of picrocrocin retention; A) 30% TS and B) 4

Total solids content affected the powder moisture content(Fig. 3). By increasing TS from 30 to 40%, MC decreased from 5.33 to2.705% revealing solids content had a positive effect on powder MC.The increase in total solids concentration results in higher viscosityand less water available for evaporation, leading to lower moisturecontent. However, for solids concentrations above 30%, the increasein emulsion viscosity may reduce water diffusion, resulting inpowders with higher MC. Similarly, Fernandes et al. (2008),investigation spray drying microencapsulation of Lippia sidoidesessential oil, found that increase in the TS from 30% to 60% led to adecrease in MC from 5% to 4%.

3.4. Effect of wall material proportions on the retention of saffronbioactive components during encapsulation

As shown in Figs. 4e6, change in the wall material proportionsresulted in SAC retention variations. This trend could be explainedthrough emulsion properties i.e. viscosity and surface tensionwhich are crucial parameters to evaluate the behavior of solutionsduring spray drying considering the morphology of spray-driedpowders and the incident of particle ballooning (Hecht & King,2000). Increasing emulsion viscosity up to a point that is relevantto optimum level could increase encapsulation efficiency. An in-crease in the viscosity of the initial emulsion should help retentionbecause of reduction of internal circulations within droplets andrapid semi-permeable membrane formation (Jafari et al., 2008).Also, lower surface tensions considered as an index to claim theemulsion is stable; better emulsion stability, higher efficiency(Rosenberg & Sheu, 1996).

In the case of all three bioactive components, at 30% TS, increaseand decrease of MD and GA proportions from reference blend had

0% TS, Contour plot of picrocrocin retention; C) 30% TS and D) 40% TS.

Fig. 5. Cox response trace plots of safranal retention; A) 30% TS and B) 40% TS, Contour plot of safranal retention; C) 30% TS and D) 40% TS.

Fig. 6. Cox response trace plots of crocin retention; A) 30% TS and B) 40% TS, Contour plot of crocin retention; C) 30% TS and D) 40% TS.

H. Rajabi et al. / Food Hydrocolloids 51 (2015) 327e337332

H. Rajabi et al. / Food Hydrocolloids 51 (2015) 327e337 333

an inverse impact on the SAC retention. The use of MD up to anoptimum level depending on the core type, total solid content andemulsion properties could improve efficiency. Pang et al. (2014)reported this amount was 5.33% for encapsulation of O. stamineusextracts by spray drying. Optimum MD level in our research at 30%TS based on the lowest surface tension (data not shown) andhighest SAC retention was 87.5% (w/w). In the case of GA,decreasing its proportion followed by increasing the MD amount inthe mixture caused a decrease in SAC retention due to decrease inthe emulsion viscosity and increase in the surface tension. HigherGE proportions from reference blend up to 1% (w/w) due to increasein viscosity caused an increase in SAC retention and vice versa.Some researchers have increased the viscosity of the emulsionwithout significantly changing its solids content through additionof thickeners (�1% w/w of wall materials concentration) like so-dium alginate or gelatin and found similar results with ours (Liuet al., 2001; Rosenberg et al., 1990).

Retention of each bioactive component at 40% TS was similar toeach other. In this way, SAC retention was increased by increasingthe GA proportion due to improvement in emulsion stability i.e.increase in viscosity and decrease in surface tension. Hogan et al.(2001) showed that microencapsulation efficiency of soy oil withmilk proteins and carbohydrate blends was positively correlatedwith emulsion stability during the process. Increase of GE propor-tion from reference blend due to excessive rise in viscosity andrelated problems such as impossibility or difficulty of droplet at-omization and larger exposure during atomization (Jafari et al.,2008) could cause a decrease in the retention.

3.4.1. Picrocrocin retentionIt can be observed in Fig. 4A that retention of picrocrocin at 30%

TS decreased as the amount of MD and GA varied from referenceblend (GE ¼ 2.5%, GA ¼ 10% and MD ¼ 87.5%). In the case of GEeffect on retention, its levels had an inverse effect on response(retention of picrocrocin) than other two wall materials and theretention was increased as the amount of GE increased fromreference blend. Cox trace plots showed that changes in GA andMDlevels had similar effects.

