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Chemistry of Color Fixation in Crude, Physically Refined and Chemically Refined Rice Bran Oils upon Heating.

IR@CSIR-CFTRI

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Relation http://ir.cftri.com/11644/
http://doi.org/10.1007/s11746-014-2520-4
 
Title Chemistry of Color Fixation in Crude, Physically Refined
and Chemically Refined Rice Bran Oils upon Heating.
 
Creator Rekha, B.
Lokesh, B. R.
Gopala Krishna, A. G.
 
Subject 19 Lipids-oils/fats
 
Description Compared to other vegetable oils, rice bran oil
(RBO) has a characteristic dark color which further deepens
upon heating or frying of foods in the oil. Darkening of
the oil during heating has been studied. The dark colorcausing
material in crude, chemically refined and physically
refined rice bran oils was separated using a silica gel
column for a hexane-eluted oil fraction and a methanol
eluted fraction. The methanol eluted fraction for all the
above three types of RBO produced a dark color upon
heating, hence the physically refined RBO methanol fraction
was investigated further and contained monoglycerides
(23.4 %) and diglycerides (67.4 %) of
linoleic ? linolenic acids in its methanol fraction as analyzed
by column chromatography and HPLC which
decreased in concentration after heating. The linoleic acid
level of 37.7 % in the methanol fraction was reduced significantly
to 18 % after heating (52.3 % reduction). The IR
and NMR spectra were similar to those of a monoglyceride/
diglyceride with NMR spectra indicating a lower
amount of olefinic protons for the heated sample. These
results showed that the darkening of RBO was due to the
oxidation and polymerization of monoglycerides/diglycerides
containing linoleic acid/linolenic acid.
 
Date 2014
 
Type Article
PeerReviewed
 
Format application/pdf
 
Language en
 
Rights —
 
Identifier http://ir.cftri.com/11644/1/Jl_amer_oil_chem_soc_91_10_2014_1677.pdf
Rekha, B. and Lokesh, B. R. and Gopala Krishna, A. G. (2014) Chemistry of Color Fixation in Crude, Physically Refined and Chemically Refined Rice Bran Oils upon Heating. Journal of the American Oil Chemists' Society, 91. pp. 1665-1676.