Detection of soybean allergens based on isotope dilution mass spectrometry: Development, validation, and applications in complex food matrices

Abstract

An effective and versatile method based on isotope dilution mass spectrometry (IDMS) has been developed for the detection of soybean allergens in complex food matrices. The sample treatment method and MRM conditions in MS have been optimized to achieve the highest extraction efficiency and maximum intensity. The signature peptides VLIVPQNFVVAAR from Gly m 6 G1 subunit, TISSEDEPFNLR from Gly m 5 beta subunit, QQQEEQPLEVR and LFEITPEKNPQLR from Gly m 5 alpha’ subunit were selected, and the corresponding isotopically labeled peptides were served as the internal standards to minimize the matrix effects. The standard solutions showed a good linearity ranging from 1 to 200 ng/mL. The recoveries were in the range of 84.61 %–115.63 % and relative standard deviations were in the range of 0.66 % to 12.77 %. The method detection limits (MDLs) and quantitation limits (MQLs) of Gly m 6 G1 subunit, Gly m 5 beta subunit, and Gly m 5 alpha’ subunit in four matrices were less than 2.5 μg/g and 10 μg/g. By utilizing the developed method, three soybean allergens were determined in soy milk and ham sausage which contained soybean. The butter cookies that were not made of soy were also detected to contain soybean allergens, possibly due to manufacturing contamination. Surprisingly, soybean allergens were detected in the sesame paste labeled as soybean free, showing the importance to re-evaluate the soybean allergens after production. Our work laid the groundwork for the development of a versatile and sensitive method to evaluate soybean allergens in food products.