For retention of picrocrocin at 40% TS, a different trend wasobserved (Fig. 4B). Picrocrocin retention decreased and increased asthe level of MD varied from reference blend. Also increase in GAfrom references blend had a similar effect on retention; it remainedconstant with GA decrease from references blend. However, as seenin Fig. 1A, GE had a different trend than GA and MD. Picrocrocinretentionwas decreased as the amount of GE varied from referenceblend. Cox trace plots showed that in both TS, GE level had thegreatest impact on retention of picrocrocin than MD and GA.

Fig. 7. Cox response trace plots of spray dried saf

Retention contour plot (Fig. 4C) for 30% TS showed that area formaximum retention (100% of initially added amount) was close tothe points, where GE was present at maximum. In practice, use ofthis amount of GE due to increase in the emulsion viscosity fol-lowed by problems in spraying, was not possible. At the point thatMD:GA:GEwas at the ratio of 25.5:3:1.5, retentionwas at accessiblemaximum level, namely 60% of initially added amount. In the caseof 40% TS (Fig. 4D), we found that the area of maximum retention(80% of initially added amount) was at points, where GE was keptunder 0.5% of TS. Retention levels dropped to 70% of initially addedamount at a point with the highest amount of MD and without GA.

3.4.2. Safranal retentionCox trace plot (Fig. 5A) showed that the behavior of bothMD and

GE on retention of safranal at 30% TSwas approximately similar andshowed a trend similar to the picrocrocin. In contrast, the GA levelhad a different effect on response than the other two componentsand retention of safranal was slightly decreased as the amount ofGA increased and remained constant with decreased from refer-ence blend.

As shown in Fig. 5B, retention trend of safranal at 40% TS wasdifferent from others. Safranal retention decreased and increased asthe level of MD and GA decreased and increased from referenceblend. But as seen in Fig 3B, GE had a different influence comparedwith GA andMD. Safranal retentionwas decreased as the amount ofGE varied from reference blend. Cox trace plots showed that in bothTS, GE level had the greatest impact on the retention of safranalthan MD and GA.

Contour plot (Fig. 5C) for retention levels of safranal at 30% TSshowed that the area of maximum retention was at points, whereGE was at maximum amounts that as mentioned above was un-reachable. Retention levels decreased from 70 to 60% of initiallyadded amount with increase in MD level and decrease in GE levelwithout any GA. Retention level in all of the experimental points in40% TS (Fig. 5D) varied in the range of 60e80% of initially addedamount that had an incremental trend with decrease in GE level.

3.4.3. Crocin retentionCox trace plot (Fig. 6A) showed that retention of crocin at 30% TS

increased as the amount of GE increased from reference blend. Aninteresting trend was observed when GA amount decreased fromreference blend that retention at first was increased and thendecreased. Crocin retention was decreased in four conditions: in-crease and decrease of MD, increase of GA and decrease of GE fromreferences blend.

About crocin retention at 40% TS, as shown in Fig. 6B, weobserved a trend similar to safranal retention, although MD had

fron powder yield; A) 30% TS and B) 40% TS.

Fig. 8. Cox response trace plots of powder moisture; A) 30% TS and B) 40% TS.

H. Rajabi et al. / Food Hydrocolloids 51 (2015) 327e337334

severe effects on crocin retention than picrocrocin. Also, it clearlyshows that GE level had the greatest impact on the retention ofcrocin than MD and GA.

In the case of MD selection with different DE, in the pretestexperiments (data not shown), we found that MD with a high DE(16.5e19) was better than low DE for SAC retention. In contrast toour results, Wagner and Warthesen (1995), revealed that amongMD with different DE, the highest efficiency was obtained withmaltodextrin 4 DE for a- (89%) and b-carotene (87%). Desobry,Netto, and Labuza (1999) also reported an efficiency of 62 and78% for trans- b-carotene encapsulated, with MD 25 DE and MD 4DE/glucose (82:18), respectively.

Fig. 9. Scanning electron micrographs of spray-dried saffron microcapsules at 30

Contour plot of crocin retention (Fig. 6C) in all of the experi-mental points was in the range of 50e60% of initially added amountthat represents the low efficiency of this wall materials at 30% TS.On the opposite side at 40% TS (Fig. 6D), retention level at 13 pointsin constraint region was at acceptable range from 70 to 90% ofinitially added amount that may be due to achieving an optimumviscosity as a result of increase in TS and also the use of GE.

