Scholarly article on topic 'Transfer of Water and Active Molecules at the Interfaces in Complex Food Systems: Theoretical and Practical Aspects'

Transfer of Water and Active Molecules at the Interfaces in Complex Food Systems: Theoretical and Practical Aspects Academic research paper on "Agriculture, forestry, and fisheries"

CC BY-NC-ND
0
0
Share paper
Academic journal
Procedia Food Science
OECD Field of science
Keywords
{Interface / measurement / "heterogeneous systems" / thermodynamic / kinetic}

Abstract of research paper on Agriculture, forestry, and fisheries, author of scientific article — Andrée Voilley, Anne-Marie Seuvre, Régis Gougeon, Thomas Karbowiak, David Chassagne, et al.

Abstract During processing, storage and consumption, mass transfer of various molecules (water, gases, flavour compounds or other solutes) occur between the different phases in complex food products, and/or also between the complex food and its surroundings. These mass transfers can lead to physical and/or chemical changes and thus induce food quality modifications. The objective of this presentation is to better understand the behaviour of small molecules at the interfaces, especially in model heterogeneous food systems. Different techniques have been developed to characterize their properties and their impact on the mass transfers. Particularly, techniques such as rotative diffusion cell or Fourier Transform Infra-Red spectroscopic analyses with modelling have been set up. Five examples of results are displayed to demonstrate the influence of the physical-chemical parameters (thermodynamic such as partition coefficient, hydrophobicity… or kinetic parameters like sorption, diffusion and permeation coefficients) on mass transfers. These examples focus on water (liquid or vapour) through polysaccharidic edible films, on flavour compounds in dairy emulsions or in pectic gels. Not only the composition of the matrix but both the structure and the process also influence the mass transfer. Observed results can be explained by similar phenomena, even if applications seem very different.

Academic research paper on topic "Transfer of Water and Active Molecules at the Interfaces in Complex Food Systems: Theoretical and Practical Aspects"

Available online at www.sciencedirect.com ^^^^^^^^^^^^^^^

SciVerse ScienceDirect PrOCGd ¡0

Food Science

Procedia Food Science 1 (2011) 879 - 885

11th International Congress on Engineering and Food (ICEF11)

Transfer of water and active molecules at the interfaces in complex food systems: theoretical and practical aspects

Andrée Voilley *a,b, Anne-Marie Seuvrea c, Régis Gougeona d, Thomas Karbowiaka b, David Chassagnead, Frédéric Debeaufortac

aEA EMMA, Université de Bourgogne, 1 esplanade Erasme, 21000 Dijon, France b Agrosup Dijon, 26 Boulevard Docteur Petitjean, 21079 Dijon, France c IUT Génie Biologique, Université de Bourgogne, Bd Docteur Petitjean, 21078 Dijon, France d Institut Universitaire de la Vigne et du Vin "Jules Guyot", Université de Bourgogne, 21078 Dijon, France

Abstract

During processing, storage and consumption, mass transfer of various molecules (water, gases, flavour compounds or other solutes) occur between the different phases in complex food products, and/or also between the complex food and its surroundings. These mass transfers can lead to physical and/or chemical changes and thus induce food quality modifications. The objective of this presentation is to better understand the behaviour of small molecules at the interfaces, especially in model heterogeneous food systems. Different techniques have been developed to characterize their properties and their impact on the mass transfers. Particularly, techniques such as rotative diffusion cell or Fourier Transform Infra-Red spectroscopic analyses with modelling have been set up. Five examples of results are displayed to demonstrate the influence of the physical-chemical parameters (thermodynamic such as partition coefficient, hydrophobicity... or kinetic parameters like sorption, diffusion and permeation coefficients) on mass transfers. These examples focus on water (liquid or vapour) through polysaccharidic edible films, on flavour compounds in dairy emulsions or in pectic gels. Not only the composition of the matrix but both the structure and the process also influence the mass transfer. Observed results can be explained by similar phenomena, even if applications seem very different.

© 2011 PublishedbyElsevierB.V.Selectionand/orpeer-review underresponsibilityof11thInternationalCongress onEngineeringandFood(ICEF11)Executive Committee.

