Some Links Between Total Nitrogen, beta-Glucan, and Steeliness in Relation to Barley and Malt Quality
MBAA TQ vol. 44, no. 1, 2007, pp.
32-39 |
VIEW ARTICLE
R. C. Agu. The Scotch Whisky Research Institute,
Research Park, North Riccarton, Edinburgh, Scotland.
Abstract
The relationships between total nitrogen, beta-glucan, and
steeliness with regard to barley and malt quality were investigated. The
results obtained showed that some important relationships exist between
these three quality parameters of barley. An inverse relationship was
found between beta-glucan and percentage of steeliness in barley. In
contrast, a direct relationship was found between percentage of steeliness
and nitrogen content of barley. The relationship also showed that while
nitrogen content of barley was linked with those proteins that can produce
both free amino nitrogen (FAN) and peptide nitrogen, steeliness in barley
was linked with those proteins that produce only FAN in malted barley.
Furthermore, although the proteins associated with nitrogen are involved
in the production of enzymes in malted barley, the proteins associated
with steeliness in barley did not show similar involvement in enzyme
production in malted barley. This confirms the well-known saying that �all
enzymes are proteins, but not all proteins are enzymes.� Steeliness and
beta-glucan in barley seem to play a more important role in determining
the level of extract yield obtained from malted barley than does total
nitrogen content.
Keywords: alpha-amylase, barley, beta-glucan, extract, nitrogen,
soluble nitrogen, steeliness
S�ntesis
Se investig� la relaci�n que existe entre nitr�geno total,
beta-glucano y �steeliness� (�dureza como acero�) y su influencia sobre la
calidad de la cebada y malta. Los resultados obtenidos demuestran que
existen algunas relaciones importantes entre estos tres par�metros de
cebada. Se encontr� una relaci�n inversa entre beta-glucano y
�steeliness�, mientras que se encontr� una relaci�n directa entre el
contenido de nitr�geno y �steeliness.� Tambi�n se observ� que el contenido
de nitr�geno de la cebada estaba relacionada con aquellas prote�nas que
producen tanto amino-nitr�geno libre (FAN) como nitr�geno pept�dico,
mientras que el �steeliness� estaba relacionada con aquellas prote�nas que
�nicamente produc�an FAN de la cebada malteada. Es m�s, si bien las
prote�nas asociadas con nitr�geno est�n involucradas en la producci�n de
enzimas en cebada malteada, las prote�nas asociadas con �steeliness� en
cebada no mostraron igual propensi�n en la producci�n de enzimas. Esto
confirma el viejo dicho �toda enzima es proteica, pero no todas las
prote�nas son enzimas.� �Steeliness� y beta-glucano en cebada parecieran
tener un papel m�s importante que el contenido de nitr�geno total en la
determinaci�n del rendimiento de extracto de la cebada malteada.
Palabras claves: alfa-amilasa, beta-glucano, cebada, extracto,
nitr�geno, nitr�geno soluble, �steeliness�
