Two Japanese grape varieties (Koshu and Muscat Bailey) and two European ones (Chardonnay and Cabernet sauvignon) were used for trials carried out to determine the extraction kinetics of the free and total amino acids, peptides and proteins from the grape skin. Two synthetic musts were also used : ethanol was added in the first one whereas the fermentation was processing in the second one . The results clearly showed that dissolved nitrogen increases with time and depends on then grape variety. Nitrogen compounds are slowly extracted from the seeds, while those from the skins are fully dissolved after only one day. High nitrogen content in the must, particularly free amino acids – is crucial for the achievement of alcoholic fermentation and the overall quality of the wine. (We advise you to read the whole article. Original title: Changes in amounts of nitrogenous compounds from skins and seeds of four grape cultivars during extraction using juice or fermenting must-like model solutions.)

Related sheets: