Using a tubular heat exchanger to improve the conditioning process of the olive paste: Evaluation of yield and olive oil quality


Leone, A; Esposto, S; Tamborrino, A; Romaniello, R; Taticchi, A; Urbani, S; Servili, M

European Journal of Lipid Science and Technology 118(2): 308-317

2016


308
Eur.
J.
Lipid
Sci.
Technol.
2016,
118,
308-317
Research
Article
Using
a
tubular
heat
exchanger
to
improve
the
conditioning
process
of
the
olive
paste:
Evaluation
of
yield
and
olive
oil
quality
Alessandro
Leone',
Sonia
Esposto
2
,
Antonia
Tamborrino
3
,
Roberto
Romaniello',
Agnese
Taticchi
2
,
Stefania
Urbani
2
and
Maurizio
Servili
2
1
Department
of
the
Science
of
Agriculture,
Food
and
Environment,
University
of
Foggia,
Foggia,
Italy
2
Department
of
Agricultural,
Food
and
Environmental
Science,
University
of
Perugia, Perugia,
Italy
3
Department
of
Agricultural
and
Environmental
Science,
University
of
Bad
Aldo
Moro,
Bad,
Italy
In
this
research,
the
evaluation
of
the
pre-heating
effect
on
olive
paste
before
malaxation
was
performed.
The
olive
paste
was
treated
by
means
of
a
tubular
heat
exchanger.
The
heat
exchanger
performances
on
yield
and
olive
oil
quality
were
evaluated
considering
two
different
types
of
olive
paste
obtained,
respectively,
by
means
of
a
disc
crusher
and
a
de-pitter
machine.
The
experimental
tests
were
conducted
on
an
industrial
olive
oil
extraction
plant.
The
results
of
the
experimental
test
showed
that
it
is
possible
to
reduce
the
malaxation
time
by
about
10
min,
maintaining
constant
the
extraction
yield,
when
a
disc
crusher
was
used.
On
the
other
hand,
using
the
heat
exchanger
to
condition
the
de-stoned
paste,
a
reduction
of
the
malaxation
time
compared
to
the
control
test
was
observed,
but
with
significant
loss
in
extraction
yield.
Concerning
the
olive
oil
quality,
the
flash
thermal
treatment
of
the
olive
paste
after
the
crushing
operation
improves
the
phenolic
and
volatile
compound
content
significantly
with
respect
to
the
traditional
process,
in
which
the
malaxation
time
has
a
duration
of
at
least
30
min.
By
employing
a
tubular
heat
exchanger
we
observed
some
advantages,
like
the
reduction
of
malaxation
time
and
the
improving
of
phenolic
and
volatile
compounds.
Practical
applications:
The
practical
application
of
this
research
concerns
the
possibility
of
evaluating
the
effects
inherent
in
the
insertion
of
a
tubular
heat
exchanger
before
the
malaxer,
in
an
industrial
olive
oil
extraction
plant.
The
effects
were
evaluated
on
an
industrial
scale
olive
oil
extraction
plant
considering
these
quantitative
parameters:
extraction
efficiency
of
the
decanter
and
the
amount
of
oil
lost
in
the
husk.
The
olive
oil
quality
was
also
evaluated.
The
research
provides
useful
information
to
the
operators
of
the
olive
oil
sector
and
to
researchers
in
understanding
the
changes
manifested
in
the
extraction
plant
in
traditional
configuration
and
innovative
configuration
with
the
tubular
heat
exchanger.
Keywords:
Aromatic
fraction
/
De-pitter
/
Heat
exchanger
/
Malaxer
/
Olive
oil
quality
Received:
November
28,
2014
/
Revised:
March
16,
2015
/
Accepted:
April
2,
2015
DOI:
10.1002/ejlt.201400616
Correspondence:
Dr.
Roberto
Romaniello,
Department
of
the
Science
of
Agriculture,
Food
and
Environment,
University
of
Foggia,
Via
Napoli,
Foggia
25-71122,
Italy
E-mail:
unifg.
it
Fax:
+39
0881
589120
Abbreviations:
ANOVA,
analysis
of
variance;
DAD,
diode
array
detector;
DC,
disk
crushing;
DCCT,
difference
compared
to
the
control
test;
DP,
de-
pitting;
DVB/CAR/PDMS,
divinylbenzene/carboxen/polydimethylsiloxane;
EFC,
electronic
flow
controller;
El,
electron
ionization;
EY,
extraction
yield
(%w/w);
FLD,
fluorescence
detector;
GC/MS,
gas
chromatography
mass-
spectrometry;
HPLC,
high
performances
liquid
chromatography;
HS-
SPME,
headspace-solid
phase
micro
extraction;
NMR,
nuclear
magnetic
resonance;
VOO,
virgin
olive
oil;
W
011
,
mass
of
extracted
oil
(kg);
mass
of
processed
olives
(kg)
1
Introduction
Malaxation
is
an
operation
ofthe
virgin
olive
oil
WOO)
extraction
process
during
which
various
phenomena
occur:
mechanical,
physical,
physico-chemical,
and
chemical-biochemical.
The
main
goal
of
malaxation
is
to
break
the
emulsions
formed
during
the
crushing
process
and
to
improve
the
coalescence
of
the
oil
drops.
An
effect
of
this
phenomenon
is
the
paste
viscosity
decrease.
These
aspects
are
most
important
to
improve
the
efficiency
of
the
horizontal
centrifuge
decanter
[1,
2,
3,
4].
Several
modifications
to
the
chemical
and
organoleptic
properties
of
the
olive
oil
occur
during
the
malaxation
operation
[5,
6,
7,
8].
©
2015
WILEY-VCH
Verlag
GmbH
&
Co.
KGaA,
Weinheim
www.ejlst.com
Eur.
J.
Lipid
Sci.
Technol.
2016,
118,
308-317
Tubular heat
exchanger
in
an
olive
oil
extraction
plant
309
Therefore,
malaxation
can
be
considered
an
important
phase
of
the
extraction
process
due
to
its
influence
on
the
olive
oil
yield
and
quality.
