Mass transfer and aroma compounds Flavour release from food products Violaine ATHES, Cristian TRELEA...

Mass transfer and aroma compounds

Flavour release from food products

Violaine ATHES, Cristian TRELEA

october 2012

Erasmus Mundus Master Course FIPDesFood Innovation & Product Design

• Small volatile molecules (MM<300g/mol), which partial pressure at atmospheric pressure is sufficient to induce a stimulus on olfactive sensors.

Aroma compounds

Aroma compounds « Key» compounds of organoleptic quality of

foods

Aroma compounds properties

Volatile molecules: odorous

Low MM

Low concentrations in food products

Complex medium = Interactions between aroma compounds and other constituents of the food matrix

How to formulate food products (aromatisation) for a perception meeting consumers expectations?

Product developpement

Formulation/Process

Storage in packaging Consumption

Unit operations

- mixing- cooking- Drying- separation- …

Food Matrix

Headspace

Packaging

Food Matrix

Oral cavity, Pharynx, Nasal cavity

Aroma compounds transfer in processes and products

From process engineering to product engineering…

Sensorial analysisConsumers studies

Food & AromaFormulation / Process

Reverse engineering

Physico-chemical properties of aroma

compounds

Sensorial analysis

“Flavour Release” in air

“unit operation”Mass transfer

coupled to heat and momentum transfer

Food & AromaFormulation / Process

“Flavour Release” in mouth

“unit operation in mouth”Mass transfer

coupled to heat and momentum transfer

Flavour release during food consumptionFlavour release during food consumption

Nasal cavity

Oral cavityPharynx

ŒsophagusTracheus

=> Difference in behaviours of flavour release8

Flavour release

Velo-pharynx opening

Olfactive receptorsOlfactive receptors

Step 1: in mouth

Nasal cavity

Oral cavityPharynx

ŒsophagusTracheus

9

Step 1: in mouth

Step 2: Pharynx

Flavour release

Olfactive receptorsOlfactive receptors

Flavour release during food consumptionFlavour release during food consumption

=> Difference in behaviours of flavour release

=> Layer on pharynx mucosa

Atmospheric Pressure Chemical Ionisation Mass Spectrometry

Airsampling

Heating (100°C)

Ionisation

Detection (mass spectrometry)

Quantification (Real time evolution of known volatile compounds concentration)

IN VITRO ANALYSIS

IN VIVO ANALYSIS

EXPERIMENTAL in vitro

DEVICE

GAZ

Foodsample

Flow air

Flow air + aroma

API- MS

Atmospheric pressure ionisation - mass spectrometer

Calibration

Cgas

time (min) Each volatile compound

Constant temperature

t = 0

“Headspace”

IN VITRO

GAS

LIQUID

Interface

Concentration

Dg=0

C(t=0)

C ’(t=0)x

Partition

EQUILIBRIUM : initial condition in the case of a closed packaging

HomogeneousLIQUID

Convection (kl)

Convection (kg)

C(t)

C’( x,t)

ConcentrationPartition+Transfer

Interface

GAS

DgDg+C(t)Dg

DYNAMIC DILUTION of GAS PHASE Opening of packaging

« convective» model : liquid product

I. Thermodynamic properties

Equilibrium

PARTITION COEFFICIENT

GAS

LIQUID

Interface

Concentration

Dg=0

C(t=0)

C ’(t=0)x

Partition

EQUILIBRIUM at interface

THERMODYNAMIC PROPERTIESVapour – Liquid equilibrium

Binary mixture: solvent (j: water) + aroma (i)

1. Vapour phase

«Ideal» : Dalton law à T :

2. Liquid phase2.1 «Ideal» solution : Raoult law2.2 «non ideal» solution : activity coefficient

a) diluted solution : Henry law ( )b) concentration dependance ( )

i

i

Pi yi P .

