Headspace gas analysis of salad oils by mass spectrometry

A mass spectrometer was used to analyze the content of hydrogen, nitrogen, oxygen, carbon dioxide and argon in headspace gas of commercially packaged soybean, cottonseed and corn salad oils. A leakproof sampling system was designed to avoid air contamination and obtain a representative headspace gas sample. Some edible oils are packaged under pure nitrogen, whereas other samples contained various amounts of oxygen in the headspace gas. The presence or absence of argon in the headspace gas indicates that some oils are packaged with pure nitrogen and others with nitrogen obtained by controlled burning of hydrocarbons to remove all the oxygen in air. The presence of hydrogen in some samples where argon was also present suggested that catalytic purifiers were used to remove the last traces of oxygen and to ensure pure nitrogen for packaging oils. The decrease in oxygen of oils bottled in air was followed during storage at room and at elevated temperatures. No. Market. and Nutr. Res. Div., ARS, USDA.