DSpace at VNU: Comparison of enzyme-assisted and ultrasound-assisted extraction of vitamin C and phenolic compounds from acerola (Malpighia emarginataDC.) fruit

Original articleComparison of enzyme-assisted and ultrasound-assisted extraction of vitamin C and phenolic compounds from acerola Malpighia emarginata DC.. Ultrasound-assisted extraction

Original article

Comparison of enzyme-assisted and ultrasound-assisted extraction

of vitamin C and phenolic compounds from acerola (Malpighia

emarginata DC.) fruit

Hong Van Le & Van Viet Man Le*

Department of Food Technology, Ho Chi Minh City University of Technology, 268 Ly Thuong Kiet Street, District 10, Ho Chi Minh City,

Vietnam

(Received 7 September 2011; Accepted in revised form 7 January 2012)

extraction of vitamin C and phenolic compounds from acerola fruit Ultrasound-assisted extraction (UAE) took only 6 min to achieve the highest level of vitamin C and phenolic compounds as well as antioxidant activity of acerola juice, while enzyme-assisted extraction (EAE) took up to 120 min to obtain the maximal values On the basis of kinetic model of second-order extraction, the extraction rate constant of vitamin C and phenolics in UAE increased approximately 3.1 and 2.7 times, respectively, in comparison with that in EAE In addition, the maximal level of vitamin C, phenolics and the antioxidant activity evaluated by 1,1-diphenyl-2-picrylhydrazyl (DPPH), and 2,2¢-azinobis-(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) methods in UAE was 4.6%, 3.5%, 4.6% and 3.3%, respectively, higher than those in EAE Obviously, UAE is a useful method for the extraction of antioxidants from plant materials

Keywords Acerola fruit, antioxidant activity, enzyme-assisted extraction, kinetic, phenolic compounds, ultrasound-assisted extraction,

vitamin C.

Introduction

Acerola (Malpighia glabra L or Malpighia emarginata

DC.) is a fruit found from Central America to northern

South America It has recently been introduced in

subtropical areas throughout the world, including

Southeast Asia The pulp is very juicy, especially

possesses fruity and sweet flavour (Boulanger &

Crou-zet, 2001) This fruit is well known to be one of the best

natural sources of ascorbic acid (vitamin C), and has

become extremely popular in daily life (Hanamura

et al., 2006) This fruit also contains phenolic

com-pounds Both vitamin C and phenolic compounds are

powerful antioxidants, and their biological functions

prevent common degenerative processes (Hanamura

et al., 2008) Acerola juice with high vitamin C and

phenolic contents has, therefore, attracted much more

interest in human diet (Matta et al., 2004)

The classical techniques for juice extraction are

pressing (Chemat et al., 2008) and enzymatic

macera-tion (Kashyap et al., 2001; Matta et al., 2004; Lieu &

Le, 2010) Nevertheless, these methods are often

time- and energy-consuming as well as their extraction efficiency is usually low

Nowadays, a number of novel methods for target component extraction from plant materials have been applied, for example, supercritical fluid extraction (Pin-elo et al., 2007), accelerated solvent extraction (Hossain

et al., 2011), microwave-assisted extraction (Bai et al., 2010) and ultrasound-assisted extraction (UAE) (Vilkhu

et al., 2008; Khan et al., 2010) Among these methods, the technology of UAE has shown high extraction efficiency, low-energy and solvent consumptions (Pan

et al., 2011)

In recent years, there have been several researches on the application of UAE of various bioactive compounds, for instance, UAE of phenolic compounds from straw-berries (Herrera & Luque de Castro, 2005), coconut shell powder (Rodrigues & Pinto, 2007), citrus peel (Ma et al., 2009; Khan et al., 2010) and olive fruit (Jerman et al., 2010) However, so far, there has not been report on UAE of antioxidant-rich acerola juice yet, which has both high vitamin C and phenolic contents

The objectives of this study were to (i) investigate the effects of enzyme-assisted extraction (EAE) and UAE variables on extraction yield of vitamin C and phenolic compounds from acerola fruit, (ii) determine the kinetic

