Chemical reactions involved in the catalytic hydrogenation of oils. III. Further identification of volatile by‐products

Abstract

Abstract Two distinct types of hydrogenation flavor may originate from catalytic hydrogenation of fats and oils. One is the characteristic flavor developed during hydrogenation. After it is removed by deodorization, the second type of hydrogenation flavor may develop during the storage of the bland deodorized hydrogenated fat. The precursors of the characteristic flavor developed during catalytic hydrogenation were demonstrated as the hydroperoxides of the unsaturated fatty esters. A total of 37 compounds was chemically identified by the combination of infrared and mass spectrometry as the major components of the volatile by‐products developed during catalytic hydrogenation of soybean oil with nickel as catalyst. Out of the 37 compounds, 14 were hydrocarbons, eight were alcohols, one was an ester, four were aldehydes, eight were ketones, and two were lactones. The seven largest peaks of the gas chromatogram of the volatile by‐products were all alcohols and hydrocarbons. It was concluded that the characteristic flavor developed during catalytic hydrogenation appears to be due to the higher members of the aldehydes, ketones, and alcohols and the lactones.