Microstructure and some functional properties of spray dried cheddar whey concentrated by ultrafiltration or combination of ultrafiltration and vacuum evaporation


Aryana, K.J.; Haque, Z.Z.

Food Science and Technology Research 8(1): 17-20

2002


In order to study the influence of the vacuum evaporation (VE) process on the functionality of whey protein concentrates (WPC's), Cheddar WPC's were produced with and without VE, viz. by (i) ultrafiltration (UF) and spray drying (SD) (UFSD), and by (ii) UF, VE and SD (UFVESD). Gelling properties and interfacial microstructure around residual fat were studied by transmission electron microscopy. Both WPC's were hydrated with 0.1 M NaCl at pH 7.0 (10% protein w/v) and gels were made in glass tubes by heating for 15 min at 90 degrees C. Electron dense membrane like structures were seen at the oil-water interface of gels prepared with UFVESD whey implying the presence of large amphipathic aggregates. Samples from UFSD which had not been subjected to VE, did not show such structures. Gels made from UFVESD had significantly higher strain values than UFSD gels. Functional attributes studied were packing density (PD) and water holding capacity (WHC). The packing density of the UFVESD powders was three times that of the UFSD powders indicating markedly larger powder particles. Data thus indicated changes in the interfacial microstructure and some functional attributes due to the incorporation of VE.

Food
Sci.
Technol.
Res.,
8
(1),
17-20,
2002
Note
Microstructure
and
Some
Functional
Properties
of
Spray
Dried
Cheddar
Whey
Concen-
trated
by
Ultrafiltration
or
Combination
of
Ultrafiltration
and
Vacuum
Evaporation
Kayanush
J.
ARYANA
and
Zahur
Z.
HAQUE*
Department
of
Food
Science
and
Technology,
Mississippi
State
University,
Mississippi
State,
MS
39762,
USA
Received
April
18,
2001;
Accepted
October
19,
2001
In
order
to
study
the
influence
of
the
vacuum
evaporation
(VE)
process
on
the
functionality
of
whey
protein
con-
centrates
(WPC's)
,
Cheddar
WPC's
were
produced
with
and
without
VE,
viz.
by
i)
ultrafiltration
(UF)
and
spray
drying
(SD)
(UFSD),
and
by
UF,
VE
and
SD
(UFVESD).
Geling
properties
and
interfacial
microstructure
around
residual
fat
were
studied
by
transmission
electron
microscopy.
Both
WPC's
were
hydrated
with
0.1
M
NaC1
at
pH
7.0
(10%
protein
w/v)
and
gels
were
made
in
glass
tubes
by
heating
for
15
min
at
90
°
C.
Electron
dense
membrane
like
structures
were
seen
at
the
oil-water
interface
of
gels
prepared
with
UFVESD
whey
implying
the
presence
of
large
amphipathic
aggregates.
Samples
from
UFSD
which
had
not
been
subjected
to
VE,
did
not
show
such
structures.
Gels
made
from
UFVESD
had
significantly
higher
strain
values
than UFSD
gels.
Functional
attributes
studied
were
pack-
ing
density
(PD)
and
water
holding
capacity
(WHC).
The
packing
density
of
the
UFVESD
powders
was
three
times
that
of
the
UFSD
powders
indicating
markedly
larger
powder
particles.
Data
thus
indicated
changes
in
the
interfacial
microstructure
and
some
functional
attributes
due
to
the
incorporation
of
VE.
Keywords:
dairy,
dehydration,
role,
proteins
Whey,
the
liquid
fraction
that
is
drained
from
the
curd
during
cheese
manufacture,
has
a
biological
oxygen
demand
(BOD)
value
of
30,000
to
60,000
ppm
(Cheryan,
1998).
The
high
BOD
value
makes
it
difficult
to
dispose
off.
Typically,
production
of
10
kg
of
cheese
(Cheddar,
Edam)
results
in
the
byproduction
of
90
kg
of
whey
(Kosikowski,
1982a).
Whey
has
a
low
total
solids
content
(7%),
low
protein
content
(0.83%)
and
a
high
lactose
content
(4.9%)
(Kilara,
1994)
making
it
difficult
to
utilize.
