Summary
This study determined the Se species in Se‐enriched peanut, and Se losses during peanut protein processing by enzymatic extraction, high‐performance liquid chromatography (HPLC) separation and inductively coupled plasma‐mass spectrometry determination. The study revealed that mixed enzymes (protease and lipase, 2:1 w/w) in Na2S2O3, assisted by 1 h ultrasonic processing, could effectively extract Se speciation from defatted peanut powder. Separation of organic Se by HPLC was optimised using pentafluoropropionic anhydride at a concentration of 0.1% in 2% methanol as mobile phase. Selenomethionine is the dominant Se species in peanut, accounting for 65% of the total Se. During the peanut protein preparation, nearly 37% of Se losses were due to the complexity of the multistage process. The loss can be ascribed to volatilisation, dissolution, degradation or other physical modes of transfer or loss.