Enzymatic process of rice bran: a stabilized functional food with nutraceuticals and nutrients.

Rice bran (RB), a byproduct of rice milling industry,
is a rich source of nutraceuticals and nutrients. However its
utility is limited due to the presence of lipase and lipoxygenase
which initiates rancidity on milling. The aim of this investigation
is to prevent oxidation of free fatty acids by enzymatic
approach for its effective utilization. The enzymatic treatment
comprised of alcalase treatment for complete inactivation of
lipase along with reduction in lipoxygenase (LOX) activity
and endoglucanase for improving the soluble fiber content.
The enzyme treated rice bran was drum dried for further use.
The nutraceutical molecules like γ-oryzanol, α-tocopherol
and polyphenols were retained in the range of 68 to 110 %
and the total antioxidant activity was improved. By the action
of endoglucanase the complex carbohydrate was converted
into glucose (72.28 %), cellobiose (18.36 %) and cellotriose
(9.36 %). The prebiotic effect of enzyme treated rice bran was
evaluated by the action of lactobacillus which was measured
through the release of the short chain free fatty acids (SCFAs)
analyzed by HPLC. The SCFAs; acetic acid and propionic
acid increased by 1.72 folds and 2.12 folds respectively. Bcomplex
vitamins showed maximum retention with vitamins
like B1 (66.3 %), B2 (68.3 %) and B3 (55.0 %) after enzyme
treatment. At different humidity levels, storage studies
showed no change in LOX activity and also retained
ubiquinol-10 in reduced state in enzyme treated RB for a
period of 3 months. A stabilized RB has been developed
enriched with short chain prebiotics and antioxidant
molecules.