For
this
reason
different
scientific
studies
have
been
done
to
optimize
this
unit
operation
[9,
10,
11].
Malaxation
is
the
only
batch
operation
in
the
olive
oil
extraction
process.
In
fact,
all
other
operations,
from
olive
washing
to
liquid—liquid
separation,
are
continuous.
Malaxer
machine
consists
of
a
stainless
steel
chamber
with
cradle
or
circular
section,
having
in
its
inside
a
horizontal
shaft
mounting
a
series
of
stainless
steel
blades
to
slow
mixing
the
olive
paste
[12].
The
circulation
of
hot
water
in
the
interspace
of
the
external
chamber
ensures
the
indirect
heating
of
the
olive
paste.
During
malaxation,
the
olive
paste
loading
and
unloading
occurs
at
different
times
causing
discontinuity.
In
the
recent
years,
important
research
lines
have
been
conducted
by
several
authors
who
have
investigated
the
possibility
of
transforming
the
malaxation
discontinuous
operation
in
continuous
operation.
Amirante
et
al.
[13]
studied
on
the
introduction
of
a
heat
exchanger
having
spiral-shaped
plates,
before
the
malaxer,
for
de-pitter
olive
paste.
The
study
showed
that
the
use
of
the
heat
exchanger
increases
the
conditioning
efficiency
of
the
de-stoned
paste
because
the
yield
is
increased
with
respect
to
the
traditional
process.
In
addition,
the
heat
exchanger
showed
significant
improvements
of
olive
oil
quality.
Esposto
et
al.
[14]
carried
out
a
study
focused
on
the
use
of
a
flash
heating
for
the
olive
paste
by
introducing
a
tubular
heat
exchanger
in
an
industrial
olive
oil
extraction
plant.
These
investigations
have
reported
that
the
use
of
a
heat
exchanger
before
malaxtion
can
be
opportunely
chosen
to
improving
the
aromatic
fraction
and
the
relative
VOO
quality.
These
studies
confirm
both
the
possibility
of
using
a
heat
exchanger
to
rapidly
increase
the
olive
paste
temperature
before
malaxation
and
the
possibility
to
decreasing
the
olive
paste
conditioning
time.
Nevertheless,
none
of
the
two
studies
show
the
possibility
to
use
the
heat
as
a
solution
to
replace
the
classic
malaxation,
always
necessary
even
if
for
a
shorter
time.
Recent
studies
have
focused
on
the
substitution
of
malaxer
machine
with
a
microwave
machine
to
condition
the
olive
paste
in
continuous
mode
[15,
16,
17].
The
results
of
these
research
demonstrated
that
the
microwave
produces
a
non-thermal
effect
in
addition
to
the
thermal
effect
that
allows
to
release
the
oil
contained
in
the
vacuoles
and
to
increase
the
coalescence
phenomenon.
The
microwave
process
resulted
in
a
high
extraction
efficiency
that
was
comparable
to
that
obtained
using
traditional
malaxation.
In
addition,
the
decreased
time
for
olive
paste
conditioning
resulted
in
a
lower
oxidation
of
the
olive
oil,
in
a
reduction
of
the
phenolic
compounds
associated
with
spicy
and
bitter
notes
and
in
an
increase
of
the
aromatic
substances
contained
in
the
oils
obtained
using
the
microwave-assisted
treatment.
The
study
showed
that
the
microwave
pre-treatment
system
could
be
applied
to
condition
the
olive
paste
replacing
the
malaxer
machines.
Considering
the
important
scientific
studies
already
carried
out
on
the
use
of
heat
exchangers,
the
purpose
of
this
paper
is
to
continue
to
deepen
the
knowledge
on
this
research
line
to
evaluate
the
olive
oil
yield
and
quality
using
a
tubular
heat
exchanger
to
condition
the
olive
paste
obtained
with
two
crushing
systems:
disc
crusher
and
de-pitter
crusher.
2
Materials
and
methods
Two
different
crushing
systems,
a
disc
crusher
and
a
de-pitter
machine,
working
in
an
industrial
olive
oil
extraction
plant
were
compared
to
evaluate
the
effect
of
olive
paste
heating
using
a
tubular
heat
exchanger
on
yield
and
olive
oil
quality.
The
disc
crusher
is
always
used
in
the
mills
and
it
is
able
to
produce
a
homogeneous
paste
by
breaking
the
stones,
skin,
and
pulp
[18].
While
the
de-pitter
machine
was
recently
introduced,
it
is
able
to
crush
the
olives
obtaining
a
homogeneous
paste
and
simultaneously
able
to
separate
the
stones.
2.1
Mechanical
extraction
plant
involved
in
experimental
tests
The
industrial
olive
oil
mill
involved
in
the
experimental
tests
was
located
in
Torremaggiore
(FG),
Puglia,
Italy,
and
it
was
constituted
of
a
series
of
interconnected
machines: a
defoliator
(mod.
Condor
2,
Clemente
&
C.
Snc,
Matera,
Italy);
a
washing
machine
(mod.
VK,
Santoro
Cosimo,
Ceglie
Messapica,
Italy);
two
different
crushing
systems,
disc
crushing
(Alfa
Laval
Corporate
AB,
Lund,
Sweden)
and
de-
pitter
machine
(Alfa
Laval
Corporate
AB);
four
malaxers
(Alfa
Laval
Corporate
AB);
a
three-phase
solid/liquid
horizontal
centrifugal
decanter
(mod.
NX
X7,
Alfa
Laval
Corporate
AB);
and
two
liquid/liquid
vertical
plate
centri-
fuges
(Alfa
Laval
Corporate
AB).
During
the
experimental
tests
a
tubular
heat
exchanger
(mod.
ViscoLine
TM
,
Alfa
Laval
Corporate
AB)
was
placed
between
crushers
and
malaxers.
Figure
1
shows
the
olive
oil
extraction
process
flow
chart.
2.2
Specifications
of
the
tubular
heat
exchanger
Modular
units
of
tubes
connected
in
series
and
grouped
on
a
common
frame
constituted
the
tubular
heat
exchanger
used
during
the
experimental
tests.