Keywords: Interface; measurement; heterogeneous systems; thermodynamic; kinetic

* Corresponding author. Tel.: +00-33-3-80774059; fax: +00-33-3-80774011. E-mail address: a.voilley@agrosupdijon.fr, andree.voilley@u-bourgogne.fr.

ELSEVIER

2211-601X © 2011 Published by Elsevier B.V. Selection and/or peer-review under responsibility of 11th International Congress on Engineering

and Food (ICEF 11) Executive Committee.

doi:10.1016/j.profoo.2011.09.133

1. Introduction

The behaviour of small molecules such as water and aroma compounds at the interfaces in complex food systems (with or without edible barriers) has a key role of the quality and stability of food products [1]. Figure 1 shows how the boundary layers (stagnant) affect the concentration profile at the interface between two fluids.

Concentration profile

Fluid 1 Solute C1

Ax1 { k i"

Inteiface ! Ax2! Fluid 2 -1-„ \Ci,

Transfert direction

Fig. 1. Schematic representation of mass transfer at the interface (boundary layers)

This presentation focuses on the kinetics (diffusivity, permeability, transfer coefficients...) and thermodynamics (phase equilibrium, partition coefficients..) phenomena occurring at the interfaces with or without changes of the physical state at the interfaces. Each case will be discussed and illustrated by some examples. Hereafter, the permeation process is illustrated including the sorption-diffusion model (figure 2).

Inner compartment_

Pi - Mi - awi - RHi

Condensation-sorption

Desorption-evaporation

outer compartment p2 - M1 - aw2 - RH2

Diffusion

Fig. 2. Permeation of small molecules through thin layers (interfaces)

The physical-chemical and structural characteristics of both small molecules and matrices are taken into account and related to the properties of the interfaces.

The objectives are to present recent research in relation with the role of surface properties of different materials on mass transfers.

2. Materials & Methods

Many techniques have been set up to measure mass transfers and the interface properties. All the conditions are given with different approaches, classical or not, from molecular to macroscopic scale [2]. An experimental design was developed by Harvey et al [3] and based on the Levich equations. This permits to determine the resistances of mass transfer at the interfaces between two liquids such as in emulsions (figure 3).

Protein at water /lipid interface Lipid in filter pores Flavour compound

Fig. 3. Liquid-liquid mass transfer through a lipid layer - proteins at water/lipid interface: Diagram of the rotating diffusion cell

Another methodology was set up by Karbowiak et al [4] who developed a Fourier Transform InfraRed (FTIR) spectroscopic technique to study the apparent diffusivity of water in thin layers in relation with the surface properties. The figure 4 gives the principle of the apparent diffusivity measurement applied to edible films.

from source

Fig. 4. Attenuated Total Reflectance (ATR) sampling unit for measuring apparent diffusivity in thin layer membranes

3. Results & Discussion

A review of our recent works on volatile compounds is given to demonstrate the role of mass transfer between different phases on the quality of food [1]. The first example studied deals with the release of aroma compounds from complex food matrices.

- The aroma release from a food product strongly influences the perception and then the quality. This release depends on the transfers at the solid/vapour or liquid/vapour interfaces and of the hydration level.

For instance, in a complex food matrix, the mass transfer coefficients of aroma compounds (esters) at the vapour matrix interfaces not only depend on the composition (presence of fat) but also on the structure of the pectic gel compared to dairy gel without fat (figure 5).

-t—1

o ,—.

a ^ £

en C£>

2.0 -1.5

0.5 -0.0

eaJ ea£~

A Dairy gel (D.G.) 0% fat EIi t a D.G. 5% fat IEB

0 Pectic gel (P.G.)

o c EB

EA: ethyl acetate El: ethyl isobutanoate EB: ethyl butanoate EH: ethyl hexanoate

ÎEH Interface-1

'eh vapour/matrix

1.5 logP

Fig. 5. Matrix effect on vapour / matrix transfer coefficient

The coupled transfers must also be taken into account because each diffusing molecule moves in different directions according to the time, as illustrated in figure 6. As water content increases progressively, the pH highly rises whereas the aroma compound concentration exponentially decreases.

