Study on microencapsulation of curcumin pigments by spray drying.pdf

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O R I G I N A L P A P E R

Study on microencapsulation of curcumin pigments by spraydrying

Yu Wang

Zhaoxin Lu

Fengxia Lv

Xiaomei Bie

Received: 13 November 2008/ Revised: 25 March 2009/ Accepted: 30 March 2009 / Published online: 18 April 2009

Springer-Verlag 2009

Abstract Curcumin has strong coloring power, safety

and innocuity, comprehensive pharmacological function,but its low stability and water insoluble limit its applica-

tion. Curcumin microcapsules were prepared by spray-

drying process using porous starch and gelatin as wall

material here. Results showed optimal condition as fol-

lows: the ratio of core and wall material of 1/30, embed-

ding temperature of 70 C, embedding time 2 h, inlet gas

temperature of 190 C, feed flow rate 70 mL/min and

drying air flow 70 m3 /h, at which the microencapsules had

good encapsulation efficiency. The stability of microen-

capsulation curcumin against light, heat, pH was effec-

tively improved and its solubility was increased greatly.

This study would be helpful to the industrial application of

curcumin.

Keywords Curcumin Pigment Microencapsulation Spray drying Stability

Introduction

Natural pigment is a vital quality attribute of foods, and

plays an important role in sensory and consumer accep-

tance of products [8, 28, 29].Curcumin is an important

permitted natural colorant used in food, nutritious and

pharmaceutical preparations among others [22, 26]. It is a

fat soluble pigment, while it is insoluble in aqueous med-

ium [10]. It is susceptible to oxidants, light and heat, which

can be easily deteriorated when exposed to such factors as

pH, temperature, light, metallic ions, enzymes, oxygen, and

ascorbic acid [27]. Because of its low stability, it cannotreally be widely used in the food processing industry [10].

Microencapsulation has been widely used for the sta-

bilization of labile compounds [7, 13]. It is defined as a

process in which tiny particles or droplets are surrounded

by a coating, or embedded in homogeneous or heteroge-

neous matrix, to give small capsules with many useful

properties [17, 21]. In systems, stabilization occurs because

the wall material acts as physical and a permeability barrier

for molecular oxygen and other molecular diffusion [3, 11,

14, 23], consequently, the shelf life of the encapsulated

products could be prolonged.

Various kinds of microencapsulation techniques such as

spray drying, spray cooling, extrusion, centrifugal extru-

sion, freeze drying, molecular inclusion among others,

have been developed, among which, spray drying is the

most commonly used one due to its low cost, available

equipment, continuous production and easiness of indus-

trialization, solid dispersions of curcumin in different ratios

with PVP prepared by spray drying can improve its bio-

availability such as its limited aqueous solubility and

degradation at alkaline pH, but it give no further research

for its property study, which limits its industrialization[1, 6,

16, 20].

Microencapsulation efficiency and microcapsules sta-

bility are largely dependent on wall material composition

[15, 16, 30]. Wall materials can be selected from a wide

variety of natural and synthetic polymers such as natural

gum, proteins and maltodextrins. Among them, gelatin is a

good choice due to its good properties of film-formation,

water-solubility, edibility, biodegradation and a tendency

to form a fine dense network upon drying, results of study

indicate that microencapsulation using gelatin simple

coacervation method can reduce the color staining effect

Y. Wang (&) Z. Lu F. Lv X. Bie

College of Food Science and Technology, Nanjing Agricultural

University, 210095 Nanjing, China

e-mail: [email protected]

1 3

Eur Food Res Technol (2009) 229:391–396

DOI 10.1007/s00217-009-1064-6



and enhance the stability of curcumin, but it give no

technological parameter for its industrialization [5, 9, 12,

19].

Optimal spray-drying conditions must also be consid-

ered. Among the main factors that must be optimized are

feed temperature, feed rate, air inlet temperature, low rate

and air outlet temperature [2].

When the feed temperature is increased, viscosity anddroplets size should be decreased but high temperatures

can cause volatilization or degradation of some heat-sen-

sitive ingredients. The rate of feed is adjusted to ensure that

each sprayed droplet reaches the desired drying level

before it comes in contact with the surface of the drying

chamber [25].

Air inlet temperature and flow rate is important. When

the air inlet temperature is low, the low evaporation rate

causes the formation of microcapsules with high density

membranes, high water content, poor fluidity, and easiness

of agglomeration [18]. The air inlet temperature which can

safely be used without damaging the product or creatingoperating hazards and the comparative cost of heat sources.

