MALDI-TOF-MS Profiling For Differential Proteomic Aanalysis Of Bovine Milk Products

Bovine milk is an important nutrition source in human diet and the quality of the products is essential for the health of the consumers.As there are many different milk products being sold in the market,it is important to establish a new method that could realize fast and lowlabor analysis for differentiation and identification.In this thesis,we report on a method that utilizes matrix-assisted laser desorption/ionization time-of-flight mass spectrometry（MALDITOF-MS）profiling of bovine milk,aiming to obtain the panels of characteristic peptide/protein peaks for correct classification and assignment of milk products.The main content and results of the work are as follows.1)The method for MALDI-TOF-MS profiling of bovine milk was established,in which the key procedures and conditions were optimized,including the dilution fold of samples,the spoting volume,whether delipidation was necessary,the preparation of matrix solution,and the m/z ranges and detection modes of the MS acquisition.2)MALDI-TOF-MS profiling was performed on 12 brands of bovine milk,totally 30 products that are sold domestically.Tentative assignment of 71 peptide peaks in low m/z range and 24 protein peaks in middle m/z range were performed by the accurate m/z matching with the reported values.3)Analysis of these mass spectra were performed with the soft Clin Pro Tools,for establishing models to differentiate bovine milk products,between the different fat-content products of the same brand,and between the different brands with the same fat contents（whole,low and non fat）,respectively.Different math models were tested and the genetic algorithm model showed results with the highest scores on cross validation and recognition capacity.External validation demonstrated the models,with the defined characteristic peak panels,could be used to identify unknown milk products（within the model coverage）.We think this work provided a rapid and simple method for fast profiling and differentiating the bovine milk products and we hope it could further used for manufacturing,quality control and inspection.