Abstract:

A gas chromatography-tandem mass spectrometric (GC-MS/MS) method was set up for selenomethionine determination based on the collision-induced ion fragmentation pattern of its derivatives in order to investigate the change of selenomethionine content in edamame during processing and storage. After 4 weeks of storage at 4 ℃, fresh edamame presented a selenium loss of 13% (based on the content of selenomethionine). Throughout the whole storage of 6 months at room temperature, the selenomethionine degradation of dehydrated edamame remained lower than that of edamam juice significantly increasing. This indicates that dehydration greatly contributes to selenomethionine retention. Blanching had little effect on selenomethionine loss and the percentage retention of selenomethionine still kept over 85%. Lypholization resulted in the highest percentage retention of selenomethionine, followed by vacuum drying and hot air drying and the resultant percentage retentions of selenomethionine were all over 80%. The lowest percentage retention of selenomethionine (30%－40%) was found in edamame dehydrated by spray drying. This is probably due to large contact area with air.

Key words: edamame, selenomethionine, GC-MS/MS, degradation rate