*Correspondent: E-mail: lvvman@hcmut.edu.vn

parameters of vitamin C and phenolic extraction

pro-cess, and (iii) compare the acerola juice quality obtained

from both methods

Materials and methods

Materials

Enzyme source

Commercial enzyme preparation ‘Celluclast 1.5L’

pro-duced by Trichoderma reesei was obtained from

Sigma-Aldrich (Singapore) The enzyme activity is 1500 Novo

Cellulase Unit per gram (NCU g)1) One NCU is the

amount of enzyme which, under standard conditions,

degrades carboxymethylcellulose to reducing

carbohy-drates with a reduction power corresponding to 1 lmol

glucose per minute (Arapoglou et al., 2010) The optimal

temperature and pH of this enzyme preparation are

50–60C and 4.5–6.0, respectively (Sørensen et al., 2003)

Plant material

Acerola (Malpighia emarginata DC.) used in this study

was purchased from a farm in Go Cong, Vietnam The

fruits were harvested during the period from July to

December in 2010 The bright orange fruits without

disease symptoms were selected

Chemicals

6-Hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic

acid (Trolox), 1,1-diphenyl-2-picrylhydrazyl (DPPH),

and 2,2¢-azinobis-(3-ethylbenzothiazoline-6-sulphonic

acid) (ABTS) were purchased from Sigma-Aldrich

(Singapore) Folin–Ciocalteu reagent, l-ascorbic acid,

methanol, ethanol, gallic acid, potassium persulphate

(K2S2O8), 85% phosphoric acid (H3PO4) solution,

potassium dihydrogen phosphate (KH2PO4) and

anhy-drous sodium carbonate (Na2CO3) were obtained from

Merck (Darmstadt, Germany) All reagents were

of analytical grade Double-distilled water was used

throughout experiments

Extraction methods

Acerola was destemmed, washed and crushed in a

blender (Panasonic, MJ 70M, Selangor, Malaysia)

In this study, water was used as the extraction solvent

for both methods Water was considered to be an efficient

extraction solvent for antioxidant production from some

plant materials (Mezadri et al., 2008; Pan et al., 2011)

Moreover, water is an environmentally friendly

extrac-tion solvent, and using water, we could obtain

antioxi-dant-rich acerola juice, but not only antioxidant

compounds (vitamin C and phenolics) in acerola fruit

After crushing, acerola mash was mixed with water at

the weight ratio of water to acerola mash of 2:1 and

subsequently used for juice extraction

Enzyme-assisted extraction For each assay, samples of 30 g diluted acerola mash were taken and placed into 250-mL beakers, which were covered with aluminium-foil papers to prevent the oxidative change from light

First series: Different amounts of Celluclast 1.5L were added into beakers of samples Enzyme concentrations were 0.15%, 0.3%, 0.45%, 0.6%, 0.75%, and 0.9% (v⁄ w) These values were equivalent to 0, 2.7, 5.4, 8.1, 10.8, 13.5, and 16.2 NCU g)1 of diluted acerola mash (NCU g)1), respectively The samples were then incu-bated in the period of 30 min

Second series: An amount of Celluclast 1.5L (8.1 NCU g)1) was added into beakers of samples The extraction times were varied from 30 to 150 min

In both series, the control samples were untreated with enzyme preparation Extraction temperature was adjusted to 50C using a thermostatic water bath (Memmert, Jakarta, Indonesia) After the period of incubation, the mash was filtered through a cheese cloth The obtained suspension was separated by a refrigerated centrifuge (Sartorius, Sigma 3K30, Geneva, Switzer-land) at 1370 g for 10 min at 10C, and the supernatant was collected for further analysis

Ultrasound-assisted extraction The UAE was performed with a horn-type ultrasonic probe with frequency of 20 kHz (Sonics and Materials Inc, VC750, Newtown, MA, USA) For each assay, samples of 30 g of diluted acerola mash were taken and placed into 100-mL beakers which were covered with aluminium-foil papers to prevent oxidative change from light

First series: Ultrasonic power levels were adjusted to

150, 300, 450 and 600 W, respectively Because each sample contained 30 g diluted acerola mash, the ultrasonic power per gram of the material would be 5, 10, 15 and

20 W g)1, respectively The ultrasonic time was 2 min Second series: The ultrasonic power of 15 W g)1was applied The ultrasonic times were ranged from 2 to

10 min

In both series, the control samples were untreated with ultrasound Because the temperature of the samples was gradually increased during the UAE, a water bath with cooled water (5–8C) was used to maintain the sample temperature not to exceed 50C At the end of the process, the mash was also filtered and separated in the same way as shown in the EAE

Determination of kinetic parameters of vitamin C and phenolic extraction from the second-order kinetic model