3.5. Effect of wall materials proportion on the powder yield

As shown in Fig. 7, the effect of wall material proportion onpowder yield at 30 and 40% TS was completely disparate. In the 30%

% TS. (A) MDeGA (90:10), (B) MDeGE (90:10), and (C) MDeGAeGE (85:1:5).

H. Rajabi et al. / Food Hydrocolloids 51 (2015) 327e337 335

TS, powder yield was increased with higher GA and MD and lowerGE from reference blend. Also, powder yield was rapidly decreasedwith higher GE and lower MD from reference blend. It could be saidthat GA decreases from reference blend had not effect on powderyield.

In the case of 40% TS, powder yield increased with variation ofMD and GE from reference blend. In contrast toMD and GE, powderyield decreased with variation of GA from reference blend. In both30 and 40% TS, GE level had the greatest influence on the powderyield than MD and GA.

3.6. Effect of wall materials proportion on powder moisture content

It can be observed from Cox trace plot (Fig. 8A) that the MC ofmicroencapsulated powders decreased as the amount of MD andGA decreased and GE increased from reference blend. As shown inFig. 8B, the effect of GA and GE on MC was similar to 30% TS. Whilethe MC of powders varied as the amount of MD decreased fromreference blend. Thus, the wall material type and ratio can influ-ence the MC of microencapsulated powders. In contrast to our re-sults, Dian, Sudin, and Yusoff (1996) reported that MC values formicroencapsulated palm oil by spray drying method were notaffected by the type of wall material.

3.7. SEM analysis

The SEM microphotographs of the encapsulated powders pro-duced at the various conditions (30 and 40% TS) are shown in Figs. 9and 10.

Fig. 10. Scanning electron micrographs of spray-dried saffron microcapsules at 40%

It could be found that saffron extract microcapsules showed anearly spherical shape. Particle size distribution varied from 0.54 to20.47 mm and the mean particle diameter for 30% and 40% TS was6.69 mm and 7.81 mm, respectively. The increase in total solidscontent resulted in larger particle sizes. This can be explained bythe viscosity of the feed emulsion, which increased with solidsconcentration (Jafari et al., 2008). Hogan et al. (2001) and Jinapong,Suphantharika, and Jamnong (2008) reported that particles' meandiameter was increased with the rise of total solids content. Theyattributed this result to the increment of the feed emulsionviscosity.

The high temperature in the drying chamber and the size ofatomized droplets which are very fine leads to a rapid withdrawalof water from it, resulting in wrinkles and depressions in thepowder surfaces (Rosenberg, Kopelman,& Talmon,1985), as shownin our samples too.

It was observed (Figs. 9 and 10) that the type and concentrationof each wall material had a meaningful impact on the morphologyof particles. Pang et al. (2014) found similar results in spray dryingof O. stamineus extracts while, different results are reported byFernandes et al. (2008). They observed microparticles producedfrom different solid contents (30, 40, 50 and 60%) or from differentMD:GA proportions (4:1, 3:2, 2:3 and 0:1) had no significant dif-ferences in appearance. Also, Ameri andMaa (2006) illustrated thatthe water withdrawal rate from droplet and the type and concen-tration of wall material as well as wall:core ratio are the mainfactors which determine the shape and morphology of spray driedparticles. Optimal process conditions must be in away to maximizethe drying rate.

TS. (A) MDeGA (90:10), (B) MDeGE (97.5:2.5), and (C) MDeGAeGE (94:5:1).

H. Rajabi et al. / Food Hydrocolloids 51 (2015) 327e337336

Fig. 9B and C shows a fragmented microcapsule, where it ispossible to observe its wall, that may be due to decrease in totalsolids and viscosity. This defect in the structure may be one of thereasons for the decrease in SAC retention at 30% TS compared withother samples. Rocha, Trindade, Netto, and Favaro-Trindade (2009)and Favaro-Trindade, Santana, Monterrey-Quintero, Trindade, andNetto (2010) found similar results in casein hydrolyzate encapsu-lation using MD and using blends of GE and soybean protein isolateas carriers, respectively. The amount of dented particles in thepowder produced without GA was minimum, while, the percent ofdented particles tended to increase linearly with the increase in GAconcentration. At lower TS (30%) and high amount of MD, theparticle seems to have smooth and spherical surface along withpartial fragmented appearances in contrast to the ones at higher TS(40%) and high amount of GA, which show more shrinkage. Inagreement with this finding, Pang et al. (2014) reported that in-crease in the MD concentration from 0.53% to 10.67% leads toparticles with a smoother surface. Many researchers have reportedthat the use of GA as wall material lead to nearly spherical dentedparticles, while particles obtained from MD have a broken andincomplete structure (Fernandes et al., 2008; Kanakdande et al.,2007; Krishnan, Bhosale, et al., 2005; Krishnan, Kshirsagar, et al.,2005; Vaidya, Bhosale, & Singhal, 2006).

