Renuka Devi, R; Dr.Arumughan, C; Dr. Jayalekshmy, A(Regional Research Laboratory (CSIR), April , 2005)
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Abstract:
Antioxidants are substances that when present at low concentrations
compared to that of an oxidisable substrate significantly delays or inhibits
oxidation of that substrate in food products or in living systems. Antioxidants
are either endogenous to the body or derived from the diet. Several types of
synthetic antioxidants like BHT, BHA, TBHQ etc. are also used in the food
industry. However, findings and subsequent publicity has fostered significant
consumer resistance to the use of synthetic food additives as antioxidants,
colourants etc. and therefore food industry is in search of potential natural
antioxidants from edible sources.The major dietary sources of antioxidant phytochemicals are cereals,
legumes, fruits, vegetables, oilseeds, beverages, spices and herbs. In the present
study, we have focused on rice bran and its byproducts. Rice is one of the
oldest of food crops and has been a staple food in India from very ancient
times. It is also the staple food for about 60% of the world's population. Rice
bran is a byproduct of the rice milling industry and is a potential commercial
source of a healthy edible oil viz. rice bran oil and a variety of bio-active
phytochemicals.Defatted rice bran (DRB), a byproduct of rice bran oil extraction, is also
a good source of insoluble dietary fiber, protein, phytic acid, inosito I, vitamin B
and a variety of other phytochemicals. Though the antioxidant potential of
DRB has been demonstrated, it still remained a relatively unexplored source
material, which demanded further investigation especially with regard to its
detailed phytochemical profile leading to practical application. The focus of the
present investigation therefore has been on DRB primarily to establish its
phytochemical status and feasibility of using it as a source of bio-active
phytochemicals and natural antioxidants leading to value addition of DRB
otherwise used as cattle feed. To gain a better understanding of the value of
rice bran as a source of phytochemicals, five popular rice varieties of the
region viz. PTB 50, PTB 39, PTB 38, JA Y A, and MO 10 and a wild variety
(oryza nivara) that is mainly used for medicinal applications in traditional
ayurvedic system were characterized along with commercial samples of rice
bran. The present study also explains the feasibility of a process for the
extraction, enrichment, and isolation of antioxidant compounds from DRB.
The antioxidant potential of the extracts were evaluated both in bulk oils and in food relevant model emulsions, using standard in vitro models. Radical
scavenging effects, indicative of possible biological effects, were also
evaluated.