Enzymatic processing of pigmented and non pigmented rice bran on changes in oryzanol, polyphenols and antioxidant activity.

Bran from different rice varieties is a treasure of nutrients and
nutraceuticals, and its use is limited due to the poor sensory
and functional properties. Application of enzymes can alter
the functional and phytochemical properties. So the effect of
endo-xylanase, cellulase and their combination on microstructural,
nutraceutical and antioxidant properties of pigmented
(Jyothi) and non-pigmented (IR64) rice bran were investigated.
Scanning electron micrograph revealed micro structural
changes in fibre structures on processing. All the enzymatic
processing methods resulted in an increase in the content of
oryzanol, soluble, bound and total polyphenols, flavonoid and
tannin. It also showed an increase in the bioactivity with respect
to free radical scavenging activity and total antioxidant
activity. However, extent of the increase in bio-actives varied
with the type of bran and enzyme application method. Endoxylanase
showed higher percentage difference compared to
controls of Jyothi and IR64 bran extracts respectively in the
content of the bound (10 & 19 %) and total (20 & 14 %)
polyphenols. Combination of both the enzymes resulted in
higher percentage increase of bioactive components and properties.
It resulted in greater percentage difference compared to
controls of Jyothi and IR64 extracts respectively in the content
of soluble (58 & 17 %) and total (21 & 14 %) polyphenols,
flavonoids (12 & 38 %), γ-oryzanol (10 & 12 %), free radical
scavenging activity (64 & 30 %) and total antioxidant activity
(82 & 136 %). It may be concluded that enzymatic bioprocessing
of bran with cellulose and hemicellulose degrading
enzymes can improve its nutraceutical properties, and it may
be used for development of functional foods.