Chemical method (also GG analysis, GG assay, GG sample) for the determination of aromatic substances or substances in grapes and wines by measuring the potential of the aroma and thus, to a certain extent, the quality of the wine. It was initially developed by the Australian Wine Research Institute AWRI on a complex, manual basis and has since been automated. In simple terms, the glycosides (aroma precursors or primary aromas) are isolated and their conversion to glucose (glucose) is quantified. This can be done already in the early ripening stage of grapes and also in aged wines. Studies have shown that the GG value decreases with increasing ageing of the wine. The analysis is mainly used to determine the influence of different winemaking techniques. The method is to be used as an additional objective possibility for a qualitative wine evaluation. In connection with the analysis, the new growing season term Engustment was developed. See also under quality system.