Effects of processing steps on the contents of minor compounds and oxidation of soybean oil.

The effects of minor compounds on the oxidative stability of soybean oil were studied by measuring the contents of peroxides, headspace oxygen and volatile compounds. The effects of processing on minor component contents were also studied. Fatty acids, mono- and diacylglycerols, thermal or oxidized triacylglycerols, oxidized tocopherols and peroxides acted as prooxidant in soybean oil during storage at 55 degrees C. The phospholipids acted as prooxidant or antioxidant depending on the presence or absence of metals in the oil. The tocopherols acted as prooxidant or antioxidant depending on their concentration in the oil. The chlorophyll acted as a sensitizer to generate singlet oxygen in the photooxidation of soybean oils.