Abstract:
Rice bran is a source of lipids and γ-oryzanol, which provides nutritious health
benefits. The classical methods used in extraction and determination of lipids and γ-
oryzanol are time consuming and use a large amount of solvents. This study aimed to
develop an alternative method of determining total lipid and γ-oryzanol content in rice
bran from the adsorption coefficient (K) value by partial extraction method and
solving two simultaneous mathematics equations.
The total lipid and γ-oryzanol content in rice bran as determined by partial
extraction method with hexane and the classical method were approximately the
same. Total lipids were 20.68 and 21.25 % (dry weight basis) and γ-oryzanol content
was 2.82 mg/g and 3.06 mg/g (dry weight basis), as determined by using partial
extraction method with hexane, and Soxhlet extraction method, respectively. The total
lipid and γ-oryzanol content in nine rice bran varieties determined by partial
extraction method with hexane were 18.16-21.18 % (K = 1.159-1.996) and 1.95-3.07
mg/g (K = 2.023-2.653) (dry weight basis), respectively. The rice bran from the Dor
Dum 5647 variety had the highest total lipid and γ-oryzanol content. The γ-oryzanol
determined by using di-n-butyl ether and diisopropyl ether were 1.97-3.38 mg/g (K =
2.371-3.071) and 1.96-3.18 mg/g (K = 2.267-2.906) (dry weight basis), respectively.
The reason that di-n-butyl ether can extract higher γ-oryzanol from every part of rice
bran may be due to its higher polarity. Moreover, the K value of total lipid and γ-
oryzanol decrease when the moisture content of rice bran increases. Therefore, it is
concluded that partial extraction method and solving two simultaneous mathematics
equations is an alternative method for determining total lipid and γ-oryzanol content
from rice bran. This method is simple, rapid and inexpensive.