The highest size distribution uniformity, maximum percent ofdented particles and the highest encapsulation efficiency wereobserved in the formulation containing all three wall materials at40% TS that may be due to achieving an optimum viscosity as aresult of increase in TS and also the use of GE (Fig. 10C). Further-more, as shown in Fig. 10, the lack of wall fissures or porosity on theparticle surfaces at 40% TS indicates a complete coverage of thegum over the SAC.

4. Conclusion

The present study describes the use of three types of wall ma-terials i.e. maltodextrin, gum Arabic and gelatin for the microen-capsulation of saffron extract using spray-drying technique. Totalsolids content had a positive influence on the encapsulation effi-ciency and the SAC retention. These results could be related toemulsion properties, mainly viscosity. Higher solids concentrationleads to bigger particle sizes, lower moisture contents and higherpowder yields. As far as the blends were concerned, the stability ofSAC increased as the quantity of gelatin decreased in its blend withmaltodextrin and gum Arabic up to 1% (w/w). The microencapsu-lation process was optimized at 40% total solids, consisting ofmaltodextrin, gum Arabic and gelatin in the w/w ratio of0.94:0.05:0.01. The knowledge obtained from this study could beimportant to improve the stability of worthwhile activecompounds.

Acknowledgment

Iran National Science Foundation (grant number 90000994) andthe Research Institute of Food Science and Technology should beacknowledged for their financial support.

References

Ahmed, M., Akter, M. S., Lee, J.-C., & Eun, J.-B. (2010). Encapsulation by spray dryingof bioactive components, physicochemical and morphological properties frompurple sweet potato. LWT e Food Science and Technology, 43(9), 1307e1312.

Akhavan, S., Jafari, S. M., Ghorbani, M., & Assadpoor, E. (2014). Spray-dryingmicroencapsulation of anthocyanins by natural biopolymers: a review. DryingTechnology, 32(5), 509e518.

Ameri, M., & Maa, Y.-F. (2006). Spray drying of biopharmaceuticals: stability andprocess considerations. Drying Technology, 24(6), 763e768.

Balassa, L. L., Fanger, G. O., & Wurzburg, O. B. (1971). Microencapsulation in the foodindustry. Critical Reviews in Food Science & Nutrition, 2(2), 245e265.

Baranauskien _e, R., Venskutonis, P. R., Dewettinck, K., & Verh�e, R. (2006). Propertiesof oregano (Origanum vulgare L.), citronella (Cymbopogon nardus G.) and mar-joram (Majorana hortensis L.) flavors encapsulated into milk protein-basedmatrices. Food Research International, 39(4), 413e425.

Barbosa, M., Borsarelli, C., & Mercadante, A. (2005). Light stability of spray-driedbixin encapsulated with different edible polysaccharide preparations. FoodResearch International, 38(8), 989e994.

Bayram, €O. A., Bayram, M., & Tekin, A. R. (2005). Spray drying of sumac flavour usingsodium chloride, sucrose, glucose and starch as carriers. Journal of Food Engi-neering, 69(2), 253e260.

Beck-Broichsitter, M., Schmehl, T., Seeger, W., & Gessler, T. (2011). Evaluating thecontrolled release properties of inhaled nanoparticles using isolated, perfused,and ventilated lung models. Journal of Nanomaterials, 2011, 3.

Bhusari, S., Muzaffar, K., & Kumar, P. (2014). Effect of carrier agents on physical andmicrostructural properties of spray dried tamarind pulp powder. PowderTechnology, 266, 354e364.

Borgogna, M., Bellich, B., Zorzin, L., Lapasin, R., & Ces�aro, A. (2010). Food microen-capsulation of bioactive compounds: rheological and thermal characterisationof non-conventional gelling system. Food Chemistry, 122(2), 416e423.

