Instrumental analysis of volatile (flavour) compounds in milk and dairy products

Abstract

The present article reviews the most commonly used methods, techniques and equipments for instrumental analysis of volatile (flavour) compounds in milk and daily products. After listing some previous important review articles, several methods commonly used for sample treatment are described, as well as the following techniques for extraction and concentration prior to gas Chromatographic (GC) analysis: static and dynamic headspace, steam distillation, high-vacuum distillation, molecular distillation, direct extraction (liquid/liquid or liquid/solid), supercritical fluid extraction (SFE), simultaneous (steam) distillation extraction (SDE), dialysis, solid-phase extraction (SPE) and solid-phase microextraction (SPME). Two classical injection devices are also described: on-column injection and the so-called 'purge and trap' system. The main advantages and disadvantages of current commercially available types of fused silica capillary columns are briefly considered. The newly developed 'chiral' phases are also described. The article reviews some of the numerous detection systems used for qualitative and/or quantitative analyses such as FID or MS detection, FTIR detection, SCD, FPD and NPD detectors used for sulfur-and nitrogen-containing components, AED detection and the 'sniffing device'. Some useful library search systems such as PBM, INCOS™ and SISCOM (ie, MassLib®) are mentioned to complete the overview of this topic. Finally, this paper briefly points out some other methods (ie, photometric), capable of determining various specific chemical functions responsible for flavour (carbonyl compounds, etc), as well as promising techniques involving new electronic noses.