EFW 6-8 april 2008 - Nurtingen Transfer of water and active molecules at the interfaces in complex food systems : theoretical and practical aspects Pr A. Voilley, Pr F. Debeaufort, Dr A.M Seuvre ENSBANA, Université de Bourgogne, Dijon France 1
EFW 6-8 april 2008 - Nurtingen
Transfer of water and active molecules at the interfaces in complex food systems :
theoretical and practical aspects
Pr A. Voilley, Pr F. Debeaufort, Dr A.M SeuvreENSBANA, Université de Bourgogne, Dijon France
1
EFW 6-8 april 2008 - NurtingenEFW 6-8 april 2008 - Nurtingen
I. Basic of mass transfer and some physico-chemicalproperties of volatiles
II. Case studies – Mass transfers at the interfacesII.I without change of the physical stateII.II with changes of the physical state
III. Conclusions and perspectives
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EFW 6-8 april 2008 - NurtingenEFW 6-8 april 2008 - Nurtingen
I. Basic of mass transfer and some physico-chemicalproperties of volatiles
3
EFW 6-8 april 2008 - NurtingenEFW 6-8 april 2008 - Nurtingen
Interface
Fluid 1
Fluid 2
Transferdirection
∆x1
∆x2
C1
C2
Ci1Ci2
Concentration profile
C
xSolute B
x
Interface
Boundarylayer ∆x
Transferdirection
Concentration profile
C1
C2C
Solid
Solute B
J: compound flow (kg. s-1. m-2)M: compound mass (kg)t: time (s)A: surface (m2)D: compound diffusion coefficient (m2. s-1)C: compound concentration (kg. m-3)x: distance (m)k: compound transfer coefficient (m. s-1) = D / dx
dCkdxdCD
dtAdmJ ..
=−==
4
EFW 6-8 april 2008 - NurtingenFLAVOUR COMPOUND PROPERTIES
Flavour compound = volatile and odorous organic compound at atmospheric pressure
satiP
Compound insolution Solubility in water
wateriγPartition with airActivity coefficient
Hydrophobic constantlog P
Volatility
Pure compoundSaturated vapour pressure (Pa) - T boiling
Compound incomplex solution
liq*i
gaz*il/g
i CCk =Apparent partition coefficient
Partition with octanol(as a reference phase)
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EFW 6-8 april 2008 - Nurtingen
PHYSICOCHEMICAL CHARACTERISTICS OF AROMA COMPOUNDS
Aroma compounds
2.8
1.7
0.6
2.2
2.9
Log P calc**
0.051-144C8H16O2Ethyl hexanoate
0.612-116C6H12O2Ethyl butyrate
8.692-88C4H8O2Ethyl acetate
0.244.45.5130C6H16O2Isoamyl acetate
0.040.30.4142C9H18O2-Nonanone
calc*exp.
Solubility in water
(g/100ml)25°C
Saturatedvapour
pressure (mmHg) 25°C
MolecularweightFormula
* Calculated from Lee-Kesler model (1975)** Calculated from Rekker method (1977) 6
EFW 6-8 april 2008 - Nurtingen
CARBOHYDRATE MASS CONCENTRATION EFFECT ON FLAVOUR COMPOUND DIFFUSIVITY (25°C)
Diffusivity (10-10m2.s-1)
Acetone
Diacetyl
n-Hexanol
Mass concentration (%) of glucose syrup DE 61.5
7
EFW 6-8 april 2008 - Nurtingen
DIFFUSION COEFFICIENT OF FLAVOUR COMPOUNDS IN DIFFERENT MATRICES
Diffusivity (m2.s-1)
10-10 10-910-1110-1210-1310-14 … 10-5
Water4, 5, 7,11
• Aqueous solutions of proteins4, 5
or polysaccharides6, 7
• Oil4• Gels (pectin8, alginate9,
carrageenans10, 11)
Porous solids2, 3Edible films1
Plastic flims1
Gas (air)
1Quezada-Gallo (1999)2Souchon et al. (1996)3Takeuchi and Suzuki (1984)4Rogacheva et al. (1999)5Landy et al. (1995)6Voilley and Roques (1987)7Voilley and Bettenfeld (1985)8Rega et al. (2002)9Lian et al. (2004)10Gostan et al. (2004)11Rondeau-Mouro et al. (2004)
In the same matrix, diffusion coefficient of flavour compounds
of the same order 8
SOLUBILITY OF ETHYL ACETATE IN AQUEOUS SUCROSE SOLUTIONS
EFW 6-8 april 2008 - Nurtingen
0
50
100
150
200
-10 -5 0 5 10 15 20 25
Temperature (°C)
Solubility (g/L)
