Solid-phase microextraction spectrometry: A new approach to the rapid characterization of cheeses

This work describes a new method for the rapid characterization of cheeses by solid-phase microextraction coupled with mass spectrometry (SPME-MS), Af ter four types of fiber were tested and the main extraction parameters stud ied, the volatile components were extracted using a Carboxen/PDMS 75-mum fi ber placed for 10 min at 20 degreesC in the headspace of the cheese. The su bstances adsorbed were then transferred directly: from the injector to the inlet of a mass spectrometer through a l-m deactivated silica capillary col umn heated to 210 degreesC, The mass spectra thus obtained without prior ch romatographic separation formed a "fingerprint" of the analyzed sample, For data analysis, the mass fragments of each spectrum (45 < m/z < 150 amu) we re considered as potential descriptors of the composition bf the headspace of the cheeses: Stepwise discriminant analysis was used to select a limited number of mass fragments that afforded an operational classification of th e batches of cheeses studied, This new method offers the advantage of minim izing thermal, mechanical, and chemical modifications of the matrix, thereb y reducing the risk of analytical artifacts. SPME-MS provides a simple and effective approach to rapid quality control by analysis of the volatile fra ction of foods.