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Electron. J. Environ. Agric. Food Chem.
ISSN 1579-4377
1313
ISSN: 1579-4377
CHANGE IN ANTIOXIDANT ACTIVITY OF SPICES –TURMERIC AND
GINGER ON HEAT TREATMENT
Vandana Tiwari, Rakhi Shanker, Jyoti Srivastava and Padma S Vankar*
Facility for Ecological and Analytical Testing(FEAT). Indian Institute of Technology, Kanpur
KEYWORDS
Turmeric and Ginger essential oils, Spices, Curcuma longa, Zinger officinale.
ABSTRACT
Spices show potential health benefits as they possess antioxidant activity, we tried to evaluate the fate of
antioxidant activity during the process of cooking. Out of the many spices used in Indian cooking,
turmeric and ginger are used in major quantities. Although these dietary spices are resistant to thermal
denaturation, interestingly, in the case of turmeric the AA increase on heating while in the case of ginger
it shows reduction of AA when powders and oils of these spices were analyzed
INTRODUCTION
Turmeric and ginger are very integral part of Indian cooking both in vegetarian as well as non-vegetarian
cooking. These spices are common food adjuncts that impart color, flavor and aroma. The active
ingredient in turmeric is curcumin and that in ginger are gingerol and hexahydrocurcumin1-3. Both these
compounds prevent oxidation of oils and fats. As these spices are added as flavoring agents to food
preparations as crushed paste or dry powder and cooked at high temperature, the present study was
undertaken to evaluate the thermal stability and antioxidant activity of these two spices by DPPH method.
We analyzed powders and oils of turmeric and ginger, before and after heat treatment (120°C).
H3CO
HO
OHO
H3CO
HO
OO OH
OCH3
Gingerol Curcumin
H3CO
HO
OOH
OCH3
Hexahydro-curcumin
* Facility for Ecological and Analytical Testing(FEAT). Indian Institute of Technology, Kanpur-208 016. Email:psv@iitk.ac.in
Vankar et al. EJEAFChe, 5 (2), 2006. [1313-1317]
Electron. J. Environ. Agric. Food Chem.
ISSN 1579-4377
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Table 0. Composition percentage Turmeric and Ginger essential oils4
Compound Curcuma longa Zinger officinale
Tricyclene 0.25
α-Pinene 1.1 3.31
Camphene 9.98
β-Pinene 0.52
Myrcene 0.69 0.92
α-Phellandrene 20.42 0.41
α-Terpinene 1.26
p-Cymene 3.61
β-Phellandrene 7.67
1,8-Cineole 10.3
3-Carene 0.35
Cis-Ocimene 0.39
γ-Terpinene 1.01
Terpinolene 6.19
Borneol 1.02
α-Terpineol 0.48
Citronellol 0.37
Nerol 0.63
Geraniol 1.11
Geranial 0.17
Bornyl acetate 0.29
δ-Elemene 0.25
α-Cubebene 0.84
β-Elemene 1.19
Sesquithujene 0.51
β-Ylangene 0.68
β-Copaene 0.43
α, cis-Bergamotene 0.19 0.36
γ-Elemene 0.91
Aromadendrene 0.53
β, cis-Farnesene 0.36 0.67
α-Humulene 0.23
Allo-Aromadendrene 0.53
γ-Muurolene 1.81
Ar–Curcumene 8.93
γ-Curcumene 0.7
α-Curcumene 2.9
Zingiberene 6.9 23.94
β-Bisabolene 1.23 11.4
γ-Cadinene 3.82
Cis, γ-Bisabolene 0.37 0.61
β-Curcumene 0.51
β-Sesquiphellandrene 5.45 10.9
Cis-Nerolidol 0.51
Ar–Turmerol 0.93
α-Turmerone 19.8
β-Turmerone 7.35
β-Eudesmol 0.23
Ar–Turmerone 1.08
Monoterpene hydrocarbons 34.6 23.1
Monoterpenes oxygenated 10.3 4.07
-Alcohols 2.59
-Aliphatics 2.59
Ketones 1.02
-Esters 0.29
-Aldehydes 0.17
-Ethers 10.3
Sesquit. hydrocarbons 18.8 68.1
Sesquit. oxygenated 29.2 0.74
Total 92.9 95.9
Vankar et al. EJEAFChe, 5 (2), 2006. [1313-1317]
Electron. J. Environ. Agric. Food Chem.
ISSN 1579-4377
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MATERIAL AND METHODS
Chemicals
Ginger and turmeric powders were bought from the market ( Ashok Masale)
Ginger and turmeric oils were purchased from Swaraj Ashram( Rishikesh). DPPH(2,2-diphenyl-1-
picrylhydrazyl free radical was purchased from Aldrich Chemical company. Pyragallol was purchased
from S.D.Fine Chemical company. All other chemicals were of the highest analytical grade and
purchased from common sources.
Spice extracts
One gram each of turmeric powder and turmeric oil were weighed separately and extracted in methanol.
This extract was centrifuged at 5000 rpm and the supernatant was used as source of spice extract. While
for ginger powder and oil, methanol: ethyl acetate (50:50) was used as extracting solvent. The spice
extract was used directly for DPPH analysis.
Heated Spice extracts
The spices ( powder and oil) were heated at 120°C for 1 hour and then allowed to cool at room
temperature and extracted in the same manner and evaluated for antioxidant activity.
