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The nature of the C 18 polyethenoic fatty acids of butter fat
Author(s) -
Sambasivarao K.,
Brown J. B.
Publication year - 1962
Publication title -
journal of the american oil chemists' society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.512
H-Index - 117
eISSN - 1558-9331
pISSN - 0003-021X
DOI - 10.1007/bf02638799
Subject(s) - silicic acid , chemistry , linoleic acid , isomerization , organic chemistry , linolenic acid , conjugated linoleic acid , gas chromatography , chromatography , fatty acid , degree of unsaturation , double bond , catalysis
Methyl C 18 polyenoate concentrates were prepared from two samples of butter fat by low temperature crystallization and fractional distillation. The concentrates were fractionated on a silicic acid column and the resulting fractions were analyzed by ultraviolet and infrared spectrophotometric methods. About 42 and 30% repectively, of the non‐conjugated dienoate in the two samples were shown to have the cis,trans configuration. Fractions rich in dienoate and trienoate were prepared from the C 18 polyene concentrates by silicic acid chromatography and the nature of these acids was studied by bromination, lipoxidase enzyme methods, and by alkali isomerization for varying periods of time. About 65 and 73%, respectively, of the non‐conjugated dienoate in the two samples investigated were found to consist of linoleic acid while 79 and 71% of the trienoate were linolenic acid. Linoleic and linolenic acids were identified by preparing the characteristic tetra‐ and hexabromostearic acids. A trans,trans isomer of linoleic acid does not seem to be present in butter fat. A major proportion of the non‐conjugated dienoic acid other than linoleic acid was found to have widely separated double bonds with cis,trans configuration. Occurrences of a C 15 saturated acid, a branchedchain C 17 saturated acid, and a heptadecenoic acid were indicated by gas chromatography.