water
57.5%
Solubility varies with the composition of the matrix and temperature 9
EFW 6-8 april 2008 - Nurtingen
SOME EXPLANATIONS :
Maximal density of bulk water:
maximum hydrogenbonds water-water
Weaker water-water hydrogenbonds and water
clusters:
=> allowingaroma
dissolution
44Temperature (°C)
30% sucrose43.5% sucrose57.5% sucrose
Solubility of hexanol(g/L)
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EFW 6-8 april 2008 - Nurtingen
COMPARISON BETWEEN HYDROPHOBICITY AND SOLUBILITY OF AROMA COMPOUNDS (25°C)
Solubility in water (g.L-1)
2-undecanone
2-nonanone
2-octanoneIsoamyl acetate
2-heptanoneAcetophenone
cis-3-hexenol
2,5-dimethyl-pyrazine
-2
-1
0
1
2
3
4
5Log P
0.01 0.4 1.5 2.4 4.3 7.1 18 ∞
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EFW 6-8 april 2008 - Nurtingen
VAPOUR LIQUID PARTITION COEFFICIENTS
K x 103
0.5
1.5
2.5
Benzaldehyde Linaloolvegetable oil
waterwith salt (NaCl)
with 3% dairy protein
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EFW 6-8 april 2008 - Nurtingen
VOLATILITY OF AROMA COMPOUNDS IN A 57.5% SUCROSE SOLUTIONAS A FUNCTION OF TEMPERATURE
0.00
4.00
8.00
12.00
16.00
20.00
-15 -10 -5 0 5 10 15 20 25 30 35Temperature (°C)
Kmassethyl hexanoate in water
ethyl acetate in water
ethyl hexanoate in sucrose solution
ethyl acetate in sucrose solution
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EFW 6-8 april 2008 - Nurtingen
II. Case studies – Mass transfers at the interfaces
II.I without change of the physical state
14
EFW 6-8 april 2008 - NurtingenLIQUID-LIQUID MASS TRANSFER
THROUGH A LIPID LAYER – PROTEINS AT WATER/LIPID INTERFACEDiagram of the Rotative Diffusion Cell
Cylindrical rotating baffle
Outercompartment
Filter saturatedwith the lipid
Inner compartment witharoma compounds
Thermostattedwater
Protein at water /lipid interface
Lipid in filter pores15Flavour compound
EFW 6-8 april 2008 - Nurtingen
TRANSFER IN THE ROTATIVE DIFFUSION CELL
OVERALL RESISTANCE TO THE MASS TRANSFER
16
PDL
k2
DZ2
k1R
0iaq α+
α+==
1/k: total resistance (m-1.s)Daq : solute diffusion coefficient (m2.s-1)Z : thickness of the stagnant layer (m)ki : permeability coefficient (m.s-1)α : porosity of the filter (0.8)L : thickness of the oil membrane (m)Do : solute diffusion coefficient in oil (m2.s-1)P : solute liquid-liquid partition coefficient
RESISTANCES
Diffusion in aqueous stagnant layer = Raq
Interfacial transfer = RI
Diffusion in oil = Roil
aqDZ2
PDL
0α
ik2α
WATER
OIL MEMBRANE
WATER
Levich model
EFW 6-8 april 2008 - Nurtingen
RESISTANCE TO THE MASS TRANSFER OF THE AROMA COMPOUNDS
Ioil RRRaqk1 ++=
Levich equation
Raq, resistance to the diffusion in the aqueous phase;Roil , resistance to the diffusion in the lipidic phase; RI, resistance to the diffusion in the two limit aqueous layers
Aroma compound β-lactoglobulin (%, w/w) Raq (%) Roil (%) RI (%)benzaldehyde 0 89.2 5.9 4.9 benzaldehyde 3 78.3 4.8 16.9 2-nonanone 0 55.7 0.3 44.0
2-nonanone (pH 3) 3 38.9 0.6 60.5 2-nonanone (pH 9) 3 64.1 0.9 35.0
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EFW 6-8 april 2008 - Nurtingen
18
t.D2xerfc
21
CC
0
)t,x( =
x
0CC
x
0CC Without barrier With barrier
Homogeneous and same mediumin each cylinder
CONCENTRATION PROFILE METHODE FOR THE DIFFUSIVITY DETERMINATION WITH SOLID PHASES
At t=0
At t time
x
0CC Interface
EFW 6-8 april 2008 - Nurtingen
WATER CONTENT PROFILE FOR A SPONGE CAKE IN CONTACT WITH A GEL AT 20°C
-2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.520
30
40
50
60
70
80
Dis tance (cm)
Teneur en eau (g/100g m.h.)
