Brazil is a major producer of grains, such as sorgh
um and corn, which are used for export. Sorghum
and corn grains have in its composition 9.5% and 9.
8 protein, respectively. Proteins are the most
abundant and most diverse functions in living syste
ms molecules. Currently, food proteins are
increasingly recognized as a source of beneficial b
ioactive peptides, and they are physiologically
released during digestion. The aim of the work was
to evaluate the protein extraction (four methods)
and antioxidant activity of sorghum and corn grains
. The proximal composition of grains was
evaluated in relation to moisture, protein, lipids
and ash contents, furthermore were quantified
proteins concentration and antioxidant activity by
FRAP method in the four extracts. The corn and
sorghum grains were ground, homogenized (60 mesh) a
nd stored at 5°C until analysis. The protein
extraction utilized were: 1) dichloromethane/methan
ol; 2) NH
4
HCO
3
(5mM, pH 8.0)/heat treatment;
3) water/ethanol/heat treatment; and 4) alkaline ex
traction and precipitation. The corn and sorghum
presented, protein 6.62% and 9.87%, lipids 4.45% an
d 4.32%, moisture 8.87% and 8.23%, ash
0.96% and 1.15%, carbohydrates 79.01% and 76.41%, t
otalizing a caloric value of 382.9 and 384.1
Kcal g
-1
, respectively. The 2 and 3 methods in corn grain p
resented highest protein content 133.16
and 142.24 μ g g
-1
, respectively. In sorghum grain, methods 1, 2 and
3 presented protein content
between 173.59 – 223.63 μg g
-1
. The antioxidant activity of protein extracts was
between 0.90 –
9.73μM of ferrous sulphate for corn and between 4.4
1 – 15.04μ M of ferrous sulphate for sorghum.
The best results in the extraction using the method
3 for both grains could be due to the structure of
proteins (zein and kafirins) which are soluble in a
lcoholic solutions and insoluble in water. In
conclusion, method 3 - water/ethanol/heat treatment
(corn: 142.24 μg g
-1
and sorghum: 223.63 μg g
-
1
) and method 3 (corn: 9.73 μM and sorghum: 15.04 μ M
) showed the best results for extracting
protein and antioxidant activity, respectively. The
protein extracts obtainedhave great potential as
natural antioxidant
