A methodology study to evaluate quality of soybeans stored at different moisture levels

The quality of soybeans and oil extracted from seeds stored at different moisture contents was evaluated by static headspace gas chromatography, near‐infrared spectrometry, fluorescence measurements, and silicic acid chromatography. Headspace gas chromatographic analysis of both ground beans and crude oils provided a sensitive measure of oxidative deterioration based on hexanal and total volatiles. Near‐infrared analyses at 2260 nm showed a correlation coefficient of 0.864 with titratable free fatty acids. Fluorescence measurements on chloroform‐methanol extracts were much less sensitive and showed an increase only in the most damaged samples. Silicic acid chromatography of crude oils showed a significant decrease of polar lipids and increase of less polar lipids with storage at high moisture levels, in agreement with the decrease in phosphorus observed. Among the methods tested, headspace gas chromatography is most sensitive to evaluate oxidative deterioration, and near‐infrared analysis is most suitable and rapid to evaluate hydrolytic deterioration in stored soybeans. This methodology can be used to evaluate factors affecting the food quality of soybeans for domestic and foreign markets.