Antioxidant activity of ginger extract in sunflower oil

Antioxidant activity of ginger extract insunflower oilZia-ur-Rehman,* AM Salariya and Farzana HabibBiotechnology and Food Research Centre, PCSIR Laboratories Complex, Ferozepur Road, Lahore 54600, Pakistan

Abstract: The antioxidant activity of dichloromethane extract from ginger was evaluated during 6

months of storage of refined sunflower oil at 25 and 45�C. Free fatty acid (FFA) content, peroxide value

(POV) and iodine value (IV) were used as criteria to assess ginger extract as an antioxidant. After 6

months of storage at 45�C, sunflower oil containing 1600 and 2400ppm ginger extract showed lower

FFA contents (0.083 and 0.080%) and POVs (24.5 and 24.0meqkg�1) than the control sample (FFA

contents 0.380%, POV 198.0meqkg�1). Sunflower oil containing 200ppm butylated hydroxyanisole

(BHA) and butylated hydroxytoluene (BHT) showed FFA contents of 0.089 and 0.072% and POVs of

26.5 and 24.7meqkg�1 respectively after 6 months of storage at 45�C. Similarly, after 6 months of

storage at 45�C, IVs of sunflower oil containing 1600 and 2400ppm ginger extract were 80 and 92

respectively, higher than that of the control sample (53). However, IVs of sunflower oil treated with

200ppm BHA and BHT were 94 and 96 respectively after 6 months of storage at 45�C. These results

illustrate that ginger extract at various concentrations exhibited very strong antioxidant activity,

almost equal to that of synthetic antioxidants (BHA and BHT). Ginger extract also showed good

thermal stability and exhibited 85.2% inhibition of peroxidation of linoleic acid when heated at 185�Cfor 120min. Therefore the use of ginger extract in foods is recommended as a natural antioxidant to

suppress lipid oxidation.

# 2003 Society of Chemical Industry

Keywords: antioxidant activity; ginger extract; sunflower oil

INTRODUCTION

Synthetic antioxidants, especially butylated hydroxy-

anisole (BHA) and butylated hydroxytoluene (BHT),

are commonly used to reduce oxidative rancidity of

fats and oils in foodstuffs during storage.1,2 These

synthetic antioxidants are known to have toxic and

carcinogenic effects on human health.3 Synthetic

antioxidants may cause liver swelling and influence

liver enzyme activities.4 Accordingly, there is a strong

need for effective antioxidants from natural sources as

alternatives to prevent deterioration of foods. Natu-

rally occurring materials provide advantages over

synthetic antioxidants because they may be safer to

humans. The literature is replete with reports of

extracts from natural sources that have demonstrated

strong antioxidant activity.5 Extracts from spices,

herbs and hulls are known to have various degrees of

antioxidant activity.6,7 These extracts have been

reported to be more effective than some major

synthetic antioxidants.8,9 Recently, dichloromethane

extract of ginger rhizome showed higher antioxidant

activity than a-tocopherol owing to the presence of

shogol, gingerol, gingerdiol and cumcumin as major

antioxidant compounds in the extract.10 In an earlier

study, Lee and Ahn11 proved the effectiveness of

gingerol in a b-carotene/linoleic acid water emulsion.

However, if an antioxidant such as ginger extract is to

be used in foods, its effectiveness will depend on

various factors such as thermal stability, storage

temperature and time. Therefore these factors have

to be investigated to determine the feasibility of using

ginger extract as an antioxidant in foods. Keeping in

view these facts, the present study was undertaken to

investigate the effect of storage temperature and time

on the antioxidant activity of ginger extract in sun-

flower oil. Heat treatment of ginger extract was also

carried out in order to assess the stability of the extract

at the frying temperature (185�C) of oil.

MATERIALS AND METHODS

Refined, bleached and deodorised sunflower oil was

obtained from a local refinery. Fresh ginger was

purchased from a local market. Synthetic antioxidants

BHA and BHT were purchased from Sigma Chemical

Co (St Louis, MO, USA).