Air outlet temperature depends on the drying characteris-

tics of the material. The ideal air outlet temperature for the

microencapsulation of food ingredients such as flavors has

been reported to be 50–80 C [24].

The objective of this study is to develop a spray-drying

method for preparation of curcumin microcapsules using

gelatin as wall materials and to determine the effects of

different spray-drying operational variable on the curcumin

microcapsules to evaluate the effects on the properties of

spray-dried powders and their stability, which are valuable

for the advancement of drying technology and give tech-

nological parameter for its industrialization in the food

industry.

Materials and methods

Wall and core materials

Wall materials used here included edible gelatin (G200,

Shanghai Chemical Reagent Corporation, China) and por-

ous starch (Chongqing Taiwei Ecoagriculture Ltd, China).

Core materials used here were curcumin samples

(Hangzhou Lvtian Biotechnology Ltd, China).

Microencapsulation process

Gelatin (purity 96%) and porous starch (purity 98%) were

dissolved in hot distilled water, being stirred, to form an

aqueous solution containing different ratios of gelatin and

porous starch (mass ratio of core to wall material, M c / M w,

1/20, 1/30, and 1/40). Curcumin sample, preheated to

dissolve in acetone (solution concentration is 10%), was

dripped into the aqueous solution by stirring to form a

coarse emulsion at the following conditions (shown in

Table 1): embedding temperature, T et, 60, 70, and 80 C;

embedding time, t et, 1, 1.5 and 2 h.

Spray-drying process

The emulsion were carried out on a Model YC-105 Spray

Dryer (Pilotech Instrument & Equipment Co., Ltd,

Shanghai, China) equipped with a spray-drying chamber

with dimensions of 150 cm height and 80 cm diameter, a

high-speed centrifugal atomizer, a cyclone separator, plus a

hot air blower and an exhaust blower. The emulsion was

then fed to the spray dryer at the following conditions

(shown in Table 2): feed flow rate of microencapsulating

composition, W ff , 60, 70, and 80 mL/min; inlet gas tem-

perature, T gi, 180, 190, and 200 C; drying air flow, W af ,

50, 60 and 70 m

3

/h. Samples of the spray-dried particleswere collected during the experiments.

Analysis

The encapsulation efficiency

The encapsulation efficiency (EE) was calculated as fol-

lows [4, 27]:

EE(% ) ¼ C E

C T 100 ð1Þ

where C T refers to total added curcumin mass and C E refersto the mass of curcumin in the microencapsulated.

Table 1 Orthogonal design for the optimization of curcumin

microencapsulation

Number T et (C) M c / M w t et (h) EE (%)

1 (1) 60 (1) 1:20 (2) 1.5 75.0

2 (1) 60 (2) 1:30 (1) 1 83.5

3 (1) 60 (3) 1:40 (3) 2 94.4

4 (2) 70 (1) 1:20 (1) 1 92.1

5 (2) 70 (2) 1:30 (3) 2 96.1

6 (2) 70 (3) 1:40 (2) 1.5 93.8

7 (3) 80 (1) 1:20 (3) 2 67.8

8 (3) 80 (2) 1:30 (2) 1.5 73.2

9 (3) 80 (3) 1:40 (1) 1 57.6

K 1 252.9% 234.9% 243.4%

K 2 282.0% 252.8% 241.9%

K 3 208.8% 256.0% 258.3%

Range 73.2% 21.1% 16.4%

392 Eur Food Res Technol (2009) 229:391–396

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Quantification of curcumin

Twenty milligrams of microcapsule sample was dissolved

in absolute alcohol to form homogeneous solution (solution

concentration is 20%). Its absorbance and mass was

determined by a Model 752 UV spectrophotometry

(Shanghai jinghua Instrument Ltd, China) at

kmax = 425 nm. Curcumin concentration in the sample

was calculated using absorption value of the standard

solution.

Ten milligram of pure curcumin was dissolved in

absolute alcohol and up to 100 mL constant volume, fromwhich 10 mL solution was fetched. When it was up to

100 mL constant volume again, the standard curcumin

solution was obtained. In all, 1.0, 2.0, 3.0, 4.0, and 5.0 mL

standard solutions were up to 10 mL constant volume,

respectively, whose absorbances were determined by the

752 UV spectrophotometry at kmax = 425 nm. Its standard

curve and regression equation were then achieved, by

which the mass of curcumin in the encapsulated was

calculated.