Brenner, J. (1983). The essence of spray dried flavors: the state of the art. Perfumerand Flavorist, 8, 40e44.

Caballero-Ortega, H., Pereda-Miranda, R., & Abdullaev, F. I. (2007). HPLC quantifi-cation of major active components from 11 different saffron (Crocus sativus L.)sources. Food Chemistry, 100(3), 1126e1131.

Carmona, M., Zalacain, A., S�anchez, A. M., Novella, J. L., & Alonso, G. L. (2006).Crocetin esters, picrocrocin and its related compounds present in Crocus sativusstigmas and Gardenia jasminoides fruits. Tentative identification of seven newcompounds by LCeESIeMS. Journal of Agricultural and Food Chemistry, 54(3),973e979.

Castro-Mu~noz, R., Barrag�an-Huerta, B. E., & Y�a~nez-Fern�andez, J. (2014). Use ofgelatinemaltodextrin composite as an encapsulation support for clarified juicefrom purple cactus pear (Opuntia stricta). LWT e Food Science and Technology,62(1, Part 1), 242e248.

Chen, B., & Tang, Y. (1998). Processing and stability of carotenoid powder fromcarrot pulp waste. Journal of Agricultural and Food Chemistry, 46(6), 2312e2318.

convention, U. S. p. (2007). USP XXX: United States pharmacopoeia convention:Mack Printing Rockville.

Cort�es-Rojas, D., Souza, C., & Oliveira, W. (2014). Assessment of stability of a spraydried extract from the medicinal plant Bidens pilosa L. Journal of King SaudUniversity-Engineering Sciences.

Couto, Martins, F. S., Chaul, L. T., Conceiç~ao, E. C., Freitas, L. A. P., Bara, M. T. F., et al.(2013). Spray drying of Eugenia dysenterica extract: effects of in-process pa-rameters on product quality. Revista Brasileira de Farmacognosia, 23(1),115e123.

Couto, R., Araújo, R., Tacon, L., Conceiç~ao, E., Bara, M., Paula, J., et al. (2011).Development of a phytopharmaceutical intermediate product via spray drying.Drying Technology, 29(6), 709e718.

Deladino, L., Anbinder, P. S., Navarro, A. S., & Martino, M. N. (2008). Encapsulation ofnatural antioxidants extracted from Ilex paraguariensis. Carbohydrate Polymers,71(1), 126e134.

Deo, B. (2003). Growing saffrondthe world's most expensive spice. Crop & FoodResearch, 20(1), 1e4.

Desobry, S., Netto, F., & Labuza, T. (1999). Influence of maltodextrin systems Atanequivalent 25DE on encapsulated b-carotene loss during storage. Journal of FoodProcessing and Preservation, 23(1), 39e55.

Dian, N. L. H. M., Sudin, N. A., & Yusoff, M. S. A. (1996). Characteristics of micro-encapsulated palm-based oil as affected by type of wall material. Journal of theScience of Food and Agriculture, 70(4), 422e426.

Ersus, S., & Yurdagel, U. (2007). Microencapsulation of anthocyanin pigments ofblack carrot (Daucus carota L.) by spray drier. Journal of Food Engineering, 80(3),805e812.

Favaro-Trindade, C., Santana, A., Monterrey-Quintero, E., Trindade, M., & Netto, F.(2010). The use of spray drying technology to reduce bitter taste of casein hy-drolysate. Food Hydrocolloids, 24(4), 336e340.

Fazaeli, M., Emam-Djomeh, Z., Ashtari, A. K., & Omid, M. (2012). Effect of spraydrying conditions and feed composition on the physical properties of blackmulberry juice powder. Food and Bioproducts Processing, 90(4), 667e675.

Fernandes, L. P., Candido, R. C., & Oliveira, W. P. (2012). Spray drying microencap-sulation of Lippia sidoides extracts in carbohydrate blends. Food and BioproductsProcessing, 90(3), 425e432.

Fernandes, L. P., Turatti, I. C., Lopes, N. P., Ferreira, J. C., Candido, R. C., &Oliveira, W. P. (2008). Volatile retention and antifungal properties of spray-dried microparticles of Lippia sidoides essential oil. Drying Technology, 26(12),1534e1542.

