Daniel GRANES, Edouard MEDINA, Lucile BLATEYRON, Céline ROMERO, Eric BRU, Christophe ROUX, Caroline BONNEFOND, Agnès PIPERNO, Myriam ROUANET, Thomas O

In the living world, nitrogen is an essential element which is present in the composition of amino acids, peptides and proteins. For yeasts in particular, these proteins are constitutive elements of the cell and of its organelles (structural proteins) or of enzymes which intervene as transporters or in metabolic reactions (functional proteins). Nitrogen is therefore a key factor for the multiplication and physiological activity of the yeasts. When one talks about nitrogen, all the molecules which consist of one or more nitrogen atoms are encompassed. However, not all the nitrogen can be used by the yeasts: P. Barre, V. Jiranek and others therefore defined assimilable nitrogen as the quantity of nitrogen in mg/L which is at the time available and susceptible to be used by the yeasts. When we will speak further of nitrogen, it will always be in reference to this definition, unless otherwise indicated. The assimilable nitrogen consists of amino nitrogen and amino acids. Among all the amino acids, certain ones such as proline are not assimilable by the yeasts. The measurement of the assimilable nitrogen takes into account only the assimilable amino acids. On a synthetic medium and in pure culture, the complete fermentation of 200g/L of sugar (around a potential of 12°) can only be completed when initial levels of assimilable nitrogen are higher than 150mg/L, due to this fact, this is defined as the level of “absolute deficiency”. The assimilable nitrogen can represent less than 50% of the total nitrogen. The quantity of nitrogen assimilated by the yeasts has four important impacts and these in part depend on one another. The supplies during the multiplication phase and stationary phase are the most efficient. It is therefore always of preference to act preventatively. Attention however to negatively interpreting a supply said to be “initial”. For the classic supply at the end of the growth phase, the addition combined with O2 must be standardized for reds as for with white or rosés.
Published on 08/28/2008
Related sheets
    E. Aguera, J.M. Sablayrolles
    The seasonal character of harvests limits winemaking considerably, especially oenological research. Thus, conserving sterile musts during the whole year to carry out experiments is certainly a very...
    Published on:08/10/2005
    A new device for stabilisation of white wines throughout a continous flow system
    Parpinello, G.P., Ricci, A., Serantoni, M., Balducci, A., Ragni, L., Versari, A.; University of Bologna, Italy
    Proteins occurring in wine originate from several sources during the winemaking process. Protein content in wines ranges from traces up to hundreds of mg/L, and may cause physical instability in wh...
    Published on:01/15/2020
    A new life for winemaking lees: from waste to photovoltaics
    Manuel Meneghetti, DSMN, Università Ca’ Foscari Venezia
    The sun, the main natural resource of our planet, has been studied in recent years optimizing materials, technologies and processes to obtain electrical energy thanks to the best renewable and clea...
    Published on:09/09/2020
    A novel electrochemical approach for rapid analysis of white grapes polyphenols and monitoring of pre-fermentative operations
    M. UGLIANO, J. WIRTH, S. BÉGRAND, J. B. DIÉVAL, C. PASCAL, S. VIDAL; Università degli Studi di Verona - Vinventions, Francia
    The ability to rapidly quantify and characterize phenolic composition of grapes and must is critical in the optimization of winemaking practices. In the case of white wine production, measurement o...
    Published on:05/02/2019
    An electrochemical method for real time measurement of polyphenols during winemaking
    By Christine Pascal, Nelly Champeau, Jean Baptiste Diéval, Stéphane Vidal; Vinventions, Enology team, France
    Polyphenols are known to play a major role in must oxidation as well as in wine aging and oxidation. However, they are difficult to measure in the cellar due to lack of adequate technology. Therefo...
    Published on:02/03/2020
    Application of unconventional tannins as markers of authenticity
    E. Longo, F. Rossetti, V. Merkyte, M. Jourdes, P.L. Teissedre and E. Boselli; Univ. of Bolzano, Univ. Politec. delle Marche-Italy, ISVV-France
    This work aimed at the identification of novel macro-cyclic ‘crown’ prodelphinidins (c-PD) in 19 PDO wines from South Tyrol (vintage 2016) obtained from several regional (Lagrein and Vernatsch/Schi...
    Published on:10/21/2020
© All Right Reserved
ISSN 1826-1590 VAT: IT01286830334
powered by Infonet Srl Piacenza
Privacy Policy
This website and its related third-party services make use of cookies necessary for the purposes described in the cookie policy. If you want to learn more about cookies or how to disable them (either totally or partially), please see the cookie policy. By closing this banner, scrolling through this page, clicking on a link or continuing navigation in any other way, you consent to the use of cookies.
More informationOK

- A +
ExecTime : 2,640625