Use of different supports for oil encapsulation in powder by spray drying

Powder Technology 255 (2014) 103–108

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Use of different supports for oil encapsulation in powder by spray drying C. Turchiuli a,b,c,⁎, M.T. Jimenez Munguia d, M. Hernandez Sanchez a, H. Cortes Ferre a, E. Dumoulin a,b,c a

AgroParisTech, UMR 1145 Ingénierie Procédés Aliments, 1 avenue des olympiades, 91300 Massy, France INRA, UMR 1145 Ingénierie Procédés Aliments, 1 avenue des olympiades, 91300 Massy, France c CNAM, UMR 1145 Ingénierie Procédés Aliments, 1 avenue des olympiades, 91300 Massy, France d Universidad de las Américas, Sta Catarina Martir, 72810 Puebla, Mexique b

a r t i c l e

i n f o

Available online 28 August 2013 Keywords: Dry emulsion Spray drying Powder Encapsulation

a b s t r a c t Spray drying of oil-in-water emulsions containing hydrophilic carriers is used to encapsulate lipophilic compounds into powders. Oil droplets are dispersed within the solid matrix of carriers acting like a barrier. To study the influence of the nature of the carrier on both the properties of the initial and dry emulsion and on the spray drying process, α-tocopherol dispersed in olive oil (weight ratio 1/4) was used as a model lipophilic molecule. Eight initial oil-in-water emulsions containing 4% w/w oil phase and 36% w/w carrier consisting of different food polymers as maltodextrin DE12, acacia gum and inulin, mixed in different proportions were prepared by rotorstator homogenization and characterized for their size, size distribution and viscosity. They were spray dried in a pilot spray dryer in the same conditions (inlet and outlet air temperatures of 180 °C and 90 °C respectively, emulsion flow rate 57 g⋅min−1) and the properties of the dry emulsions produced were characterized. Whatever the support used, the powder yield of the spray drying process was higher than 50% without optimization of the operating conditions. The dry emulsions produced had similar properties (size, size distribution, density and flowability) and contained more than 73% of the initial oil with only 5% of the oil phase on the particle surface (unencapsulated). After powder dissolution in water, the reconstituted emulsions had a size distribution similar to that of the initial emulsions, indicating that spraying did not modify the emulsion structure. Due to its emulsifying and film forming properties, the use of acacia gum, in combination with maltodextrin and/or inulin, allowed obtaining more stable initial emulsions with controlled size distribution (~2 μm, monodispersed) leading to higher powder yield for spray drying (e.g., superior to 65%). Agave inulin was found to be a possible alternative to maltodextrin to produce powders with increased health benefits. © 2013 Elsevier B.V. All rights reserved.

1. Introduction Encapsulation of active molecules aims at creating a barrier between the molecules and the environment. It is used to protect active molecules against light, humidity and oxygen in order to avoid or delay their degradation and stabilise them during storage before use. It also allows limiting or controlling their transfer to the environment in order to avoid losses, to mask some of their properties (taste, odour, catalytic activity) or to get a controlled (at given time and place) and dosed (total or progressive) delivery [1]. Encapsulation is widely used in the food, chemical and pharmaceutical industry where active molecules are often lipophilic compounds ⁎ Corresponding author at: AgroParisTech, UMR 1145 Ingénierie Procédés Aliments, 1 Avenue des Olympiades, 91300 Massy, France. Tel.: +33 1 69 93 50 71; fax: +33 1 69 93 50 05. E-mail addresses: [email protected] (C. Turchiuli), [email protected] (M.T. Jimenez Munguia), [email protected] (M. Hernandez Sanchez), [email protected] (E. Dumoulin). 0032-5910/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.powtec.2013.08.026

(aroma, vitamins, antioxidants, drugs), not or poorly soluble in water. Their encapsulation may consist in creating an oil in water emulsion by dispersing them, eventually after dilution in oil, in an hydrophilic continuous phase containing long chain polymers. These polymers will protect the oil active molecules by isolating them from the environment and limiting their mobility. Removing water from the aqueous phase by spray drying allows obtaining a powdered dry emulsion where oil droplets containing the active molecules are dispersed within the solid polymer matrix of powder particles. The powder form is stable and allows easier dosage and mixing with other powders. However, for efficient encapsulation, the proportion of unencapsulated molecules on the particle surface has to be low; and for easy handling, the powder must have good flowability and mixing ability and allow the reconstitution of the initial wet emulsion by rehydration in water [2]. Encapsulation efficiency and powder properties are influenced by the different steps of the spray drying process comprising (1) the preparation of the initial oil in water wet emulsion with a given structure, (2) its spraying in small drops into hot air and (3) the drying of each individual drop leading finally to dry

