Article

Rapid determination of partition and diffusion properties for salt and aroma compounds in complex food matrices

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

The measurement of physicochemical properties, such as partition or diffusion coefficients of small molecules like salt and aroma compounds, represents an important challenge to better understanding stimuli release and perception. Owing to the lack of simple and fast methods, we developed three methods for practical and rapid determination of partition and diffusion coefficients respectively of salt and aroma compounds. Our approach is based on the combination of on-line measurements with mechanistic modelling leading to accurate determination of these two parameters. Validation was performed by comparing the values obtained with agar gel and model cheeses to those available in the literature.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... Measurement of Aroma Compound Release Kinetics. Aroma compound release kinetics were determined using the Volatile Air Stripping Kinetic method (VASK) (37). Figure 1 represents the diagram of the experimental assembly used in the VASK method. ...
... Determination of the Water/Product Partition Coefficient of NaCl. The NaCl water/product partition coefficient, defined as the ratio of the equilibrium concentration of NaCl between the product and the water, was determined using the solid/liquid phase ratio variation (SL-PRV) as described by Lauverjat et al. (37). Seven bottles (250 mL, Schott, France) containing different volumetric ratios (r) of salted matrix and deionized water were placed in a thermostated bath at 13°C for 48 h to reach thermodynamic equilibrium between the water and the product. ...
... Determination of the Diffusion Coefficient of NaCl. The NaCl diffusion coefficient was determined using the Solid/Liquid Nonvolatile Release Kinetic method (SL-NVRK) (37). This method is based on mass transfer analysis of solutes between the product and the liquid phase. ...
Article
Physicochemical properties (partition and diffusion coefficients) involved in the mobility and release of salt and aroma compounds in model cheeses were determined in this study. The values of NaCl water/product partition coefficients highlighted interactions between proteins and NaCl. However, these interactions were not modified by the product composition or structure. On the contrary, model cheese composition and structure influenced NaCl diffusion and both partition and diffusion for aroma compounds. Analysis of in-nose measurements of aroma release during eating, with regard to physicochemical properties, showed that product and aroma properties partly contributed to flavor release. Depending on the model cheese composition, structure and firmness, physicochemical properties, food breakdown, and chewing behavior can lead to different aroma release profiles. Finally, a discussion of all the results with regard to salt and flavor perception of the model cheese showed that both physicochemical and cognitive mechanisms contributed to perception.
... The first parameter above is directly calculated from the product flavouring protocol (Section 2.2), and the second one is estimated via the non linear phase ratio variation method described in Atlan, Trelea, Saint-Eve, Souchon, and Latrille (2006). The mass transfer coefficient was measured with the headspace method (Lauverjat, de Loubens, Deleris, Trelea, & Souchon, 2009). Experimental protocols are described in detail in Section 2.4. ...
... The method used for mass transfer coefficient measurements was based on two studies: the Static Equilibrium and Headspace Dilution Analysis (Marin, Baek, & Taylor, 1999) and the Volatile Air Stripping Kinetic (VASK) method (Lauverjat et al., 2009). ...
... In the Volatile Air Stripping Kinetic (VASK) method (Lauverjat et al., 2009), the product containing the volatile compound is equilibrated with the headspace air in a closed flask. At time t = 0, the headspace is stripped with a constant airflow, and the volatile compound concentration in the outlet air is continuously measured by PTR-MS. ...
Article
The objective of this study was to analyse the viscosity effect of liquid Newtonian products on aroma release, taking human physiological characteristics into account. In vivo release of diacetyl from glucose syrup solutions varying widely in viscosity (from 0.7 to 405mPas) was assessed by five panelists using Proton Transfer Reaction Mass Spectrometry (PTR-MS). The physicochemical properties of the solutions and the physiological parameters of subjects were experimentally measured.In parallel, a mechanistic model describing aroma release while eating a liquid food was developed. Model predictions based on the characteristics of the glucose syrup solution were invalidated when compared to in vivo measurements. Therefore, the assumption that the post-deglutitive pharyngeal residue was considerably diluted with saliva was introduced into the model. Under this hypothesis, the model gives a satisfactory prediction of the in vivo data. Thus, relevant properties to be considered for in vivo release were those of product-saliva mixes.
... The aim of this study was to compare diffusion properties of aroma compounds in model food products determined by three methodologies. The diffusion cell (Déléris et al., 2008) and the Volatile Air Stripping Kinetic (VASK) (Lauverjat et al., 2009) methods use a global approach and enable the determination of apparent or effective diffusion, D app , at macroscopic scale. Pulsed Field Gradient (PFG-) NMR spectroscopy is a high resolution technique for measuring local diffusion at a microscopic scale in a non invasive way (Antalek, 2002;Cohen et al., 2005;Price, 2000;Stallmach and Galvosas, 2007). ...