Preparation of ginger extract (natural antioxidant)

The ginger was washed manually, peeled with a sharp

knife and then dried in a hot air oven (horizontal

forced air drier, Proctor and Schwartz Inc, Philadel-

phia, PA, USA) at 55�C. The dried ginger was ground

(Received 5 August 2002; accepted 28 October 2002)

*Correspondence to: Zia-ur-Rehman, Biotechnology and Food Research Centre, PCSIR Laboratories Complex, Ferozepur Road, Lahore

54600, Pakistan

# 2003 Society of Chemical Industry. J Sci Food Agric 0022–5142/2003/$30.00 624

Journal of the Science of Food and Agriculture J Sci Food Agric 83:624–629 (online: 2003)DOI: 10.1002/jsfa.1318

to a fine powder in a mill (Cemotec 1090 sample mill,

Tecator, Hoganas, Sweden). The material that passed

through an 80 mesh sieve was retained for use. The

ground ginger (10g) was extracted with 100ml of

various organic solvents (ethanol, methanol, acetone,

hexane, dichloromethane and diethyl ether) overnight

in a shaker at room temperature. The extract was

filtered through cheesecloth and the residue was re-

extracted under the same conditions. The combined

filtrate was evaporated in a rotary evaporator (EVF-

530-010K, Gallenkamp, UK) below 40�C. The

extract obtained after evaporation of organic solvent

was used as a natural antioxidant.

Application of ginger extract to sunflower oil

Sunflower oil free from additives was used as the

substrate for oxidation studies. Sunflower oil samples

(100ml) containing 800, 1600 and 2400ppm ginger

extract were prepared separately and placed in 250ml

airtight brown glass bottles. In addition, synthetic

antioxidants BHA and BHT were tested in sunflower

oil for comparative purposes at their legal limit of

200ppm as reported in the literature.12,13 Control

samples of sunflower oil without added antioxidant

were also prepared and bottled under identical

conditions. All oil samples of each treatment were

prepared in triplicate and stored at 25 and 45�C for 6

months. Oil samples of each treatment were with-

drawn at 1 month intervals to assess the antioxidant

activity of ginger extract.

Heat treatment of ginger extract

The extract was first evaporated to remove organic

solvent. Samples of ginger extract (5mg) were placed

individually in 10ml beakers and heated at frying

temperature (185�C) for 0, 10, 30, 40, 50, 60, 90 and

120min. The beakers were then cooled to room

temperature and their contents were dissolved in

0.3ml of methanol for the measurement of antioxidant

activity.

Antioxidant activity testing

The antioxidant activity (thermal stability) of ginger

extract after heat treatment was determined by a

modified thiocyanate method.14 First, 200ml of gingerextract was added to a mixed solution of linoleic acid

(0.13ml) in 99.0% ethanol (10ml) and 0.2mM

phosphate buffer (pH 7.0, 10ml) and the volume

was made up to 2ml with distilled water. The mixed

solution was then incubated in an airtight conical flask

at 40�C. To 0.1ml of this solution were added 9.7ml

of 75% ethanol and 0.1ml of 30% ammonium

thiocyanate. Precisely 3min after the addition of

0.1ml of 20mM ferrous chloride in 3.5% hydrochloric

acid to the reaction mixture, the absorbance of the

resultant red colour was measured at 500nm with a

spectrophotometer (Hitachi 2205, Nagoya, Aichi,

Japan). Distilled water was used as a control.

The effectiveness of ginger extract as an antioxidant

was tested by the determination of free fatty acid

(FFA) content, peroxide value (POV) and iodine value

(IV) during storage of sunflower oil at 25 and 45�C.

The FFA content (% oleic acid) was estimated using

an alkali titration method. The peroxide value

(meqkg�1 oil) was measured by titration with 0.1M

sodium thiosulphate solution using starch as an

indicator.15 The iodine value was determined by Wij’s

method.15 All determinations were carried out in

triplicate and mean values were calculated. Significant

differences (P<0.05) were calculated using Duncan’s

multiple range test as described by Steel and Torrie.16

RESULTS AND DISCUSSION

The data presented in Table 1 show the percentage

yield of ginger extract obtained after refluxing ground

ginger with different organic solvents, ie ethanol,

methanol, acetone, hexane, diethyl ether and dichloro-

methane. Between 2.58 and 21.28% ginger extract

was obtained with these six organic solvents, the

maximum amount being extracted with dichloro-

methane. The findings of Kikuzaki and Nakatani10

revealed that 12 different antioxidant compounds were

present in the non-volatile fraction of dichloromethane

extract of ginger. Therefore the antioxidant activity of

dichloromethane extract of ginger was tested in refined

sunflower oil at 25 and 45�C during 6 months of

storage. Free fatty acid contents, peroxide values and

iodine values were determined to assess the develop-

ment of rancidity during storage of sunflower oil.

