Advantage of LC-MS metabolomics methodology targeting hydrophilic compounds in the studies of fermented food samples.

The utility of a liquid chromatography mass spectrometry (LC-MS) method, using a pentafluorophenylpropyl (PFPP) bonded silica, was demonstrated in a metabolomics study of fermented food samples. Our LC-MS method was applied to Japanese fermented food (miso) of different stages of ripeness. The data acquired were evaluated by principal component analysis (PCA). The score plots indicated that the miso samples could be approximately classified into three groups, based on the stage of miso ripeness. The loading plots indicated that the ions responsible for group separation included not only amino acids and citric acid but also Amadori compounds. On the other hand, the miso samples were also analyzed by a conventional LC-MS method using an octadecyl (C(18)) column for comparison. The group separation of score plots from the conventional method was less clear than that from our method. The advantage of our LC-MS method is due to the different retention properties of the PFPP column and the C(18) column with hydrophilic compounds. Our LC-MS method will be useful for the metabolic profiling of fermented food samples.