Solid-phase microextraction and gas chromatography mass spectrometry analysis of dairy product volatiles for the determination of shelf-life

Fermented milk varieties and fresh cheeses, which are appreciated by consumers for their sensory quality, have a shelf-life at refrigeration temperatures that usually does not exceed 4–5 weeks (depending on manufacturing and packaging). The aim of the research was to study the composition of the volatiles of artisanal and commercial samples of fermented milk and fresh cheeses during the shelflife period using an optimised, rapid and repeatable method: solid phase microextraction/gas chromatography coupled with mass spectrometry. More than 60 volatile components were identified in all the samples and confirmed using spectral data, authentic standards and linear regression indices. Analysis of variance and principal component analysis were applied to estimate the significant differences in volatile composition during storage, determination of the decrease in cheese ‘‘freshness’’, and definition of the possible critical days during shelf-life.