VIEW ARTICLE DOI: 10.1094/ASBCJ-56-0085
Factors Involved in the Formation of Two Precursors of Dimethylsulfide During Malting. Bing Yang (1) and Paul Schwarz, Department of Cereal Science; and Richard Horsley, Department of Plant Sciences, North Dakota State University, Fargo 58105. (1) Corresponding author. Phone: 701-231-7732; Fax: 701-231-7723. J. Am. Soc. Brew. Chem. 56(3):85-92, 1998. Accepted August 12, 1998.
L-Methionine
S-methyltransferase
(SMM synthetase)
was found to
be present in
barley, and
its activity
increased almost
two-fold during
germination.
The level of
this enzyme
in barley was
positively correlated
with the levels
of S-methylmethionine
(SMM) in green
malt (r
= 0.79, P
<= 0.01),
kilned malt
(r =
0.85, P
<= 0.01),
and the level
of dimethylsulfoxide
(DMSO) in kilned
malt (r
= 0.76, P
<= 0.05).
SMM primarily
was synthesized
during germination.
The level of
SMM in green
malt seemed
to determine
the level of
SMM (r
= 0.97, P
<= 0.005)
and DMSO (r
= 0.80, P
<= 0.01)
in kilned malt.
Barley genotype,
row type, and
malt modification
also were major
factors associated
with the levels
of SMM and DMSO
in malt. Steeping
and germination
temperature
influenced the
synthesis and
levels of SMM
in green malt,
but kilning
temperature
determined the
final levels
of SMM and DMSO
in malt. SMM
started to degrade
into dimethylsulfide
(DMS) at 70°C.
DMSO formation
began at the
same time. SMM
was almost completely
degraded at
110°C,
while levels
of DMSO increased
under these
higher temperatures.
It was concluded
that the level
of SMM synthetase
activity in
barley determined
the level of
SMM in green
malt, which
in turn influenced
the concentrations
of both SMM
and DMSO in
kilned malt.
Keywords: Barley,
Dimethylsulfoxide,
Malt, S-Methylmethionine,
S-Methylmethionine
synthetase
S-Metiltransferasa
de L-metionina
(SMM sintetasa)
fue encontrada
presente en
cebada y su
actividad se
increments casi
al doble durante
la germinación.
El nivel de
esta enzima
en cebada fue
positivamente
correlacionado
con los niveles
de S-metilmetionina
(SMM) en malta
verde (r
= 0.79, P
<= 0.01),
malta seca (r
= 0.85, P
< 0.01),
y el nivel de
dimetilsulfoxido
(DMSO) en malta
seca (r
= 0.76, P
<= 0.05).
SMM fue primeramente
sintetizado
durante germinación.
El nivel de
SMM en malta
verde parece
determinar el
nivel de SMM
(r =
0.97, P
<= 0.005)
y DMSO (r
= 0.80, P
<= 0.01)
en malta seca.
Genotipos de
cebada, tipo
de hilera, y
modificación
de la malta
también
fueron factores
asociados con
los niveles
de SMM y DMSO
en malta. Temperatura
de germinación
y remojo influyen
en la síntesis
y niveles de
SMM en malta
verde, pero
la temperatura
de secado determina
los niveles
finales de SMM
y DMSO en malta.
SMM empieza
a degradarse
a dimetilsumro
(DMS) a 70°C.
La formación
de DMSO comienza
al mismo tiempo.
SMM fue casi
completamente
degradada a
110°C,
mientras que
niveles de DMSO
se incrementan
bajo esas altas
temperaturas.
Se concluye
que el nivel
de la actividad
de sintetasa
SMM en cebada
determina el
nivel de SMM
en malta verde,
la cual a su
vez influye
en las concentraciones
de ambos SMM
y DMSO en malta
seca.