... e Experimental data (Déléris et al., 2008). f Experimental data (Lauverjat et al., 2009). g Experimental data (Jouquand et al., 2004). ...
... The Volatile Air Stripping Kinetic method (VASK) is based on the measurement of the variation in aroma compound gaseous concentration above a layer of product when a gaseous flow rate is applied ( Fig. 1B). An aliquot of 25 g of flavoured product (product height h gel = 7.5 Â 10 À3 m) was gelled in 0.25 L flasks (Schott, France) closed with gastight caps (Omnifit 00945Q-2V) and placed in a thermostated vault (25 or 30°C) during 12 h to let the thermodynamic equilibrium between the product and the headspace set up before measurement, as already described by Lauverjat et al. (2009). Flasks were then connected to a high sensitivity Proton Transfer Reaction-Mass Spectrometer (PTR-MS) (Ionicon Analytik, Innsbruck, Austria). ...
Article
Diffusion properties at macroscopic and microscopic scales for three aroma compounds (in solution and gel systems) were characterized using three different methodologies: the diffusion cell and the Volatile Air Stripping Kinetic methods for the determination of apparent diffusion coefficients and the pulsed-field-gradient Nuclear Magnetic Resonance method for the determination of self-diffusion coefficients. The accuracy of the methods was established by comparing ethyl hexanoate diffusion coefficient in water or D2O solution and in 1%-agar gel system at 25 and 30 °C. The robustness of the three methodologies was also investigated in 1%-iota-carrageenan system with different NaCl content leading to gel strengthening.In 1%-agar gel as well as in 1%-iota-carrageenan systems, the apparent or self-diffusion coefficients of aroma compounds had the same order of magnitude regardless of the approach, ranging between 2.3 × 10−10 and 10.4 × 10−10 m2 s−1. Diffusion properties were discussed in terms of the different observation scales (diffusion scales) and of the nature of gel network.
... Saliva collection during cheese eating was also performed in order to determine sodium release by HPLC (High Performance Liquid Chromatography) or API-MS (Atmospheric Pressure Ionisation e Mass Spectrometry) (Phan et al., 2008;. Other studies are related to in vitro salt mobility in cheese, leading to the determination of partition and diffusion coefficients of salt in water (Lauverjat, de Loubens, Déléris, Tréléa, & Souchon, 2009) or in artificial saliva (Floury, Rouaud, Le Poullennec, & Famelart, 2009). Due to the complexity of mechanisms occurring in mouth during food consumption (breakdown by mastication, dilution, mixing and interaction of food with saliva), it is often difficult to identify the respective roles of composition, structure and texture on salt release and on salty perception. ...
... Salt (NaCl) diffusion coefficient was measured using the method developed by Lauverjat (Lauverjat, de Loubens, et al., 2009). To measure the release kinetics of NaCl from product to water, 30 g of model dairy product was poured in a 12 mm dialysis tube and put in 2 L of deionised water stirred with a helix. ...
... Temperature was controlled and regulated at 13 C with a thermostated bath. The diffusion coefficients of NaCl and the other electrolytes were determined using a mechanistic model based on mass transfer analysis, according to the second Fick's law (Lauverjat, de Loubens, et al., 2009). ...
Article
The aim of this study was to better understand salt release and perception in model dairy products, having different composition, structure and/or texture. Sensory and instrumental methods were used to quantify and relate texture to salt mobility and perception. A high dry matter content (protein and fat jamming) and a gel structure with a protein network formation induced a decrease of diffusion coefficient of salt in matrices. Moreover, salty perception was higher for non-renneted products than for gelled ones. For gels, saltiness was enhanced in fat products. These results were discussed in regards with textural and physico-chemical food properties: the structural parameter tan δ was the most correlated with salty perception highlighting the impact of product structure on saltiness. Results also demonstrated that physiology and complex events (mastication, dilution and mixing with saliva, dynamic of bolus formation) occurring during food consumption must be considered to go further in understanding.Graphical abstract
... Measuring unidirectional diffusion from a semi-infinite food cylinder geometry with different boundary conditions is the most frequently applied method to determine the effective diffusion coefficient of a solute in cheese. If the semiinfinite cylinder, containing an initial concentration C 0 of the solute, is in contact – – Slow: several days of diffusion – accurate determination of solute concentrations is required in both compartments [20] [ – Lack of specificity of the measure with the conductivity probe – modelling difficulties because of the two unknown parameters: the effective diffusion coefficients of salt and of the other electrolytes of the product – can be applied to ionic solutes only [46] [47] PFG-NMR – Based on the attenuation of individual proton resonances under the influence of linear field gradients – the amplitude of the signal is directly related to the selfdiffusion coefficient of the molecule with a well-stirred solution containing a constant concentration C s of the solute at the interface (C s > C 0 ) (Fig. 1), the external mass transfer resistance can be neglected [71] and the boundary conditions are as follows: ...
