Formation of volatile compounds in soy flour by singlet oxygen oxidation during storage under light

Volatile compounds in soy flour stored under light and in the dark at 30 degreesC were studied by a combination of solid-phase microextraction-gas chromatography-mass spectrometry and sensory evaluation. As storage time increased from 0 to 6 d, the total volatile compounds in soy flour stored in the dark and under light increased by 60% and 300%, respectively. Dimethyl disulfide increased significantly under light, and 2-pentylfuran, 1-octene, and 2-heptenal were identified only in soy flour under light. This indicates that the singlet oxygen oxidation was taking place in soy flour stored under light. Sensory off-flavor scores were significantly higher in samples stored under light than in the dark.