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solid particles [3–6]. The behaviour of the product during the spraying and drying steps depends on the emulsion properties. Especially, the composition of both hydrophilic and lipophilic phases, their weight ratio, the dry matter content and oil droplet size distribution of the emulsion and its viscosity were found to be key parameters for aroma encapsulation [7–11]. Different studies have shown that the decrease of the emulsion oil droplets size (down to 2 μm) causes an increase of the encapsulation efficiency, e.g., a better retention of the active molecule during spray drying, a lower quantity of non encapsulated oil on the particle surface or a better protection of the oil phase regarding oxidation [12,13]. The initial emulsion oil droplet size distribution is therefore a key parameter to control. The choice of the carrier materials that will constitute the dry solid matrix is also important [14,15]. They must have good spray drying ability: allow forming aqueous solutions with reasonable viscosity to be pumped and sprayed, be not too sticky or hygroscopic products for rapid and efficient drying and good stability of the powder during storage. In the food industry, the main carriers used for oil encapsulation are polysaccharides, starches, celluloses, gums and proteins. They are used alone or in combination. To produce fine and stable emulsions and to have a better protection of the oil active molecule during spray drying, emulsifying and film forming compounds are also often necessary [16]. Local products, with good availability and offering some health benefits, may be preferred [17,8]. Acacia gum, a natural hydrocolloid obtained by exudation from acacia and known for its emulsifying and film forming properties, and maltodextrin, a neutral and inexpensive starch hydrolyzate, are often associated for the encapsulation of oil with an efficiency which is a function of proportions of each [18,19]. Due to its technical and nutritive properties, inulin may also be an interesting possible encapsulation agent. It is a fructooligosaccharide with prebiotic effects and dietary fiber action. It causes no increase of the glycemic index, which makes it a potential ingredient for diabetic food, and it is known to improve calcium biodisponibility [20]. Agave inulin is extracted from the blue agave. Unlike other types of inulin, it is very soluble in cold water and has more calcium and minerals, with a neutral and mildly sweet flavour. Properties of agave inulin make it a potential support for encapsulation, especially in Mexico where it is produced in large quantities, that will add health benefits to the product. α-Tocopherol is a lipidsoluble antioxidant contained in vitamin E. Its high oxidative sensitivity requires protection during storage. In this study, α-tocopherol was prediluted in olive oil and encapsulated into dry emulsions by spray drying. Different support materials, maltodextrin DE121 (MD), acacia gum2 (GA) and agave inulin3 (I), were used alone or mixed in different proportions. The size, size distribution and viscosity of the initial emulsions, containing 40% w/w total dry matter with 8% w/w olive oil and 2% w/w of α-tocopherol, were measured in order to follow their evolution according to the dry matter composition and to study their influence on the spray drying powder yield, on the properties of the powders obtained and on the encapsulation efficiency. 2. Material and methods

Table 1 Mass composition of emulsions studied (40% w/w dry matter). Emulsion

1 polymer 2 polymers

3 polymers

Dry matter

MD MD-I (1:1) MD-GA (1:1) GA-I (1:1) MD-GA-I (1:1:1) MD-GA-I (1:2:1) MD-GA-I (2:1:1) MD-GA-I (1:1:2)