The
modular
unit
was
a
tube-in-tube
heat
exchanger
designed
for
products
having
average
viscosity
(i.e.,
olive
paste).
A
single
tube
mounted
inside
an
outer
shell
constitutes
it.
The
product
flows
inside
the
tube
and
the
©
2015
WILEY-VCH
Verlag
GmbH
&
Co.
KGaA,
Weinheim
www.ejlst.com
I
E
Pits
I
I
Service
Fluid
310
A.
Leone
et
al.
Eur.
J.
Lipid
Sci.
Technol.
2016,
118,
308-317
Olives
B
Leaves
Fluid
I
Water
F
+
+
H
0101140
Oil
Waste
Oil
water
Figure
1.
Flow
chart
of
the
olive
oil
extraction
mechanical
process.
(A)
Loading
hopper;
(B)
defoliator;
(C)
washing
machine;
(D)
disc
crusher;
(E)
total
de-pitter;
(F)
tubular
heat
exchanger;
(G)
programmable
logic
controller;
(H)
malaxer
machines;
(I)
three-phases
solid/
liquid
horizontal
centrifugal
decanter;
(L)
liquid/liquid
vertical
centrifuges;
and
(M)
3-way
valves.
Waste
water
oil
Water
Husk
hot
service
fluid
flows
around
it
and
in
counter
currently.
The
product
tube
was
made
in
stainless
steel
AISI
316
and
the
service
tube
was
made
in
stainless
steel
AISI
304.
Figure
2
shows
the
modular
unit
flow
pattern.
During
the
exper-
imental
test
the
service
fluid
temperature
was
39.5°C,
and
the
olive
paste
temperature
was
18.5
±
0.5
in
input
and
28.0
±
0.3
in
output.
2.3
Experimental
plan
The
experimental
tests
were
performed
in
cropping
seasons
2013-2014.
Two
different
plant
configurations
were
eval-
uated
during
the
experimental
tests.
Figure
1
shows
the
production
path
line
of
the
mill
process
for
the
two
different
olive
paste
conditioning
methods
(DC
and
DP).
Four
different
test
conditions
were
performed
for
each
plant
configuration:
one
was
the
control
test
and
three
tests
were
conducted
by
setting
different
malaxation
times.
Three-way
valves,
starts
and
stops
pumps,
and
conveyors
allowed
the
changing
from
one
configuration
to
the
others.
The
processing
conditions
are
shown
in
detail
in
Table
1.
Each
test
was
performed
three
times.
Following
summarizes
other
process
parameters:
(i)
Mass
of
olive
batches
=
700
kg.
(ii)
Percentage
of
water
added
to
the
decanter
was
10%
for
all
experimental
tests.
(iii)
Decanter
mass
flow
rate
=
3000
kg/h
of
olives.
Service
fluid
INPUT
Cold
olive
paste
INPUT
I-lot
olive
paste
OUTPUT
Service
fluid
OUTPUT
Figure
2.
Modular
unit
flow
pattern.
©
2015
WILEY-VCH
Verlag
GmbH
&
Co.
KGaA,
Weinheim
www.ejlst.com
Eur.
J.
Lipid
Sci.
Technol.
2016,
118,
308-317
Tubular heat
exchanger
in
an
olive
oil
extraction
plant
311
Table
1.
Processing
conditions
Test
conditions
DC10
DC20
DC30
DCCT
DPIO
DP20
DP30
DPCT
Crushing
system
Disc
crusher
Disc
crusher
Disc
crusher
Disc
crusher
De-pitter De-pitter
De-pitter De-pitter
Out
temperature
of
ViscoLineTM
28.0
±
0.3
28.0
±
0.2
28.0
±
0.2
-
28.0
±
0.2
28.0
±
0.3
28.0
±
0.2
Malaxing
time
(min)
10
20
30
40
10
20
30
40
Malaxing
temperature
(°C)
28.0
±
0.4
28.0
±
0.5
28.0
±
0.4
28.0±0.5
28.0
±
0.5
28.0
±
0.4
28.0
±
0.4
28.0±0.5
Data
represents
mean
value
±
standard
deviation.
30
min.
Results
were
expressed
as
percentage
of
oil
on
wet
and
dry
matter.
2.4
Olive
oil
and
sampling
Olive
fruits
of
the
cultivar
Peranzana
(Olea
europaea
L.)
having
maturity
index
of
2.3
were
harvested
by
a
trunk
shaker
machine
and
processed
7
h
after
harvesting.
The
maturity
index
was
determined
according
to
the
method
proposed
by
the
International
Olive
Council
[19].
Husk
was
sampled
from
the
decanter
at
regular
time
intervals
and
stored
at
-25°C
until
analysis.
The
wastewater
was
sampled
from
the
horizontal
centrifugal
separator
at
regular
time
intervals
and
stored
at
-25°C
until
analysis.
A
500
mL
aliquot
of
olive
oil,
obtained
from
each
experimental
test,
was
acquired
and
stored
in
dark
bottles
at
13°C
until
analysis.
2.5
Extraction
yield
The
extraction
yield
(EY)
is
the
amount
of
oil
obtained
by
milling
100
kg
of
olives.
The
EY
was
calculated
using
the
following
equation:
EY
-
v
„,
W
°'
100
w
olives
(1)
where
Woil
is
the
mass
of
the
extracted
oil
(kg)
and
W
olives
is
the
mass
of
the
processed
olives
(kg).
2.6
Determination
of
the
oil
content
in
husk
and
in
wastewater
The
total
oil
content
was
determined
considering
25
g
of
sample,
previously
dehydrated
until
reaching
constant
weight.
The
oil
was
extracted
from
husk
and
waste-water
samples
using
hexane
in
an
automatic
extractor
(Randall
148,
Velp
Scientifica,
Milan,
Italy)
following
the
analytical
technique
described
by
Cherubini
et
al.
[20].
The
sample
was
initially
subjected
to
an
immersion
phase
at
139°C
for
60
min;
the
porous
container
containing
the
sample
was
immersed
directly
in
the
boiling
solvent.