Ultrafiltration
(UF)
of
whey
is
a
process
in
which
the
whey
is
passed
under
pressure
across
a
semi-permeable
membrane,
which
enables
concentration
of
proteins
and
insoluble
salts
by
allowing
lactose,
lactic
acid,
non
protein
nitrogen
and
most
of
the
water
to
pass
through
(Kosikowski,
1982a).
Vacuum
evaporation
(VE)
lowers
the
vapor
pressure
enabling
the
fluid
to
boil
at
a
lower
temperature.
However,
temperatures
in
the
range
of
60-
70°C
for
15-30
min
(depending
on
the
type
of
VE)
may
be
required
to
concentrate
the
solids
content
to
38-42%
required
for
effective
spray
drying
(Ji,
2000).
The
commercial
utilization
of
whey
is
by
spray
drying
it
into
powder
and
utilizing
that
powder
in
confectionary,
bakery,
meat
and
dairy
industries
to
support
desired
functional
properties
and/
or
to
improve
nutritional
quality
(de
Wit
et
al.,
1988).
To
spray
dry,
the
whey
has
to
be
pre-concentrated
(Fellows,
1997)
usually
by
ultrafiltration
which
does
not
cause
thermal
denaturation
(7ail,
1987).
Further
pre-concentration
of
solids
by
VE
may
bring
about
protein-lactose
interactions
and
functionality
changes.
This
investigation
was
conducted
to
study
the
impact
of
incor-
Approved
as
journal
article
#9838
of
the
Miss.
Agric.
&
For.
Exp.
Sta.,
Mis-
sissippi
State,
MS
39762.
Funded
by
MAFES
Project
#343010
*To
whom
correspondence
should
be
addressed.
porating
the
VE
process
between
UF
and
spray
drying.
Materials
and
Methods
Whey
processing
Fresh
Cheddar
whey
was
obtained
from
the
MSU
dairy
plant.
The
milk
used
was
from
a
mixed
herd
at
the
Dairy
Research
Center,
MSU.
Whey
was
pasteurized
using
a
high
temperature
short
time
plate
heat
exchanger
system
(Paul
Mueller
Co.
Springfield,
MO)
at
71°C
for
15
s.
Cream
from
the
whey
was
separated
using
a
separator
(De
Laval
Separator
Co.
Chicago).
This
whey
was
then
ultrafiltered
using
hollow
fiber
cartridges
with
membrane
type
PM
50
(Romicon
Inc.
Woburn,
MA).
Total
solids
in
the
whey
after
UF
was
7%
Brix.
This
whey
was
either
spray
dried
(model
#028047,
APV,
Soborg,
Denmark)
directly
(UFSD)
or
further
concentrated
by
VE
(model
#2606,
APV,
Soborg,
Denmark)
at
80°C
and
30
Ton,
to
38-42%
and
then
spray
dried
to
obtain
UFVESD
(Ji,
2000).
Functionalities
Packing
density
was
determined
by
weighing
2.5
g
of
the
powder
(UFSD
and
UFVESD)
in
a
tar-
rered
measuring
cylinder.
Base
of
the
cylinder
was
tapped
100
times
on
hard
surface
covered
with
paper.
The
level
(ml)
to
which
the
powders
settled
/
packed
was
recorded.
Water
holding
capacity
(WHC)
was
conducted
according
to
Handa
et
al.
(1998).
Preparation
of
gels
Proteins
were
hydrated
(10%
w/v
protein)
in
0.1
M
NaCl
at
pH
7.
Gels
were
prepared
according
to
Lee
et
al.
(1997).
Gel
stress
and
strain
Textural
attributes
namely
stress
and
strain
of
the
protein
gels
were
determined
using
an
Instron
Uni-
versal
Testing
Machine
(Series
IX
Automated
Materials
Testing
System
V
401C;
Instron
Corporation,
Canton,
MA).
One
cm.
from
each
end
of
the
tube
was
discarded
and
samples
were
cut
18
into
uniform
size
of
19
mmx19
mm
(diameterxlength).
These
samples
were
placed
on
a
flat
plate
and
the
yield
compression
test
was
carried
out
at
21°C.
The
crosshead
speed
was
50
cm/min
in
both
upward
and
downward
directions
and
the
cell
load
was
50
kg.
