Corn Size Distribution, Cold Water Extract, and Diastatic Power in Relation to Malted Barley Quality
MBAA TQ doi:10.1094/TQ-46-1-0226-01 |
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Reginald C. Agu. The Scotch Whisky Research
Institute, Research Avenue North, Riccarton, Edinburgh, EH14 4AP,
Scotland, UK.
Abstract
The results of this study provide more evidence that when barley
corns of different sizes are mixed together in a germination box during
malting, homogeneous modification is difficult to achieve. A very strong
negative relationship (R = �0.73) was found when the percentage of
thin corns (<2.2-mm sieve) was correlated with diastatic power (DP)
development. When correlation between the percentage of intermediate corns
(2.2-mm sieve) and DP was performed, a similarly strong negative
correlation resulted (R = �0.63). The study also showed that as the
corn size distribution in barley malt decreased from higher percentages of
thin (<2.2-mm sieve) or intermediate (2.2-mm sieve) corns to lower
percentages, implying a higher percentage of large corns (2.8- to 2.5-mm
sieve), the correlation results moved from a negative to a positive
correlation, because the relationship between DP and large corns were
strongly positively correlated (R = 0.69). Furthermore, the
relationship between cold water extract (CWE) and corn size distribution
showed that thin and intermediate corns modified at a faster rate, because
a direct relationship was found between CWE and thin (<2.2 mm) and
intermediate (2.2 mm) corns, corresponding to R = 0.47 and 0.43,
respectively. In contrast, large corns modified at a slower rate,
producing a negative inverse relationship between large corn size and CWE
(R = �0.49).
Keywords: barley, cold water extract, corn size, diastatic power,
malt quality
S�ntesis
Los resultados de este estudio se suman a la evidencia que
demuestra que se dificulta llevar a cabo una modificaci�n homog�nea en el
malteo cuando granos de cebada de diferentes tama�os se mezclan en una
caja de germinaci�n. Se consigui� una correlaci�n fuertemente negativa (R
= �0.73) entre el porcentaje de granos finos (cedazo de <2.2 mm) y el
desarrollo del poder diast�stico (DP). Hubo una correlaci�n similar (R
= �0.63) entre el porcentaje de granos intermedios (2.2 mm) y el
desarrollo del DP. El estudio tambi�n demostr� que al bajar los
porcentajes de granos finos y de granos intermedios, es decir, al aumentar
el porcentaje de granos mayores (2.5�2.8 mm), la correlaci�n pasaba de
negativo a positivo debido a que la relaci�n entre el porcentaje de granos
mayores y el DP es fuertemente positiva (R = 0.69). Es m�s, se
obtuvo una correlaci�n positiva entre el extracto en agua fr�a (CWE) y
granos finos o granos intermedios (R = 0.47 y R = 0.43,
respectivamente), demostrando que los granos finos e intermedios se
modifican a una mayor velocidad que los granos mayores que mostraron una
correlaci�n negativa entre el tama�o y el CWE (R = �0.49).
Palabras claves: calidad de malta, cebada, CWE (extracto agua fr�a),
poder diast�stico, tama�o de grano