The
sample
was
then
subjected
to
washing
at
139°C
for
40
min;
the
sample
container
was
removed
from
the
solvent
and
reflux
washed.
The
final
step,
solvent
recovery,
was
conducted
at
139°C
for
2.7
Marketable
parameters
Free
acidity,
peroxide
values,
and
coefficients
of
specific
extinction
at
232
and
270
nm
(K232
and
K270)
were
measured
in
accordance
with
the
European
official
methods
[21].
2.8
Reference
compounds
The
(p-hydroxyphenyl)ethanol(p-HPEA)
was
purchased
from
Fluka
(Milan,
Italy),
while
the
3,4-(dihydroxyphenyl)
ethanol(3,4-DHPEA),
produced
by
the
Cayman
Chemical
Company
(Ann
Arbor,
MI,
USA),
was
obtained
from
Cabru
S.A.S.
(Arcore,
Milan,
Italy).
The
dialdehydic
forms
of
elenolic
acid
linked
to
3,4-DHPEA
and
p-HPEA
(3,4-
DHPEA-EDA
and
p-HPEA-EDA,
respectively),
the
isomer
of
oleuropein
aglycon
(3,4-DHPEA-EA),
(+)-1-acetoxypi-
noresinol,
and
(+)-pinoresinol
were
extracted
from
VOO
according
to
the
method
developed
by
Montedoro
et
al.
[22]
.
In
this
method,
the
phenolic
compounds
were
extracted
from
the
VOO
using
a
mixture
of
methanol/water
(80:20
v/v),
then,
after
solvent
evaporation
and
a
partial
purification
of
the
crude
extract
obtained
from
VOO,
the
phenols
were
separated
by
semi-preparative
High
Performance
Liquid
Chromatography
(HPLC)
analysis.
The
HPLC
separation
was
conducted
using
a
Whatman
Partisil
10
ODS-2
column
(500
mm
x
9.4
mm
i.d.).
The
mobile
phase
was
composed
by
0.2%
of
acetic
acid
(pH
3.1)
in
water
(A)
and
methanol
(B)
and
the
elution
was
performed
at
a
flow
rate
of
6.5
mL/min.
The
total
running
time
was
150
min
and
the
gradient
changed
as
follows:
the
starting
composition
was
95%
A/5%
B,
then
the
percentage
of
B
was
increased
to
74%
A/26%
B
in
2.5
min,
64%
A/36%
B
in
4.5
min,
and
this
percentage
was
maintained
for
33
min,
61%
A/39%
B
in
35
min,
0%
A/100%
B
in
35
min,
and
this
percentage
was
maintained
for
20
min,
returning
at
the
end
to
initial
conditions
(95%
A/5%
B)
in
20
min.
The
phenols
were
detected
using
a
Diode
Array
Detector
(DAD)
at
a
wavelength
of
278
nm.
The
purity
of
these
substances
was
tested
by
analytical
HPLC
[23]
and
their
chemical
structures
verified
by
NMR
using
the
same
©
2015
WILEY-VCH
Verlag
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Co.
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Weinheim
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312
A.
Leone
et
al.
Eur.
J.
Lipid
Sci.
Technol.
2016,
118,
308-317
operating
conditions
reported
in
previous
papers
[22]
by
recording
1
H
and
13
C
spectra.
Pure
analytical
standards
of
volatile
compounds
Fluka
and
Aldrich
were
purchased
from
Sigma—Aldrich
(Milan,
Italy).
The
extraction
of
VOO
phenolic
compounds
was
performed
in
accordance
with
Montedoro
et
al.
[24].
The
HPLC
analyses
of
the
phenolic
extracts
were
conducted
according
to
Selvaggini
et
al.
[23]
with
a
reversed-phase
column
using
an
Agilent
Technologies
system
Model
1100
(Agilent
Technologies,
Santa
Clara,
CA,
USA)
which
was
composed
of
a
vacuum
degasser,
a
quaternary
pump,
an
autosampler,
a
thermostated
column
compartment,
a
DAD,
and
a
fluorescence
detector
(FLD).
The
C18
column
used
in
this
study
was
a
Spherisorb
ODS-1
250
x
4.6
mm
with
a
particle
size
of
5
µm
(Waters,
Milford,
MA,
USA);
the
injected
sample
volume
was
20
µL.
The
mobile
phase
was
composed
of
0.2%
acetic
acid
(pH
3.1)
in
water
(solvent
A)/
methanol
(solvent
B)
at
a
flow
rate
of
1
mL/min
and
the
gradient
changed
as
follows:
95%
A/5%
B
for
2
min,
75%
A/
25%
B
in
8
min,
60%
A/40%
B
in
10
min,
50%
A/50%
B
in
16
min,
and
0%
A/100%
B
in
14
min;
this
composition
was
maintained
for
10
min,
then
returned
to
initial
conditions
and
equilibration
in
13
min;
the
total
running
time
was
73
min.
All
phenolic
compounds
were
detected
by
DAD
at
278
nm.
2.9
Volatile
compounds
analysis
The
evaluation
and
quantification
of
volatile
compounds
in
EVOOs
were
done
by
headspace—solid
phase
micro
extraction
(HS-SPME)
followed
by
gas
chromatography—
mass
spectrometry
analysis
(HS-SPME-GC/MS)
according
to
Selvaggini
et
al.
[10]
with
few
modifications.
For
the
headspace
volatile
compounds
sampling,
SPME
was
applied
as
follows:
three
grams
of
VOO
were
placed
in
a
10
mL
vial
and
thermo
stated
at
35°C,
then
the
SPME
fiber
(a
50/30
µm
divinylbenzene/carboxen/polydimethylsiloxane
(DVB/CAR/PDMS))
having
1
cm
length,
StableFlex,
Supelco,
Inc.,
Bellefonte,
PA,
USA)
was
exposed
to
the
vapour
phase
for
30
min
to
sample
the
volatile
compounds.
Afterwards,
the
fiber
was
inserted
into
the
GC
injector,
set
in
splitless
mode,
using
a
splitless
inlet
liner
of
0.75
mm
i.d.
for
thermal
desorption,
where
it
was
held
for
10
min.