Water

MD

GA

I

Olive oil

α-Tocopherol

36.4 18 18 — 12 9 18 9

— — 18 18 12 18 9 9

— 18 — 18 12 9 9 18

2.9 3.2

0.7 0.8

60

AA, Nexira, Fr). The total dry matter content of all initial emulsions (hydrophilic and lipophilic compounds) was 40% w/w in which the lipophilic compounds represented 10% w/w (comprising 2% w/w αtocopherol). 2.2. Initial emulsions Aqueous solutions were prepared by slow dissolution of the carrier(s) in water at 40 °C under mechanical stirring and, for the oil phase, α-tocopherol was mixed with olive oil under magnetic stirring. Emulsions were obtained using a rotor–stator homogenizer (AXR, Silverson Machines Ltd, Fr) to disperse the oil phase into the aqueous one. Emulsions were homogenized for 20 min with a rotation speed of 3500 rpm. Homogenization caused an increase of the emulsion temperature up to 60 °C that seemed to be favourable to obtain fine and homogeneous emulsions (size about 1 μm). 2.3. Spray drying Initial emulsions were spray dried in a Niro Minor pilot scale spray dryer (Niro, Dk). It is a one step co-current spray dryer with an evaporative capacity comprised between 1 and 4 kg⋅h−1. The emulsion feed flow rate was fixed to 57.6 g⋅min−1, corresponding to a water flow rate of 34.6 g⋅min−1. For spraying, a rotary wheel was used with a rotation speed of 25000 rpm (5 bar compressed air). Drying air was taken from the ambient by a fan (43 Hz) with a flow rate of 110 kg⋅h−1. Its inlet and outlet temperatures (TIN and TOUT) were measured using thermocouples (K type). Exit moist air and dry powder were separated by a cyclone at the outlet of the chamber. The powder was collected continuously in glass jars where its temperature was measured, and it was stored in sealed refrigerated jars until analysis. Assuming total removal of water during drying and no product loss, spray drying of 1 kg of initial emulsion should allow producing 400 g of dry emulsion (powders) containing 10% w/w encapsulated oil comprising 2% w/w α-tocopherol.

2.1. Products

2.4. Emulsions and powders characterization

Oil phase represented 4% w/w of initial oil in water emulsions. It consisted of α-tocopherol (Sigma, Ge) and olive oil (Lesieur, Fr—15% w/ w saturated, 77% w/w mono-unsaturated and 8% w/w poly-unsaturated fatty acids) with a weight ratio of 1:4. In the aqueous phase, different hydrophilic carriers were used alone or in mixes with different ratios (Table 1): maltodextrin DE12 (MD) (Glucides, Roquette, Fr), agave inulin (I) (Oligofructine, Nutriagaves, Mx) and acacia gum (GA) (Instantgum

The density of emulsions (20 °C) was measured by pycnometry. Their apparent viscosity μ (Pa⋅s) and their rheological behaviour at 25 °C were measured using a rotational rheometer with coaxial cylinders (Rheomat R180, Lamy, GB). Apparent viscosity was deduced from shear stress values τ (Pa) measured for different velocity gradients γ (s−1) imposed between the rotor and the stator (Newton's law μ = τ⋅γ−1). The size and size distribution of emulsions and powders were measured by laser granulometry (Mastersizer 2000, Malvern, GB). For the emulsions, the analysis was performed in wet mode, dispersing a few drops of emulsion in deionized water (Hydro 2000). Powders were analyzed in dry mode (Scirocco 2000) with a compressed air pressure of 1 bar ensuring the dispersion of the particles.

1 2 3

MD: maltodextrin DE12. GA: acacia gum. I: agave inulin.

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They had very similar densities, between 1050 and 1170 kg⋅m−3 (20 °C), but their apparent viscosity and oil droplets size distribution were different depending on the polymers used in the aqueous phase and especially on the presence or absence of acacia gum. The six emulsions containing acacia gum were similar in size. They had a monomodal and relatively narrow size distribution with similar volume median diameters d50, between 1.8 and 2.4 μm. Both emulsions prepared without acacia gum (MD and MD-I), on the contrary, had wide oil droplet size distributions, with several peaks. Their median volume diameters d50 were larger (4.6 and 13.9 μm, respectively) with the presence of oil droplets above 10 μm (Table 2). The presence of these “big” drops does not seem to be compatible with a good oil encapsulation in the powder particles produced with a pilot spray dryer that generally have diameters inferior to 40 μm. Furthermore, both emulsions had a poor stability over time with some coalescence of oil droplets observed after about 1 hour. Maltodextrin and inulin are support materials. They are poor emulsifier agents, and obtaining stable fine emulsions required using acacia gum for its emulsifying properties. All the emulsions studied had a slightly pseudoplastic shear thinning behaviour. However, their viscosity was different depending on the polymers used in the aqueous phase (Fig. 1). In particular, the viscosity of the emulsion increased with the proportion of acacia gum and decreased when increasing the proportion of inulin. Both bimodal emulsions with highest sizes were also less viscous. The emulsion viscosity depends on the oil fraction, on the viscosities of the lipophilic and aqueous phases and on the oil droplets size. It is likely to influence their behaviour during spray drying, including changing the drying kinetics or diffusion of active molecules. In addition, spraying more viscous emulsions can lead to larger drops, more difficult to dry, which will give larger and more humid particles. The use of inulin enables to prepare emulsions with a dry matter content compatible with the spray drying requirements (e.g., 40% w/w) while reducing their viscosity.