The solubility of curcumin

The curcumin solubility in water was determined as fol-

lows. The mixture of the powder in the water solution

(0.3% w/v) was gently stirred until solid solubilization. The

powder was considered soluble when the time of solubili-

zation was not greater than 5 min.

The time necessary for complete microcapsule solubi-

lization was recorded. The results were conducted in

triplicate.

Evaluation of the curcumin stability

Effect of heating temperature and heating time on heat

resistance stability

The mixture of the powder in the water solution (0.5% w/v)

was prepared. Ten-milliliter solutions were heated 10 min

at a certain temperature, T h, 0, 60, 70, 80, 90 and 100 C,respectively, the absorbance value of them were deter-

mined by the spectrophotometry at kmax = 425 nm.

Ten-milliliter solutions were kept at 100 C for a certain

heating time, t ht, 10, 20, 30, 40 and 50 min, respectively,

the absorbance values were also determined by the

instrument.

Effect of pH on acid fastness stability

Curcumin can easily be deposited at the acidity condition,

which restricts its application in acid food. Improvement of

its acid fastness is necessary. When it is in alkali condition,its color turns into russety, the alkali fastness stability have

not studied because of it.

The mixture of the powder in the water solution (0.5%

w/v) was prepared. Ten-milliliter solutions were regulated

to pH 1, 2, 3, 4,5, 6 and 7 with 1 mol/L hydrochloric acid,

respectively, the absorbance values of them were deter-

mined at 425 nm.

Effect of illumination time on light stability

The mixture of the powder in the water solution (0.5% w/v)

was prepared, 100 mL solutions were exposed in daylight

for certain days (illumination time), t i, 1, 4, 6, 8, 12, 16 and

30 days. Absorbance values were determined using the

previously described technique.

Experimental design and results

The standard curve is shown in Fig. 1. Its regression

equation was as follows:

Y ¼ 12:278 X þ 0:3281 ð2Þ

where X referred to the absorbance value and Y referred tothe concentration of curcumin. Furthermore, its R2 was

0.9998.

Optimization of curcumin encapsulation process

To determine the optimal condition of curcumin encapsu-

lation process, the results of its orthogonal system was also

shown in Table 1. The best of EE 96.1% is in the

Table 2 Orthogonal design for the optimization of spray-drying

operation conditions

Number T gi (C) W ff (mL/min) W af (m3 /h) EE (%)

1 (1) 180 (1) 60 (1) 50 73.3

2 (1) 180 (2) 70 (2) 60 88.1

3 (1) 180 (3) 80 (3) 70 77.8

4 (2) 190 (1) 60 (2) 60 86.85 (2) 190 (2) 70 (3) 70 98.4

6 (2) 190 (3) 80 (1) 50 92.2

7 (3) 200 (1) 60 (3) 70 90.9

8 (3) 200 (2) 70 (1) 50 93.0

9 (3) 200 (3) 80 (2) 60 88.1

K 1 239.1% 251.0% 258.4%

K 2 277.34% 279.4% 263.0%

K 3 272.0% 258.0% 267.1%

Range 38.3% 28.4% 8.7%

Eur Food Res Technol (2009) 229:391–396 393

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experiment number 5, so the optimal condition was as

following: T et, 70 C; M c / M w, 1/30; t et, 2 h.

Furthermore, compared their K 1, K 2, K 3 and range, it

demonstrated that the embedding temperature was the best

important factor which effected on the encapsulation, while

mass ratio of core to wall material and embedding time was

relatively minor.

Optimization of curcumin spray-drying process

The results of spray-drying operation condition were

shown in orthogonal table (Table 2). The best of EE 98.4%

was in the experiment number 5, the optimal condition was

T gi = 190 C, W

ff = 70 mL/min and W

af = 70 m3 /h.

Compared their K 1, K 2, K 3 and range, the best important

factor was inlet gas temperature, the second was feed flow

rate, drying air flow was minor.

The solubility of curcumin

In the water-solubility experiment, free curcumin was not

solved with water as solvent at normal temperature while

encapsulated curcumin was resolved immediately after

4 min. There was no deposit in solution, whose color and

luster of solution was vivid and transparent.

When encapsulated curcumin turned into powders afterspray-drying process, powders was immediately resolved

after 2 min. The solubility of encapsulated curcumin has

further improved.