The
Instron
was
interfaced
with
a
computer
which
was
programmed
to
calculate
stress
and
strain
at
the
point
of
failure
at
80%
deformation
manually
indicated
by
a
cursor
at
the
peak
of
the
curve.
This
was
done
to
assure
that
the
stress
and
strain
out-
put
detected
by
the
computer
was
exactly
at
the
point
of
failure.
Stress
at
failure
was
given
by
the
expression:
F[1—(d)hlh]tro
2
(kN/m
2
),
where,
F
was
compressive
force,
h
was
sample
height,
r
was
radius
of
cross
section,
and
dh
was
the
displacement.
Strain
at
failure
was
given
by
the
expression;
Strain=dh/h
(Lee
et
al.,
1997).
Microstructure
of
the
gels
Sample
were
prepared
for
scanning
electron
microscopy
(SEM)
and
transmission
electron
microscopy
(TEM)
according
to
Aryana
and
Haque
(2001)
with
slight
modification.
The
En-Block
staining
was
not
conducted
here
since
it
was
not
required
for
these
samples.
For
SEM,
five
representative
blocks
of
each
of
the
three
replications
were
mounted
as
one
replication
per
stub.
From
these
five
blocks
per
stub,
three
representative
blocks
were
selected
at
random.
On
these
three
blocks
many
fields
were
quickly
looked
at
before
a
representative
field
of
15
pLmx15
1.1,m
was
randomly
selected
and
photographed.
This
was
done
for
each
of
the
three
replications.
Samples
were
viewed
using
a
Cambridge
S
360
scanning
elec-
tron
microscope
(Leo,
Electron
Microscopy
Inc.
Thomwood,
NY
10594)
at
15
kV.
Images
were
recorded
on
Polaroid
Type
55
P/N
film
(Polaroid
Corp.
Cambridge,
MA)
and/or
stored
in
elec-
tronic
media.
For
TEM,
five
resin
blocks
were
prepared
for
each
of
the
three
replications.
From
these
five
resin
blocks
two
were
randomly
selected
for
thin
sectioning.
Seven±one
sections
were
picked
up
per
grid.
Two
grids
were
prepared
(one
per
resin
block).
Many
fields
were
viewed
on
both
grids
before
a
represen-
tative
field
of
10
ilmx10
1.1,m
was
photographed.
This
was
done
for
each
of
the
three
replications.
Experimental
design
and
data
analyses
The
experiment
was
conducted
using
a
completely
randomized
design.
The
two
treatments
were
UF
combined
with
spray
drying
(UFSD)
and
UF
plus
VE
followed
by
spray
drying
(UFVESD).
Three
replica-
tions
were
conducted.
Data
were
analyzed
by
analysis
of
vari-
ance
using
Proc
GLM
of
the
Statistical
Analysis
System
(SAS,
1999).
Differences
between
means
were
determined
using
Fisher's
protected
Least
Significant
Difference
test.
Significant
differences
were
determined
at
«,).05.
Results
and
Discussion
The
UFVESD
powders
packed
three
time
tighter
than
the
UFSD
powders
(Table
1)
indicating
significantly
higher
bulk
density.
This
tight
packing
of
the
UFVESD
powders
was
due
to
the
size
and/or
density
of
the
powder
particles.
Masters
(1991)
reported
that
the
most
important
factors
influencing
the
bulk
den-
sity
of
milk
powders
were
particle
material
density
and
content
of
occluded
air
within
the
particle.
The
former
was
influenced
by
the
composition
and
the
density
of
the
individual
components
forming
the
powder,
while
the
latter
was
governed
by
aeration
in
the
course
of
feed
pumping,
feed
agitation
and
feed
automiza-
tion.
K.J.
ARYANA
&
Z.Z.
HAQUE
Ji
(2000)
reported
the
moisture,
protein,
fat
and
ash
content
to
be
4.15,
29.73,
15.1
and
5.57%
for
UFSD
and
0.95,
27.31,
7.82
and
5.5%
for
UFVESD.
There
was
no
difference
in
the
WHC
of
the
powders
(Table
1).
This
was
because
the
protein
contents
of
the
UFSD
and
UFVESD
were
comparable
(Ji,
2000)
and
protein
structure
was
perhaps
not
altered
significantly
by
the
VE
process.