Free fatty acid content and peroxide value during

storage of sunflower oil without antioxidant

Table 2 summarises the effect of storage conditions on

the FFA content, POV and IV of refined sunflower oil.

A gradual increase in FFA content and POV was

observed during storage of sunflower oil at 25 and

45�C for 6 months. However, a decrease in IV was

noted during storage. These changes were more

pronounced at 45 than at 25�C. Initially, the FFA

content, POV and IV of sunflower oil without

antioxidant (control) were 0.030%, 0.5meqkg�1 and

121 respectively. After 6 months of storage, FFA

contents were 0.308 and 0.380% and POVs were 90.0

and 198.0meqkg�1 at 25 and 45�C respectively. On

the other hand, IVs of untreated sunflower oil

(control) decreased from 121 to 60 at 25�C and to

53 at 45�C after storage for 6 months. The decrease in

Table 1. Percentage yield of ginger extract obtained with different organic

solvents

Solvent Ginger extract yield (%) a

Ethanol 17.40�1.15

Methanol 15.61�1.07

Acetone 9.88�1.00

Hexane 6.79�0.38

Diethyl ether 2.58�0.17

Dichloromethane 21.28�0.60

ag oil per 100g dried ginger.

J Sci Food Agric 83:624–629 (online: 2003) 625

Antioxidant activity of ginger extract

IV could be attributed to the breakage of double bonds

of unsaturated fatty acids of lipids during storage of

sunflower oil at elevated temperature, as reported

earlier.12 Generally, the principal route of fat de-

terioration is through oxidative rancidity, which takes

place at the double bond in the triglyceride mol-

ecule.17 In fat deterioration the initial step is the

formation of free fatty acids which are susceptible to

oxygen attack in the presence of light, resulting in the

formation of many organic compounds and free fatty

acids which are responsible for the development of

rancidity and off-flavours in fatty food materials.18

Production of free fatty acids and increase in peroxide

value are the best predictors of fat deterioration which

can be used to monitor the extent of oil spoilage. It is

well known that decrease in iodine value is another

factor by which fat deterioration can be examined.

Free fatty acid content and peroxide value after

addition of synthetic antioxidants

The changes in FFA content and POV during storage

of sunflower oil at 25 and 45�C after addition of

synthetic antioxidants are given in Table 3. It is

apparent from these results that addition of BHA and

BHT retarded the development of rancidity in sun-

flower oil, but BHT gave better protection than BHA.

FFA contents were reduced from 0.380% (control) to

0.089 and 0.072% and POVs decreased from

198.0meqkg�1 (control) to 30.5 and 24.7meqkg�1

with addition of BHA and BHT respectively after 6

months of storage at 45�C. At 25�C, addition of BHA

and BHT caused a reduction in FFA content from

0.308% (control) to 0.068 and 0.069% respectively

after storage for 6 months. Similarly, POVs were

reduced from 90.0meqkg�1 (control) to 26.5 and

21.8meqkg�1 by addition of BHA and BHT respec-

tively after 6 months of storage at 25�C. These results

are consistent with the findings of Kiyomi and

Yasuko19 and Yanping et al,20 who reported that lipid

peroxides were significantly reduced by addition of

antioxidants to processed foods and oils. Kathy et al21

suggested that addition of BHA along with another

antioxidant inhibited food deterioration during storage

at both high and ambient temperatures. It had already

been reported that addition of BHA and BHT

retarded the development of rancidity in fried banana

chips during storage.12 Statistical analysis of the data

revealed that the FFA content and POV of sunflower

oil were significantly (P<0.05) reduced by addition of

BHA and BHT.

