Research Article
Received: 9 January 2014 Revised: 24 April 2014 Accepted article published: 19 May 2014 Published online in Wiley Online Library:
(wileyonlinelibrary.com) DOI 10.1002/jsfa.6742
Tocopherol and tocotrienol contents
of different varieties of rice in Malaysia
Balakrishnan Shammugasamy, Yogeshini Ramakrishnan,
Hasanah M Ghazali and Kharidah Muhammad
*
Abstract
BACKGROUND: The present study examined the contents of tocopherols and tocotrienols and their distribution in 58 different
varieties of whole rice cultivated in Malaysia. The analytical method used was saponification of samples followed by dispersive
liquid–liquid microextraction and reverse phase high-performance liquid chromatography.
RESULTS: The total vitamin E contents of different varieties of whole rice ranged between 19.36 and 63.29 mg kg
-1
. Contents of
vitamin E isomers varied among rice varieties both within and between grain color groups. Black-pigmented rice showed signifi-
cantly higher mean contents of -tocopherol, -tocopherol and -tocotrienol than non-pigmented rice and red-pigmented rice.
Red-pigmented rice had significantly lower mean contents of -tocotrienol and total vitamin E than non-pigmented rice. The
mean contents of -tocotrienol and total vitamin E in non-pigmented rice, however, were similar to those in black-pigmented
rice. -Tocotrienol was the predominant form of vitamin E isomer in all analyzed varieties. The Pearson correlations among
vitamin E isomers and total vitamin E content of whole rice were also studied.
CONCLUSION: This study provides information on vitamin E content of different rice varieties that would be beneficial for
decision making in genetic breeding of bioactive compound-rich rice varieties.
© 2014 Society of Chemical Industry
Keywords: tocopherol; tocotrienol; rice varieties; Malaysia: microextraction
INTRODUCTION
Rice (Oryza sativa L.) is one of the most important cereal commodi-
ties in the world and a main staple food in many countries, espe-
cially in Asia. Annual rice production is growing steadily and the
estimated global production of rice for the year 2012 was 486.9
million tonnes (milled basis), which included 441.6 million tonnes
(milled basis) produced in Asian countries.
1
Rice is consumed
mostly as milled rice; however, consumption of non-milled or
whole rice is increasing with the growing knowledge of its health
benefits. Whole rice contains the bran, germ and endosperm,
whereas in milled rice the bran and the germ of the rice ker-
nel are removed during the milling process. The endosperm con-
sists mainly of carbohydrate and contains lower amounts of lipid
and fiber than the germ and bran. The majority of bioactive com-
pounds of whole rice are present in the bran and germ fractions.
Whole rice contains a wide range of bioactive compounds such
as vitamin E (tocopherols and tocotrienols), -oryzanols, phenolic
acids, flavonoids and phytic acid.
2 – 4
In addition, black-pigmented
rice and red-pigmented rice have been reported to contain antho-
cyanins and proanthocyanidins respectively.
5,6
These bioactive
compounds have been associated with the possibility to reduce
the risk of developing chronic diseases, including cardiovascu-
lar disease, type 2 diabetes, obesity and cancer.
7 – 9
Among these
bioactive compounds, vitamin E (tocopherols and tocotrienols)
and -oryzanols are the major and most characterized com-
pounds. Rice and other cereals are the main sources of vitamin
E.
10,11
The highest content of vitamin E was found in rice bran, fol-
lowed by whole rice and milled rice.
4,12
It is noteworthy that the
content of vitamin E in milled rice is even lower than that in the
rice husk.
12
The rise in health awareness and demand for health-promoting
food has encouraged the cultivation and development of some
special rice varieties that are rich in bioactive compounds. One of
the features in determining the quality of rice is the content of vita-
min E, which is variable and dependent on rice genetic and envi-
ronmental conditions.
13
The vitamin E contents of whole rice of
different varieties found in Taiwan,
12
South Korea,
4,14
Venezuela,
15
Brazil
16
and Sri Lanka
17
have been reported. The contents of vita-
min E in bran of rice varieties from Japan
3
and the southern USA
13
were also studied. However, information on the vitamin E content
of Malaysian rice varieties is lacking even though rice is one of the
main agricultural commodities of Malaysia.
The Malaysian Agricultural Research and Development Institute
(MARDI) plays a significant role in developing new high-yielding
and disease-resistant rice through specific breeding programs.
MARDI has been breeding many new varieties, and up to 42
varieties of rice have been released for commercial cultivation in
Malaysia since the first variety was introduced in 1964. Apart from
that, there are also many wild rice varieties grown traditionally
∗
Correspondence to: Kharidah Muhammad, UPM-BERNAS Research Laboratory,
Faculty of Food Science and Technology, Universiti Putra Malaysia, 43400 UPM
Serdang, Selangor Darul Ehsan, Malaysia. E-mail: kharidah@upm.edu.my
UPM-BERNAS Research Laboratory, Faculty of Food Science and Technology,
Universiti Putra Malaysia, 43400 UPM Serdang, Selangor Darul Ehsan, Malaysia
J Sci Food Agric (2014) www.soci.org © 2014 Society of Chemical Industry