The powder water content X (g water/100 g dry matter) was measured by oven drying (~2 g, 103 °C) till reaching a constant weight (average of two determinations). Their water activity aw was measured at 20 °C with an aw-meter (TH2, Novasina, Ch) (~2 g). For sorption isotherms X = f (aw), powder samples were first stored at 20 °C for several weeks in a dry atmosphere (P2O5) to be dehydrated. They were then placed at 20 °C under different relative humidities fixed by saturated salt solutions: LiCl (11%), MgCl2 (33%), K2CO3 (43%), Mg(NO3)2 (53%) and NaCl (75%) until equilibrium (constant weight). The water content X for each relative humidity, equal to the water activity of the powder at equilibrium, was then measured by oven drying (103 °C). Powders bulk and tapped densities were obtained measuring the volume occupied by a mass M of powder placed in a 25-cm3 measuring cylinder before (ρb) and after (ρt) 5 min of tapping (1250 falls of 3 ± 0.2 mm) (Density tester, Varian, Fr). The solid true density was measured using an air pycnometer (AccuPyc, Micromeritics, Fr). The determination of the total oil content of the powder required first the reconstitution of the liquid emulsion by dissolving the spraydried powder in deionized water ensuring a dry matter content of 40% w/w. The oil droplets size distribution of the reconstituted emulsion was measured and its oil content was determined after oil extraction using a methanol/chloroform/water mix (volume ratio 1:1:1). After the addition of glacial acetic acid and methanol and stirring (UltraTurrax, 3000 min−1, 30 s), chloroform was added in three times with the addition of sodium chloride and stirring between each addition (Ultra-Turrax, 3000 min−1, 30s). The organic phase containing the oil was then separated by centrifugation (10 000 min−1, 15 min, 4 °C). The solvent was evaporated under vacuum (Rotavapor, Buchi, 400 mbar, 40 °C), and the last traces were removed by nitrogen gas circulation for 15 min. The oil content of the powder sample was then obtained by weighing the extract. The extraction yield, measured for initial emulsions with a known oil content, was 80 wt%. The surface oil content was measured using Soxhlet extraction method with petroleum ether (reflux, 20 g, 80 °C, 6 h).

3.2. Spray drying of emulsions For all the eight emulsions, the inlet temperature of the drying air (TIN) was approximately 180 °C (ranging between 174 °C and 188 °C for the different trials), leading to air temperature at the output (TOUT) of approximately 90 °C (between 86 and 98 °C). The emulsions were sprayed for at least 30 min at a constant rate of 57.6 g⋅min−1. This allowed producing at least 300 g of each of the eight dry emulsions. Indeed, the powder yields (powder mass produced/total dry matter mass sprayed) were very different depending on the composition of the emulsion and in particular on the presence or absence of emulsifier. For the six emulsions containing acacia gum, the powder yield was

3. Results and discussion 3.1. Properties of initial emulsions The eight emulsions prepared in the same conditions (high shear homogenizer) with different carrier polymers had the same total oil content (4% w/w) and the same amount of total dry matter (40% w/w) (except for the emulsion with maltodextrin alone where the oil content was 3.6%) (Table 1).

Table 2 Volume diameters d10, d50 and d90 of initial and reconstituted emulsions, oil droplet size distribution and viscosity (μ∞, γ N 1000 s−1, 25 °C) of initial emulsions with the different polymers in different weight ratio.

