Comprehensive phytochemical profile of soy protein isolate

Although an FDA health claim for soy protein has been issued, the potential health benefits of soy foods remain controversial among scientists, especially with regard to soy infant formula. The UV detectable isoflavones have been the focus of the majority of studies concerning health-related effects of soy protein isolate (SPI). However, the chemical identities and health effects of other SPI phytochemicals without UV absorption properties are less well-studied. In the current study, we employed liquid chromatography-tandem mass spectrometry methods to reveal a complicated phytochemical profile for SPI consisting of 136 phytochemicals. Also, we have quantitated many of these SPI phytochemicals so that dietary intakes can be estimated for foods containing SPI. On a weight/weight basis, fatty acids are the largest group of phytochemicals in the extract (64.13% total fat), followed by saponins (21.48%), and then isoflavones at 6.82%. Of the 56 lysophospholipids identified in SPI, 0.50% was lysophosphatidylcholines and 0.23% was lysophosphatidylethanolamines.