Fern�andez, J.-A., & Pandalai, S. (2004). Biology, biotechnology and biomedicine ofsaffron. Recent Research Developments in Plant Science, 2, 127e159.

Frascareli, E., Silva, V., Tonon, R., & Hubinger, M. (2012). Effect of process conditionson the microencapsulation of coffee oil by spray drying. Food and BioproductsProcessing, 90(3), 413e424.

Hecht, J. P., & King, C. J. (2000). Spray drying: influence of developing dropmorphology on drying rates and retention of volatile substances. 1. Single-drop experiments. Industrial & Engineering Chemistry Research, 39(6),1756e1765.

H. Rajabi et al. / Food Hydrocolloids 51 (2015) 327e337 337

Hogan, S. A., McNamee, B. F., O'Riordan, E. D., & O'Sullivan, M. (2001). Emulsificationand microencapsulation properties of sodium caseinate/carbohydrate blends.International Dairy Journal, 11(3), 137e144.

Jafari, S. M., Assadpoor, E., He, Y., & Bhandari, B. (2008). Encapsulation efficiencyof food flavours and oils during spray drying. Drying Technology, 26(7),816e835.

Jafari, S. M., He, Y., & Bhandari, B. (2007a). Encapsulation of nano-particles of d-limonene by spray drying e role of emulsifiers and emulsifying techniques.Drying Technology, 25(6), 1069e1079.

Jafari, S. M., He, Y., & Bhandari, B. (2007b). Role of powder particle size on theencapsulation efficiency of oils during spray drying. Drying Technology, 25(6),1081e1089.

Jangam, S. V., & Thorat, B. N. (2010). Optimization of spray drying of ginger extract.Drying Technology, 28(12), 1426e1434.

Janiszewska, E. (2014). Microencapsulated beetroot juice as a potential source ofbetalain. Powder Technology, 264, 190e196.

Jayasundera, M., Adhikari, B., Adhikari, R., & Aldred, P. (2011). The effect of proteintypes and lowmolecular weight surfactants on spray drying of sugar-rich foods.Food Hydrocolloids, 25(3), 459e469.

Jinapong, N., Suphantharika, M., & Jamnong, P. (2008). Production of instant soymilkpowders by ultrafiltration, spray drying and fluidized bed agglomeration.Journal of Food Engineering, 84(2), 194e205.

Kafi, M., Koocheki, A., Rashed, M., & Nassiri, M. (2006). Saffron (Crocus sativus)production and processing (Vol. 8). Enfield, NH: Science Publishers.

Kanakdande, D., Bhosale, R., & Singhal, R. S. (2007). Stability of cumin oleoresinmicroencapsulated in different combination of gum arabic, maltodextrin andmodified starch. Carbohydrate Polymers, 67(4), 536e541.

Khazaei, K. M., Jafari, S., Ghorbani, M., & Kakhki, A. H. (2014). Application ofmaltodextrin and gum arabic in microencapsulation of saffron petal's antho-cyanins and evaluating their storage stability and color. Carbohydrate Polymers,105, 57e62.

King, C. (1988). Spray drying of food liquids, and volatiles retention. In S. Bruin (Ed.),Paper presented at the preconcentration and drying of food materials: Thijssenmemorial symposium: Proc of the international symposium on preconcentrationand drying of foods. Eindhoven, The Netherlands, Nov 5e6, 1987.

Knewstaubb, C., & Henry, B. (1988). Natural colours e a challenge and anopportunity.

Krishnan, S., Bhosale, R., & Singhal, R. S. (2005). Microencapsulation of cardamomoleoresin: evaluation of blends of gum arabic, maltodextrin and a modifiedstarch as wall materials. Carbohydrate Polymers, 61(1), 95e102.

Krishnan, S., Kshirsagar, A. C., & Singhal, R. S. (2005). The use of gum arabic andmodified starch in the microencapsulation of a food flavoring agent. Carbohy-drate Polymers, 62(4), 309e315.

Le�on-Martínez, F., M�endez-Lagunas, L., & Rodríguez-Ramírez, J. (2010). Spray dryingof nopal mucilage (Opuntia ficus-indica): effects on powder properties andcharacterization. Carbohydrate Polymers, 81(4), 864e870.

Liu, Atarashi, T., Furuta, T., Yoshii, H., Aishima, S., Ohkawara, M., et al. (2001).Microencapsulation of emulsified hydrophobic flavors by spray drying. DryingTechnology, 19(7), 1361e1374.