Antioxidant Activity
The antioxidant properties were assessed by DPPH radical scavenging method. This method is useful for
determining the activity of both hydrophilic and lipophilic substrates, thus ensuring a better comparison
of the results. Based on a study on onion5, we decided to study the effect of heat on turmeric and ginger
oil and dry powders.
Free radical scavenging activity of dry powder was carried out by the following method: The dry powder
extracts of ginger and turmeric were measured in terms of hydrogen donating or radical scavenging
ability using a stable radical DPPH. 2.8 ml of DPPH solution (45 μg/ ml) were rapidly mixed with 200 μl
and 400 μl of methanolic solution of plant extract one at a time in cuvette placed in the
spectrophotometer.
The absorbance at 515 nm was measured after 5 min. The initial absorbance of the DPPH was 1.2 -1.3.
The decline in radical concentration indicated the radical scavenging activity of the sample. Pyragallol
solution (125 μg/ ml) was used as a reference corresponding to 100% radical scavenging activity. Radical
scavenging activity or antioxidant properties was evaluated as percentage was calculated as
(
)
()
100
0
0×
−
−
ref
test
AA
AA
where as A0 is the initial absorbance (DPPH + sample absorbance) and Aref and Atest are absorbance after
5 min with pyragallol solution and sample solution.
Vankar et al. EJEAFChe, 5 (2), 2006. [1313-1317]
Electron. J. Environ. Agric. Food Chem.
ISSN 1579-4377
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Free radical scavenging activity of oils were determined by the following method: An aliquot of ginger or
turmeric oil(10 μl) was mixed with 900 μl of 100mM Tris-HCl buffer (pH 7.4), 40 μl of ethanol and 50 μl
of 0.5% (w/w) Tween 20 solution and then added to 1 μl of 0.5mM DPPH in ethanol. The mixture was
shaken vigorously and then immediately placed in UV-Vis spectrophotometer to monitor the decrease in
absorbance at 515 nm.
Table 1 DPPH results of Dry powders of Ginger and Turmeric
Dry Ginger / Powder Turmeric powder
Standard Before After Before After
BHT 8.46% 6.16% 10.81% 6.01%
Pyragallol 3.19% 1.63% 4.13% 1.36%
Table 2 DPPH results of Oils of Ginger and Turmeric
Turmeric oil Ginger oil
Before heating 1.46 1.54
After heating 3.16 1.35
RESULTS AND DISCUSSION
Ginger and turmeric are very commonly used dietary spices in Indian cooking both in vegetarian and non-
vegetarian preparations. Both of them are cooked at temperatures higher than 100°C. The main objective
of this study is to evaluate antioxidant potential of crude spice extract and to check their thermal stability
during the process of cooking.
We evaluated both the dry powder as well as the oils of these two spices. The crude extracts of the spices
and their oils contain more than one antioxidant so it is the synergistic effect of all the potent antioxidant
molecules that cumulatively show their antioxidant activity.
It is interesting to note that when ginger and turmeric dry powders and oils were heated for 120°C for 1
hour as shown in Table-I and II, the turmeric oil not only retained the antioxidant activity but also showed
significantly higher antioxidant activity, as it is known to have higher monoterpenic abundance(34.6) in
oil, the situation on the dry powder is reverse. indicating that the spice constituents were resistant to
thermal denaturation.
The possible release of bound antioxidant principles during heat treatment could be responsible for the
higher antioxidant activity. However, it was reverse in the case of ginger oil.
These observations imply that thermal stability of spices varies with the individual spice and the cooking
conditions. One study related to freeze-dried ginger powder6 shows that heat treatment by boiling and
frying, shows no change in the antioxidant activity. The heat treatment had no effect on the antioxidant
activity. But we have results which show apparent change in antioxidant properties of both these spices.
With these results, it might be possible for the food industry to use secondary plant products instead of
synthetic compounds to increase the storage stability of processed food items, which might be a good
alternative asked for by the consumer.
Vankar et al. EJEAFChe, 5 (2), 2006. [1313-1317]
Electron. J. Environ. Agric. Food Chem.
ISSN 1579-4377
1317
CONCLUSION
Often it is difficult to decide how to protect the antioxidant property from denaturation while cooking
,this study shows when and how to add spices to food for retaining their fullest antioxidant properties, for
best antioxidant and/or scavenging activities.
0
0.5
1
1.5
2
2.5
3
3.5
Ginger Turmeric
Different oil before and after heating
Antioxidant activity (%)
Before
After
ACKNOWLEDGEMENT
The authors wish to thank Department of Science and Technology, DST, New Delhi under State
Council’s program on location specific research and technology program- grant.
REFERENCES
1. O.P. Sharma,, Biochemical Pharmacology, Vol-25, 1811, (1976).
2. Y. Masuda; H. Kikuzaki, M.Hisamoto; N. Nakatani, BioFactors 21(1-4), 293, (2004).
3. Sugiyama, Y., Kawakishi, S. and Osawa, T., Biochemical Pharmacology,Vol-52, 519, (1996).
4. G. Sacchetti, S. Maietti, M. Muzzoli, M. Scaglianti, S. Manfredini, M. Radice, and R. Bruni,
Food Chemistry,(in press), (2005).
5. M. Takenaka; K. Nanayama; I. Ohnuki; M. Udagawa,; E. Sanada; S. Isobe, Food Science and
Technology Research 10(4), 405, (2004). .
6. K. Shindo; N. Masui; Y. Yamada; M. Asano; R. Nakamura, Nippon Kasei Gakkaishi 55(5), 375,
(2004).