To determine the extraction rate constant of vitamin

C, the second-order rate law was applied (Pan et al., 2011) The general second-order model can be written as:

where, k is the second-order extraction rate constant

(L g)1min)1), Ce is the extraction capacity (the

equi-librium concentration of vitamin C in acerola juice)

(g L)1), and Ct is the concentration of vitamin C in

acerola juice at a given extraction time (g L)1)

The integrated rate law for a second-order extraction,

under the boundary conditions t = 0 to t and Ct= 0 to

Ct, can be written as an equation (2) or a linearised

equation (3):

2

t

Ct¼ 1

kC2þ t

The initial extraction rate, h (g L)1min)1), as Ct⁄ t

when t approaches 0, can be defined as equation (4):

h¼ k C2

The initial extraction rate, h, the extraction capacity,

Ce, and the second-order extraction rate constant, k, can

be determined experimentally from the slope and the

intercept by plotting t⁄ Ctvs t

The kinetic parameters of phenolic extraction were

also calculated in the same way of those of vitamin C

extraction

Comparison of acerola juice quality obtained from

enzyme-assisted extraction (EAE) and ultrasound-enzyme-assisted

extraction (UAE)

Enzyme-assisted extraction and UAE were carried out

in the appropriate conditions obtained from the above

experiments of each method The two methods were

compared on the increased percentage of vitamin C,

phenolic compounds and the antioxidant activity of

acerola juice using control sample as the base The

control sample was untreated with both enzyme

prep-aration and ultrasound

Analytical methods

Phenolic compounds

Total phenolic content in acerola juice was determined

as previously described by Luque-Rodrı´guez et al

(2007), using Folin–Ciocalteu reagent The results were

expressed as the equivalent to grams of gallic acid per

litre of acerola juice (g GAE L)1)

Vitamin C

In this study, vitamin C was quantified by HPLC The

HPLC system used included a pump (Shimadzu,

LC-10AS, Kyoto, Japan), a UV detector (Shimadzu,

(250 · 4.6 mm I.D., 5 lm) (Shimadzu, Gemini 5u C18 110A, Kyoto, Japan) The procedure was carried out according to the method of Abushita et al (1997) with slight modifications The mobile phase was a mixture of two solvents: A (potassium dihydrogen phosphate in water adjusted to pH 2.8) and B (methanol) with the ratio

of 9:1 (v⁄ v) The constant flow rate was 1.5 mL min)1 The column was maintained at room temperature, and the injection volume was 20 lL Ascorbic acid elution was monitored at 245 nm

The content of ascorbic acid in acerola juice was expressed as grams per litre (g L)1) and was calculated using an external calibration curve prepared with the standard ascorbic acid According to Mezadri et al (2008), ascorbic acid is the predominant form of vitamin

C in acerola; hence, the content of ascorbic acid was used to present the content of vitamin C in acerola juice

in our study

Antioxidant activity The procedure for antioxidant activity evaluation followed the method of Thaipong et al (2006) with slight modifications

For DPPH assay, briefly, the stock 0.1 mm DPPH violet solution was diluted with methanol to obtain an absorbance of 1.1 ± 0.02 units at 515 nm The reaction medium contained 5 mL of diluted DPPH•solution and

265 lL diluted acerola juice for the sample or methanol solution of Trolox (25–700 lm) for the standard, or water for the blank The reaction mixture was kept at room temperature in the dark for 20 min, and the absorbance was measured at 515 nm Antioxidant activity of acerola juice was expressed as millimolar Trolox equivalent antioxidant capacity per litre (mm TEAC)

For ABTS assay, once the radical was formed, the ABTS·+solution was diluted with ethanol to obtain an absorbance of 0.7 ± 0.02 units at 734 nm The reaction then started by adding 400 lL diluted acerola juice to

5 mL of diluted ABTS•+ radical cation solution, and the absorbance was measured after 1 min at 734 nm Standard Trolox solutions (25–500 lm) were also eval-uated against the radical Antioxidant activity of acerola juice was expressed as mmol Trolox equivalent antiox-idant capacity per litre (mm TEAC)

Statistical analysis All experiments were performed in triplicate The experimental results obtained were expressed as means ± SD (standard deviation) Mean values were considered significantly different when P < 0.05 Anal-ysis of variance was performed using the software Statgraphics plus, version 7.0 (Manugistics, Inc., Rock-ville, MD, USA)

