The Effects of Formaldehyde on Enzyme Development in Sorghum Malts
MBAA TQ vol. 43, no. 3, 2006, pp.
177-182 |
VIEW ARTICLE
E. J. Nso (1), M. Nanadum (2), and G. H. Palmer (3). 1. National Advanced
School of Agro-Process Industries (ENSAI), University of Ngaoundere, P.O. Box
455, Ngaoundere, Cameroon. 2. Facult� de Sciences Exactes et Appliqu�es,
University de Njamena, B.P. 1027, Njamena, Tchad. 3. International Centre for
Brewing and Distilling (ICBD), Heriot-Watt University, Riccarton, Edinburgh,
Scotland, EH14 4AS.
Abstract
We studied the effects of washing the grains of three sorghum cultivars
(Safrari, Madjeru, and S.35) in 0.1% (v/v) formaldehyde prior to malting to
assess the brewing potential of the resulting malts. Formaldehyde washing
reduced the enzyme potential of the principal mashing enzymes. The scope of the
reduction of the development level of alpha-amylase, beta-amylase, and
endo-beta-glucanase was most pronounced in the late rather than in the early
stages of germination for all three of the sorghum cultivars. The level of
alpha-amylase development was reduced by about 22% for �Safrari�, 52% for
�Madjeru�, and 24% for �S.35�; the level of beta-amylase development was reduced
by 32% for �Safrari�, 57% for �Madjeru�, and 44% for �S.35�; and the level of
endo-beta-glucanase development was reduced by 34% for �Safrari�, 45% for
�Madjeru�, and 66% for �S.35�. Only the mashes of the malts of �Safrari� and
�S.35� were filterable since very poor modification of �Madjeru� rendered
mashing difficult and filtration impossible for the formaldehyde-treated malt
sample. Free alpha-amino nitrogen (FAN) content of the malts was also reduced
by 21% for �Safrari� and 27% for �S.35�, while HPLC analysis displayed reduced
levels of most free amino acids in the worts. Levels of fermentable sugars of
�Safrari� and �S.35� were also reduced; maltose levels were reduced by about 18
and 19%, respectively.
Keywords: alpha-amylase, beta-amylase,
endo-beta-glucanase, fermentable sugars, formaldehyde, free alpha-amino nitrogen
S�ntesis
Se ha estudiado el efecto de lavar los granos de tres cultivos de sorgo
(Safrari, Madjeru y S.35) en formaldeh�do al 0,1% (v/v) antes de maltearlos, con
el fin de evaluar el potencial de esas maltas para uso en la cervecer�a. El
lavado con formaldeh�do reduce el potencial de las principales enzimas de la
maceraci�n. La magnitud de la reducci�n en el nivel de desarrollo de
alfa-amilasa, beta-amilasa y endo-beta-glucanasa fue m�s pronunciado en las
�ltimas etapas de la germinaci�n para los tres tipos de sorgo. El nivel del
desarrollo de la alfa-amilasa se redujo en cerca de 22% para �Safrari�, 52% para
�Madjeru� y 24% para �S.35�; el de la beta-amilasa se redujo en 32% para
�Safrari�, 57% para �Madjeru� y 44% para �S.35�; el de la endo-beta-glucanasa se
redujo en 34% para �Safrari�, 45% para �Madjeru� y 66% para �S.35�. �nicamente
las mezclas de las maltas de �Safrari� y �S.35� se pudieron filtrar; la muy
pobre modificaci�n de �Madjeru� dificult� la maceraci�n e imposibilit� la
filtraci�n de la muestra tratada con formaldehido. El contenido de nitr�geno
alfa-amino libre (FAN) de las maltas fue reducido por 21% para �Safrari� y 27%
para �S.35�, mientras que el an�lisis por HPLC mostr� niveles bajos para la
mayor�a de los amino �cidos libres en el mosto. El nivel de azucares
fermentecibles en �Safrari� y �S.35� tambi�n sufri� una reducci�n; el contenido
de maltosa se redujo en 18% y 19%, respectivamente.
Palabras claves:
alfa-amilasa, beta-amilasa, endo-beta-glucanasa, azucares fermentecibles,
formaldeh�do, nitr�geno alfa-amino libre (FAN)
