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Mashing with Unmalted Barley�Impact of Malted Barley and Commercial Enzyme (Bacillus spp.) Additions

Peer-Reviewed Paper

MBAA TQ vol. 42, no. 3, 2005, pp. 184-198  |  VIEW ARTICLE

Declan L. Goode (1), Hilde H. Wijngaard (1), and Elke K. Arendt (2). 1. Department of Food and Nutritional Sciences, Bio-Transfer Unit, National University of Ireland, University College Cork, Ireland. 2. Department of Food and Nutritional Sciences, National University of Ireland, University College Cork, Ireland.

Abstract
This paper reports on the effects that the addition of both malted barley and commercial enzymes (Bacillus spp.) has on the processability and quality of worts when brewing with inclusions of raw barley. Increased inclusion of malted barley resulted in increases in extract recovery levels, wort alpha-amino nitrogen levels, and fermentability and in decreases in wort viscosity and beta-glucan levels. While increases in wort amino acid levels resulted from inclusions of high levels of malt, the endogenous malt enzymes were found to exhibit very poor raw barley protein-hydrolyzing ability. Likewise, the endogenous malt amylases were found to exhibit very poor raw barley starch-hydrolyzing ability. As the level of malt was increased, its raw barley hydrolytic effects decreased. When mashing with 100% raw barley substrate and commercial enzymes, exogenous protease (B. subtilis) additions yielded increases in total soluble nitrogen levels, alpha-amino nitrogen levels, wort color, and extract recovery levels. However, the protease efficiency decreased as the level of protease was increased. Exogenous beta-glucanase (B. subtilis) had little impact on mash filtration, but it reduced high-molecular-weight wort beta-glucan levels. Exogenous alpha-amylase (B. subtilis) was found to have the greatest positive impact on mash separation. Likewise, exogenous alpha-amylase level increases resulted in higher wort glucose and maltotriose levels and lower maltose levels. Optimal addition of an exogenous high-heat thermostable alpha-amylase (B. licheniformis) in combination with the exogenous alpha-amylase (B. subtilis) was found to be necessary for complete starch conversion and maximum extract recovery from the raw barley substrate.
Keywords: adjunct, barley, commercial enzymes, enzymes, mashing, wort quality

 

S�ntesis
Se presentan los efectos que tiene la adici�n de cebada malteada o de enzimas comerciales (Bacillus spp.), sobre la procesabilidad y la calidad de mostos elaborados con la inclusi�n de cebada no malteada. Un aumento de la cantidad de malta agregada result�a en un aumento del rendimiento de extracto, de la fermentabilidad y del contenido de alfa amino nitr�geno, a la vez que disminuy� la viscosidad y los niveles de beta-glucanos del mosto. Si bien la utilizaci�n de altas cantidades de malta aumenta los niveles de amino �cidos en el mosto, las enzimas end�genas de la malta exhibieron una muy pobre capacidad de hidrolizaci�n de las prote�nas y del almid�n de la cebada. Al aumentar la proporci�n de malta, disminuye su efecto hidrol�zante sobre la cebada. Al macerar con 100% cebada cruda junto con enzimas comerciales, el aumento de proteasa ex�gena (B. subtilis) result� en un aumento de nitr�geno soluble total, alfa amino nitr�geno, color del mosto y mayor rendimiento de extracto. Sin embargo, la eficiencia de la proteasa disminuy� al aumentar la proporci�n de proteasa agregada. La beta-glucanasa ex�gena (B. subtilis) tuvo poco impacto sobre la filtraci�n del macerado, pero redujo los niveles de beta-glucanos de alto peso molecular en el mosto. La alfa-amilasa ex�gena (B. subtilis) tuvo su mayor impacto sobre la filtraci�n del macerado, pero result� en mayores niveles de glucosa y maltotriosa, y menores niveles de maltosa, en el mosto. Fue necesario optimizar la adici�n de una alfa-amilasa ex�gena termoestable a altas temperaturas (B. licheniformis) en combinaci�n con una alfa-amilasa ex�gena (B. subtilis) para conseguir una conversi�n total del almid�n y una recuperaci�n m�xima de extracto de la cebada cruda.
Palabras claves: adjuntos, cebada, enzimas comerciales, enzimas, maceraci�n, calidad del mosto

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