Results and discussion

Enzyme-assisted extraction

Figure 1 shows the changes in the antioxidant content

and antioxidant activity of acerola juice with respect to

enzyme concentration The level of the target

compo-nents significantly improved with the increase in enzyme

concentration and approached the highest value at

enzyme concentration of 8.1 NCU g)1 Higher enzyme

concentration did not result in higher vitamin C and

phenolic contents According to Mosier et al (1999),

cellulase preparation from T reesei contained many

enzymes such as endoglucanase, cellobiohydrolase and

b-glucosidase These enzymes would be expected to

degrade structural cellulose that makes up 27% in the

primary cell wall of the acerola pulp (Lima et al., 1996)

That enhanced the efficiency of the extraction process

Owing to the increase in vitamin C and phenolic contents, the antioxidant activity of acerola juice also raised with the increase in enzyme concentration However, the antioxidant activities determined by DPPH method were always lower than those measured

by ABTS method It could be explained that anthocy-anin, which is one of the main polyphenol components

in acerola fruit, absorbs maximally at 520 nm (Zanatta

et al., 2005); therefore, its colour would interference with the DPPH chromogen, which has maximum absorbance at 515 nm This would lead to the results

in the relatively lower activity measured by DPPH method (Awika et al., 2003)

The influence of enzymatic extraction time on the antioxidant content and activity of acerola juice is listed

in Fig 2 A positive effect on vitamin C and phenolic level was observed when the time of EAE was not longer

(a)

(b)

17.2 18.2 19.2 20.2 21.2 22.2

17.2

17.7

18.2

18.7

0 2.7 5.4 8.1 10.8 13.5 16.2 18.9

–1 )

Enzyme concentration (NCU g –1 )

Phenolics Vitamin C

90

100

110

120

130

0 2.7 5.4 8.1 10.8 13.5 16.2 18.9

Enzyme concentration (NCU g –1 )

DPPH ABTS

phenolics, and (b) antioxidant activity of acerola juice.

(b)

90 100 110 120 130 140

Time of enzymatic treatment (min)

DPPH ABTS

(a)

17.2 19.2 21.2 23.2 25.2 27.2

17.2 17.7 18.2 18.7 19.2

–1 )

–1 )

Time of enzymatic treatment (min)

Phenolics Vitamin C

C, phenolics, and (b) antioxidant activity of acerola juice.

than 120 min A further increase in the extraction time

resulted in significantly (P < 0.05) lower concentrations

of vitamin C and phenolic compounds Hence, the

antioxidant activity of acerola juice also declined when

the biocatalytic time was prolonged

To clearly understand the effect of the extraction time

on the performance of vitamin C, an additional

exper-iment was conducted with the standard solution of

ascorbic acid under the same temperature and enzyme

concentration The results (unpublished data) showed

that the ascorbic acid level was stable during the first

30 min and then slightly decreased about 3.2% after

120-min incubation as compared to the initial level

Finally, a remarkable reduction of 10.9% in the ascorbic

acid level was observed in the 150-min treated sample

compared to that in the 120-min treated sample This

was attributed to the thermo-oxidative degradation

caused by high temperature and overlong extraction

time It is interesting to note that the percentage

reduction in vitamin C in the 150-min treated acerola

juice compared to the 120 min treated acerola juice was

10.8% (Fig 2) This similarity suggested that the

extraction of vitamin C could not continue when the

enzymatic extraction time was longer than 120 min

In summary, the results indicated that the efficient

extraction period with enzyme concentration of

8.1 NCU g)1 was 120 min Under these appropriate

conditions, the level of vitamin C, phenolics and

antioxidant activity of acerola juice based on DPPH

and ABTS methods rose approximately 35.7%, 9.0%,

23.9% and 22.6%, respectively, in comparison with

those of the control sample Although pectinase has

been widely used in juice extraction (Kashyap et al.,

2001; Lieu & Le, 2010), our results revealed that

cellulolytic enzyme is also a potential biocatalyst to

obtain antioxidant-rich fruit juice

Ultrasound-assisted extraction

Figure 3 illustrates the effect of ultrasonic power on the

level of vitamin C, phenolic compounds and antioxidant

activity of acerola juice The antioxidant concentrations

increased when the ultrasonic power augmented from 5

to 15 W g)1(P < 0.05); however, these values did not

change significantly at higher ultrasonic power

(P > 0.05)

