Synthetic anti-oxidants such as butylated hydroxyanisole (BHA)
and butylated hydroxytolune (BHT) have restricted use in foods as
these synthetic anti-oxidants are suspected to be carcinogenic.
Therefore, the importance of the search for and exploitation of natural
anti-oxidants, especially of plant origin, has greatly increased
in recent years (Singh, Murthy, & Jayaprakasha, 2002). Plant based
anti-oxidants are extracted from raw materials or waste products
of food industry by organic solvents such as methanol, diethyl
ether, and acetone. Methanol is an effective extractant for a broad
range of polyphenols, therefore it is a frequently used solvent for
both a laboratory scale and an industrial extraction process. Methanol
is cheap and easily accessible and the manufacturing of herbal
medicine usually uses methanol as a solvent to extract natural
ingredients, a fact that will also concern us about the residual level
of methanol in these products (Wang, Wang, & Choong, 2004).