All
of
the
SPME
operations
were
automated
by
using
a
Varian
CP
8410
Auto
Injector
(Varian,
Walnut
Creek,
CA,
USA).
The
analysis
of
the
volatile
compound
sampled
with
SPME
was
conducted
as
reported
in
Selvaggini
et
al.
[10]
with
few
modifications.
A
Varian
4000
GC/MS
equipped
with
a
1079
Universal
Capillary
Injector
(Varian)
was
used.
An
Agilent
J&W
fused
silica
capillary
column
was
employed
(DB-WAXetr,
50
m,
0.32
mm
i.d.,
1
µm
film
thickness,
Agilent
Technologies,
Santa
Clara,
CA,
USA).
The
column
was
operated
with
helium
at
a
constant
flow
rate
of
1.7
mL/min
maintained
by
an
electronic
flow
controller
(EFC).
The
GC
oven
heating
program
started
at
35°C.
This
temperature
was
maintained
for
8
min,
then
increased
to
45°C
at
a
rate
of
1.5°C/min,
increased
to
150°C
at
a
rate
of
3°C/min,
increased
to
180°C
at
a
rate
of
4°C/min,
and
finally
increased
to
210°C
at
a
rate
of
3.6°C/min;
this
temperature
was
then
held
for
14.5
min.
The
total
time
of
analysis
was
80
min.
The
injector
temperature
was
main-
tained
at
250°C
and
the
temperature
of
the
transfer
line
was
fixed
at
170°C.
The
mass
spectrometer
was
operated
in
electron
ionization
(EI)
mode
using
ionization
energy
of
70
eV,
scanning
in
the
mass
range
of
m/z
25-350
amu
at
a
scan
rate
of
0.79
s/scan,
and
a
trap
set
point
temperature
of
150°C.
The
GC-MS
was
operated
with
the
Varian
MS
Workstation
Software,
Version
6.6
(Varian).
The
volatile
compounds
were
identified
comparing
their
mass
spectra
and
retention
times
with
those
of
authentic
reference
compounds.
The
integration
of
all
chromatographic
peaks
was
performed
by
choosing
the
three
masses
with
the
highest
intensities
among
those
specific
for
each
compound
to
selectively
discriminate
them
from
their
nearest
neigh-
bors.
The
volatile
compound
results
were
calculated
on
the
basis
of
the
calibration
curves
for
each
compound
and
expressed
in
micrograms
per
kilogram
of
oil
[10].
2.10
Statistical
analysis
The
experimental
data
of
quantitative
parameters
were
analysed
using
analysis
of
variance
(ANOVA)
and
Duncan's
test
with
p
<
0.05
using
the
MATLAB
®
statistics
toolbox.
The
experimental
data
of
qaulitative
parameters
were
analyzed
using
priori
one-way
analysis
of
variance
and
Tukey's
test,
using
SigmaPlot
software
package,
version
12.3
(Systat
Software,
Inc.,
San
Jose,
CA,
USA).
3
Results
This
section
explains
the
effects
of
the
tubular
heat
exchange
for
the
flash
heating
of
olive
pastes,
installed
inside
the
industrial
extraction
olive
oil
plant,
on
quantitative
plant
performance
and
olive
oil
quality.
3.1 Quantitative
results
of
the
olive
oil
extraction
plant
Table
2
shows
the
quantitative
performance
of
the
extraction
plant,
measured
as
oil
content
in
husks
(wet
and
dry
matter)
and
extraction
yield.
As
reported,
waste-water
samples
shows
traces
of
oil
for
all
tests
performed.
When
the
disc
crusher
was
used
the
EY
values
did
show
statistically
significant
differ-
ences
(p
<
0.05)
between
the
three
conditions
considered
at
10,
20,
and
30
min
of
malaxation
after
the
heat
exchanger
treatment.
In
addition,
the
DC30
condition
did
not
show
statistically
significant
difference
compared
to
the
control
test
(DCCT).
The
same
EY
obtained
in
the
control
test
can
be
obtained
using
the
DC30
condition,
gaining
10
min
of
©
2015
WILEY-VCH
Verlag
GmbH
&
Co.
KGaA,
Weinheim
www.ejlst.com
Eur.
J.
Lipid
Sci.
Technol.
2016,
118,
308-317
Tubular heat
exchanger
in
an
olive
oil
extraction
plant
313
Table
2.
Quantitative
performance
of
the
olive
oil
extraction
plant
Test
conditions
DC10 DC20 DC30
DCCT
DP10 DP20
DP30
DPCT
Moisture
content
of
pomace
(%)
56.9
±
0.8a
57.2
±
0.6a
56.6
±
0.8a
57.0
±
0.7a
63.8
±
0.5a
64.2
±
0.7a
64.7
±
0.8a
64.7
±
0.7a
Oil
content
in
husk
(%wm)
7.7
±
0.2a
7.3
±
0.1b
6.1
±
0.2c
6.1
±
0.2c
10.3
±
0.4a
9.9
±
0.2a
9.4
±
0.2b
8.4
±
0.6c
Oil
content
in
husk
(%dm)
17.5
±
0.3a
17.0
±
0.2b
13.4±0.4c
14.1
±
0.4c
27.3
±
0.8a
27.6
±
0.5a
26.7
±
0.4b
24.0±
1.1c
EY
(kg
100/kg)
10.5
±
0.3c
11.1
±
0.2b
11.9±0.2a
12.0
±
0.3a
10.7
±
0.5b
10.8
±
0.3b
10.9
±
0.4b
11.4
±
0.3a
In
all
the
tests
performed,
the
samples
of
wastewater
have
shown
a
content
of
oil
in
trace.
Data
represents
mean
value
±
standard
deviation.
Different
letters
in
rows,
for
each
quartet
of
columns,
denotes
significant
statistical
differences
(p
<
0.05).
processing
time.
These
data
were
also
confirmed
by
the
oil
content
in
husk
values.
When
the
extraction
plant
was
adjusted
in
configuration
DP,
using
the
de-pitter
machine,
the
three
conditions
considered,
DP10, DP20,
and
DP30,
does
not
shown
statistically
significant
differences
in
terms
of
EY.
