Headspace congeners of blended Scotch whiskies of different product categories from SPME analysis

Flavour congeners in headspaces of 40 blended Scotch whiskies, of 4 differe nt product categories (Deluxe, standard, retailer and West Highland), were collected by solid phase micro extraction (SPME) over 10 ml diluted (23% ab v) whisky. Fibres (100 mum diameter) were thermally desorbed for 5 min in a split/splitless injection port and congeners quantified by high resolution gas chromatography. Two bonded SPME phases (polydimethylsiloxane and polya crylate) were evaluated: exposure time was varied between 5 and 30 min; wit h whisky at either nosing (25 degreesC) or tasting (37 degreesC) temperatur e. Optimal analysis was with polyacrylate fibres at 37 degreesC for 15 min but extraction at 25 degreesC generated data relevant to sensory (nosing) d ata. Principal component (PCA) and discriminant partial least square (DPLS) analyses of mean % peak areas for all 57 resolved HRGC components and cong eners (38) common to all whiskies gave product spaces showing clear separat ion of Deluxe, retailer and West Highland blends, but dispersed standard bl ends. In DPLS2 product clustering was similar whether relative (%) or absol ute peak area was used in analyses but congeners loadings differed. From pr oduct spaces it was possible to assess contributions of flavour congeners, mainly esters and alcohols, to headspaces of individual blends and product categories.