This recommended practice enables the quantification of volatile compounds in flavourings to be made by gas chromatography with flame-ionization detection, without having authentic compounds available, and also in many cases it can avoid time-consuming calibration procedures. The relative-response factors (RRF) can be predicted from the molecular formula of the compound, and this approach can be applied to compounds containing the atoms C, H, O, N, S, F, Cl, Br, I, and Si, providing that the molecular formula and number of benzene rings in the analytes are known. The purity of chemicallydefined flavouring substances or chromatographic standards can also be estimated using these predicted RRF, and this procedure can also be used to quantify (poly)hydroxylated compounds, after their derivatization into trimethylsilyl ethers or esters.

Vetiver oil is a highly esteemed basic ingredient of modern perfumery, but the nature of the constituents that really impart its typical and most sought woody-earthy scent has remained controversial. Indeed, vetiver oil is considered as one of the most complex essential oils, being mostly composed of several hundreds of sesquiterpene derivatives with a large structural diversity. Its complexity has hindered the direct identification of its odoriferous components. We thus aimed at using a combination of GC×GC/MS and GC-Olfactometry in order to identify most of its odor-impact constituents. The olfactory analysis of vetiver oil and vetiveryl acetate revealed a huge variety of odors in both products. While khusimone has almost unanimously been recognized as the most characteristic vetiver odorant, we have identified several even more important contributors to the typical vetiver character.

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The Maillard reaction or non-enzymatic browning corresponds to a set of reactions occurring between amines and carbonyl compounds, especially reducing sugars. The Maillard reaction is known to occur in heated, dried, or stored foods and in vivo in mammalian organisms. In food, the Maillard reaction is responsible for changes in colour, flavor, and nutritive value but also for the formation of stabilizing and mutagenic compounds. Because of the complexity of the Maillard reaction, mass spectrometry, coupled or not to separation techniques, is a key tool in this research area and we will review in this article the contribution of mass spectrometry to the understanding of this reaction. Different steps of Maillard reaction will be described and the importance and the role played by mass spectrometry will be highlighted. In addition, different approaches to investigate the Maillard reaction from the formation of Amadori products (early Maillard reaction product) to the flavor and melanoidin production will also be covered.