Liu, Furuta, T., Yoshii, H., & Linko, P. (2000). Retention of emulsified flavor in a singledroplet during drying. Food Science and Technology Research, 6(4), 335e339.

Liu, Z.-q., Zhou, J.-h., Zeng, Y.-l., & Ouyang, X.-l. (2004). The enhancement andencapsulation of Agaricus bisporus flavor. Journal of Food Engineering, 65(3),391e396.

Madene, A., Jacquot, M., Scher, J., & Desobry, S. (2006). Flavour encapsulation andcontrolled release e a review. International Journal of Food Science & Technology,41(1), 1e21.

Medina-Torres, L., García-Cruz, E., Calderas, F., Laredo, R. G., S�anchez-Olivares, G.,Gallegos-Infante, J., et al. (2013). Microencapsulation by spray drying of gallicacid with nopal mucilage (Opuntia ficus indica). LWT e Food Science and Tech-nology, 50(2), 642e650.

Melnyk, J. P., Wang, S., & Marcone, M. F. (2010). Chemical and biological propertiesof the world's most expensive spice: saffron. Food Research International, 43(8),1981e1989.

Menting, L. C., Hoogstad, B., & Thijssen, H. A. C. (1970). Aroma retention during thedrying of liquid foods. Journal of Food Science & Technology, 13, 265e280.

Nassiri-Asl, M., & Hosseinzadeh, H. (2014). Neuropharmacology effects of saffron(Crocus sativus) and its active constituents. Bioactive Nutraceuticals and DietarySupplements in Neurological and Brain Disease: Prevention and Therapy, 29.

Orfanou, O., & Tsimidou, M. (1996). Evaluation of the colouring strength of saffronspice by UVevis spectrometry. Food Chemistry, 57(3), 463e469.

Pang, S. F., Yusoff, M. M., & Gimbun, J. (2014). Assessment of phenolic compoundsstability and retention during spray drying of Orthosiphon stamineus extracts.Food Hydrocolloids, 37, 159e165.

R�e, M. (1998). Microencapsulation by spray drying. Drying Technology, 16(6),1195e1236.

Reineccius, G. A. (1988). Spray-drying of food flavors. Paper presented at the ACSSymposium Series-American Chemical Society (USA).

Reineccius, G. A. (2001). Multiple-core encapsulation: the spray drying of food in-gredients. Microencapsulation of Food Ingredients, 151e185.

Reineccius, G. A. (2004). The spray drying of food flavors. Drying Technology, 22(6),1289e1324.

Reineccius, G. A., Ward, F. M., Whorton, C., & Andon, S. A. (1995). Developments ingum acacias for the encapsulation of flavors.

Rocha, G. A., F�avaro-Trindade, C. S., & Grosso, C. R. F. (2012). Microencapsulation oflycopene by spray drying: characterization, stability and application of micro-capsules. Food and Bioproducts Processing, 90(1), 37e42.

Rocha, Trindade, M., Netto, F., & Favaro-Trindade, C. (2009). Microcapsules of acasein hydrolysate: production, characterization, and application in protein bar.Food Science and Technology International.

Rodríduez-Huezo, M., Pedroza-Islas, R., Prado-Barrag�an, L., Beristain, C., & Vernon-Carter, E. (2004). Microencapsulation by spray drying of multiple emulsionscontaining carotenoids. Journal of Food Science, 69(7), 351e359.

Rosenberg, Kopelman, I., & Talmon, Y. (1990). Factors affecting retention in spray-drying microencapsulation of volatile materials. Journal of Agricultural andFood Chemistry, 38(5), 1288e1294.

Rosenberg, & Sheu, T. (1996). Microencapsulation of volatiles by spray-drying inwhey protein-based wall systems. International Dairy Journal, 6(3), 273e284.

Rosenberg, M., Kopelman, I. J., & Talmon, Y. (1985). A scanning electron microscopystudy of microencapsulation. Journal of Food Science, 50(1), 139e144.

Sa�enz, C., Tapia, S., Ch�avez, J., & Robert, P. (2009). Microencapsulation by spraydrying of bioactive compounds from cactus pear (Opuntia ficus-indica). FoodChemistry, 114(2), 616e622.