Moreover
the
EY
obtained
in
the
control
test
(DPCT)
resulted
significantly
greater
than
the
EY
obtained
considering
the
other
conditions.
The
results
confirm
that
using
the
heat
exchanger
on
de-pitted
pastes
can
be
obtained
a
reduction
of
the
malaxation
time
compared
to
the
control
test
but
registering
a
significant
reduction
of
EY.
The
effect
of
the
malaxation
on
the
olive
paste
is
both
thermal
(heating)
and
mechanical
(mixing).
Instead,
the
effect
of
the
heat
exchanger
on
the
olive
paste
is
only
thermal.
The
experimental
results
confirms
that
in
the
case
of
DC
condition
the
thermal
effect
of
the
heat
exchanger
plus
malaxer
and
the
mixing
effect
for
30
min
were
sufficient
to
obtain
an
EY
comparable
with
that
obtained
in
the
control
test.
Considering
the
condition
DP,
the
thermal
effect
imparted
by
heat
exchanger
and
the
mixing
effect
of
30
min
were
not
sufficient
to
guarantee
the
maximum
EY.
This
is
due
to
the
necessity
of
longer
malaxation
time
for
the
de-pitted
paste,
compared
to
the
traditional
paste
obtained
by
disc
crusher.
The
longer
mixing
time
probably
was
necessary
because
the
excessive
oil
droplets'
emulsification
in
the
paste
obtained
by
the
de-pitter
machine.
3.2
Qualitative
results
of
the
olive
oil
extraction
plant
As
shown
in
Table
3,
the
crushing
system
used
and
the
application
of
a
flash
heating
on
the
olive
paste,
by
using
a
tubular
heat
exchanger,
did
not
show
significant
modifica-
tions
in
free
acidity,
peroxide
index,
and
spectrophotometric
vlaues
of
VOO.
The
lack
of
effect
on
the
marketable
parameters
of
VOO
due
to
the
use
of
flash
heating
in
olive
paste
was
in
agreement
to
a
previous
research
[14].
The
most
important
modification
in
VOO
quality
was
observed
for
phenolic
and
volatile
compounds
(Tables
4
and
5).
The
phenolic
content
of
VOO
is
improved
using
the
de-pitting
machine
instead
the
disk
crusher.
The
higher
differences
were
observed
for
the
secoiridoids
derivatives,
such
as
3,4-
DHPEA-EDA,
p-HPEA-EDA,
and
3,4-DHPEA-EA,
whereas
the
lignans
did
not
show
any
significant
variations
(Table
4).
Similar
results
were
obtained
in
other
works
comparing
the
de-pitting
process
with
a
traditional
hammer
crusher
[13,
25,
26].
The
application
of
flash
heating
on
the
olive
pastes
shows
the
same
trend
of
phenolic
concentration
between
the
two
crushers
used.
The
flash
heating
of
the
olive
paste,
after
the
crushing
operation,
permits
to
reduce
the
malaxation
time.
In
fact,
in
10
min
it
is
possible
to
obtain
oils
having
a phenolic
concentration
non
statistically
different
to
those
obtained
in
the
control
test.
Increasing
the
malaxation
time
(30
min)
after
the
flash
heating
treatment,
the
phenol
content
was
increased
of
27%
using
the
de-pitting
machine
and
of
17%
using
the
disc
crusher.
The
secoiridoids
derivatives,
which
had
higher
increase,
were
3,4
DHPEA-
EDA
(33%
for
the
disk
crusher
and
22%
for
de-pitted)
and
3,4
DHPEA-EA
(42%
for
the
disk
crusher
and
19%
for
de-
pitted
and
whereas
the
lignans
did
not
show
any
significant
variation.
The
flash
conditioning
of
the
olive
paste
also
affected
the
volatile
composition
of
VOO,
according
to
the
crusher
application
(Table
5).
The
use
of
flash
heating
modifies
the
aromatic
profile
of
VOO
improving
the
C6
aldehydes
and
esters
with
a
corresponding
reduction
of
C6
alcohols.
The
aroma
generation
seem
to
be
lower
affected
by
the
time
of
malaxation
after
flash
heating.
In
fact
a
significant
increase
of
volatile
compounds
according
to
the
malaxation
time
was
observed
only
for
the
esters.
The
other
groups
of
volatile
compounds
seem
to
be
affected
only
by
the
flash
heating
of
olive
pastes
after
crushing.
The
volatile
compo-
sition
of
VOO
was
also
affected
by
the
crushing
condition.
In
particular,
the
use
of
de-pitting
machine
reduces
the
aldehydes
generation
and,
at
the
same
time,
increases
the
esters
concentration.
In
any
case,
the
most
significant
impact
in
the
lipoxygenase
(LPO)
activity
seems
to
be
related
to
the
flash
conditioning
of
the
olive
pastes
that
affect
the
volatile
composition
regardless
the
crushing
system
applied.
The
behavior
of
volatile
compounds
of
VOO
obtained
using
the
flesh
heating,
confirms
the
results
obtained
in
a
previous
work
where
olives
of
cultivar
Peranzana
were
used
[14].
However,
these
results
should
be
integrated
by
analyses
of
oils
obtained
by
other
olive
cultivars.
In
fact,
the
temperature
©
2015
WILEY-VCH
Verlag
GmbH
&
Co.
KGaA,
Weinheim
www.ejlst.com
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Table
3.
Effect
of
flash
heating
process
on
the
marketable
parameters
in
olive
oils
cv.