Fig. 6. Coupled mass transfers: proton, water and flavour compounds between the dairy matrix and the pectic gel [5]

The nature of the matrix and the volatility of the aroma compounds affect the partition coefficient at equilibrium whereas the interface has a significant effect on the kinetics of the release. Then, to better focus the phenomenon at interface, the Harvey et al method [3] has been set up to measure the mass transfers at the interface.

- Migration phenomenon in emulsion deals with the liquid/liquid interface. The transfers of solutes between the dispersed phase and the continuous phase in emulsion are driven by the partition coefficient between oil and aqueous phase and by the structure of the globule or droplet surface. The rotating diffusion cell (figure 3) allows to determining the overall mass transfer, but also the mass transfer resistance of the interfaces, the diffusion coefficient through the stagnant layers at the surface of the droplets according equations given in figure 7. When proteins are dispersed in the aqueous continuous phase or when the water content increases, the migration of aroma compounds varies according to their physical-chemical properties such as solubility, hydrophobicity, etc. Table 1 displays the effect of protein

content on the diffusivity in the aqueous phase, in the oil and at the interface. The interfacial resistance for benzaldehyde highly increases only if p-lactoglobulin is added to 3% in the emulsion [6].

Levich model

„ 1 2Z 2 L

R = — +-+-+-

k Daq ak; aD0P

1/k: total resistance (m-1.s)

Daq : solute diffusion coefficient (m 2.s-1)

Z : thickness of the stagnant layer (m)

ki : permeability coefficient (m.s-1)

a : porosity of the filter (0.8)

L : thickness of the oil membrane (m)

Do : solute diffusion coefficient in oil (m 2.s-1)

P : solute liquid-liquid partition coefficient

OIL MEMBRANE

RESISTANCES

D Diffusion in aqueous stagnant layer = R a

aD0P _2_ ak;

Diffusion in oil = Roil Interfacial transfer = R,

Fig. 7. Lewich model for determining the diffusivity in the different phases and at interface Table 1. Resistance to the mass transfer of the aroma compounds (Levich model)

Aroma compound ß-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

- Through a study [7] related to the interactions between two closely related volatile phenolic compounds and particles of lignin extracted from oak wood, it is demonstrated that lignin is responsible for a selective sorption of these aroma compounds. Two mechanisms are involved: both physisorption and partly chemisorption for 4-vinylguaiacol occur whereas only physisorption affects the 4-ethylguaiacol sorption by lignin (figure 8).

Fig. 8. Adsorption (open symbols)-desorption (full symbols) isotherms of 4-ethylguaiacol (o,^) and 4-vinylguaiacol (□,■) on lignin at 298 K

- Food industry has a strong interest for composite foods presenting texture and composition contrasts such as stuffed biscuits or sandwiches. In these products, moisture transfers are often responsible for texture, colour and taste losses. Then controlling mass transfers at the solid/solid interfaces is needed. This can be achieved through the use of edible barriers (films and/or coatings). Recent works show that spectroscopic techniques (figure 4) allows measuring the moisture diffusivity at micrometric scale, very close to the interface between the different compartments of composite foods [4]. The figure 9 shows the importance of scale of measurement and penetration depth of infra-red signal for the analysis of the results. Moreover, the interface structure moves and can induce wrong estimation of the diffusivity. From this technique, Karbowiak et al [4] demonstrated the importance of the film surface properties on the mass transfer.

Fig. 9. Kinetics of the absorbance ratio obtained for a iota-carrageenan film: experimental data (o) and modeling (—) assuming a Fickian transfer, from analytical solution (left graph), and by taking into account the penetration depth of the infrared radiation

(right graph)

- Moreover, the state of water affects the moisture transfers through edible films related to interfacial modifications. Hambleton et al [8] confirm the Schroeder paradox occurs in alginate films due to swelling, as displayed in figure 10. Schroeder stated that the physical state (vapour or liquid) of the diffusing molecule at the ingress surface of a membrane or film strongly affects its diffusivity for a same chemical potential differential between the two surfaces. He often observed a strong increase of the diffusivity when a liquid contact occurs.