The stability of curcumin

Effect of heating temperature and heating time on heat

resistance stability of curcumin

Effects of heating temperature for 10 min on the stability

of free curcumin, micro-encapsulated curcumin before and

after spray drying were shown in Fig. 2.For three forms of curcumin, when heating temperature

was below 70 C, the variation of temperature had no

effect on curcumin stability. Along with increasing tem-

perature, absorbance values of free curcumin fell off rap-

idly while those of microencapsulated curcumin before and

after spray drying declined tardily. Compared their absor-

bance values variation of curcumin at the temperature from

0 to 100 C, the reducing ratio of absorbance value for free

curcumin was 6.2%, while these for microencapsulated

curcumin before and after spray drying were 1.2 and 0.8%,

respectively.

Effects of heating time at temperature 100 C on the

stability of free curcumin, microencapsulated curcumin

before and after spray drying were shown in Fig. 3.

For curcumin, when heating temperature was 100 C,

along with increasing heating time, absorbance values of

free curcumin decreased rapidly while those of microen-

capsulated curcumin before and after spray drying leveled

off. Compared their absorbance values variation of curcu-

min from 10 to 50 min, the reducing ratio of absorbance

value for free curcumin was 25.9%, while these for mi-

croencapsulated curcumin before and after spray drying

were 5.9 and 2.8%, respectively.

When curcumin was microencapsulated, the heat resis-

tance stability had been improved obviously, microencap-

sulated curcumin had better heat resistance stability.

Effect of pH on acid fastness stability

Effects of pH on the stability of free and microencapsulated

curcumin before and after spray drying were shown in

Fig. 4. When their solutions were in condition from pH 6 to

pH 1, their orange color and lustre were stable. From pH 6

0.0 0.1 0.2 0.3 0.4 0.50

1

2

3

4

5

6

7

y = 12.278x + 0.3281

R2= 0.9998

c u r c u m i n c o n c e n t r a i t o n ( m g / L )

aborbance value (A)

Fig. 1 The standard curve of curcumin solution

0 20 40 60 80 100

0.252

0.254

0.256

0.258

0.260

0.262

0.264

0.266

0.268

0.270

0.272

0.274

0.276

a b s o r b a n

c e

v a l u e

( A )

heating temperature ( )

microencapsulated curcumin before spray drying primary curcumin

microencapsulated curcumin after spray drying

Fig. 2 Effect of heating temperature on curcumin stability


1 3



to pH 4, absorbance value of free curcumin was invariable,

while from pH 4 to pH 1, it cut down. From pH 6 to pH 1,

the reducing ratio of absorbance value for microencapsu-

lated curcumin before and after spray drying were 3.3 and

2.6%, while that of free curcumin is 15.7%. Microencap-

sulation of curcumin had better acid fastness stability.

Effect of illumination time on light stability

Effects of illumination on the stability of free curcumin,

microencapsulated curcumin before and after spray drying

were shown in Fig. 5. When their solutions were exposed

to light, orange color was stable. From 1 to 15 days,

absorbance value of free curcumin kept stable, along with

increasing illumination time from 15 to 30 days,

absorbance values of free curcumin decreased rapidly, the

whole reducing ratio from 1 to 30 days was about 17.4%,

while those of microencapsulated curcumin before and

after spray drying were minor, which were 1.4 and 0.9%.

Microencapsulation of curcumin also had better stability to

illumination for a long time.

Conclusion

Curcumin microcapsules were successfully prepared by a

spray-drying method using a wall system consisting of gelatin and porous starch. EE were significantly affected by

the ratio of core to wall materials, embedding temperature,

inlet gas temperature and feed flow rate. The optimal

condition was determined as follows: the ratio of core and

wall material of 1/30, embedding temperature of 70 C,

embedding time of 2 h, inlet gas temperature of 190 C,

feed flow rate of 70 mL/min and drying air flow of 70 m3 /

h, at which microencapsulated curcumin before and after

spray drying showed good solubility and stability, such as

heat resistance stability, acid fastness stability and light

stability. This study would be helpful to promote the

application of curcumin and the food industry.

Acknowledgments This work was supported by the Youthful Sci-

entific Innovation Foundation of Nanjing Agricultural University(no.

29972020).

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10 20 30 40 50

0.18

0.19

0.20

0.21

0.22

0.23

0.24

0.25

0.26

a b s o r b a n c e

v a l u e ( A )

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Fig. 5 Effect of illumination on light stability of curcumin

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