The mechanism of UAE is ascribed to the acoustic

cavitation, which includes the formation, growth and

implosive collapse of bubbles in a liquid (Chowdhury &

Viraraghavan, 2009) The implosion of cavitation

bub-bles generates severe turbulence, high-velocity

inter-particle collisions and perturbation in microporous

particles of the materials, which accelerates the eddy

diffusion and internal diffusion Moreover, cavitation

within the proximity of solid surface causes surface

erosion and particle breakdown This effect provides

exposure of new surfaces further increasing mass trans-fer (Vilkhu et al., 2008) Our results are consistent with previous findings (Ma et al., 2009; Pan et al., 2011) Ma

et al (2009) and Pan et al (2011) reported that the yields of phenolic compounds from citrus and pome-granate peel depended significantly on the ultrasonic power level In our study, nevertheless, the content of vitamin C and phenolics kept unchanged when the ultrasonic power was higher than 15 W g)1 This may be attributed to the fact that the cavitation bubbles may grow too big to collapse or collapse weakly which could cause the reduction in the cavitation effect Also, many bubbles may hamper the propagation of the ultrasound wave (Sun et al., 2011)

A positive correlation between the content of antiox-idants and the antioxidant activity of acerola juice was observed (Fig 3a, b) The increase in biologically active compounds may lead to enhance the antioxidant activity

(a)

17.2 18.2 19.2 20.2 21.2 22.2 23.2

17.2 17.7 18.2 18.7 19.2

Ultrasonic power (W g –1 )

Phenolics Vitamin C

(b)

90 100 110 120 130

Ultrasonic power (W g –1 )

DPPH ABTS

phenolics, and (b) antioxidant activity of acerola juice.

of the extract Besides, ultrasound could separate sugar

moiety from acerola glycosides to create aglycones It

was reported that aglycones are more potent

antioxi-dants than their corresponding glycosides

(London˜o-London˜o et al., 2010) Furthermore, the moderate

sonochemical hydroxylation of phenolic compounds,

which was caused by hydroxyl radicals produced during

the sonolysis of water, could improve their antioxidant

properties (Ashokkumar et al., 2008)

The results in Fig 4 have shown that prolongation of

the ultrasonic time augmented the level of vitamin C,

phenolics and antioxidant activity of acerola juice;

maximum of these values achieved after 6-min

sonica-tion The vitamin C content rose approximately 40.3%

compared to that in the control sample, while the

increase in phenolic content was much lower with just

roughly 12.5% (Fig 4a) The antioxidant activities of

acerola juice measured by DPPH and ABTS methods under this condition also increased 28.5% and 25.9%, respectively, as compared to those in the control sample (Fig 4b)

To evaluate the stability of the antioxidants under sonication, the standard solution of ascorbic acid was exposed to ultrasound with the same conditions of UAE Because of polyphenol-protective ability of ascor-bic acid (Altunkaya & Gokmen, 2009), we chose this component to investigate the stability of the antioxi-dants in acerola juice As seen from Fig 5, when the temperature was controlled to be inferior to 50C (the ultrasonic conditions in our study), the concentration of ascorbic acid in the standard solution did not change, whilst this value dramatically reduced up to 29.2% in the period of 10-min ultrasonic treatment without temperature control The reduction in ascorbic acid concentration under the uncontrolled temperature con-dition may be due to (i) the interaction of this compound with hydroxyl radicals, and⁄ or (ii) the adverse effect of temperature on the structure of ascorbic acid Nonetheless, according to Entezari et al (2003) and Khan et al (2010), sonication at frequency of

20 kHz during short duration produced low concentra-tion of hydroxyl radicals It was therefore concluded that the loss of ascorbic acid may be related to the decomposition of analyte caused by thermal degrada-tion Thus, temperature was an important variable for ultrasonic extraction of vitamin C We suggested that the temperature of UAE for antioxidants in acerola fruit should not exceed 50C

(a)

(b)

17.2 19.2 21.2 23.2 25.2 27.2

17.2

17.7

18.2

18.7

19.2

19.7

20.2

–1 )

Ultrasonic time (min)

Phenolics Vitamin C

90

100

110

120

130

140

Ultrasonic time (min)

DPPH ABTS

phenolics, and (b) antioxidant activity of acerola juice.