Sahin-Nadeem, H., Dinçer, C., Torun, M., Topuz, A., & €Ozdemir, F. (2013). Influence ofinlet air temperature and carrier material on the production of instant solublesage (Salvia fruticosa Miller) by spray drying. LWT e Food Science and Technol-ogy, 52(1), 31e38.

Sarfarazi, M., Jafari, S. M., & Rajabzadeh, G. (2015). Extraction optimization of saffronnutraceuticals through response surface methodology. Food Analytical Methods,1e13. http://dx.doi.org/10.1007/s12161-014-9995-3.

Schultz, T., Dimick, K., & Makower, B. (1956). Incorporation of natural fruit flavorsinto fruit juice powders. 1. Locking of citrus oils in sucrose and dextrose. FoodTechnology, 10(1), 57e60.

Shahidi, F., & Han, X. Q. (1993). Encapsulation of food ingredients. Critical Reviews inFood Science & Nutrition, 33(6), 501e547.

Shu, B., Yu, W., Zhao, Y., & Liu, X. (2006). Study on microencapsulation of lycopeneby spray-drying. Journal of Food Engineering, 76(4), 664e669.

Silva, V., Vieira, G., & Hubinger, M. (2014). Influence of different combinations ofwall materials and homogenisation pressure on the microencapsulation ofgreen coffee oil by spray drying. Food Research International, 61, 132e143.

Soottitantawat, Bigeard, F., Yoshii, H., Furuta, T., Ohkawara, M., & Linko, P. (2005).Influence of emulsion and powder size on the stability of encapsulated D-limonene by spray drying. Innovative Food Science & Emerging Technologies, 6(1),107e114.

Soottitantawat, Yoshii, H., Furuta, T., Ohgawara, M., Forssell, P., Partanen, R., et al.(2004). Effect of water activity on the release characteristics and oxidativestability of D-limonene encapsulated by spray drying. Journal of Agricultural andFood Chemistry, 52(5), 1269e1276.

Soottitantawat, Yoshii, H., Furuta, T., Ohkawara, M., & Linko, P. (2003). Microen-capsulation by spray drying: influence of emulsion size on the retention ofvolatile compounds. Journal of Food Science, 68(7), 2256e2262.

Souza, C. R., & Oliveira, W. P. (2006). Powder properties and system behavior duringspray drying of Bauhinia forficata link extract. Drying Technology, 24(6),735e749.

Szente, L., & Szejtli, J. (1986). Molecular encapsulation of natural and syntheticcoffee flavor with b-cyclodextrin. Journal of Food Science, 51(4), 1024e1027.

Tarantilis, P. A., Polissiou, M., & Manfait, M. (1994). Separation of picrocrocin,cisetrans-crocins and safranal of saffron using high-performance liquid chro-matography with photodiode-array detection. Journal of Chromatography A,664(1), 55e61.

Taylor, A. (1983). Encapsulation systems and their applications in the flavour in-dustry. Food Flavourings, Ingredients, Processing and Packaging, 5, 48.

Toneli, J., Park, K., Negreiros, A., & Murr, F. (2010). Spray-drying process optimizationof chicory root inulin. Drying Technology, 28(3), 369e379.

Tonon, R. V., Grosso, C. R., & Hubinger, M. D. (2011). Influence of emulsioncomposition and inlet air temperature on the microencapsulation of flaxseedoil by spray drying. Food Research International, 44(1), 282e289.

Turchiuli, C., Munguia, M. J., Sanchez, M. H., Ferre, H. C., & Dumoulin, E. (2014). Useof different supports for oil encapsulation in powder by spray drying. PowderTechnology, 255, 103e108.

Vaidya, S., Bhosale, R., & Singhal, R. S. (2006). Microencapsulation of cinnamonoleoresin by spray drying using different wall materials. Drying Technology,24(8), 983e992.

Wagner, L. A., & Warthesen, J. J. (1995). Stability of spray-dried encapsulated carrotcarotenes. Journal of Food Science, 60(5), 1048e1053.

Xuabin, N. (1992). Research progresses on the saffron crocus (Crocus sativus).Zhongcaoyao, 23(2), 100e107.

Zilberboim, R., Kopelman, I., & Talmon, Y. (1986). Microencapsulation by a dehy-drating liquid: retention of paprika oleoresin and aromatic esters. Journal ofFood Science, 51(5), 1301e1306.