Peranzana
obtained
by
mechanical
extraction
with
disc
crusher
(DC)
and
de-pitter
(DP)
Test
conditions
DC10
DC20
DC30
DCCT
DP10
DP20 DP30
DPCT
Acidity
(%)
0.28
±
0.02a
0.28
±
0.02a
0.31
±
0.03a
0.30
±
0.02a
0.30
±
0.02a
0.29
±
0.02a
0.29
±
0.03a
0.30
±
0.02a
Peroxide
value
(meq
0
2/kg)
7.86
±
0.60a
7.91
±
0.64a
7.79
±
0.71a
7.78
±
0.51a
8.27
±
0.73a
8.19
±
0.69a
7.79
±
0.52a
7.88
±
0.73a
K232
1.76±0.10a
1.77
±
0.20a
1.79
±
0.20a
1.73±0.10a
1.84±0.10a
1.88±0.10a
1.87
±
0.20a
1.83±0.10a
K270
0.14±0.01a
0.12±0.01a
0.12±0.01a
0.12±0.01a
0.13±0.01a
0.14±0.01a
0.14±0.01a
0.13±0.01a
AK
-0.001
±
0.0005a
-0.001
±
0.0006a
-0.001
±
0.0006a
-0.001
±
0.0001a
-0.001
±
0.0001a
-0.001
±
0.0001a
-0.001
±
0.0001a
-0.001
±
0.0001a
Data
represents
the
mean
values
of
three
independent
experiments
and
standard
deviation,
Different
letters
in
rows,
for
each
quartet
of
columns,
denotes
significant
statistical
differences
(p
<
0.05).
Table
4.
Effect
of
flash
heating
process
on
the
phenolic
composition
(mg/kg)
in
olive
oils
cv.
Peranzana
obtained
by
mechanical
extraction
with
disc
crusher
(DC)
and
de-pitter
(DP)
Test
conditions
DC10
DC20 DC30
DCCT
DP10
DP20 DP30
DPCT
3,4-DHPEA
2.9
±
0.2a
3.8±0.1b
3.1
±0.2ab
4.6
±
0.3c
3.5
±
0.2a
4.5±0.3b
3.8
±
0.2a
5.5
±
0.3c
3,4-DHPEA-EDA
214.6
±
13.3a
249.3
±
15.5ab
280.9
±
17.4b
210.5
±
13.1a
257.6
±
18.0a
299.2
±
15.6ab
337.1
±
24.3b
276.6
±
17.2a
3,4-DHPEA-EA
67.3±4.7b
69.8±4.9b
73.2±5.1b
51.4
±
3.6a
80.7
±
4.7a
83.7
±
6.9a
87.9
±
5.2a
73.7
±
5.6a
p-HPEA
3.4±0.2b
3.9±0.4bc
2.5
±
0.2a
4.3
±
0.3c
4.1±0.3b
4.7±0.3bc
3.1
±
0.2a
5.2
±
0.3c
p-HPEA-EDA
44.4
±
2.8a
44.9
±
3.8a
46.2
±
3.0a
42.4
±
2.6a
53.3
±
4.8a
53.8
±
2.9a
55.5
±
2.6a
50.9
±
3.2a
Ligstroside
aglycon
6.8±0.5ab
7.2±0.5b
5.7
±
0.4a
6.8±0.5ab
8.2
±
0.4a
8.7
±
0.5a
6.8
±
0.3a
8.1
±
0.6a
(+)-1-Acetoxypinoresinol
5.3
±
0.3a
6±0.4a
5.9
±
0.4a
5.9
±
0.4a
7.2
±
0.4a
7.0
±
0.4a
6.8
±
0.4a
7.9
±
0.5a
(+)-Pinoresinol
13.1
±
0.9a
13.1
±
0.9a
13.4
±
1.0a
13.8
±
1.0a
15.7
±
0.7a
14.5
±
0.4a
14.9
±
0.4a
14.2
±
0.8a
Total
phenol
357.9
±
13.6ab
398
±
16.7bc
431
±
18.4c
339.7
±
13.8a
430.3
±
19.3a
476.1
±
17.3ab
515.8
±
25.0b
442
±
18.3a
Data
represents
the
mean
values
of
three
independent
experiments
and
standard
deviation.
Different
letters
in
rows,
for
each
quartet
of
columns,
denotes
significant
statistical
differences
(p
<
0.05).
w!
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Table
5.
Effect
of
flash
heating
process
on
the
volatile
compounds
(µg/kg)
in
olive
oils
cv.
Peranzana
obtained
by
mechanical
extraction
with
disc
crusher
(DC)
and
de-pitter
(DP)
Test
conditions
DC10
DC20
DC30
DCCT
DPIO
DP20
DP30
DPCT
Aldehydes
(E)-2-Pentenal
86
±
la
97±
lb
102±2c
82±2a
97
±
4a
115
±2b
138±
lc
99±3a
Hexanal
638
±
8bc
598
±
9b
536
±
20a
661
±
23c
496
±
15b
426
±
23a
447
±
2a
430
±
3a
(E)-2-Hexenal
63545
±
1464c
58465
±
1648b
62615
±
1252c
50275
±
1276a
48800
±
640b
47785
±
503b
48090
±
269b
32095
±
403a
(E-E)-2,4-Hexadienal
870
±
17ab
944
±
12b
739
±
110a
842
±
13ab
971
±
44a
1103
±
10b
1113±1b
1105
±
35b
2,4-Hexadienal
(i)
579
±
16b
600
±
6b
467
±
81a
550
±
10ab
613
±
16a
653
±
8b
661
±
lb
664
±
14b
(E)-2-Heptenal
143±8a
146±8a
120
±
8b
129
±5ab
144
±
3c
144±4c
123±2a
134±2b
Sum
of
aldehydes
65860
±
1464c
60848
±
1648b
64578
±
1259c
52538
±
1277a
51121
±
642b
50224
±
504b
50570
±
269b
34527
±
405a
Alcohols
1-Penten-3-ol
195
±2a
197±8a
200
±
3a
198±5a
212±6c
209
±
12c
192
±
4b
180±
la
(E)-2-Penten-l-ol
26
±
la
25
±
la
25
±
la
26
±
la
28
±
5a
30
±
3a
29
±
la
28
±
la
1-Hexanol
2108
±
32b
2238
±
46c
1273
±
27a
4611
±
22d
2866
±
2b
3014±8c
1754±11a
5193±23d
(Z)-3-Hexen-l-ol
1559±
1lb
1839
±
4c
1215
±
2a
2178
±
4d
1940
±
28b
2336
±
51c
1627
±
6a
3674
±
23d
(E)-2-Hexen-l-ol
1927
±
28c
1760
±
27b
1568
±
59a
4376
±
95d
2060
±
8d
1808
±
6b
1544
±
14a
1957
±
33c
Sum
of
alchols
5813
±
44b
6058
±
54c
4280
±
65a
11388
±
97d
7105
±
31b
7396
±
53c
5146±
19a
11031
±46d
Esters
Hexyl
acetate
1363
±
21b
1404
±
23b
1392
±
18b
1276
±
2a
1438
±
4a
1560±11c
1892
±
7d
1506
±
4b
(Z)-3-Hexenyl
acetate
2267
±
33a
2701
±52b
2775
±
69b
2201
±
45a
2890
±
45a
3499
±
lb
4787
±
4c
3428
±
40b
Sum
of
esters
3630
±
39b
4105
±
56c
4167±72c
3476
±
45a
4327
±
45a
5059±11c
6679
±
8d
4934
±
40b
Ketones
3-Pentanone
191
±
5a
213±
lc
142
±
4b
330
±
3d
255
±
6b
285
±
lc
211
±
4a
461
±
6d
1-Penten-3-one
202±
lb
222
±
7c
259
±
12d
140
±
2a
211±
lb
244
±
3c
331
±
8d
192±3a
Sum
of
ketones
393
±
5a
435
±
7b
401
±
13a
470
±
4c
466
±
6b
529
±
3a
541
±
9a
653
±
6c
Data
are
the
mean
values
of
three
independent
experiments
and
standard
deviation.
