Sorghum ß-Amylase Production: Relationship With Grain Cultivar, Steep Regime, Steep Liquor Composition and Kilning Temperature
J.
Okungbowa1,
J.
A.
N.
Obeta1
and
L.
I.
Ezeogu1,2
1Brewing
Science
Laboratory,
Department
of
Microbiology,
University
of
Nigeria,
Nsukka
2Corresponding
author.
Email:
lewisih@yahoo.com
J. Inst. Brew. 108(3), 362-370, 2002 | VIEW ARTICLE
ABSTRACT
Steep
regime,
nature
of
alkaline
liquor,
and
kilning
conditions
were
studied
for
their
effects
on
sorghum
malt
β-amylase
development
in
four
Nigerian
sorghum
cultivars.
Malt
β-amylase
activity
was
markedly
(p
<
.001)
influenced
by
all
the
four
factors
as
well
as
their
various
interactions.
Overall,
malts
from
KSV
8
variety
were
the
most
β-amylolytic
followed
in
sequence
by
those
from
Local
Red
(LR),
SK
5912,
and
Local
white
(LW)
respectively.
The
presence
or
absence
of
air
rests
in
steep
regimes
was
a
significant
(p
<
.001)
determinant
of
sorghum
β-amylase
response
to
final
warm
steeping,
steep
liquor
and
kilning
condition.
The
nature
of
the
alkaline
steep
liquor
was
also
a
major
determinant
of
the
pattern
of
malt
β-amylase
response
to
the
kilning
condition.
Steeping
in
Ca(OH)2
enhanced
malt
β-amylase
activity
at
the
higher
temperature
of
kilning,
while
KOH
produced
the
opposite
effect.
Ca(OH)2
enhancement
of
b-amylase
development,
at
a
kilning
temperature
of
50°C,
was
variety-dependent
suggesting
that
different
sorghum
cultivars
may
employ
different
biosynthesis
models
for
β-amylase
synthesis.
The
regime-dependence
of
β-amylase
response
to
kiln
temperature
suggests
that
this
was
an
important
modulator
of
sorghum
germination
physiology.
Key words:
Alkaline liquor, β-amylase, kilning temperature, sorghum malt, steeping regime, cultivars.
Publication no. G-2002-0827-079 ©2002 The Institute & Guild of Brewing