Effect of processing on protein digestibility, biological value and net protein utilization of millet and legume based infant mixes and biscuits


Geervani, P.; Vimala, V.; Pradeep, K.U.a; Devi, M.R.ma

Plant Foods for Human Nutrition 49(3): 221-227

1996


Effect of combinations of millet and legume and processing on digestibility, biological value and net protein utilization was evaluated using albino rats. The millets and legumes selected for the study include sorghum, pearl millet, finger millet, chickpea and green gram (P radiatus). The processes tested include dehulling, boiling, roasting, malting and baking. Among the combinations tested, the sorghum-chickpea combination had significantly (p lt 0.05) higher digestibility. Between the processes tested, roasting resulted in significantly higher net protein utilization. Results of biological study on biscuits prepared by using millet and legume combination flours, indicated the biscuits to be of good protein quality.

Plant
Foods
for
Human
Nutrition
49:
221-227,
1996
(0
1996
Kluwer
Academic
Publishers.
Printed
in
the
Netherlands.
Effect
of
processing
on
protein
digestibility,
biological
value
and
net
protein
utilization
of
millet
and
legume
based
infant
mixes
and
biscuits
P.
GEERVANI,
V.
VIMALA,
K.
UMA
PRADEEP
&
M.
RAMA
DEVI
Department
of
Foods
&
Nutrition,
P.G.
and
Research
Center,
A.P.
Agricultural
University,
Rajendranager,
Hyderabad-500030,
India
Received
28
June
1994;
accepted
in
revised
form
3
August
1995
Key
words:
Millet,
Legumes,
Infant
mixes,
Biscuits,
Processing,
Digestibility,
Biological
value
Abstract.
Effect
of
combinations
of
millet
and
legume
and
processing
on
digestibility,
biological
value
and
net
protein
utilization
was
evaluated
using
albino
rats.
The
millets
and
legumes
selected
for
the
study
include
sorghum,
pearl
millet,
finger
millet,
chickpea
and
green
gram
(P
radiatus).
The
processes
tested
include
dehulling,
boiling,
roasting,
malting
and
baking.
Among
the
combinations
tested,
the
sorghum-chickpea
combination
had
significantly
(p
<
0.05)
higher
digesti-
bility.
Between
the
processes
tested,
roasting
resulted
in
significantly
higher
net
protein
utilization.
Results
of
biological
study
on
biscuits
prepared
by
using
millet
and
legume
combination
flours,
indicated
the
biscuits
to
be
of
good
protein
quality.
Introduction
Several
infant
foods
including
biscuits
produced
in
India
using
wheat
and
defatted
oil
seed
flour
with
added
milk
solids
have
gained
consumer
acceptance
and
are
marketted
in
India.
Millets
and
legumes
have
not
been
used
in
the
production
of
infant
foods
and
biscuits
in
India.
Sorghum
and
millets
are
drought
resistant
crops,
grown
in
dryland
regions
of
India
and
consumed
by
poorer
sections
of
population.
The
importance
of
these
grains
as
a
good
source
of
protein
as
well
as
micro
nutrients
is
because
of
the
drought
and
desertifica-
tion
which
characterize
some
of
the
African
and
Asian
countries
[1].
If
C!*(*is
developed.
Pearl
millet
and
sorghum
are
deficient
in
lysine
and
their
protein
quality
is
poor
[2,
3].
But
studies
have
demonstrated
that
millets
have
accept-
able
protein
quality
when
combined
with
legumes
in
preparations
of
millet
based
weaning
foods
[1,
4-8].
In
the
present
study
an
attempt
was
made
to
develop
and
evaluate
low
cost
millet
and
legume
based
infant
mixes
and
biscuits
for
possible
use
in
supplementary
feeding
programmes.
Material
and
methods
Sorghum
(variety
Moti)
and
pearl
millet
(variety
Visakha
composite)
were
obtained
in
bulk
from
Andhra
Pradesh
Agricultural
University,
Hyderabad,
222
India.
Finger
millet,
Chickpea
and
P.
radiatus
were
purchased
from
the
local
market
of
Hyderabad,
India.
Preparation
of
infant
mixes
The
combinations
and
processes
tested
were:
Whole
raw
sorghum
+
raw
dehusked
chickpea/P.
radiatus
Raw,
dehulled
sorghum
+
raw
dehusked
chickpea/P.
radiatus
Boiled,
dehulled
sorghum
+
boiled
dehusked
chickpea/P.
radiatus
Roasted,
dehulled
sorghum
+
roasted
dehusked
chickpea/P.
radiatus
Malted
sorghum
+
malted
chickpea/P.
radiatus.