... However, these Fickian approaches based on the concentration profiles of the diffusing solute can be adapted for various small molecules, ionized or not, easy to detect and quantify (water, solutes, colourants and aroma compounds) [15]. Lauverjat et al. [47] recently developed a method, also based on the Fickian approach, for easier and faster determination of diffusion properties of salt in complex matrices. This method, called the solid liquid nonvolatile release kinetic method (SL-NVRK), is based on the on-line monitoring of release kinetics of NaCl from a product containing a salt concentration C s into water. ...
... Stefan-Maxwell diffusion coefficients are mainly determined empirically by doing a large number of assumptions . Payne and Morison [61] fitted experimental data from Geurts et al. [27] and Wesselingh et al. [84] to model [47] the Stefan-Maxwell diffusion coefficients. The model successfully predicted independent shrinkage arising from an excess of outgoing diffusion of water over the incoming diffusion of salt. ...
Article
Full-text available
In cheese technology, the mass transfer of small solutes, such as salt, moisture and metabolites during brining and ripening, is very important for the final quality of the cheese. This paper has the following objectives: (i) to review the data concerning the diffusion coefficients of solutes in different cheese types; (ii) to review the experimental methods available to model the mass transfer properties of small solutes in complex matrices such as cheese; and (iii) to consider some potential alternative approaches. Numerous studies have reported the transfer of salt in cheese during brining and ripening. Regardless of the type of cheese and its composition, the effective diffusion coefficients of salt have been reported to be between 1 and 5.3 × 10−10 m2·s−1 at 10–15 °C. However, few papers have dealt with the mass transfer properties of other small solutes in cheese. Most of the reported effective diffusion coefficient values have been obtained by macroscopic and destructive concentration profile methods. More recently, some other promising techniques, such as nuclear magnetic resonance, magnetic resonance imaging or fluorescence recovery after photobleaching, are currently being developed to measure the mass transfer properties of solutes in heterogeneous media at microscopic scales. However, these methods are still difficult to apply to complex matrices such as cheese. Further research needs to focus on: (i) the development of nondestructive techniques to determine the mass transfer properties of small solutes at a microscopic level in complex matrices such as cheese; and (ii) the determination of the mass transfer properties of metabolites that are involved in enzymatic reactions during cheese ripening.
... Le coefficient de partage peut être mesuré expérimentalement par différentes méthodes (cf. Annexe A, p.200) telles que la méthode de Phase-Ratio-Variation (PRV) développée par Ettre et al. (1993), valable aussi bien pour les composés volatils que pour les composés sapides (Lauverjat et al., 2009a). ...
... Le coefficient de diffusion D ou le coefficient de transfert de matière k p peuvent-être mesurés par des méthodes de dilution de l'espace de tête (Marin et al., 1999;Lauverjat et al., 2009a) ou l'air est balayé en continu par un débit d'air et analysé. ...
... La méthode utilisée pour déterminer les coefficients de transfert de matière est basée sur des méthodes de dilution de l'espace de tête (Marin et al., 1999;Lauverjat et al., 2009a). Les conditions initiales sont : ...
Thesis
Full-text available
Understanding and modeling phenomena governing stimuli release during food consumption make it possible to respect both nutritional and sensorial criteria during its for- mulation. A model of salt release during the course of mastication was developed for “solid” products. The breakdown was comprehended by the generation of the area of contact between the product and the saliva that governs the transfers of stimuli. The area of contact was written as the product of two functions. The first was related to the subject and was function of his masticatory performance. The second was related to the product and depended on its breakdown behavior that can be determined by in vitro tests. During the pharyngeal stage, the biomechanics of swallowing governs pharyngeal mucosa coating and aroma compounds present in this layer. These phenomena are due to a thin film flow, stationary in a soft elastohydrodynamic contact whose the kinematics is equivalent to a forward roll coating process lubricated by saliva. Two sets of conditions were distinguished. When the saliva film is thin, food bolus viscosity has a strong impact on mucosa coating and on flavour release. When the saliva film is thick, the food bolus coating the mucosa is very diluted by saliva during the swallowing process and the impact of product viscosity on flavour release is weak. This second set of condition allowed us to explain the physical origin of in vivo observations on flavour release.
