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A colorimetric bran pigment method for determining the degree of milling of rice.

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Title A colorimetric bran pigment method for determining the degree of milling of rice.
 
Creator Bhattacharya, K. R.
Sowbhagya, C. M.
 
Subject 01 Rice
04 Milling
 
Description The alkaline alcohol bran-pigment extraction method has been developed into a
simple and reliable quantitative colorimetric method. A requisite quantity
(0.1-1.0 g, depending on the degree of milling of the sample) of rice powder is
soaked overnight with a 1 : 2 (v/v) mixture of 2 % aqueous KOH-n-propanol(1 ml
for each 0.1 g powder). Next day, the balance of 10 ml of the solvent is added, the
mixture vigorously shaken and centrifuged. The yellow-brown solution is read in a
Spectronic 20 (filter colorimeters did not give linear readings) at 400 nm. On
plotting the absorbance/g/lO ml data expressed as percentage of that of the
corresponding brown rice against the degree of milling, the values in three raw
and one parboiled rice varieties fell into a single smooth curve. The extent of
milling of an unknown sample could, therefore, be determined by testing its
absorbance and that of the corresponding brown rice.
The extractant chosen, selected from different solvent combinations, gave a
clear extract and a negligible difference in reading between normal and red rice
kernels. The intensity of the colour was maximum at about pH 10.5 and above,
and its A,,,,, was at 360 nm (but 400 nm was used for convenience). The colour
was rather unstable, but was more stable in presence of excess rice flour. Hence
it was necessary to use a constant rice-to-solvent ratio during the extraction
for all analyses.
The concentration of the extractable pigment in successive layers of bran decreased
linearly from the outermost to the innermost layer. The fat content, on
the other hand, first increased and then decreased.
 
Date 1972
 
Type Article
PeerReviewed
 
Format application/pdf
 
Language en
 
Identifier http://ir.cftri.com/2436/1/J.%20Sci.%20Fd%20Agric.%201972%2C%2023%2C%20161-169.pdf
Bhattacharya, K. R. and Sowbhagya, C. M. (1972) A colorimetric bran pigment method for determining the degree of milling of rice. Journal of the Science of Food and Agriculture, 23 (2). 161-169, 10 ref..