1. B.E.T
Surface
Area
• Results
when
compared
to
literature
shows
that
the
pump
flow
rate
and
the
choice
of
the
templa;ng
agents
greatly
affects
the
porosity
of
powders,
as
expected.
• Glucose
at
25%
(8
mL/min)
pump
flow
rate
is
highly
responsive
as
it
has
the
greatest
rate
of
change,
11
m2/g
(from
13
±
3
m2/g
to
24
±
2
m2/g)
over
a
20°C
temperature
change.
• Sucrose
at
5%
(1.6
mL/min)
pump
flow
rate
has
a
slow
response
;me
as
it
has
the
lowest
rate
of
change,
2
m2/g
(from
34
±
2
m2/g
to
36
±
2
m2/g)
over
a
60°C
temperature
change.
• Sucrose
had
the
lowest
varia;on
of
B.E.T
surface
area
sugges;ng
insignificant
change
from
110
±
1°C
to
170
±
1°C,
while
glucose
showed
significant
varia;on
from
150
±
1°C
to
170
±
1°C.
• Choice
of
the
templa;ng
agents
affect
the
total
maximum
stacking
energy
and
the
minimised
unit
cell
due
to
different
self-­‐assembly
mechanisms
of
par;cles.
The
Glass-­‐Transi;on
Temperature
(Tg)
• Order
of
temperatures
does
not
decrease
numerical
as
expected.
• Par;al
templa;ng
of
crystalline
structure.
• Couchman-­‐Karasz
equa;on
es;mates
Tg
reasonable
well.
The
Yield
• Similar
trends
to
binary
mixtures
(Bhandari,
et
al.,
2013).
• Different
pump
flow
rates
and
templa;ng
agent
combina;ons
produce
different
yields.
• Highest
yields
obtained
are
at
130
±
1°C
to
150
±
1°C
with
yields
of
79
±
4%
and
79
±
1%
for
sucrose.
The
Moisture
Content
Moisture
Content
• Lowest
moisture
at
170
±
1°C
indicates
the
highest
crystallinity.
• Increase
in
moisture
content
from
190
±
1°C
to
210
±
1°C
due
to
hygroscopic
affects
and
small
yields
obtained
at
these
temperatures.
The
Degree
of
Crystallinity
• Highest
degree
of
crystallinity
occurs
at
170
±
1°C.
• Suggests
good
powder
to
test
for
B.E.T
surface
area.
• Limita;on
to
the
degree
of
crystallinity
due
to
moisture
content,
hygroscopic
effects
and
crystal
self-­‐assembly.
How and why do operating conditions
affect the surface areas of highly-porous
food powders?
Kierin van Berkel, Prof. Timothy Langrish, Ph.D.
Amirali Ebrahimi Ghadi & Ph.D. Morteza Saffari
School of Biomolecular
& Chemical Engineering
Background
• Highly-­‐porous
powders
have
significant
applica;ons
for
agricultural,
food
and
pharmaceu;cal
industries
such
as
reduc;on
in
transport
costs,
increased
drug
delivery/loading
and
increased
shelf-­‐life.
• Significant
research
has
been
done
for
binary
mixtures,
however
mul;-­‐
component
mixtures
have
been
overlooked.
• Possible
improvements
to
the
yield,
degree
of
crystallinity
and
the
B.E.T
surface
area
can
be
made.
Aim
• How
and
why
do
opera;ng
condi;ons
affect
the
surface
areas
of
highly-­‐
porous
food
powders.
• Analysing
the
final
product
through
the
yield,
moisture
content
analysis,
sorp;on
analysis,
Differen;al
Scanning
Calorimetry
(DSC),
and
B.E.T
surface
area.
Method
&
Theory
Areas
Interest
• Parameters
of
interest
include
the
yield,
the
degree
of
crystallinity,
the
glass-­‐transi;on
temperature
and
the
B.E.T
surface
area.
• Condi;ons
analysed
include
the
inlet
temperature,
the
liquid
pump
flow
rate
and
the
templa;ng
agent.
Spray-­‐drying
Produc;on
• 10%
w/v
Lactose,
1%
w/v
Sucrose,
and
89%
w/v
dis;lled
water
spray
dried
from
110°C
to
210°C,
5%
pump
flowrate
(1.6
mL/min),
aspira;on
of
100%
and
nozzle
pulsa;on
of
5.
• Method
was
repeated
for
glucose
in
place
of
sucrose,
however
at
25%
pump
flowrate
(8
mL/min).
Highly
Porous
Powder
Characterisa;on
Pr
Produc;on
of
Highly
Porous
Powders
• Templa;ng
agent
is
crystallised
with
the
desired
par;cle
forming
a
composite
par;cle.
• Ethanol
is
mixed
and
s;rred
over
two
24
hour
cycles
to
fully
dissolve
the
templa;ng
agent
(Saffari,
Ebrahimi
and
Langrish,
2015).
