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The Importance of Free Amino Nitrogen in Wort and Beer

MBAA TQ vol. 42, no. 2, 2005, pp. 113-116  |  VIEW ARTICLE

C. Lekkas (1), G. G. Stewart (1), A. Hill (1), B. Taidi (2), and J. Hodgson (2). 1. International Centre of Brewing and Distilling (ICBD), Heriot-Watt University, Riccarton, Edinburgh, EH14 4AS, U.K. 2. Scottish Courage Ltd., Technical Centre, 160 Canongate, Edinburgh, EH8 8DD, U.K.

Abstract
Supplementation of wort (15°P containing 30% very-high-maltose [VHM] syrup) was carried out with five times the natural wort concentration of L-lysine or L-methionine. Control lager fermentations reached target specific gravity (sp gr) within 96 h, while wort supplemented with either methionine or lysine resulted in fermentations that achieved completion within 103 and 48 h, respectively. The vicinal diketone (VDK) concentration in the fermented wort with added lysine was greater compared with that generated at the end of control fermentations. The VDK levels present at the end of fermentations with supplemented methionine were lower than the levels at the end of the control fermentations.
Keywords: amino acids, ammonia, fermentation performance, free amino nitrogen, vicinal diketones, wort supplementations

 

Síntesis
Se le añadió L-methionina y L-lisina a cinco veces la concentración normal, a un mosto de 15°P que tenía 30% de un jarabe VHM (de muy alto contenido de maltosa). La fermentación (baja) de un control sin los aditivos alcanzó el Ea deseado en 96 h, mientras que el mosto adicionado de methionina o lisina tardaron 103 h y 48 h, respectivamente. La concentración de diketonas vicinales (VDK) en el mosto fermentado con lisina fue mayor que la del mosto de control, mientras que la con methionina fue menor que la del control.
Palabras claves: amino ácidos, amonio, desempeño de fermentación, amino nitrógeno libre, diketones vicinales, suplementos para mosto

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