Pi i xi Pi T ai Pi T . . ( ) . ( )0 0

Vapour

Liquid

P

• Equilibrium

• Partition coefficient between gas and liquid

Ky

x

P T

Pglig

i

i i

T

. ( )0

P x P T y Pi i i i ig

T . . ( ) .0

gazigazvapeurT PPPPP

Ky

x

P T

Pglig

i

i i

T

. ( )0

xi 0

Henry Constant

( )i

Vapour+Gas

Liquid

PT

à T :

THERMODYNAMIC PROPERTIESLIQUID – GAS (AIR) EQUILIBRIUM

THERMODYNAMIC PROPERTIESPARTITION COEFFICIENT

Activity coefficient(non ideality in solution)

Pi T0( )

i Pi T. ( )0

volatility = partition coefficient

Vapour Pressure(pure compounds)

T

i

xi0 1

1

j

Partition coefficients of some aroma compounds in water

Molecule MW (g/mol) C’

(kg/m3)

Activity coeff.

Infinite dilution in water

Vapor pressure

at 25°C (Pa)

K exp.

Water

K calc.

Water (*)

2,5-Dimethyl-pyrazine

108.14 8.37E-3 23 448 5.7E-5 6.3E-5

Diacetyl 86.09 9.61E-4 11 8 283 3.9E-4 5.7E-4

E-(2)-hexenal 98.1 5 ppm 687 390 1.6E-3 -

Acetaldehyde 44.05 1.1E-3 4 120 000 2.7E-3 2.9E-3

Menthone 154.25 8.93E-5 24 870 44.5 7.1E-3 6.9E-3

Anethole 148.2 5 ppm 63 405 4 8.2E-3 -

Ethyl acetate 88 5 E-4 12 112 66 7 E-3 5 E-3

Ethyl butyrate 116.6 5 ppm 1 116 2 300 4 E-2 -

Ethyl hexanoate 144.2 5 ppm 17 260 150 4 E-2 -

Ethyl octanoate 172.3 5 ppm 313 328 16 2 E-2 -

Dimethylsulfide 62.13 8.46E-4 208 62 980 2.5E-2 8.1E-2

Volatility variation (K) from 10-2 to 10-5 depending on aroma

(*) Theoretical

K

II. Kinetic properties

Mass transfer

• DIFFUSION

• CONVECTION

LIQUIDhomogeneous

Convection (kl)

Convection (kg)

C(t)

C’( x,t)

ConcentrationPartition+Transfer

Interface

GAS

DgDg+C(t)Dg

Convective model

TRANSFERGAS-LIQUID INTERFACE

)CC(kJ *LLLi

CL

CG

)CC(kJ G*GGi

GAS LIQUID(A)

kL

kG

*L

*G

glC

CK

Ji kO KglCL CG ( )

1 1

kO kG

KglkL

(Resistancesin serie)

2.2. Mass transfer at interface liquid/air:

Cg(t))(KglCl(t)ko J(t) -= Kgl1

klkg+=

ko

1

2.3. Mass balance in liquid J(t).Adt

(t)dClVl. -=

2.1. Mass balance in air Dg.Cg(t)J(t).Adt

dCg(t)Vg. -=

Interface liquid / air :

Condition initiale : Cg(t=0) = Kgl. Cl(t=0) = 0

Kgl = Cg*/Cl*

Numerical solution (Matlab)

Cg(t) & Cl(t)

Convective model for a flavour release from a liquid in mouth (in

vitro)

Quantification of interactions between aroma compounds and non-volatile compounds (water, fat)

References Complex food matrix

wateri

airiwaterair

i C

Ck /

wateri

fatieaufat

i C

Ck /

Partition coefficientair / water

Partition coefficientfat* / water

producti

airiproductair

i C

Ck /

Partition coefficient in emulsions

* Data often available for organic solvent (octanol)rather than fat (LogP)

diacetyl - décalactone

water water oil+

airairair

wateri

airiwaterair

i C

Ck /

Guyot et al., 1996

wateri

fatiwaterfat

i C

Ck /

)( /

//

/

waterfatfatwater

waterairemulsionair

i

emulsioni

airiemulsionair

i

kFF

kk

C

Ck

Buttery et al., 1973

Fat content % m/mFat content % m/m

emulsionairik

/ emulsionairik

/

emulsionairik

/Example of result

Partition coefficient prediction of aroma compounds in an emulsion : k air/emulsion

ANALYSE IN VIVO