J+1J+3J+7J+14
Gelatin gel Sponge cake
-2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.520
30
40
50
60
70
80
Dis tance (cm)
Teneur en eau (g/100g m.h.)
J+1J+3J+7J+14
Gelatin gel Film Sponge cake
Wat
er c
onte
nt (g
/100
g w
.b.)
Wat
er c
onte
nt (g
/100
g w
.b.)
60% fat emulsified in iota-carrageenan film (100µm)
19
StrEFW 6-8 april 2008 - Nurtingen
INFLUENCE OF WATER ACTIVITY ON THE FLUORESCEIN DIFFUSIVITY IN CARRAGEENAN EDIBLE FILMS
0 0.2 0.4 0.6 0.8 10
0.4
0.8
1.2
1.6
aw
Fluorescein Diffusion Coefficient D (x10 -12 m2.s-1)
Change in structural propertiesof the carrageenan matrix
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EFW 6-8 april 2008 - Nurtingen
II. Case studies – Mass transfers at the interfaces
II.II with changes of the physical state
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EFW 6-8 april 2008 - Nurtingen
Liquid or Solid matrices Vapour phaseinterface
Simple systemSolubility in the matrix
Partition with air Volatility
Complex system
*/
*
gazg l ii liq or solid
i
CkC
=
Apparent partition coefficient
Partition between the different phases of the matrix
22
EFW 6-8 april 2008 - NurtingenVAPOUR/MATRIX MASS TRANSFER COEFFICIENT OF ETHYL
HEXANOATE IN DIFFERENT FOOD MATRICES
MATRIX
MASS TRANSFER COEFFICIENT OF
ETHYL HEXANOATE
(×107 m.s-1)
EXPERIMENTAL CONDITIONS
REFERENCE
Water 9.2
7.6
Dynamic cumulative headspace, 25°C
Static headspace, 25°C
Juteau et al.
(2004)
Oil in water emulsion (2% fat)
10 Dilution by a stream of
gas, 22°C Doyen et al.
(2000)
Iota-carrageenan gel 2 Static headspace, 25°C
Starch gel 6.9 Dynamic cumulative
headspace, 25°C
Juteau et al. (2004)
Dairy gel with 5% fat 9
Pectin gel 1.9 Static headspace, 10°C
Nongonierma
et al. (2005)
Great influence of the experimental conditions on the values23
EFW 6-8 april 2008 - Nurtingen
Ethyl butanoate Pentan-2-one
Ethyl acetate Ethyl hexanoate
RATE OF RELEASE OF SOME AROMA COMPOUNDS INDIFFERENT MATRICES WITH SAME VISCOSITY(37°C°
water carbohydrate matrix emulsion complex matrix 24
EFW 6-8 april 2008 - Nurtingen
MATRIX EFFECT ON VAPOUR / MATRIX TRANSFER COEFFICIENT
Dairy gel (D.G.) 0% fat
EAEB EH
EI
0 0.5 1 1.5 2 2.5 3
logP
0.0
0.5
1.0
1.5
2.0
2.5
Mas
s tr
ansf
erco
effic
ient
(1
06m
.s-1
)
EA
EI
EB
EH
D.G. 5% fatPectic gel (P.G.)
