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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

 

Síntesis
Se presentan los efectos que tiene la adición de cebada malteada o de enzimas comerciales (Bacillus spp.), sobre la procesabilidad y la calidad de mostos elaborados con la inclusión de cebada no malteada. Un aumento de la cantidad de malta agregada resultóa en un aumento del rendimiento de extracto, de la fermentabilidad y del contenido de alfa amino nitrógeno, a la vez que disminuyó la viscosidad y los niveles de beta-glucanos del mosto. Si bien la utilización de altas cantidades de malta aumenta los niveles de amino ácidos en el mosto, las enzimas endógenas de la malta exhibieron una muy pobre capacidad de hidrolización de las proteínas y del almidón de la cebada. Al aumentar la proporción de malta, disminuye su efecto hidrolízante sobre la cebada. Al macerar con 100% cebada cruda junto con enzimas comerciales, el aumento de proteasa exógena (B. subtilis) resultó en un aumento de nitrógeno soluble total, alfa amino nitrógeno, color del mosto y mayor rendimiento de extracto. Sin embargo, la eficiencia de la proteasa disminuyó al aumentar la proporción de proteasa agregada. La beta-glucanasa exógena (B. subtilis) tuvo poco impacto sobre la filtración del macerado, pero redujo los niveles de beta-glucanos de alto peso molecular en el mosto. La alfa-amilasa exógena (B. subtilis) tuvo su mayor impacto sobre la filtración del macerado, pero resultó en mayores niveles de glucosa y maltotriosa, y menores niveles de maltosa, en el mosto. Fue necesario optimizar la adición de una alfa-amilasa exógena termoestable a altas temperaturas (B. licheniformis) en combinación con una alfa-amilasa exógena (B. subtilis) para conseguir una conversión total del almidón y una recuperación máxima de extracto de la cebada cruda.
Palabras claves: adjuntos, cebada, enzimas comerciales, enzimas, maceración, calidad del mosto

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