Digestibility of carbohydrates of raw and cooked bengal gram (Cicer arietinum), green gram (Phaseolus aureus) and horse gram (Dolichos biflorus)


Khader, V.; Rao, S.V.

Food Chemistry 7(4): 267-272

1981


In vitro digestion with pancreatin, preceded by pepsin, increased the rate of liberation of maltose from soaked Bengal gram, Green gram and Horse gram on blending first in water prior to cooking instead of cooking first before blending. The fecal bulk and cecal volume were not significantly different when the legumes were fed to rats after cooking as such, or cooking prior to, or after, blending. The results indicate that increasing the rate of digestion of carbohydrates may not be of value in reducing the flatulence caused by these legumes.

Food
Chemistry
7
(1981)
267-271
DIGESTIBILITY
OF
CARBOHYDRATES
OF
RAW
AND
COOKED
BENGAL
GRAM
(CICER
ARIETINUM),
GREEN
GRAM
(PHASEOLUS
AUREUS)
AND
HORSE
GRAM
(DOLICHOS
BIFLOR
US)
VIJAYA
KHADER*
&
S.
VENKAT
RAO
Discipline
of
Biochemistry
and
Applied
Nutrition,
Central
Food
Technological
Research
Institute,
Mysore,
India
(Received:
29
April,
1980)
ABSTRACT
In
vitro
digestion
with
pancreatin,
preceded
by
pepsin,
increased
the
rate
of
liberation
of
maltose
from
soaked
Bengal
gram,
Green
gram
and
Horse
gram
on
blending
first
in
water
prior
to
cooking
instead
of
cooking
first
before
blending.
However,
the
faecal
bulk
and
caecal
volume
were
not
significantly
different
when
the
legumes
were
fed
to
rats
after
cooking
as
such,
or
cooking
prior
to,
or
after,
blending.
The
results
indicate
that
increasing
the
rate
of
digestion
of
carbohydrates
may
not
be
of
value
in
reducing
the
flatulence
caused
by
these
legumes.
INTRODUCTION
Legumes
are
well
known
as
inducers
of
flatulence
in
experimental
animals
and
human
subjects
(Hellendoorn,
1969;
Steggerda
&
Dimmick,
1966;
Hedin,
1962;
Steggerda,
1967).
This
property
of
legumes
is
a
drawback
to
their
wider
use
in
infant
and
geriatric
foods.
The
hypothesis
advanced
for
the
causation
of
flatulence
is
that
the
carbohydrates
escaping
digestion
and
absorption
in
the
small
intestine
may
be
subjected
to
bacterial
attack
in
the
large
intestine,
resulting
in
the
production
of
gases
such
as
carbon
dioxide,
hydrogen
and
methane.
Kon
et
al.
(1971)
reported
that
cells
of
cooked
legume
products
were
very
resistant
to
breakage
and
a
high
percentage
survived
common
blending
and
digestive
processes.
They
reported
that
blending
raw
beans
before
cooking
resulted
in
a
considerable
increase
in
the
rate
of
liberation
of
maltose
as
compared
with
beans
*
Present
address:
Postgraduate
Department
of
Food
and
Nutrition,
Sardar
Patel
University,
Vallabh
Vidyanagar,
Gujarat,
India.
267
Food
Chemistry
0308-8146/81/0007-0267502.75
©
Applied
Science
Publishers
Ltd,
England,
1981
Printed
in
Great
Britain
268
VLTAVA
KHADER,
S.
VENKAT
RAO
cooked
first
and
then
ground.
Subba
Rao
&
Desikachar
(1964)
observed
that
the
caecal
volume
and
faecal
bulk
of
rats
fed
legume
diets
were
distinctly
greater
than
those
of
rats
fed
a
casein
diet,
due
possibly
to
indigestible
residues.
Since
blending
raw
beans
before
cooking
improved
the
digestibility
of
starch,
it
was
of
interest
to
study
whether
such
a
treatment
would
also
affect
the
faecal
bulk
and
caecal
volume
of
rats
fed
three
common
legumes
Bengal
gram,
Green
gram
and
Horse
gram.
The
studies
reported
in
this
paper
deal
with
in
vitro
and
in
vivo
experiments
on
the
affect
of
blending,
before
and
after
cooking
the
legumes,
on
carbohydrate
digestibility,
as
determined
by
enzyme
digestion,
faecal
bulk
and
caecal
volume.
MATERIALS
AND
METHODS
Materials
Bengal