Teo
et
al.
(1996)
reported
a
decrease
in
WHC
of
WPC
gels
with
an
increase
in
temperature
in
the
range
of
5-90°C.
Kneifel
et
al.
(1990)
observed
a
steady
increase
in
WHC
of
caseinates
with
an
increase
in
temperature
of
preheating
skim
milk
from
60
to
120°C
with
a
10°C
increment.
There
was
no
difference
in
the
stress
(hardness)
of
the
UFSD
and
UFVESD
gels.
A
gel
is
a
protein
network
with
entrapped
water.
Since
the
protein
contents
of
UFSD
and
UFVESD
were
almost
the
same
(Ji,
2000),
the
gels
that
were
made
from
them
had
the
same
degree
of
hardness
(stress).
The
UFVESD
gels
had
higher
strain
values
indicating
more
elasticity
than
the
UFSD
gels.
Although
the
protein
contents
of
UFSD
and
UFVESD
were
comparable,
the
latter
had
a
higher
packing
density.
Closer
packing
favors
stronger
protein-protein
interactions
leading
to
greater
elasticity
(strain).
Scanning
electron
microscopy
showed
the
UFSD
gel
matrix
(Fig.
1A)
to
be
less
compact
compared
to
the
UFVESD
gel
matrix
(Fig.
1B).
This
may
be
due
to
the
tight
packing
tendency
of
the
UFVESD
powders
(Table
1).
The
size
of
the
pores
(tailed
arrows)
that entrapped
the
water
in
the
UFSD
gel
matrix
(Fig.
1A)
were
larger
than
the
size
of
the
pores
(tailed
arrows)
that
entrapped
the
water
in
the
UFVESD
gel
matrix
(Fig.
1A).
The
fat
globules
(arrowheads)
in
the
UFSD
gels
(Fig.
1A)
appeared
also
to
be
larger
than
the
fat
globules
(arrowheads)
in
the
UFVESD
gels
(Fig.
1B).
There
also
were
more
of
these
large
fat
globules
in
UFSD
gels
compared
to
the
UFVESD
gels.
This
was
because
UFSD
was
reported
to
have
a
significantly
higher
fat
content
compared
to
UFVESD
(Ji,
2000).
The
UFSD
process
may
be
favoring
tenacious
hydrophobic
interactions
between
fats
and
proteins.
Transmission
electron
microscopy
showed
electron
dense
membrane
around
the
fat
globules
in
gels
made
with
UFVESD
(Fig.
2A).
On
the
contrary,
such
interfaces
were
not
seen
in
the
UFSD
gels
(Fig.
2B)
even
though
its
fat
content
was
significantly
higher.
McPherson
and
Kitchen
(1983)
reported
that
drying
(lyo-
philization)
may
cause
loss
of
milk
fat
globule
membrane
(MFGM)
material.
The
MFGM
components
were
also
lost
dur-
ing
heating
(McPherson
&
Kitchen,
1983).
The
UFVESD
sam-
ples
were
exposed
to
a
longer
duration
of
heat
compared
to
the
UFSD
samples.
Houlihan
et
al.
(1992)
reported
that
increasing
the
duration
of
heating
(80°C)
from
2.5
min
to
20
min,
signifi-
cantly
increased
the
incorporation
of
skim
milk
proteins,
mainly
3-lactoglobulin
into
the
milk
fat
globule
membrane.
McPherson
Table
1.
Some
functional
attributes
of
the
whey
powders
and
their
gels.
Treatment
Packing
Density
Water
Holding
Stress
Strain
(g/cc)
Capacity
(%)
(x10
2
N/m
2
)
(x10
-2
dh/h)
UFSD
0.13
6
2.82'
40.23'
7
6
UFVESD
0.40'
2.59'
40.37'
10'
Different
letters
in
the
same
column
indicate
significant
differences
(a=
0.05).
Functionality
of
Processed
Whey
19
40;
,
Ar4
"tt
O.5
p
m
.41
ij
Fig.
1.
Scanning
electron
micrograph
of
A)
UFSD
gel
and
B)
UFVESD
gel.
Tailed
arrows
point
to
pores
that
held
water
in
the
gel
matrix.
Arrow-
head
points
to
fat
globule
entrapped
in
the
matrix.
et
al.