Free fatty acid content and peroxide value after

addition of ginger extract

Addition of ginger extract caused a significant reduc-

tion in FFA content and POV of sunflower oil during

storage at 25 and 45�C (Table 4). It is evident from

Table 2. Effect of storage conditions on free fatty acids (FFA) content (% oleic acid), peroxide value (POV; meqkg�1 oil) and iodine value (IV) of sunflower oil

without antioxidant (control)

Storage time

(months)

25�C 45�C

POV FFA IV POV FFA IV

0 0.5a�0.12 0.030a�0.01 121a�1.37 0.5a�0.12 0.030a�0.01 121a�1.37

1 6.0b�0.16 0.045a�0.02 118a�1.20 9.0b�0.21 0.050a�0.02 109a�1.17

2 13.5b�0.35 0.060b�0.02 114a�1.11 27.0b�0.27 0.065a�0.02 101a�1.41

3 27.0b�0.82 0.095b�0.03 105b�1.19 48.0b�0.41 0.120b�0.05 90b�1.08

4 51.0c�1.00 0.135b�0.04 95b�1.07 70.5c�0.58 0.205b�0.00 81b�1.60

5 72.5c�1.09 0.250c�0.03 79c�1.12 105.0c�0.43 0.275c�0.13 70c�1.32

6 90.0d�1.11 0.308c�0.07 60c�1.40 198.0d�1.39 0.380c�0.18 53c�1.20

Values are mean�SD of triplicate determinations.

Mean values within a column with different letters are significantly different at P<0.05.

Table 3. Effect of synthetic antioxidants and storage conditions on free fatty acids (FFA) content (% oleic acid) and peroxide value (POV; meqkg�1 oil) of sunflower

oil

Storage time

(months)

BHA 200ppm BHT 200ppm

25�C 45�C 25�C 45�C

POV FFA POV FFA POV FFA POV FFA

1 3.0a�0.12 0.030a�0.01 3.5a�0.13 0.035a�0.01 2.5a�0.10 0.028a�0.02 3.7a�0.01 0.032a�0.01

2 4.8a�0.16 0.041a�0.02 6.0a�0.15 0.040a�0.01 4.0a�0.13 0.035a�0.02 5.0a�0.17 0.040a�0.10

3 9.8b�0.13 0.044a�0.02 12.0b�0.14 0.048a�0.02 7.5b�0.19 0.038a�0.03 9.5b�0.21 0.043a�0.01

4 17.0b�0.15 0.050b�0.02 20.0b�0.21 0.055b�0.02 14.0b�0.51 0.045b�0.02 17.0b�0.44 0.054b�0.02

5 21.0c�0.73 0.055b�0.02 25.0c�0.39 0.068b�0.03 18.5c�0.66 0.055b�0.02 22.0c�0.69 0.065b�0.02

6 26.5c�0.52 0.068c�0.01 30.5c�0.19 0.089c�0.03 21.8c�0.79 0.069c�0.03 24.7c�0.72 0.072c�0.01

BHA, butylated hydroxyanisole; BHT, butylated hydroxytoluene.



626 J Sci Food Agric 83:624–629 (online: 2003)

Zia-ur-Rehman, AM Salariya, F Habib

the results in Table 4 that, as the concentration of

ginger extract increased, the inhibitory effect on FFA

content and POV also increased considerably. After 6

months of storage at 45�C, sunflower oil treated with

800, 1600 and 2400ppm ginger extract had FFA

contents of 0.088, 0.083 and 0.080% and POVs of

40.0, 26.7 and 24.0meqkg�1 respectively. A signifi-

cant difference (P<0.05) was found between the

control and sunflower oil treated with (800ppm)

ginger extract, which slowed the rate of peroxide

formation. The autoxidation of sunflower oil was,

however, greatly inhibited in the presence of ginger

extract at concentrations of 1600 and 2400ppm.

Moreover, there was no significant difference

(P<0.05) between synthetic antioxidants (200ppm)

and ginger extract (1600 and 2400ppm) in the

inhibition of sunflower oil peroxidation. These results

confirmed the findings of earlier workers who identi-

fied various antioxidant compounds, especially ginger-

ol, gingerdiol and shogal, in the non-volatile fraction of

dichloromethane extract from ginger; these com-

pounds exhibited higher antioxidant activity than

a-tocopherol.10,22 In an earlier experiment the anti-

oxidant activity of dichloromethane extract of ginger

had also been shown to be due to the presence of

gingerol.11 Therefore the development of rancidity in

sunflower oil was suppressed owing to the presence of

these antioxidant compounds in ginger extract.