EHEAEBEI
EA: ethyl acetateEI: ethyl isobutanoateEB: ethyl butanoateEH: ethyl hexanoate
Interface vapour/matrix
25
D.G. 5% fat logP
P.G. Transfer P.G. << D.G.
Effect of the fat
Main effect of the pectic gel
D.G. 0% fat no différence
EFW 6-8 april 2008 - Nurtingen
Aro
ma
C/
C0
0,0
0,2
0,4
0,6
0,8
1,0
0 200 400 600 800Time (h)
3,0
3,2
3,4
3,6
3,8
4,0
4,2
pH
1,40
1,45
1,50
1,55
1,60
Wat
er c
onte
nt
(kg
HO
/kg
d.b
.)2
COUPLED MASS TRANSFERS : PROTON, WATER and FLAVOUR COMPOUNDS BETWEEN THE DAIRY MATRIX AND THE PECTIC GEL
• H3O+ and flavour compounds transfers require same time scale compared to water
26
EFW 6-8 april 2008 - NurtingenMECHANISM OF MOISTURE OR CONDENSABLE VAPOURS
TRANSFER THROUGH BARRIER LAYERS
Permeation of small molecules through thin layers (interfaces) implies a molecular diffusion due to a chemical potential differentialbetween the two sides of the layer
Inner compartmentp1 - µ1 - aw1 - RH1
C1
C2
Desorption-evaporation
Condensation-sorptionouter compartmentp2 - µ1 - aw2 - RH2
Diffusion
Mass transfer mechanism : a 3 steps process :
• sorption coupled or not to condensation• diffusion of the small molecule in a liquid state• desorption coupled or not to evaporation
P = D x S
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EFW 6-8 april 2008 - Nurtingen
RELATIONSHIP BETWEEN DIFFUSIVITY AND PERMEABILITY
E-acetate
E-isobutyrate
2-pentanone
E-butyrate2-heptanone
2-pentanone
2-nonanone2-octanone
2-heptanone
E-acetate
D-Limonene
E-hexanoate
E-butyrateE-isobutyrate
1
10
100
1000
10000
100000
0,1 1 10 100
Diffusivity (10-13 m²/s)
Perm
eabi
lity
(10-1
4 g/m
.s.P
a)Gluten MC
There is no apparent relationship between the diffusivityand permeability of aroma compounds through neithermethylcellulose nor wheat gluten films
28
EFW 6-8 april 2008 - Nurtingen
EFFECT OF AROMA HYDROPHOBICITY ON THEIR TRANSFER THROUGH METHYLCELLULOSE FILMS
2-nonanone
2-pentanone
isobutyrate d'éthyleethyl acetate
Log P Hydrophobicity constant
0
5
10
15
20
25
30
35
40
45
0 0,5 1 1,5 2 2,5 3 3,5 4 4,5 5
Perm
eabi
lity
(10-
11g.
m-1
.s-1
.Pa-
1 )
2-heptanone
ethyl butyrate
2-octanone
1 octen-3 ol
ethyl hexanoate
Aroma hydrophobicity seems to be a key factor of the barrier properties
29
EFW 6-8 april 2008 - Nurtingen
COUPLED TRANSFER RATES OF BOTH MOISTURE (RH)AND AROMA (1octen-3-ol)
0
50
100
150
200
250
0 20 40 60 80 100Water vapour transfer rate (10-4 g.m-2.s-1)
1-oc
ten-
3-ol
tran
sfer
rate
(1
0-6g.