• Highly
crystallised
and
porous
powder
are
lec
as
a
result.
Referenced
from
Iskander,
et
al.,
(2009).
Stage
1
• Spray-­‐Drying
• Determines
the
yield
&
moisture
content.
Stage
2
• Sorp4on
Analysis
• Determines
the
degree
of
crystallinity.
Stage
3
• Brunauer,
Emme=
and
Teller
(B.E.T)
• Determines
the
porosity
&
surface
area
through
5-­‐point
B.E.T
surface
analysis.
Stage
4
• Differen4al
Scanning
Calorimetry
• Determine
the
s;ckiness
factor
&
bulk
crystallisa;on
when
compared
to
the
Couchmann-­‐Karasz
Equa;on.
110°C
130°C
150°C
170°C
190°C
210°C
20
25
30
35
40
45
50
55
60
65
70
0.02 0.03 0.04 0.05 0.06 0.07 0.08
Glass-transitionTemperature(°C)
Water Mass Fraction
Effect of Temperature on the glass transition
temperature for Sucrose & Lactose at 5% pump
flowrate
Couchmann-Karasz Estimation 1st Transition - Differential Scanning Calorimetry
0
1
2
3
4
5
6
7
8
0 100 200 300 400 500 600 700 800
MoistureContent%
Time (Mins)
Effect of Temperature on the Degree of Crystallinity
for Sucrose & Lactose at 5% pump flowrate
110°C
130°C
150°C
170°C
190°C
210°C
Highest crystallinity peak
Lowest crystallinity peak
Resolution
Late nucleation phase
Opera4ng
Temperature
at
110°C
&
150°C,
respec4vely
Temperature
at
170°C
Sucrose
(Pump
Flowrate
5%,
1.6
mL/min)
34
±
2
m2/g
36
±
2
m2/g
32
,
33
&
37
33,
35,
38
&
38
Glucose
(Pump
Flowrate
25%,
8
mL/min)
13
±
3
m2/g
24
±
2
m2/g
11,
13
&
15
23,
23
&
25
Results
&
Discussion
Conclusion,
Recommenda4ons
&
Acknowledgements
Conclusion
1. The
B.E.T
surface
area
is
greatly
affected
by
the
temperature,
pump
flow
rate
and
templa;ng
agent.
2. Surface
area
limita;on
exists
due
to
molecular
and
physical
proper;es
caused
by
the
s;ckiness
factor,
moisture
content
and
the
degree
of
crystallinity.
Recommenda;ons
• The
amount
of
infusion
occurring
between
templa;ng
agent
and
lactose.
• Addi;onal
study
for
the
B.E.T
surface
area
range
from
110
±
1°C
to
210
±
1°C.
• The
affect
of
ethanol
washing
cycle
on
the
porosity
of
powders.
Acknowledgements
• School
of
Biomolecular
and
Chemical
Engineering
at
the
University
of
Sydney.
• Prof.
Timothy
Langrish,
Ph.D.
supervisors,
Amirali
Ebrahimi
Ghadi
and
Morteza
Saffari.
References
Bhandari,
B.,
Nidhi,
B.,
Min,
Z.
&
Pierre,
S.,
2013.
Process
and
Properi;es
-­‐
Limita;on
of
the
Solid-­‐Phase
Crystallisa;on
Model.
s.l.:Woodhead
Publishing.
Im;az-­‐Ul-­‐Islam,
M.
&
Langrish,
T.,
2009.
Comparing
the
crystallisa;on
of
sucrose
and
lactose
in
spray
dryers.
Food
and
Bioproducts
Processing,
Issue
87,
pp.
87-­‐95.
Iskandar,
F.
et
al.,
2009.
Produc;on
of
morphology-­‐controllable
porous
hyaluronic
acid
par;cles
using
a
spray-­‐drying
method.
Acta
Biomaterialia,
Issue
5,
pp.
1027-­‐1034.
Saffari,
M.,
Ebrahimi,
A.
&
Langrish,
T.,
2015.
Highly-­‐porous
mannitol
par;cle
produc;on
using
a
new
templa;ng
approach.
Food
research
interna;onal,
Issue
67,
pp.
44-­‐51.
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
60 80 100 120 140 160 180 200 220
Yield%
Temperature (°C)
Effect of Temperature on the Yield for Sucrose &
Lactose at 5% pump flow rate
Inlet
Temperature
Outlet
Temperature
Approaching the
stickiness barrier
Vertex of the yield
0%
1%
2%
3%
4%
5%
6%
7%
8%
60 80 100 120 140 160 180 200 220
MoistureContent%
Temperature (°C)
Effect of Temperature on the Moisture Content for
Sucrose & Lactose at 5% pump flow rate
Inlet
Temperatur
e
Outlet
Temperatur
e
Lowest moisture content
Abnormal moisture
content