The
grains
were
dehusked
for
7
minutes
(85%
recovery)
using
a
dehuller
developed
by
State
Agro
Industries.
Sorghum
and
chickpea/P.
radiatus
in
the
proportion
of
4:1
by
weight
was
used
for
preparation
of
infant
mixes
as
this
proportion
was
found
to
be
acceptable
in
consumer
trials
conducted
earlier
by
the
same
team.
Preparation
of
biscuits
Sweet
and
salt
biscuits
were
prepared
using
dehulled
sorghum,
pearl
millet
and
finger
millet
flours
in
combination
with
dehulled
chickpea/P.
radiatus
flours.
The
grains
were
ground
into
flour
to
pass
through
60
mesh
sieve
for
prepara-
tion
of
mixes.
The
composition
of
biscuit
mixtures
is
given
in
Table
1.
Sweet
biscuits
were
used
to
find
the
adverse
effect
if
any
on
protein
quality
due
to
addition
of
sugar.
Storage
of
mixes
and
biscuits
The
biscuits
were
prepared
in
bulk
for
the
whole
experiment
ground
to
pass
through
60
mesh
sieve
and
stored
in
refrigerator.
Table
1.
Composition
of
salt
&
sweet
biscuits
made
with
a
combination
of
millet
and
legume
Ingredients
Salt
Sweet
(g)
(S)
Millet
flour
50.0 50.0
Legume
flour
25.0
12.5
Palmoleine
oil
25.0
25.0
Sugar
13.0
25.0
Ammonium
bicarbonate
0.4
0.7
Salt
1.5
Baking
powder
0.4
0.7
223
Biological
studies
Formulation
of
diets.
Infant
mixes
developed
using
sorghum
chickpea
and
sorghum
P.
radiatus
were
used
as
a
source
of
N
in
the
diets.
The
diets
were
formulated
using
the
infant
mixes
as
a
source
of
protein.
The
nitrogen
content
of
the
diets
containing
the
infant
mixes
was
adjusted
to
1.5%
by
the
addition
of
N-free
mixture
containing
80.7%
starch,
8.9%
sucrose,
5.2%vegetable
oil,
and
5.2%
non
nutritive
cellulose.
Mineral
and
vitamin
mixtures
prepared
according
to
the
composition
given
by
the
National
Institute
of
Nutrition,
India
[9]
were
added
to
all
diets
at
4%
and
2%
level
of
diets,
respectively.
Experimental
trials.
Nitrogen
balance
studies
were
conducted
in
male
albino
rats
procured
from
the
National
Institute
of
Nutrition,
Hyderbad,
using
the
diets
formulated
as
a
source
of
protein.
The
procedure
for
N
balance
and
digestibility
described
by
Eggum
[10]
was
followed.
Eight
rats
were
used
for
each
group
and
individually
housed.
Food
and
water
was
provided
adlibitum.
True
protein
digestibility
(TD)
and
biological
value
(BV)
were
determined
by
correcting
for
endogenous
excretion
of
nitrogen
[2]
and
net
protein
utilization
(NPU)
calculated
as
a
factor
of
TD
and
BV.
Analytical
methods.
Nitrogen
was
estimated
according
to
standard
AOAC
method
(10)
using
the
Kjel-Tec
protein
analyser.
These
data
were
subjected
to
analysis
of
variance
[11].
Significance
accepted
was
at
p
<0.05.
Results
and
discussion
Effect
of
combination
and
processing
of
infant
mixes
The
TD,
BV
and
NPU
of
sorghum
and
legume
combination
infant
mixes
tested
in
the
present
study
were
similar
to
those
reported
by
Badi
et
al.
[1]
for
sorghum
based
baby
foods
containing
17%
milk
powder
(Table
2).
This
shows
legume
supplementation
with
sorghum
is
equally
effective
and
also
economical.
The
results
of
the
present
study
reiterated
that
a
combination
of
millet
with
legume
in
the
proportion
of
4:1
improves
nutritional
quality
even
under
traditional
systems
of
food
processing.
Boiling
and
malting
processes
decreased
the
protein
digestibility
significantly
(p
<0.05)
in
both
the
types
of
mixes
but
had
no
such
effect
on
roasting
and
dehulling.
