Abstract:
Antioxidants protect cells and tissues from free radical damage and therefore, are important in the
prevention and management of a variety of chronic diseases. Bran of pigmented rice are potent sources
of naturally occurring antioxidants. Rice being the staple diet of Sri Lankans and traditional rice
gaining more attention at present, investigating the effect of processing and cooking on total phenol
content and antioxidant potentials of selected traditional rice varieties were the aims of this study.
Differently processed (raw undermilled, raw polished [4%] and parboiled undermilled) six rice
varieties, namely, Godaheenati, Batapola el, Dik wee, Dahanala, Unakola samba and, Hangimuththan
were used in the study. The antioxidant properties of rice flour extracted with phosphate buffer solution
(PBS) were determined by 2,2’-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical
scavenging activity, 1,1-diphenyl-2-picrylhydrazine (DPPH) radical scavenging activity and, ferric
reducing antioxidant power (FRAP)assays. Moreover, the total polyphenolic content (TPC) of
differently processed rice was analysed. Mean TPC of both uncooked and cooked, raw polished rice
was the least (4.9-6.1 mg GAE/g) followed by parboiled (4.9-6.1 mg GAE/g). The highest TPC was in
raw (5.3-6.7 mg GAE/g) rice. Mean ABTS activity of raw polished rice (0.8-1.9 mg TE/g) was the least
followed by parboiled (1.2- 2.3 mg TE/g) and raw rice (1.3-2.1 mg TE/g). Mean DPPH scavenging and
FRAP activities followed the same pattern with raw rice having the highest (4.5-6.2 mg AE/100g; 4.6-
14.4 mg AE/100g) followed by parboiled (4.4-5.1 mg AE/100g); 5.0-15.2 mg AE/100g) and the least in
raw polished (4.0-4.6 mg AE/100g; 5.1-18.5 mg AE/100g) respectively. Phenolic compounds and
antioxidant potential increased in the order of raw polished, parboiled, and raw rice flour in both
cooked and uncooked rice. Rice grains with red coloured bran produced higher antioxidant activity
compared to varieties with white bran. However, cooking reduced the antioxidant potentials in all
differently processed varieties.