(1984)
reported
that
skim
milk
components,
mainly
13-lac-
toglobulin
were
present
in
the
milk
fat
globule
membrane
frac-
tion.
The
VE
step
(max
80°C)
between
OF
and
SD
(220°C
inlet
temp)
(UFVESD)
resulted
in
prolonged
exposure
to
heat
in
addi-
tion
to
concentration
of
the
samples
compared
to
UFSD
treat-
ment.
It
is
possible
that
whey
proteins
formed
tenacious
hydropho-
bic
interactions
with
the
residual
fat
due
to
thermal
denaturation
during
VE.
That
could
explain
the
significant
reduction
in
fat
(ex-
tracted
by
petroleum
ether)
from
UFVESD
even
though
the
same
whey
was
used
for
both
WPC's
(Ji,
2000).
McPherson
et
al.
(1981)
detected
13-lactoglobulin
in
a
lipoprotein
complex
iso-
lated
from
butter
serum.
This
complex
originated
from
a
low
density
fraction
of
the
MFGM
interacting
with
13-lactoglobulin
during
pasteurization
of
cream
prior
to
churning
(McPherson
et
al.,
1981).
At
a
higher
magnification
the
MFGM
varied
from
a
single
broad
diffused
line
(arrowhead)
to
a
narrow
sharp
line
(tailed
arrow)
(Fig.
2C).
This
may be
due
to
the
three
dimensional
nature
of
the
aggregate
and
the
two
dimensional
nature
of
the
cross
section
for
TEM.
Similar
observations
of
a
broad
diffused
line
and
a
narrow
sharp
line
of
the
MFGM
have
been
reported
f5e
,
,
r
t
-
Fig.
2.
Transmission
electron
micrograph
of
A)
UFSD
gel.
Tailed
arrow
points
to
the
fat
globule
and
B)
UFVESD
gel.
Tailed
arrow
points
to
mem-
brane
covered
fat
globule.
C)
UFVESD
gel
at
a
higher
magnification.
Tailed
arrow
points
to
narrow
sharp
line
while
arrowhead
points
to
broad
diffused
line
of
the
milk
fat
globule
membrane.
earlier
(Henson
et
al.,
1971).
Recently,
proteins
in
the
MFGM
have
been
reported
to
have
anticancer
properties
(Gorewit
&
Spitsberg,
1998).
The
VE
caused
the
formation
of
electron
dense
aggregate,
improved
packing
density
(which
is
important
in
packaging
the
powders
on
mass
production)
and
improved
gel
elasticity.
These
are
several
advantages
to
the
incorporation
of
VE.
The
disadvan-
tage
of
addition
of
the
VE
process
is
that
it
adds
to
the
processing
cost.
It
would
be
up
to
the
processor
to
weigh
the
advantages,
disadvantages
and
decide
whether
to
incorporate
VE
in
the
over-
all
processing.
,
"
1rn
,„
miiiit
20
K.J.
ARYANA
&
Z.Z.
HAQUE
References
Aryana,
K.J.
and
Haque,
Z.U.
(2001).
Effect
of
commercial
fat
replac-
ers
on
the
microstructure
of
low-fat
Cheddar
cheese.
Int.
T.
Food
Sci.
Tech.,
36,
169-177.
Cheryan,
M.
(1998).
Ultrafiltration
and
Microfiltration
Handbook.
Technomic
Publication
Co.,
Lancaster,
PA.
de
Wit,
J.N.,
Backx,
E.H.
and
Adamse,
M.
(1988).
Evaluation
of
func-
tional
properties
of
whey
protein
concentrates
and
whey
protein
iso-
lates.
3.
Functional
properties
in
aqueous
solution.
Neth.
Milk
Dairy
J.,
42,
155-172.
Fellows,
P.
(1997).
Dehydration.
Ch
14
in
Food
Processing
Technol-
ogy
Principles
and
Practices.
Woodhead
Publishing
Ltd.
Cambridge,
England.
Ji,
T.
(2000).
Effect
of
dehydration
process
on
physicochemical
prop-
erties
of
Jersey
and
mixed
Cheddar
whey
protein
concentrates
and
their
effect
on
the
quality
of
dairy
products.
Ph.D.
Dissertation.
