Metabolism (biochemical metabolic process) refers to the uptake, transport and chemical conversion of substances in an organism, as well as the release of metabolic products into the environment. The resulting intermediate products are called metabolites, the entirety of the metabolic pathways is called metabolism. Fermentation and the processes involved in bottle ageing are also such metabolic processes. From this, metabolomics is an analytical method that can be used to determine these metabolic processes. Recently, it has also been used in the analytical testing of wines. This is because every wine is individually composed on a molecular level and has its own "chemical fingerprint". Scientists at the Max Planck Institute for Molecular Plant Physiology in Potsdam (Brandenburg) have discovered this.
With the help of high-resolution mass spectrometers, which recognise individual substances on the basis of minute differences in their molecular weight, the researchers identified up to 7,000 different constituents that occur in wine (see also under Total Extract). More than half of these chemical compounds are still unknown. Wine essentially consists of water, alcohol and a multitude of small molecules, the metabolites. Factors such as soil, weather conditions and winemaking methods leave traces in the wine and determine its molecular composition. Wine has a kind of memory, so to speak, in which its entire history is stored. This means that the origin, vintage, grape variety and also the quality can be measured.
A project team consisting of staff from the Max Planck Institute and the Universidad Técnica Federico Santa Maria (Chile) analysed the occurrence and distribution of all ingredients of four varietal Chilean red wines made from Cabernet-Sauvignon, Carmenère, Merlot and Syrah, which differed in origin, vintage and quality. What was surprising was the low number of only 9% common ingredients that existed in all four varieties. About 30% turned out to be characteristic biomarkers for one grape variety each. The remaining approximately 60% were present in several, but not all four varieties. For each variety, up to 6,400 different ingredients could be detected. The method goes much further than classical wine analysis, which only looks at individual components such as anthocyanins, phenols or acids. It will probably be used in the future for quality and origin control, as well as for detecting wine adulteration with regard to unauthorised substances.