m-2
.s-1
)
Plasticization of the polymer network by moisture
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EFW 6-8 april 2008 - Nurtingen
Carrageenansupport side
Carrageenan+ 60% fatsupport side
Carrageenan+ 60% fatair side
0 30 60 90 sec
Swelling
WVPrelative = 2,5
Side effect
WVPrelative = 1
15
Absorption
WVPrelative = 2
Contact time :
WETTING BEHAVIOUR OF CARRAGEENAN FILMS RELATED TO COMPOSITION, FACE EXPOSED AND VATER VAPOUR
PERMEABILITY (WVP)
Both the composition (emulsifiers) and the surface structure strongly influence the water transfer in edible films
31
EFW 6-8 april 2008 - Nurtingen
WATER DIFFUSION THROUGH THE FILM MEASURED BY FTIR-ATR
Multi-reflectionInfraredradiation
DetectorCrystal (ZnSe)
Film : 100 µm dp ~ 5µmLiquid water
Crystal
25003000350040000
0.5
1
1.5
2
-1
Abs
orba
nce
25003000350040000
0.5
1
1.5
2
Wave numbe r (cm-1)
Abs
orba
nce
t = 0 to 300 s(step: 15 s)
Wave numbe r (cm )
0 50 100 150 200 250 3000
0.2
0.4
0.6
0.8
1
time (s )
At/A
∞
0 50 100 150 200 250 3000
0.2
0.4
0.6
0.8
1
time (s )
At/A
∞ Air sidein contactto water
Dwater ~ 9 x10-11 m2.s-1
Carrageenan + 60% fat
0 50 100 150 200 250 300 350 4000
0.2
0.4
0.6
0.8
1
time (s )A
t/A∞
0 50 100 150 200 250 300 350 4000
0.2
0.4
0.6
0.8
1
time (s )A
t/A∞
∆t > 100 sSupport side
in contactto water
Non Fickian 32
EFW 6-8 april 2008 - Nurtingen
EFFECT OF BOTH THE WATER ACTIVITY DIFFERENTIAL AND THE PHYSICAL STATE OF WATER
ON THE TRANSFER RATE OF CHOCOLATE BASED BARRIERS
0
200
400
600
800
1000
1200
1400
1600
Wat
er tr
ansf
erra
te
(10-5
g.m
-2.s
-1)
0.8-0.2 0.9-0.2 1.0-0.2
Water activity differential
liquid
vapour
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EFW 6-8 april 2008 - Nurtingen
LIQUID CONTACT VERSUS VAPOUR CONTACT :THE SCHROEDER PARADOX
For a same activity (or a same chemical potential) differential, the transfer rate through a dense membrane is always much greater when the diffusing substance
in contact to the membrane is liquid.
Aroma transfer through silicone membrane depends on the physicalstate of the aroma in contact with the membrane
From Valleries et al., 2006 34
EFW 6-8 april 2008 - Nurtingen
kinetics = mass transfer coefficient, diffusivity…
Transfers =thermodynamics = solubility, partition coefficients,
affinity, interactions
Fick, Henry laws etc ….
An integrated approach of the mass transfers in foods :
How to take into account both :
structure/physical state and interfacial properties ???
=> from macroscopic to molecular scales36
EFW 6-8 april 2008 - Nurtingen
37
PREDICTION OF MOISTURE TRANSFERS IN COMPOSITE FOODS :APPLICATION OF CACAO BASED COATINGS TO SUGAR WAFER
02468
1012141618
Tim
eof
sto
rage
(mon
th)
Target time
Aw critical = 0.45Aw critical = 0.45Aw critical = 0.35Aw critical = 0.35
Coating 1P = 2.7
Coating 2P = 1.1
Coating 1P = 2.7
Coating 2P = 1.1 10-11g.m . s .Pa-1 -1 -1
ExperimentalCalculated
Transfers play a role on quality preservation
EFW 6-8 april 2008 - Nurtingen
RELATIONSHIPS BETWEEN TRANSFER RATE AND FLAVOUR PERCEPTION OF FRUITY STRAWBERRY ODOUR OF THE PECTIC GEL
y = 3,86x - 0,31R2 = 0,76
0
3
6
9
1,2 1,4 1,6 1,8Log10[ethyl esters]
Odo
urin
tens
ity
Transfers play a role on the sensory perception
38