Initial emulsion

Polymer (weight ratio)

d10

d50

d90

(μm)

(μm)

(μm)

MD

1.0

4.6

8.6

I-MD (1:1)

2.0

13.9

172.7

MD-GA (1:1)

1.2

1.8

I-GA (1:1)

1.3

2.2

I-MD-GA (1:1:1)

1.2

I-MD-GA (1:1:2)

Reconstituted emulsion Size

distribution

μ∞ (mPa.s)

d10

d50

d90

(μm)

(μm)

(μm)

38

0.9

3.2

18

0.9

3.5

2.6

197

0.9

1.6

3.5

88

1.2

2.0

3.2

2.4

3.0

79

1.0

1.7

2.6

1.1

1.8

2.9

133

1.0

1.5

2.4

I-MD-GA (1:2:1)

1.3

2.3

4.0

80

1.0

1.7

2.8

I-MD-GA (2:1:1)

1.2

2.3

4.1

50

1.0

2.0

3.6

Bimodal

Monomodal

20.2 185 2.4

106

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0.25

MD-GA (1:1)

µ (Pa.s)

0.2

0.15

I-MD-GA (1:1:2)

0.1

I-GA (1:1) Olive oil

I-MD-GA (1:2:1) I-MD-GA (1:1:1) I-MD-GA (2:1:1)

0.05

MD I-MD (1:1)

0 0

200

400

600

800

1000

1200

1400

γ (s-1) Fig. 1. Evolution of dynamic viscosity μ (Pa⋅s) with shear rate γ (s−1) at 25 °C for olive oil and emulsions with 4% w/w oil phase and different hydrophilic carriers.

between 65% and 69%, except for the emulsion with MD-GA, where it was 74%. For both emulsions not containing acacia gum (MD and MD-I), it was only 50%. This low yield may be due to the poor dispersion of the oil in these two emulsions whose size was greater than in the other emulsions (d50 4.6 and 13.9 μm instead of about 2 μm). However, in all cases, other operating conditions could be found to obtain better yields.

these powders without risk of caking during storage, an atmosphere of relative humidity below 40% should be maintained. The different densities of the different powders were similar (bulk 340 to 420 kg⋅m−3; tapped 560 to 650 kg⋅m−3; solid 1310 to 1400 kg⋅m−3). They correspond to Carr (100(ρt − ρb) / ρt) and Hausner (ρt/ρb) indexes between 29 and 43 and 1.42 and 1.75 respectively, characteristic of cohesive powders with poor flow properties. These powders were fine and had similar narrow monomodal particle size distributions regardless of their composition (Fig. 3). Their volume median diameter d50 was between 22 and 26 μm, with d10 and d90 of about 10 and 50 μm, respectively. According to the initial composition of the emulsions which were dried (Table 1), the lipid phase (olive oil and α-tocopherol) should represent 10% by weight of the dry powder. The total oil extraction for the different powders allowed recovering in any case more than 73% of the oil initially introduced. Considering the extraction procedure, oil losses during the spray drying process can be considered as low. The percentage of surface oil was estimated to 4.5% of the total oil. The presence of unencapsulated oil on the surface can contribute to the poor flow properties of powders. However, with more than 95% of the oil dispersed in

3.3. Powders properties (dry emulsions) The temperature of the powders collected after separation from air in the cyclone was less than 52 °C. Powder water content varied between 2.5 and 5.4 g/100 g dry matter, and water activity was between 0.13 and 0.26 without apparent relation to the composition. These values correspond to stable dry emulsions. The sorption isotherms of the different powders (Fig. 2) showed little differences for aw between 0.1 and 0.4. Above 0.4 the presence of hygroscopic components, such as acacia gum and/or inulin, increased the water sorption. The powder consisting only of oil and maltodextrin (MD) was the less hygroscopic one. Therefore, for good conservation of

I-GA(1:1) I-MD(1:1) I I-MD-GA(2:1:1) I-MD-GA(1:1:2) I-MD-GA(1:1:1) I-MD-GA(1:2:1)

22 20

X (g water/100 g DM)

18 16

I-MD-GA(1:2:1)

14

MD

12 10 8 6 4 2 0

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

aw Fig. 2. Sorption isotherms at 20 °C of inulin powder and dry emulsion powders containing ~10% w/w oil.

