Effect of Steeping Regime and Air-Rest Time on Malting Potential of Different Sorghum Varieties with Similar Nitrogen Contents
MBAA TQ vol. 45, no. 3, 2008, pp.
274-278 |
VIEW ARTICLE
E. O. Ogu (1), F. J. C. Odibo (2), and R. C. Agu (3). 1. Department of
Applied Microbiology and Brewing, Enugu State University of Science and
Technology, Enugu,
Enugu State, Nigeria. 2. Department of Applied Microbiology and Brewing, Nnamdi
Azikiwe University, Awka, Anambra State, Nigeria. 3. The Scotch Whisky Research
Institute, Research Avenue North, Riccarton, Edinburgh, Scotland.
Abstract
Four sorghum varieties, SK 5912, KSV 8, ICSV 111, and KL-2, three of which
have similar nitrogen contents, were studied to determine the effect of extended
air-rest time on the modification pattern of different sorghum varieties with
similar nitrogen contents. Results showed that grain moisture content not only
influenced the thousand corn weight (TCW) of sorghum, it also had some influence
on the out-of-steep moisture content achieved when sorghum was steeped in water
prior to malting. Sorghum varieties ICSV 111 and KL-2 not only had similar
nitrogen and grain moisture contents, they also produced similar acrospire
length and rootlet growth when germinated for 4 days. Although SK 5912 had a
nitrogen content similar to ICSV 111 and KL-2, it had higher grain and
out-of-steep moisture contents, higher TCW, and produced more rootlet growth
when germinated for 4 days. Air-rest time also had a significant effect on
sorghum malting. The longest air-rest time (2 h) resulted in higher malting
losses during sorghum malting but produced sorghum malt that had higher
diastatic power. A common factor was found when sorghum varieties with similar
nitrogen contents were assayed for free amino nitrogen (FAN) using
2,4,6-trinitrobenzene sulfonic acid (TNBS). The TNBS assay revealed similar FAN
levels. While ICSV 111 and KL-2 (lower grain moisture contents) produced similar
peptide nitrogen levels, SK 5912 and KSV 8 (higher grain moisture contents)
produced similar peptide nitrogen levels.
Keywords: air rest, free amino nitrogen, malting, sorghum, total nitrogen
S�ntesis
Cuatro variedades de sorgo (SK 5912, KSV 8, ICSV 111, y KL-2), tres de ellas
con un contenido de nitr�geno muy similar, fueron estudiadas para determinar el
efecto de un tiempo de descanso al aire extendido sobre el patr�n de
modificaci�n. Los resultados demostraron que el contenido de humedad del grano
no s�lo influye sobre el peso de mil granos (TCW) del sorgo sino que tambi�n
afecta el contenido de humedad fuera-de-remojo cuando el sorgo es remojado en
agua antes del malteo. Las variedades de sorgo ICSV 111 y KL-2 no s�lo eran
similares en sus contenidos de nitr�geno y humedad de grano, sino que tambi�n
alcanzaron tama�os similares de acrospira y de crecimiento de raicillas al ser
germinadas por 4 d�as. A pesar que la SK 5912 ten�a un contenido de nitr�geno
similar a las ICSV 111 y KL.2, tuvo mayor contenido de humedad del grano y
fuera-de-remojo, as� como un mayor TCW, y produjo mayor crecimiento de raicillas
al ser germinada durante 4 d�as. El tiempo de descanso al aire tuvo un efecto
similar sobre el malteo del sorgo. El mayor tiempo de descanso al aire (2 h)
result� en mayores p�rdidas de malteo pero produjo una malta de sorgo con un
mayor poder diast�tico. Se encontr� un factor com�n cuando se les midi� el
contenido de nitr�geno libre de aminos (FAN) (usando 2,4,6-trinitrobenzeno
�cido sulf�nico[TNBS]) en variedades de sorgo con un contenido similar de
nitr�geno. El an�lisis con TNBS mostr� niveles de FAN similares. Mientras que
las ICSV 111 y KL-2 (menor contenido de humedad en el grano) produjeron niveles
similares de nitr�geno pept�dico, las SK 5912 y KSV 8 (mayor humedad de grano)
tambi�n produjeron niveles similares de nitr�geno pept�dico (pero diferentes a
los de ICSV 111 y KL-2).
Palabras claves: descanso en aire, malteo, nitr�geno libre de aminos,
nitr�geno total, sorgo