Effect of synthetic antioxidants and ginger extract

on iodine value of sunflower oil during storage

Besides an increase in free fatty acid content and

peroxide value, a marked decrease in iodine value (by

53–56%) was observed during storage of sunflower oil

at 25 and 45�C (Table 2). In fact, the decreasing trend

of IV indicates the development of rancidity due to the

formation of secondary oxidation products during

storage. The results in Table 5 shows that addition of

synthetic antioxidants (BHA and BHT) and ginger

extract retarded the decreasing trend of IV in sun-

flower oil during storage. Addition of BHA and BHT

led to IVs of 94 and 96 respectively after 6 months of

storage at 45�C. Similarly, IVs of sunflower oil treated

with 800, 1600 and 2400ppm ginger extract were 72,

80 and 92 respectively after 6 months of storage at

45�C (Table 5). On the other hand, the IV of

untreated sunflower oil stored for 6 months at 45�Cwas 53, while that of fresh untreated sunflower oil was

121. Therefore iodine values of stored sunflower oil

treated with synthetic antioxidants and ginger extract

were distinctly higher than those of control samples of

sunflower oil. Similarly, an increase in iodine value was

also observed at 25�C during storage of treated

sunflower oil for 6 months. These results clearly

illustrate that autoxidation of sunflower oil was greatly

reduced in the presence of BHA, BHT and ginger

extract. It is also obvious from these results that iodine

values of sunflower oil treated with ginger extract

(2400ppm) and 200ppm of synthetic antioxidants

(BHA, BHT) were almost equal after 6 months of

storage at 25 and 45�C. Changes in iodine value

confirm the deterioration of oil already observed by the

increases in free fatty acid content and peroxide value

occurring during storage of sunflower oil. This study

Table 4. Effect of ginger extract (natural antioxidant) and storage conditions on free fatty acid (FFA) content (% oleic acid) and peroxide value (POV; meqkg�1oil)

of sunflower oil

Storage

time

(months)

Ginger extract 800ppm Ginger extract 1600ppm Ginger extract 2400ppm

25�C 45�C 25�C 45�C 25�C 45�C

POV FFA POV FFA POV FFA POV FFA POV FFA POV FFA

1 3.8a�0.21 0.039a�0.01 4.3a�0.17 0.044a�0.02 3.3a�0.11 0.035a�0.01 3.5a�0.18 0.040a�0.02 3.0a�0.16 0.030a�0.02 3.2a�0.19 0.037a�0.02

2 5.5a�0.26 0.050a�0.01 6.0a�0.20 0.052a�0.02 4.5a�0.20 0.042a�0.01 5.0a�0.21 0.048a�0.02 4.0a�0.19 0.040a�0.02 4.3a�0.15 0.043a�0.01

3 12.5b�0.33 0.060b�0.02 18.0b�0.41 0.065b�0.01 9.3b�0.29 0.046a�0.02 10.6b�0.40 0.052a�0.03 9.0b�0.22 0.043a�0.01 11.0b�0.21 0.049b�0.01

4 22.0b�0.72 0.068b�0.02 28.0b�0.48 0.074b�0.03 15.0b�0.30 0.050b�0.02 18.0b�0.51 0.060b�0.03 16.0b�0.27 0.054b�0.02 18.0b�0.23 0.060b�0.03

5 32.0c�0.21 0.080c�0.02 37.0c�0.55 0.085c�0.02 21.0c�0.21 0.070b�0.03 23.0c�0.44 0.076b�0.02 20.0c�0.29 0.065c�0.01 22.0c�0.20 0.080c�0.03

6 36.0c�0.41 0.085c�0.02 40.0c�0.50 0.088c�0.03 24.5c�0.28 0.075c�0.02 26.7c�0.50 0.083c�0.04 25.0c�0.31 0.080c�0.04 24.0c�0.23 0.080c�0.02



Table 5. Effect of synthetic antioxidants and ginger extract on iodine value of sunflower oil during 6 months of storage

Antioxidant

Storage time (months)

0 1 2 3 4 5 6

25�C 45�C 25�C 45�C 25�C 45�C 25�C 45�C 25�C 45�C 25�C 45�C 25�C 45�C

Control 121�1.37 121�1.37 118�2.44 109�2.11 114�2.11 101�2.05 105�1.22 90�2.11 93�2.16 81�2.00 79�1.32 70�2.17 60�1.27 53�1.25

BHA 200ppm 121�1.37 121�1.37 119�2.11 112�2.00 116�2.02 113�2.11 114�1.28 110�2.72 108�2.11 103�1.66 102�1.44 98�1.11 98�1.22 94�1.44