C. Turchiuli et al. / Powder Technology 255 (2014) 103–108

A

12 10 8

MD (d50 = 24.0 µm)

16

MD-GA (1:1) (d50 = 23.6 µm)

14

I-GA (1:1) (d50 = 22.2 µm) I-MD (1:1) (d50 = 24.3 µm)

6 4 2 0

1

10

100

Volume fraction (%)

Volume fraction (%)

A

1000

I:MD:GA (1:1:1)

Reconstituted Initial

12 10 8 6 4 2

d (µm)

B

107

0 0.10

1

10

100

1000

d (µm)

12

I-MD-GA (1:1:1) (d50 = 23.7 µm) I-MD-GA (1:1:2) (d50 = 25.8 µm)

B 10

MD

I-MD-GA (1:2:1) (d50 = 23.0 µm) 9

8

I-MD-GA (2:1:1) (d50 = 23.4 µm) 6 4 2 0 1

10

100

1000

Initial

8

Volume fraction (%)

Volume fraction (%)

10

7 6 5 4 3 2

d (µm)

Reconstituted

1 Fig. 3. Particle size distribution of powders with 10% w/w oil and different hydrophilic carriers: MD, MD-GA, I-GA and I-MD (A) I-MD-GA (1-1-1), I-MD-GA (1-1-2), I-MD-GA (1:2:1) and I-MD-GA (2:1:1) (B).

the solid matrix, the degree of encapsulation was satisfactory whatever the composition. 3.4. Properties of the reconstituted emulsions Due to the high shear stress during spraying, spray drying is likely to cause changes in the emulsion structure with some coalescence or fragmentation of oil droplets that may lead to a less efficient encapsulation. In order to study the influence of spray drying on the droplets size distribution of the emulsion, powders (dry emulsions) were gently dissolved in water to “reconstitute” the initial emulsions (with same concentration), and it was assumed that the oil droplets size distribution of reconstituted emulsions was representative of that of oil droplets encapsulated in the powder. For the six emulsions containing acacia gum, oil droplets size distributions of reconstituted emulsions (d50 ~ 2 μm) were similar to those of the original emulsions (Table 2, Fig. 4A). Spraying and drying therefore have no or small influence on the emulsion structure. And, both reconstituted emulsions not containing acacia gum (MD and MD-I) again showed a greater dispersion probably due to the coalescence of oil droplets during reconstitution. 4. Conclusions In this study, α-tocopherol dispersed in olive oil was encapsulated into dry emulsions by spray drying initial emulsions containing 40% w/w dry matter of which 8% w/w olive oil and 2% w/w α-tocopherol. Different food materials (maltodextrin, inulin and acacia gum with emulsifying properties) were used as carriers. No significant influence of the nature of the carrier used on the properties of the powders obtained and on the spray drying efficiency was

0 0.10

1

10

100

1000

d (µm) Fig. 4. Shape of oil droplet size distribution of initial and reconstituted emulsions with 4% w/w oil phase and 36% w/w hydrophilic carrier with (A) and without (B) acacia gum.

observed. However, due to its emulsifying and film forming properties, the use of acacia gum, in combination with maltodextrin and/or inulin, allowed obtaining more stable initial emulsions with a controlled size distribution (~2 μm, monodispersed) which was preserved during spray drying. The spray drying powder yield was also improved. Agave inulin was found to be a possible alternative to maltodextrin to produce powders with increased health benefits. Acknowledgements The authors would like to thank Marie-Elisabeth Cuvelier and Paola Soto (AgroParisTech, Massy, Fr) for their valuable assistance in the development of methods for oil extraction. M. Hernandez Sanchez and H. Cortes Ferre are grateful to CONACYT Mexico for its financial support. References [1] J. Adamiec, E. Marciniac, Microencapsulation of oil/matrix/water system during spray drying process, Drying 2004, Proceedings of the 14th International Drying Symposium (IDS 2004, Sao Paulo), vol. C, 2004, pp. 2043–2050. [2] K.L. Christensen, G.P. Pedersen, H.G. Kistensen, Preparation of redispersible dry emulsions by spray drying, Int. J. Pharm. 212 (2001) 187–194. [3] F. Shahidi, X.Q. Han, Encapsulation of food ingredients, Crit. Rev. Food Sci. Nutr. 33 (6) (1993) 501–547. [4] M. Fuchs, C. Turchiuli, M. Bohin, M.E. Cuvelier, C. Ordonnaud, M.N. Peyrat-Maillard, E. Dumoulin, Encapsulation of oil in powder using spray drying and fluidised bed agglomeration, J. Food Eng. 75 (2006) 27–35. [5] A. Gharsalloui, G. Roudaut, O. Chambin, A. Voilley, R. Saurel, Applications of spray-drying in microencapsulation of food ingredients: An overview, Food Res. Int. 40 (9) (2007) 1107–1121.