10.0 12.0 14.0 16.0 18.0 20.0

Ultrasonic time (min)

Uncontrolled temperature Controlled temperature

ascorbic acid standard solution was sonicated at the ultrasonic power

of 15 W g)1under both uncontrolled and controlled temperature conditions.

Extraction kinetics of enzyme-assisted extraction (EAE)

and ultrasound-assisted extraction (UAE)

Figure 6 illustrates the linearised forms of the

second-order model for the two extraction methods The

extraction capacity, Ce, the initial extraction rate, h,

the extraction rate constant, k, and the coefficient of

determination, R2, given for the two methods in Table 1,

are in accordance with the graphs in Fig 6 The results

indicated that Ce, h and k were higher in UAE than

those in EAE The values of the rate constant, k, were

found approximately 3.1 times for vitamin C and 2.7

times for phenolics as fast in UAE as in EAE; in the

same ways, the values of the extraction capacity, Ce, in

UAE were also observed to augment 9.5% and 4.5% for vitamin C and phenolic compounds, respectively, in comparison with those in EAE These results concluded that UAE efficiently enhances the extraction rate of antioxidants from acerola fruit Similar kinetic effects were evidenced by Chemat et al (2004) and Khan et al (2010) for UAE of polyphenols from orange peel and essential oils from caraway seeds, respectively Likewise, ultrasound could improve the second-order kinetic parameters of polyphenol extraction from pomegranate peel (Pan et al., 2011) However, the values and the increase in the kinetic parameters estimated by these authors were much lower than those in our study It is possible that (i) the level of phenolic content in acerola fruit was higher than that in pomegranate peel, and (ii) phenolic compounds could be extracted from fruit easier than from peel

As seen from Table 1, all kinetic parameters for vitamin C were always remarkably higher than those for phenolic compounds Thus, vitamin C could be extracted more efficiently than phenolics regardless of extraction methods The second-order model fitted well the experimental results owing to the obtained high coefficient of determination (Table 1) This confirmed that there are two main stages during the antioxidant extraction from acerola fruit

Comparison of acerola juice quality obtained from enzyme-assisted extraction (EAE) and ultrasound-enzyme-assisted

extraction (UAE)

In comparison with EAE, UAE improved the level of phenolic compounds and vitamin C as well as antiox-idant activity of acerola juice (Table 2) Regarding vitamin C, UAE increased its value 4.6% more than EAE Besides, phenolic level in UAE was also 3.5% higher than that in EAE Our results are in agreement with many findings that UAE enhanced the yield of bioactive constituents in comparison with the conven-tional techniques (Vilkhu et al., 2008; Khan et al., 2010)

As seen in Table 2, both EAE and UAE enhanced greater vitamin C content than phenolic content The possible reasons are that (i) vitamin C is more abundant than phenolic compounds in acerola fruit (Mezadri

et al., 2008), and (ii) phenolic compounds can link with various compounds of cell walls such as polysaccharides

or proteins (Lieu & Le, 2010), which may make phenolic extraction more difficult than vitamin C extraction

Owing to the increase in vitamin C and phenolic contents, the increase in antioxidant activity of acerola juice in UAE was also higher in comparison with that in EAE (Table 2) It should be noted that ultrasound improved not only the content of antioxidants but also the total antioxidant activity of these compounds in our study Further experimental work on identifying the

(a)

(b)

Time (min)

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

Phenolics Vitamin C

Time (min)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

Phenolics Vitamin C

extraction times (t) in (a) enzyme-assisted extraction (EAE) and (b)

ultrasound-assisted extraction (UAE).

types of phenolic compounds has to be carried out for

profound understanding

Conclusions

Ultrasound-assisted extraction has been shown to be an

efficient method for the extraction of vitamin C and

phenolic compounds from acerola fruit compared to

EAE The results indicated that not only higher levels of

vitamin C and phenolics were achieved but also higher

antioxidant activity of acerola juice was observed in

UAE as compared to those in EAE Furthermore, the

extraction time of UAE was significantly shorter than

that of EAE A considerable reduction in the extraction

time seems to be suitable for the extraction of thermally

labile compounds

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extraction (UAE)

Component

Extraction method

Extraction

Initial extraction

Extraction rate

enzyme-assisted extraction (EAE) and ultrasound-enzyme-assisted extraction (UAE)

Extraction

method

Increased level of components* (%)

Antioxidant activity

Different small letters in the same column mean significant difference at

P < 0.05.

*Compared to the control sample.

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