BHT 200ppm 121�1.37 121�1.37 119�2.09 113�1.80 118�1.05 115�2.19 116�2.00 110�2.20 110�1.80 104�1.70 103�1.72 100�1.16 99�1.70 96�1.40

GE 800ppm 121�1.37 121�1.37 100�1.87 96�2.00 96�1.37 88�1.72 93�2.01 83�1.80 87�1.30 79�1.77 81�2.02 75�1.08 77�1.13 72�1.33

GE 1600ppm 121�1.37 121�1.37 104�2.77 102�1.61 101�1.80 97�1.08 97�2.17 92�1.73 94�1.27 88�1.10 87�2.40 83�1.13 84�1.40 80�1.80

GE 2400ppm 121�1.37 121�1.37 117�2.00 112�1.09 111�1.56 109�1.80 107�2.11 104�2.00 104�1.16 100�1.42 99�2.03 96�1.40 95�1.73 92�1.70

BHA, butylated hydroxyanisole; BHT, butylated hydroxytoluene; GE, ginger extract.




revealed that the level of ginger extract required was 12

times greater than that of the synthetic antioxidants to

control the development of rancidity in sunflower oil.

However, natural antioxidant extract of ginger would

be preferred over synthetic antioxidants to minimise

adverse effects on mankind.

Effect of heat treatment on antioxidant activity of

ginger extract

The antioxidant activity, as determined by the

thiocyanate method, of ginger extract heated at

185�C for various times is shown in Fig 1. Heating

for 20 or 30min did not significantly (P<0.05) reduce

the antioxidant potency. The activity was reduced

slightly by heating for 40min or longer. Little change

was observed between 40 and 90min of heating.

However, ginger extract exhibited 85.2% inhibition of

peroxidation of linoleic acid on heating at 185�C for

120min. Therefore ginger extract showed good

thermal stability in comparison with BHA, which

was previously reported by Hamama and Nawar23 to

have only half of its antioxidant activity remaining after

heating at 185�C for 45min. As a whole, the

antioxidant activity of ginger extract decreased with

increasing heating time. The loss of activity at such an

elevated temperature (185�C) may result from eva-

poration of the extract as well as from chemical

decomposition.

Thermal stability testing of ginger extract during

frying of sunflower oil was also performed. For this

purpose, fresh sunflower oil containing 2400ppm

ginger extract was heated at frying temperature

(185�C) for 50h. During the frying process, oxidation,

hydrolysis, polymerisation and other chemical reac-

tions occur, leading to the deterioration of fats and

oils. It is well known that these reactions ultimately

adversely affect the free fatty acid content, peroxide

value and iodine value of sunflower oil during heating.

Therefore free fatty acid contents, peroxide values and

iodine values were used to assess the thermal stability

of ginger extract. The free fatty acid content and

peroxide value of fresh unheated sunflower oil were

0.030% and 0.5meqkg�1 respectively, which became

0.127% and 20.5meqkg�1 after 50h of heating of

sunflower oil (Table 6). However, the iodine value

decreased from 121 to 78 after 50h of heating. These

chemical characteristics remained almost unchanged

when sunflower oil containing 2400ppm ginger

extract was heated at 185�C for 50h. These results

that ginger extract is thermally stable, as the chemical

characteristics of sunflower oil did not change much in

the presence of ginger extract during prolonged

heating, and therefore may be used in the frying or

thermal processing of foods.

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Figure 1. Antioxidant activity of ginger extract as a function of heating time

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Table 6. Thermal stability of ginger extract during heating of sunflower oil for 50h

Anti-oxidant

Temp

(�C)Time

(h)

POV

(meqkg�1)

FFA

(% oleic acid) IV

Sunflower oil (control) — — — 0.5a�0.12 0.030a�0.01 12n�1.37

Sunflower oil — 185 50 20.5b�1.37 0.127b�0.15 78b�1.00

Sunflower oil GE 185 50 0.7a�0.10 0.055a�0.02 11a�1.05

POV, peroxide value; FFA, free fatty acid content; IV, iodine value; GE, ginger extract.



628 J Sci Food Agric 83:624–629 (online: 2003)

Zia-ur-Rehman, AM Salariya, F Habib

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Antioxidant activity of ginger extract in sunflower oil

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