Effect of Mashing Regime on Fermentability of Malted Sorghum
MBAA TQ doi:10.1094/TQ-48-2-0422-01 |
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Reginald C. Agu (1), Vicky Goodfellow (2), and James
H. Bryce (2). 1. The Scotch Whisky Research Institute, Research Avenue
North, Riccarton, Edinburgh, EH14 4AP, Scotland. 2. International
Centre for Brewing and Distilling, Heriot-Watt University, Riccarton,
Edinburgh, EH14 4AS, Scotland.
Abstract
The use of sorghum malt in fermentability studies is scarce. This study
was carried out to investigate the fermentability potential of sorghum
malt. The sorghum variety used in this study was malted commercially in a
tropical country and in the laboratory at 28�C. Infusion mashing was poor
in obtaining extractable materials from both commercially and laboratory
malted sorghum. Conversely, the difference in total soluble nitrogen (TSN)
results obtained when sorghum malt was mashed using either the infusion
or decantation method was marginal between the two mashing systems. Also,
production of free amino nitrogen (FAN) from the TSN released when both
mashing systems were used to extract sorghum malt was similar.
Fermentability results obtained from sorghum malt were more complex and
difficult to understand and interpret. A similar correlation was also
found between low predicted spirit yield (LPSY) obtained from
infusion-mashed sorghum malt versus higher predicted spirit yield (HPSY)
obtained from decantation-mashed sorghum malt. Furthermore, when
correlation analysis was performed between HFE obtained from
decantation-mashed sorghum malt versus HPSY obtained from
decantation-mashed sorghum malt, the result was also similar to that found
when similar correlation analysis was performed between LFE obtained from
infusion-mashed sorghum malt versus LPSY obtained from infusion-mashed
sorghum malt. While these correlation results clearly show that
fermentable extracts are strongly linked to predicted spirit yield (PSY)
obtained from malted sorghum can also give misleading information. A
researcher working on sorghum malt but using the standard infusion mashing
method developed to extract well-modified barley malt would erroneously
tend to conclude that the infusion method was as effective as decantation
mashing in extracting materials from sorghum malt. This highlights the
importance of development and use of suitable analytical methods for
sorghum and malt. Notwithstanding, the results of this study show that
sorghum malt can produce good PSY results, but like other cereals,
suitable sorghum variety, adequate malting and mashing conditions are
pre-requisites.
Keywords: decantation, infusion, malt, mashing, predicted spirit
yield, sorghum
S�ntesis
Existe poca informaci�n sobre el uso de
malta de sorgo en procesos de fermentaci�n. Este estudio se realiz� con el
prop�sito de investigar el potencial de malta de sorgo. La variedad de
sorgo utilizado fue malteado en el laboratorio a 28�C y tambi�n
comercialmente en un pa�s tropical. Una maceraci�n tipo infusi�n dio pobre
resultados en la obtenci�n de extracto, tanto del sorgo malteado
comercialmente como el del laboratorio. Solo se obtuvo una peque�a
diferencia en la obtenci�n de nitr�geno soluble total o de nitr�geno
libre de amino (FAN) al comparar la maceraci�n por infusi�n y la
maceraci�n por decantaci�n. Los resultados de las pruebas de fermentaci�n
usando malta de sorgo fueron complejos y dif�ciles de interpretar y
entender. Hubo una correlaci�n entre el LPSY (bajo rendimiento de alcohol
pronosticado) de la maceraci�n por infusi�n con el HPSY (mayor rendimiento
de alcohol pronosticado) obtenido por decantaci�n. La correlaci�n entre
HFE (higher fermentable extract) y HPSY de malta de sorgo macerado por
decantaci�n fue similar a la obtenida entre LFE (low fermentable
extract) y LPSY de malta de sorgo macerado por infusi�n. Si bien estos
resultados de correlaci�n muestran claramente que la cantidad de extracto
fermentable tiene fuerte influencia sobre el rendimiento de alcohol
pronosticado (PSY) de malta de sorgo, esto tambi�n puede llevar a
conclusiones equivocadas. Un investigador trabajando con malta de sorgo
que use el m�todo est�ndar de infusi�n (desarrollado para la maceraci�n de
cebada malteada bien modificada) podr�a concluir equivocadamente que la
maceraci�n por infusi�n era igual de efectivo en la obtenci�n de extracto
de malta de sorgo que la maceraci�n por decantaci�n. Esto destaca la
importancia de desarrollar m�todos anal�ticos apropiados para sorgo y
para malta de sorgo. Estos resultados demuestran que la malta de sorgo
puede producir buenos resultados de PSY, pero depende de la variedad de
sorgo utilizado y de las condiciones adecuados de malteo y de maceraci�n.
Palabras claves: decantaci�n, infusi�n,
maceraci�n, malta, PSY (�predicted spirit yield�), sorgo
