6/30/2016 WineLand Magazine  The complex relationship between wine aroma and amino acid utilisation by yeast http://www.wineland.co.za/technical/thecomplexrelationshipbetweenwinearomaandaminoacidutilisationbyyeast 1/7 by Hannibal Musarurwa, Alexander McKinnon & Florian Bauer / 0 Comments / March 2016, Wine Aroma, Amino Acid, Yeast, Nitrogen. Introduction Fermentation-derived aroma compounds are one of the de뤀ning features of wine quality. Primary aroma and avour compounds such as acetic acid, ethanol and glycerol are largely dependent on the quality and amount of carbon in the starter must and on fermentation conditions. Nonetheless, the jury is still out on the foundation of some distinctive avours and aromas usually associated with particular varieties and locales (Jackson, 2014). Scientists and winemakers have long suspected that yeast nutrition, along with other factors, plays a crucial role in determining the chemical pro뤀le of wine aroma. Nitrogen concentration in the grape must has been identi뤀ed as one nutritional factor crucial in aroma biosynthesis during winemaking. The important nitrogen in grape must, referred to as yeast assimilable nitrogen (YAN), determines yeast growth, development and subsequently aroma production. As a result, addition of diammonium phosphate (DAP) as a nitrogen supplement is now standard practice in most cellars. Yeast can meet its nitrogen needs by breaking down proteins, and by using amino acids and peptides present in the must. Amino acids are a signi뤀cant source of YAN, but are not all used at the same rate. Depending on how readily yeast metabolise the amino acids, they can be classi뤀ed as preferred, intermediate, non- preferred and non-utilised as shown in Table 1. Furthermore, their use by yeast will result in the production of various aroma compounds, and many amino acids are direct precursors of speci뤀c aromatic features. This report is a summary of a study that investigated the inuence of individual amino acids and amino acid classes on the aroma pro뤀les of synthetic grape must (SGM) fermented by two industrial Saccharomyces The complex relationship between wine aroma and amino acid utilisation by yeast June 2016 SunMonTueWedThuFriSat 293031 1 VinPro Pruning course: Vredendal VinPro Pruning course: Paarl/Wellingto 567 8 9 VinPro Pruning course: Franschhoek VinPro Pruning course: Robertson VinPro Worce 1213 1415 Klein Karoo Regional Information Day VinP cour 192021 22 What's New Wosa woos golden child June 2016 Growing you June 2016 Team Porex than ever June 2016 Trade Diary  