Oxidative Stability of Some Seed Oils Containing Conjugated Octadecatrienoic Fatty Acid Isomers

摘要

A comparative study of oxidative stability of conjugated and non-conjugated fatty acid containing oils of similar chain length and unsaturation,was undertaken under Schaal oven test condition(at 63+-2 deg C temperature),taking seed oils like snake gourd(Trichosanthes anguina)containing conjugated punicic acid(9 cis,11 trans,13 cis),bitter gourd or karela(Momordica charantia),having conjugated alpha-elaeostearic acid(9 cis,11 trans,13 trans)and linseed(Linum usitatissimum)oil containing non-conjugated alpha-linolenic acid(9 cis,12 cis,15 cis),as control.In this study,the oils were analyzed by U.V.,I.R.and G.C.The in vitro oxidation of crude snake gourd seed oil containing punicic acid carried out at ambient temperature,showed changes in colour,development of rancidity and formation of gel-like substance.A kind of relationship between the change of conjugated triene,and the corresponding change in colour and odour was noted.The oxidative stability of the conjugated fatty acid isomers at Schaal oven test temperature showed that there was difference in the formation of primary products(estimated by peroxide value),secondary products(estimated by TBA value),conjugated diene and triene formation,and gel-structure(confirmed by SEM study),between snake gourd and bitter gourd oils and also incase of linseed oil.