Mississippi
State
University,
Mississippi
State,
MS.
Kosikowski,
F.
(1982a).
Whey
and
whey
foods.
Ch
25
in
Cheese
and
fermented
milk
foods.
F.V.
Kosikowski
and
Associates.
Brookton-
dale,
NY.
Kosikowski,
F.V.
(1982b).
Cheese
and fermented
milk
foods.
F.V.
Kosikowski
and
Associates.
Brooktondale,
NY.
Kilara,
A.
(1994).
Whey
Protein
Functionality.
Ch
11
in
Protein
Func-
tionality
in
Food
Systems.
ed.
by
N.
Hettiarachchy,
G.
Ziegler,
Mar-
cel
Dekker,
Inc.
NY.
Kneifel,
W.,
Abert,
T.
and
Luf,
W.
(1990).
Influence
of
preheating
skimmilk
on
water-holding
apacity
of
sodium
salts
of
caseinates
and
coprecipitates.
J.
Food
Sci.,
55,
879-880.
Gorewit,
R.C.
and
Spitsberg,
V.L.
(1998).
Anticancer
properties
of
proteins
in
the
milk
fat globule
membranes
in
whey.
Int.
Dairy
Fed.
[Spec.
Issue]
9804
315-325.
Handa,
A.,
Takahashi,
K.,
Kuroda,
N.
and
Froning,
G.
(1998).
Heat-
induced
egg
white
gels
as
affected
by
pH.
J.
Food
Sci.,
63,
403-407.
Henson,
A.F.,
Holdsworth,
G.
and
Chandan,
R.C.
(1971).
Physico-
chemical
analysis
of
the
bovine
milk
fat
globule
membrane.
II.
Electron
microscopy.
J.
Dairy
Sci.,
54,
1752-1763.
Houlihan,
A.V.,
Philippa,
A.,Goddard,
S.M.,
Nottingham,
B.,
Kitchen,
J.
and
Colin,
J.M.
(1992).
Interactions
between
the
bovine
milk
fat
globule membrane
and
skim
milk
components
on
heating
whole
milk.
J.
Dairy
Res.,
59,
187-195.
Lee,
C.M.,
Filipi,
I.,
Xiong,
Y.,
Smith,
D.,
Regenstein,
J.,
Damodaran,
S.,
Ma,
C.V.
and
Haque,
Z.U.
(1997).
Standardized
failure
compres-
sion
test
of
protein
gels
from
a
collaborative
study.
J.
Food
Sci.,
63,
1163-1166.
Masters,
K.
(1991).
Applications
in
the
food
industry.
Ch
15
in
"Spray
Drying
Handbook."
Longman
Scientific
and
Technical.
Essex,
UK.
McPherson,
A.V.,
Fitz-Gerald,
C.H.
and
Kitchens,
B.J.
(1981).
Isola-
tion
of
low
density
lipoprotein
complex
from
butter
and
its
suitabil-
ity
as
a
substrate
for
lipases
from
psychrotrophic
microorganisms.
Aust.
J.
Dairy
Technol.,
36,
74-78.
McPherson,
A.V.,
Dash,
M.C.
and
Kitchen,
B.J.
(1984).
Isolation
and
composition
of
milk
fat
globule membrane
material.
L
From
pas-
teurized
milks
and
creams.
J.
Dairy
Res.,
51,
279-287.
McPherson,
A.V.
and
Kitchen,
B.J.
(1983).
The
bovine
milk
fat
glob-
ule
membrane-its
formation,
composition,
structure
and
behavior
in
milk
and
dairy
products.
J.
Dairy
Res.,
50,
107-133.
SAS
®
(1999).
User's
Guide.
Statistics,
Version
8.0
Edition,
SAS
Inst.
Inc.,
Cary,
NC..
Teo,
C.T.,
Munro,
P.A.,
Singh,
H.
and
Hudson,
R.
(1996).
Effects
of
pH
and
temperature
on
the
water-holding
capacity
of
casein
curds
and
whey
protein
gels.
J.
Dairy
Res.,
63,
83-95.
Zall,
R.R.
(1987).
Accumulation
and
quantification
of
on-farm
ultrafil-
tered
milk:
the
California
experience.
Milchwissenschaft,
42,
98.