The evolution of aroma compounds in cheese depend on numerous factors such as the intrinsic raw milk flora, the bacterial cultures used for its manufacture, ripening conditions, and the texture of the cheese. In addition, it is well known that the distribution of aroma compounds in cheese is not homogenous In order to understand which parameters influence the complex equilibrium of aromas in a large-scale food matrix such as an entire Gruyere cheese loaf, we generated a mapping of relevant aroma compound groups. In the present work we studied 40 selected volatile aroma compounds in a 32 kg commercial Gruyère cheese loaf made from raw milk. For the analyses, one-half of the loaf was divided into a total of 258 equivalent pieces, taken over 5 levels from the bottom to the top rind, smear included. Each piece was extracted and analyzed by Headspace – In –Tube Extraction – Gas Chromatography – Mass spectrometry / Pulsed Flame Photometric Detector (HS-ITEX-GC-MS/PFPD). The target molecules were classified into six chemical families. Data was processed statistically to visualize the distribution of the aroma compounds within the cheese loaf. Additionally, a trained sensory panel evaluated the samples. A clearly inhomogeneous distribution of aroma compounds was found within the Gruyère cheese. The associated variation in aroma perception was confirmed by the sensory tests. The sulphur compounds and pyrazines are more abundant in the cheese rind and migrate only a few centimetres in direction of the centre. In contrast, the intensity of carboxylic compounds is higher in the centre of the cheese. It is assumed that the observed aroma distribution is generated through chemical oxidation reactions near the rind and enzymatic, anaerobic reactions in the center, respectively. These results deliver insights into the complex distribution of aroma compounds in a cheese loaf.