gram
dhal
(split
legume),
Green
gram
dhal,
whole
Horse
gram
and
casein
used
in
the
experiments
were
obtained
from
a
local
market.
Methods
Blended
and
cooked
legumes:
The
samples
were
prepared
as
follows
for
in
vitro
digestibility.
(1)
By
blending
the
legume
soaked
overnight.
(2)
Legumes
were
soaked
overnight,
cooked
for
periods
ranging
from
20
to
50
min
and
blended
for
5
min
in
a
Waring
blender
in
the
case
of
Green
gram
and
Bengal
gram
and
for
8
min
in
the
case
of
Horse
gram.
(3)
Bengal
gram
and
Green
gram
were
soaked
overnight,
blended
for
5
min
and
cooked
for
5
min
while
the
soaked
whole
Horse
gram
was
blended
for
8
min
and
cooked
for
20
min.
For
studies
on
faecal
bulk
and
caecal
volume,
the
samples
were
prepared
as
described
above
except
that
the
samples
obtained
by
means
of
method
(1)
were
cooked
for
20-50
min
instead
of
being
blended.
The
cooked
samples
were
dried
in
a
current
of
air
at
60
°C
overnight
and
ground
to
a
fine
powder
before
incorporation
into
the
diets.
Analytical
methods:
In
vitro
digestibility
with
pancreatin,
preceded
by
pepsin,
was
investigated.
The
in
vitro
digestibility
was
determined
from
the
quantity
of
reducing
sugar
(expressed
as
maltose)
liberated
by
pancreatin,
preceded
by
pepsin
(Kon
et
al.,
1971).
In
all
cases,
the
final
concentration
of
beans
in
the
slurry
was
2
%
by
weight,
as
this
amount
contained
about
I
%
starch.
Two
millilitres
of
legume
slurry
and
3
ml
of
pepsin
(Difco)
solution
made
up
as
2
mg/ml
of
glycine—HC1
buffer,
pH
2,
were
incubated
at
37
°C
for
2
h.
The
pH
of
the
samples
was
then
adjusted
to
7.0
with
NaOH.
Next,
5
ml
of
pancreatin
(Merck),
made
up
to
contain
5
mg/ml
of
0.05
m
phosphate
buffer,
pH
7.0,
were
added
and
incubated
at
37
°C.
One
millilitre
samples
were
withdrawn
for
analysis
at
the
end
of
1,
30
and
60
min.
The
maltose
released
was
estimated
by
the
dinitrosalicylic
acid
method
(Bernfeld,
1955).
From
the
maltose
DIGESTIBILITY
OF
RAW
AND
COOKED
LEGUMES
269
values
obtained,
the
increase in
the
per
cent
of
maltose
liberated
due
to
blending
before
or
after
cooking
was
calculated.
Faecal
bulk
and
caecal
volume:
Ten
groups
of
adult
male
rats
(strain
Wistar),
weighing
230-250
g,
eight
per
group,
were
allotted
according
to
a
completely
randomised
design
and
fed
diets
containing
legumes
subjected
to
various
treatments,
or
a
casein
diet
at
a
15
%
protein
level.
The
diets
were
otherwise
similar
in
composition
to
that
used
by
Venkat
Rao
et
al.
(1971).
Faeces
were
collected
for
a
period
of
10
days,
after
a
preliminary
period
of
6
days
(Subba
Rao
&
Desikachar,
1964).
The
faecal
samples
were
preserved
in
2
%
oxalic
acid
and
dried
at
100
°C
for
determination
of
faecal
bulk.
The
rats
were
killed
at
the
end
of
16
days
and
caecal
volumes
were
measured
by
displacement
of
water
in
a
graduated
cylinder
(McCall
et
al.,
1962).
The
results
were
statistically
analysed
by
the
analysis
of
variance
method
appropriate
for
completely
randomised
design
and
differences
were
tested
for
significance
by
means
of
Duncan's
new
multiple
range
test
at
the
5
%
level
(Duncan,
1955).
RESULTS
AND
DISCUSSION
In
vitro
digestibility
of
carbohydrates
In
the
case
of
all
three
legumes
blended
after
soaking
overnight,
the
rate
of
maltose
liberation
was
low
on
digestion
with
pancreatin,
preceded
by
pepsin
(Table
1).
However,
when
the
gram
was
cooked
and
blended,
a
marked
increase in
the
rate
of
liberation
of
maltose
by
the
enzymes
was
observed.
A
further
marked
increase
in
TABLE
1
In
Vitro
DIGESTIBILITY
OF
CARBOHYDRATES
OF
BENGAL
GRAM,
GREEN
GRAM
AND
HORSE
GRAM
BY
PANCREATIN
PRECEDED
BY
PEPSIN
Materials
Milligrammes
