Quantitative Proteomics of different truffle species

Truffles of the Tuber species as expensive foods are predestined for food fraud. To find markers for distinguishing different truffle species the proteomes as phenotype determining basis were investigated. First, established sample preparation protocols subsequent to LC-MS/MS analysis for a bottom up proteomic approach were tested on a truffle sample. The sample preparation included protein extraction and in-solution tryptic digestion. For protein extraction sodium deoxycholate (SDC), sodium dodecylsulfate (SDS) and urea were tested, followed by direct tryptic digestion in solution (SDC extracted proteins) and a tryptic digestion utilizing the FASP approach with molecular cut-off filters (SDS and urea extracted proteins). By this approach the SDC sample preparation protocol was classified as the most suited one to prepare truffle samples. It resulted in a high protein identification rate, had a high reproducibility, was cost efficient and most easy to handle. By a quantitative proteomic approach using label-free and non-targeted bottom up LC-MS/MS the species T. magnatum (n=13), T. aestivum (n=16), T. uncinatum (n=4) and T. melanosporum (n=7) were compared and truffle species specific markers were identified.