Application of HS-SPME–GC-MS-derived variables for monitoring ripening-induced changes in cheese volatile compounds

Abstract

Headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) and multivariate statistical analysis (MVA) are widely employed in the analyses/comparison of cheese volatiles. One shortcoming of this approach is that the SPME fiber-coat polarity has a significant effect on the adsorption of volatiles and thus, on the results of MVA. The aim of this study was to test the applicability of different sets of MVA variables, obtained from HS-SPME-GC-MS experiments using the non-polar polydimethylsiloxane (PDMS) and the polar polyacrylate (PA) fibers, in the profiling of cheese volatile compounds and tracking ripeninginduced changes. The volatile profiles and ripening-induced changes of two different types of Pasta-Filata "Pirotski kačkavalj" cheese (prepared from raw ewe's or cow's milk) were assessed at four different stages of ripening (1, 5, 20, and 30 days). The HS-SPME-GC-MS-MVA results showed that the distribution of volatile compounds into classes gives valuable information concerning cheese type and ripening phase. The extraction with a PA fiber gives a more realistic cheese volatile profile when the relative ratio of the constituent classes is in question, whereas the PDMS fiber is better in recognizing the contribution/concentration of single dominant volatile compounds. For a better and more complete description/profiling of cheese volatiles, we propose the use of combined (transformed) variables that include the information obtained from both PA and PDMS extraction experiments.

Volatile Compounds Analysis and Off-Flavors Removing of Porcupine Liver

“…Fiber coated with PDMS was better in recognizing the contribution/concentration of single dominant volatile compounds in the previous experiment (Milosavljević et al, 2012). Before using for the extraction of the samples studied, the fiber was preconditioned according to the instruction in the GC injection port at 260℃ for 20 min.…”

Composition and Significance of Bacterial Microbiota and Volatile Organic Compounds of Swiss-Dutch-Type Cheese as Determined by PCR-DGGE and HS-GC

“…In this study, HS-GC revealed the presence of all VOC groups in Swiss-Dutch-type cheeses. The presence of alcohols, esters, ketones, short-chain and medium-chain fatty acids was also determined in Serbian Pirotski kačkavalj cheese [Milosavljević et al, 2012] and French Cantal cheese [De Freitas et al, 2007]. According to Pastink et al [2008], considerable differences in the fl avor-forming ability of LAB exist not only between species, but also between strains.…”

“…Advanced computational methods, such as HCA, PCA or partial least squares (PLS) regression, are increasingly often used in studies of this type. Milosavljević et al [2012] relied on AHC and PCA to compare contents of VOC determined by different gas chromatography methods. Based on an analysis of GC data, they concluded that the results of AHC and PCA should be analyzed in combination to produce a more comprehensive VOC profi le of ripened cheeses.…”