108

C. Turchiuli et al. / Powder Technology 255 (2014) 103–108

[6] D.J. Mc Clements, E.A. Decker, J. Weiss, Emulsion-based delivery systems for lipophilic bioactive components, J. Food Sci. 72 (8) (2007) 109–124. [7] G.A. Reineccius, The spray drying of food flavours, Dry. Technol. 22 (6) (2004) 1289–1324. [8] A. Soottitantawat, F. Bigeard, H. Yoshii, T. Furuta, M. Ohkawara, P. Linko, Influence of emulsion and powder size on the stability of encapsulated D-limonene by spray drying, Innovative Food Sci. Emerg. Technol. 6 (2005) 107–114. [9] S.M. Jafari, E. Assadpoor, Y. He, B. Bhandari, Encapsulation efficiency of food flavours and oils during spray drying, Dry. Technol. 26 (7) (2008) 816–835. [10] S.M. Jafari, E. Assadpoor, B. Bhandari, Y. He, Nano-particle encapsulation of fish oil by spray drying, Food Res. Int. 41 (2008) 172–183. [11] E.C. Frascareli, V.M. Silva, R.V. Tonon, M.D. Hubinger, Effect of process conditions on the microencapsulation of coffee oil by spray drying, Food Bioprod. Process. 90 (3) (2012) 413–424. [12] S.J. Risch, G.A. Reineccius, Spray dried orange oil. Effect of emulsion size on flavor retention and shelf stability, Flavour encapsulation, ACS Symposium Series, Washington DC, 1988, pp. 66–77. [13] A. Soottitantawat, H. Yoshii, T. Furuta, M. Ohkawara, P. Linko, Microencapsulation by spray drying: influence of emulsion size on the retention of volatile compounds, J. Food Sci. 68 (7) (2003) 2256–2262.

[14] H.C.F. Carneiro, R.V. Tonon, C.R.F. Grosso, M.D. Hubinger, Encapsulation efficiency and oxidative stability of flaxseed oil microencapsulated by spray drying using different combinations of wall materials, J. Food Eng. 115 (2013) 443–451. [15] C. Turchiuli, N. Lemarié, M.E. Cuvelier, E. Dumoulin, Production of fine emulsions at pilot scale for oil compounds encapsulation, J. Food Eng. 115 (4) (2013) 452–458. [16] C. Turchiuli, M. Fuchs, M. Bohin, M.E. Cuvelier, C. Ordonnaud, M.N. Peyrat-Maillard, E. Dumoulin, Oil encapsulation by spray drying and fluidised bed agglomeration, Innovative Food Sci. Emerg. Technol. 6 (2005) 29–35. [17] J. Finney, R. Buffo, G.A. Reineccius, Effects of type atomization and processing temperatures on the physical properties and stability of spray-dried flavours, J. Food Sci. 67 (3) (2002) 1108–1114. [18] B.R. Bhandari, E. Dumoulin, H.M.J. Richard, I. Noleau, A. Lebert, Flavor encapsulation by spray drying: application to citral and linalyl acetate, J. Food Sci. 57 (1) (1992) 217–221. [19] B.F. Mc Namee, E.D. O'Riordan, M. O'Sullivan, Effect of partial replacement of gum Arabic with carbohydrates on its microencapsulation properties, J. Agric. Food Chem. 49 (2001) 3385–3388. [20] C. Saénz, S. Tapia, J. Chávez, P. Robert, Microencapsulation by spray drying of bioactive compounds from cactus pear (Opuntia ficus-indica), Food Chem. 114 (2009) 616–622.