Heat
processing
of
sorghum
in
the
presence
of
moisture
has
been
found
to
reduce
digestibility
of
protein
due
to
the
formation
of
enzyme
resistant
starch
complex
[12,
13]
and
was
probably
the
reason
for
the
decrease
in
protein
digestibility
of
boiled
and
malted
grain
mixes.
Roasted
legumes
were
reported
to
have
promoted
higher
weight
gain,
PER
and
BV
than
sprouted
and
autoclaved
grain
[14].
Pushpamma
et
al.
[5]
also
found
that
roasting
of
sorghum
and
legumes
in
the
preparation
of
infant
mixes
resulted
in
224
Table
2.
Protein
quality
of
combination
of
sorghum
and
legume
infant
mixes
Combination
TD
BV
NPU
Sorghum
+
Whole
raw
mix
(R)
86.7+1.41*
73.5±3.58
63.8+3.69*
Chickpea
Dehulled
raw
mix
(DR)
88.5+2.12*
70.4+5.28
62.4+5.71*
Dehulled
boiled
mix
(B)
83.1
+
1.94
73.1±5.18
60.7
±
3.82
Dehulled
roasted
mix
(RO)
87.3+2.42*
81.8
±
4.56
71.4+4.58*
Malted
mix
(M)
83.9
+
1.02
78.5
+
2.19
65.6
+
1.56
Sorgh
um
+
Whole
raw
mix
(R)
87.6+
1.78*
74.1
±2.71
64.8+3.29*
P.
radiatus
Dehulled
raw
mix
(DR)
87.5+1.59*
69.6+3.46
61.1+3.70*
Dehulled
boilded
mix
(B)
72.7+6.76
73.0±
10.85
53.0+9.79
Dehulled
roasted
mix
(RO)
88.5
+
1.08*
70.5+2.82
62.4+3.25*
Malted
mix
(M)
76.0+0.65
67.7
±2.82
51.4+2.33
TD:
True
Digestibility
BY:
Biological
Value
NPU:
Net
Protein
Utilization
*Significant
(p<0.05)
higher
PER,
TD
and
BV
than
raw
and
boiled
grain
mixes.
Padmapriya
and
Kalpalathika
[15]
observed
higher
NPU
of
infant
mixes
prepared
with
pearl
millet
and
roasted
legumes
than
with
malted
legumes.
However,
roasting
of
sorghum
based
blends
was
found
to
reduce
carbohydrate
digestibility
by
5%
probably
due
to
formation
of
enzyme
resistant
starch
[16].
In
the
present
investigation
no
significant
difference
was
observed
between
the
processes
tested
in
both
combinations
used.
Therefore
any
process
would
be
suitable.
The
choice
of
process
would
depend
on
other
factors
such
as
bulk
density,
taste
and
cost
of
production.
Protein
quality
of
millet-legume
combination
biscuits
Results
of
the
study
revealed
that
biscuits
prepared
using
millet-legume
flour
mix
had
acceptable
digestibility
and
N
retention
in
rats
and
can
thus
be
used
as
food
supplements
(Table
3).
These
findings
confirm
the
findings
of
many
earlier
reports
[1,
4,
6-
8,
15,
17].
Pearl
millet
biscuits
were
found
to
have
higher
TD
and
NPU
while
finger
millet
biscuits
had
higher
BV
(Table
3).
The
NPU
of
sorghum
biscuits
were
ranging
from
57.8
to
70.4
and
was
lower
than
corresponding
values
for
pearl
millet
(62.7
to
78.6)
and
finger
millet
(68.6
to
76.2).
Badi
et
al.
[1]
also
observed
higher
BV
of
pearl
millet
based
weaning
foods
than
sorghum
based
foods
which
they
considered
to
be
a
function
of
the
better
amino
acid
composition
of
pearl
millet.
Combination
of
chickpea
flour
or
P.
radiatus
flour
to
millet
in
biscuits
did
not
make
much
difference
in
the
protein
quality
of
biscuits
although
chickpea
appeared
to
be
a
better
complement
to
pearl
millet
protein.
The
process
of
baking
did
not
have
any
adverse
effect
on
the
protein
quality
of
biscuits
including
sweet
biscuits.
However
studies
have
shown
that
fortifica-
Table
3.
Protein
quality
of
millet
+
legume
combination
biscuits
Combination
Process
Form
TD
BV
NPU
1.