Different
letters
in
rows,
for
each
quartet
of
columns,
denotes
significant
statistical
differences
(p
<
0.05).
3
T
ub
ul
ar
h
eat
ex
ch
an
ger
i
n
an
oli
v
e
oil
ext
r
acti
on
pl
ant
316
A.
Leone
et
al.
Eur.
J.
Lipid
Sci.
Technol.
2016,
118,
308-317
of
malaxation
affects
the
volatile
compounds
generation
by
LPO
pathway
[10]
but
this
effect
is
strongly
influenced
by
genotype
(CV)
used
for
the
production
of
VOO.
4
Conclusions
A
tubular
heat
exchanger
was
tested
in
an
olive
oil
extraction
plant
to
investigate
on
its
effects
on
the
quantitative
and
qualitative
performances
of
the
plants.
Considering
the
obtained
results,
it
is
possible
to
assert
that
the
pre-heating
of
the
olive
paste
obtained
by
the
disc
crusher,
before
the
malaxation
process,
showed
an
advantage
in
terms
of
reduction
of
malaxation
time,
of
about
10
min,
necessary
to
obtain
an
extraction
yield
comparable
to
that
obtained
by
using
the
traditional
process.
On
the
other
hand,
the
olive
paste
obtained
by
the
de-pitter
machine
have
not
benefitted
of
the
pre-heating,
thus
there
were
obtained
comparable
qualitative
and
quantitative
results
by
using
the
same
malaxation
time
of
the
traditional
process.
The
flash
heating
after
olives
crushing
affect
VOO
quality
in
terms
of
phenolic
composition
of
oil
and
volatile
compounds
generation
by
LPO
pathway.
Phenolic
com-
pounds
are
improved
in
the
oil
obtained
after
olive
pastes
flash
heating
applying
more
than
10
min
of
malaxation.
Volatile
compounds,
such
C6
aldehydes
and
esters,
respon-
sible
of
cut-grass
and
floral
sensory
notes,
respectively,
resulted
higher
in
all
the
VOO
obtained
using
flash
heating
treatment
in
the
olive
pastes
after
crushing,
respect
to
those
present
in
the
VOO
obtained
using
the
control
test.
The
advantage
of
using
the
heat
exchanger
is
the
opportunity
to
increase
the
olive
pastes'
temperature
after
the
crushing
operation,
more
efficiently
with
respect
to
the
heating
performed
in
the
malaxer.
In
many
geographical
areas
the
temperature
of
the
olive
paste
after
the
crushing
operation
is
often
less
than
10°C,
because
the
temperatures
of
the
olives
is
about
0°C.
This
scenario
occurs
frequently
during
the
cooler
hours
of
the
day
and
especially
when
the
olives
are
stored
in
outdoor
spaces.
This
condition
leads
to
two
possible
consequences:
lengthening
of
malaxation
time
and/or
increasing
of
temperature
of
the
malaxers'
hot
service
water.
In
both
cases
negative
effects
on
the
final
olive
oil
quality
occur.
Finally,
the
advantages
obtained
by
using
the
heat
exchanger
as
a
pre-treatment
of
olive
paste
before
the
malaxation
operation
are
reduced
proportionally
to
the
olives'
temperature
increase.
References
[1]
Tamborrino,
A.,
Olive
paste
malaxation.
in:
C.
Peri
(Ed.),
The
Extra-Virgin
Olive
Oil
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John
Wiley
&
Sons,
Ltd.,
UK
2014,
pp.
127-138.
[2]
Tamborrino,
A.,
Catalano,
P.,
Leone,
A.,
Using
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Influence
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Development
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the
influence
of
oxygen
on
extra-virgin
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a
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Selvaggini,
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S.,
et
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Optimization
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the
temperature
and
oxygen
concentration
conditions
in
the
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during
the
oil
mechanical
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J
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2014,
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Pati,
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Design
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malaxer
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equipped
with
an
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oxygen
injection
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the
olive
paste.
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2014,
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Ayr,
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Tamborrino,
A.,
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P.,
Bianchi,
B.,
Leone,
A.,
3D
computational
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Clodoveo,
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SA.,
Advance
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virgin
olive
oil
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from
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Influence
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oil
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Flash
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pastes
during
the
olive
oil
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the
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E.,
Specification
and
implementation
of
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an
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2014,
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2015
WILEY-VCH
Verlag
GmbH
&
Co.
KGaA,
Weinheim
www.ejlst.com
Eur.
J.
Lipid
Sci.
Technol.
2016,
118,
308-317
Tubular
heat
exchanger
in
an
olive
oil
extraction
plant
317
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microwave
treatment
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R.,
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