Increase
in
the
percentage
of
maltose
liberated
of
maltose
Liberated
due
from
2g
of
material
to
blending
and
cooking
Time
(min)
Time
(min)
1
60
1
60
Bengal
gram
Soaked
and
blended
1109
1287
Soaked,
cooked
and
blended
1214
1607
10
25
Soaked,
blended
and
cooked
1604
2071
45
61
Green
gram
Soaked
and
blended
1036
1286
Soaked,
cooked
and
blended
1143
1714
10
33
Soaked,
blended
and
cooked
1393
2107
35
64
Horse
gram
Soaked
and
blended
1107
1357
Soaked,
cooked
and
blended
1393
1679
27
24
Soaked,
blended
and
cooked
1750
2179
58
61
270
VIJAYA
KHADER,
S.
VENKAT
RAO
the
rate
of
liberation
of
maltose
was
observed
from
the
sample
blended
first
before
cooking.
This
may
be
due
to
an
increase
in
the
breakage
of
the
cell
walls
in
the
case
of
blended
and
cooked
samples,
with
consequent
release
of
more
cell
contents,
resulting
in
the
increase
in
the
rate
of
liberation
of
maltose
observed
by
Kon
et
al.
(1971)
in
the
case
of
California
white
beans.
Faecal
bulk
and
caecal
volume
Blending
prior
to,
or
after,
cooking
did
not
show
any
significant
difference
in
the
faecal
bulk
or
caecal
volume
of
rats
fed
on
the
three
legumes
(Table
2).
The
faecal
TABLE
2
THE
EFFECT
OF
BLENDING
PRIOR
TO,
OR
AFTER,
COOKING
IN
THE
LEGUMES
ON
THE
FAECAL
BULK
AND
CAECAL
VOLUME
IN
ADULT
RATS
Diet
Faecal
bulkt
(g/day)
Caeca!
volumet
(ml)
Bengal
gram
Soaked
and
cooked
1.66°
5.89°'
Soaked,
cooked
and
blended
1.70°
6.22°'
Soaked,
blended
and
cooked
1-71°
6.24°'
Green
gram
Soaked
and
cooked
1.51°
5.39
5
Soaked,
cooked
and
blended
1.27°
5.38
5
Soaked,
blended
and
cooked
1.51°
6.11
05
Horse
gram
Soaked
and
cooked
3.32'
5.98"
Soaked,
cooked
and
blended
3.12
5
6.85°
Soaked,
blended
and
cooked
3-32
5
+
0.14
6.48°'
+
0.41
Casein*
0.56'
+
0.15
3.06`
+
0.44
(69
df)
(69
df)
Standard
error
of
the
mean
(69
df)
+0.04
+0.41
t
Values
not
sharing
same
superscript
letters
are
significantly
different.
*
The
average
is
based
on
seven
values
only.
df
=
Degrees
of
freedom.
bulk
and
caecal
volume
of
rats
fed
on
casein
diets
were
considerably
lower
than
those
fed
on
the
legumes.
The
results
indicate
that
although
there
was
a
marked
increase
in
the
in
vitro
digestibility
of
carbohydrates
of
the
three
legumes
as
a
result
of
blending
and
cooking,
this
treatment
did
not
result
in
any
improvement
in
the
in
vivo
digestibility
of
carbohydrates
as
observed
from
data
on
faecal
bulk
and
caecal
volume.
Cooking
Chick
pea,
Cow
pea
and
Green
gram
was
reported
to
considerably
increase
the
in
vitro
digestibility
by
a-amylase
(Ganesh
Kumar
&
Venkataraman,
1976).
The
cooked
diets
also
showed
significantly
lower
flatus
compared
with
the
corresponding
values
of
raw
diets
(Venkataraman
&
Jaya,
1975).
However,
Hellendoorn
(1969)
reported
that
cooking
beans
for
longer
or
shorter
periods
of
time
DIGESTIBILITY
OF
RAW
AND
COOKED
LEGUMES
271
did
not
alter
their
flatulence
activity.
Shurpalekar
et
al.
(1973)
also
reported,
from
experiments
on
in
vitro
and
in
vivo
studies
in
rats,
that
the
flatus-inducing
capacity
of
legumes
is
correlated
with
the
digestibility
of
the
carbohydrates.
Green
gram,
which
had
the
most
digestible
carbohydrate,
produced
the
least
amount
of
flatus,
whilst
Bengal
gram
and
Red
gram,
the
least
digestible,
produced
the
maximum
amount
of
flatus.
However,
the
results
obtained
in
the
present
experiment
indicate
that
attempts
to
increase
the
rate
of
digestion
of
carbohydrates
alone
may
not
be
of
value
in
reducing
the
flatulence
activity
of
legumes.
ACKNOWLEDGEMENT
The
authors
wish
to
thank
Miss
D.
Rajalakshmi
for
help
in
the
statistical
analysis
of
the
data.
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