Sorghum
(S)
Salt
Raw
90.8+1.44
72.9+6.41
66.21±6.26
+
Chickpea
(CP)
Baked
80.6
+
2.47
74.4
±
5.87
67.5
±
6.67
Sweet
Raw
90,1±1.55
75.9+5.71
68.1±5.49
Baked
88.6
+
1.27
67.1±4.07
59.4±3.99
2.
Sorghum
(S)
Salt
Raw
86.1
+
3.08
69.6±2.56
60.0+3.46
P.
radiatus
Baked
79.7±2.73
72.4±3.02
57.8±3.97
Sweet
Raw
83.2+
1.82
77.6+4.16
64.3+2.84
Baked
84.9
+
3.24
82.9±7.33
70.4±7.35
3.
Pearl
millet
(PM)
Salt
Raw
89.0+6.82
72.0+2.80
64.2+6.39
+
Chickpea
(CP)
Baked
91.5+2.06
68.4±6.76
62.7+7.07
Sweet
Raw
92.5+2.55
74.1±9.00
74.1±10.68
Baked
94.2+3.92
83.4+9.13
78.6+9.74
4.
Pearl
millet
(PM)
Salt
Raw
89.2±3.40
79.3±7.18
70.8±7.79
+
P.
radiatus
Baked
88.9±1.70
81.5±6.58
72.4±6.33
Sweet
Raw
91.1±4.69
81.4+7.98
74.3±9.52
Baked
93.1+3.33
76.8±12.19
71.1
+
9.66
5.
Finger
millet
(FM)
Salt
Raw
84.0±3.60
84.1
+
8.33
70.4±9.69
+
Chickpea
(CP)
Baked
81.7+3.23
84.0±5.50
68.6±6.25
Sweet
Raw
77.8±2.85
87.4±5.27
68.0±4.35
Baked
81.2±3.32
92.9
+
3.85
76.2+5.10
6.
Finger
millet
(FM)
Salt
Raw
82.7
+
2.96
78.0
+
5.21
64.4
+
4.70
+
P.
radiatus
Baked
82.5±3.82
82.3
+
4.18
68.5±4.52
Sweet
Raw
79.7±4.68
83.2+4.45
66.3+5.49
Baked
81.4±2.83
84.1+6.04
68.5+6.19
TD:
True
Digestibility
BV:
Biological
Value
NPU:
Net
Protein
Utilization
Serial
number
of
means
underscored
by
the
same
line
are
not
significantly
different.
(*Significant
p
<0.05)
I.
TD
Combinations
5
6
2
1
4
3
II.
BV
Combinations
1
3
2
4
6
5
III.
NPU
Combinations
2
1
6
3
5
4
226
tion
of
cereal
flour
with
lysine,
addition
of
small
amount
of
animal
protein
food
such
as
milk
powder
and
cereal
pulse
combination
increases
the
protein
quality
of
baked
products
[18,
19].
The
increase
in
lysine
due
to
legume
combination
is
probably
sufficient
to
make
up
for
the
loss
in
baking
and
thus
not
affect
the
protein
quality.
Millets
and
legume
combination
products
can
be
used
in
supplementary
feeding
for
poorer
sections
of
population.
The
combination
and
process
can
be
selected
based
on
local
availability.
The
infant
mixes
and
biscuits
made
out
of
millet
and
legume
flours
costs
only
20%
of
any
commercial
foods
available
in
the
market,
in
India.
Food
enterprises
should
be
promoted
to
produce
low
cost
nutritious
foods
based
on
millets
and
legumes
to
increase
the
access
to
foods
to
poorer
sections
of
population
specially
pre
school
children.
Acknowledgments
The
authors
acknowledge
the
financial
support
given
by
IDRC,
Canada
for
conducting
this
research
work
under
the
project
'Rural
Food
enterprises
for
production
of
low
cost
supplementary
foods
using
millets
and
legumes'.
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S,
Pedersen
B,
Monowar
L,
Eggum
BO
(1990)
The
nutritive
value
of
new
and
traditional
sorghum
and
millet
foods
from
sudan.
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Foods
Hum
Nutr
40:
5-19.
2.
Eggum
BO,
Monowar
L,
Bach-Knudsen
KE,
Munck
L
and
Axtell
J
(1983)
Nutritional
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of
sorghum
and
sorghum
foods
from
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J
Cereal
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1:
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WC
Jr,
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GL,
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RP,
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GG
(1981)
Protein
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of
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M,
Parpia
HAB,
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D
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