Effect of Fermentable Sugars and Amino Acids on Fermentability of Malts Made from Four Barley Varieties
MBAA TQ vol. 42, no. 2, 2005, pp. 101-106 |
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Peer-Reviewed Paper
M. J. Edney and D. E. Langrell. Grain Research Laboratory, Canadian Grain
Commission, 1404-303 Main Street, Winnipeg, MB, Canada R3C 3G8.
Abstract
The commercial acceptance of a malting barley variety is dependent on the
potential of the barley�s malt to achieve an acceptable fermentability.
Factors that affect fermentability, however, are poorly understood.
Fermentation is thought to depend on the potential of a malt to provide
adequate nutrients, predominately fermentable sugars and amino acids, for
yeast metabolism. The current study investigated the fermentability of
malts made from four varieties of barley originating in Canada (AC Oxbow
and Harrington) and Australia (Schooner and Stirling). Levels of
fermentable sugars and amino acids in malt extracts were compared with
fermentabilities. AC Oxbow and Harrington, the varieties with the highest
levels of starch-degrading enzymes (alpha-amylase and diastatic power),
fermented significantly better. These two varieties tended to also produce
extracts with higher levels of fermentable sugars, but only glucose and
total fermentable sugars correlated significantly with fermentability.
Initial levels of amino acids were found to differ significantly among
varieties, but these levels had no significant effect on fermentability.
Keywords: amino acids, barley malt, fermentability, fermentable sugars
S�ntesis
La aceptaci�n comercial de una cebada de malteo depende en gran parte de su
potencial para realizar una fermentaci�n aceptable. Sin embargo, vale notar que
los factores que afectan la fermentabilidad no son bien conocidos. Se piensa que
la fermentaci�n depende de si la malta provee cantidades adecuadas de
nutrientes, principalmente azucares fermentables y amino �cidos, requeridos
para el metabolismo de la levadura. Este estudio investig� la fermentabilidad
de mostos de maltas provenientes de cuatro variedades de cebada de Canad� (AC
Oxbow y Harrington) y Australia (Schooner y Stirling). Se compar� la
fermentabilidad con los niveles de azucar fermentable y de amino �cidos en los
extractos de malta. Oxbow y Harrington, las variedades con los niveles m�s
altos de enxzimas que descomponen almid�n (seg�n el poder diast�tico y nivel
de alfa-amilasa), fermentaron significativamente mejor. Estas dos variedades
generalmente produc�an extractos con mayor nivel de azucares fermentables, pero
s�lo glucosa y azucares fermentables totales dieron una correlaciu�n
significativa con fermentabilidad. Los niveles iniciales de amino �cidos vari�
significativamente entre las diferentes variedades, pero esos niveles no
tuvieron un efecto significativo sobre la fermentabilidad de los mostos.
Palabras claves: amino �cidos, cebada malta, fermentabilidad, azucares
fermentables