Permeability (IO-,0g.m"l.s",.pa"')

1.4 t---^^m—

□ Water Vapour P _\

12 ~ □ Liquid Water P \

jHf nBH

S * S * f 1 I *

1 8 $e fe

If || *P f|

¡5 8 ? ?

Fig. 10. Liquid and vapour water contact permeability in films

- Encapsulation of aroma compounds (or other active compounds) with edible films could be used with the aim to better control the release and to prevent their loss and degradation [9]. The biopolymer network

and the presence of fat allow controlling the release kinetics of various aroma compounds. Neither the hydrophobicity nor the solubility nor the partition coefficient can explain the kinetics, which seems to mainly depend on the structural characteristics. This study allowed investigating the possibility to use edible films as active packaging. In the same way, Gharsallaoui et al [10] also display that pea proteins improve the aroma retention in emulsions during spray drying.

4. Conclusion

All these mass transfer phenomena at the different interface cases can modify the sensory quality of the foods. They can be coupled together or with chemical reactions in some complex systems. An integrated approach is often necessary to assess mass transfers in food systems by taking into account kinetic and thermodynamic parameters, but also the structural and interfacial characteristics of the matrices.

Acknowledgements

We would like to thank Drs Sonia Lequin and Alicia Hambleton for their active participation. References

[1] Voilley A. & Souchon I. 2006. Flavour retention and release from the food matrix: an overview. In: Voilley A. & Etievant P. (Eds.). Flavour in Food. CRC Press, pp117-132.

[2] Cayot N., Dury-Brun C., Karbowiak T., Savary G.& Voilley A. 2008. Measurement of transport phenomena of volatile compounds: A review Food Research International, 41(4), 349-362

[3] Harvey B. Druaux C. & Voilley A. 1995. Effect of protein on the retention and transfer of aroma compound at the liquid water interface. In Dickinson E. & Lorient D. Food Macromolecule and colloids. The Royal Society of Chemistry, pp 154-163.

[4] Karbowiak T., Ferret E., Debeaufort F., Voilley A. & Cayot C. 2011. Investigation of water transfer across thin layer biopolymer films by infrared spectroscopy. Journal of Membrane Science, 370(1-2), 82-90.

[5] Nongonierma A., Cayot P., Springett M., Le Quere J.L., Cachon R. & Voilley A. 2007. Transfers of small analytes in a multiphasic stirred fruit yoghurt model, Food Hydrocolloids, 21(2), 287-296

[6] Rogacheva S., Espinosa-Diaz M.A. & Voilley A.1999.Transfer of aroma compounds in water-lipid systems: binding tendency of b-lactoglobulin. Journal of Agricultural Food and Chemistry, 47, 259-263.

[7] Barrera-Garcia V.D., Chassagne D., Paulin C., Raya J., Hirschinger J., Voilley A., Bellat J.-P. & Gougeon R. 2011. Interaction Mechanisms between Guaiacols and Lignin: The Conjugated Double Bond Makes the Difference. Langmuir, 27(3), 1038-1043.

[8] Hambleton A., Perpinan-Saiz N., Fabra M.J, Voilley A., Debeaufort F. 2011. The Schroeder paradox or how the state of water affects the moisture transfers through edible films. Food Chemistry, in press.

[9] Marcuzzo E, SensidoniA., Debeaufort F. & Voilley A. 2010. Encapsulation of aroma compounds in biopolymeric emulsion based edible films to control flavour release. Carbohydrate Polymers, 80(3), 984-988.

[10] Gharsallaoui A. Roudaut G., Beney L., Chambin O., Voilley A. & Saurel R. 2011. Properties of spray-dried food flavours microencapsulated with two-layered membranes: roles of interfacial interactions and water, Food Chemistry, in press, 10.1016/j.foodchem.2011.03.028.

Presented at ICEF11 (May 22-26, 2011 - Athens, Greece) as paper NFP686.