HS-SPME optimization by RSM and discrimination analysis for volatile profile of X-ray irradiated mozzarella cheese
Headspace Solid-Phase MicroExtraction (HS-SPME) and subsequent analysis by gas chromatography coupled to mass spectrometry (GC-MS), provided a detailed volatolomic profile of X-ray irradiated mozzarella cheese. Response Surface Methodology (RMS), obtained from a Central Composite Design (CCD) was employed to define the optimized combination of extraction temperature (°C), extraction time (min) and sample amount (g). From the analysis of the response surfaces it can be stated that all three parameters equally influenced the extraction efficiency. The optimal HS-SPME conditions were the highest level for all the factors, i.e., at 50 °C for extraction temperature, 75 min for extraction time and 5 g for sample amount. The optimised HS-SPME were used to analyse a rapresentive number of non-irradiated and irradiated samples at three dose levels, i.e., 1.0, 2.0, 3.0 kGy. Principal Component Analysis (PCA), Partial Least Squares-Discriminant Analysis (PLS-DA) and Linear Discriminant Analysis (LDA) were applied to explore the variation of volatile profile with respect to the X-ray irradiation treatment.