... The determination of the mass transfer coefficients in the bolus k B was done by fitting a release model to experimental data. As previously done by Marin, Baek, and Taylor (1999) or Lauverjat, de Loubens, Déléris, Trelea, and Souchon (2009), the mechanistic model used here describes the main mass transfer phenomena occurring in the flask, and leads to a set of differential equations. The main assumptions were local thermodynamic equilibrium at the interface, mass flux conservation through the interfaces at all times and mass balances for each phase. ...
... Model for the determination of the Mass Transfer Coefficient In the Volatile Air Stripping Kinetic (VASK) method (Lauverjat et al., 2009), the product containing the volatile compound is equilibrated with the headspace air in a closed flask. At time t = 0, the ...
Article
In vivo aroma release during solid food consumption is a complex phenomenon that depends on food structure and composition, as well as on oral processing (combination of mastication and incorporation of saliva into the food product). The objective of this study was to understand and to predict the physico-chemical properties of aroma compounds through the dynamics of flavor release during in-mouth oral processing of food before bolus swallowing. Within this context, the evolution of two aroma compounds during bolus formation was explored by studying the two main properties that account for mass transfer: air/bolus partition and mass transfer coefficients. Four types of industrial cheese products (varying in fat and firmness) flavored with ethyl propanoate and 2-nonanone were chosen. Each matrix was mixed with various amounts of artificial saliva to mimic boluses at different stages of mastication. The air/bolus partition coefficient was determined by the static phase ratio variation method (PRV), while the mass transfer coefficient was obtained by non-linear regression from dynamic headspace experiments. Results showed that there is a dilution effect on the air/bolus partition coefficient and both a dilution and a product effect (firmness) on the mass transfer coefficient of ethyl propanoate in the bolus. These results were also validated with 2-nonanone for the low-fat cheeses.
... To study the modifications of food flavour profile in dependence on packaging material transfer property, appropriate food model systems should be selected because most food products are complex. Liquid models close to reality (fruit or vegetable juices, syrup, milk) or aqueous solutions containing some of the food components (proteins, fats, carbohydrates) have been mostly considered until now (Lauverjat et al., 2009). ...
... To study the modifications of food flavor profile in dependence on packaging material transfer property, appropriate food model systems should be selected because most food products are complex . Liquid models close to reality (fruit or vegetable juices, syrup, milk) or aqueous solutions containing some of the food components (proteins, fats, carbohydrates) have been mostly considered until now (Lauverjat et al., 2009). The transfer of flavor from the packaging involves four steps: flavor transfer (diffusion) into the food; second, flavor (volatility ) between the food and its headspace; third, flavor (sorption) between the food headspace and the packaging; and fourth, flavor transfer through the packaging (permeation). ...
Article
Darfiyeh cheese is a Lebanese traditional variety made form raw goat's milk and ripened in goatskin. Ripening tools and conditions play the role of a barrier to protect the foodstuff against deterioration. This function requires the control of small volatile molecules transfer, such as aroma compounds. Several methods have been used for the measurement of diffusion of aroma volatile compounds. Few selected aroma compounds have been employed in more or less complex food model systems. Aqueous models containing some of the food components have been adopted as appropriate models given the complexity of food matrices. In this study, we characterized fragments of goatskin microbiologically, physico- chemically and qualitatively. Furthermore, we followed the transfer of three model aroma compounds (2-butanone, 2,3-butanedione and 2-butanol) in an experimental aqueous model solution/goatskin system at 20, 40 and 60 days of exposure. The barrier properties of goatskin were assessed for aroma model molecules through permeability and sorption tests. Therefore, the behaviour/distribution of diffusing molecules was discussed on the basis of the physico-chemical properties of these molecules, the properties of the barrier material, as well as the food matrix (aqueous dilute model solution in the case of our study). Until 40 days, the transfer of model molecules was dependent on their physico-chemical properties and exposure time. After 60 days, the molecules tended to migrate from the goatskin back to the aqueous dilute model solution. In such a model, there was evidence of a tendency towards the diffusion of aroma model molecules in a cyclic way.
... The diffusion rates of particular solutes are what control the mass transport throughout the food system and due to the immobilisation of bacterial colonies within a ripening cheese; it can be assumed that substrates involved in bacterial enzyme reactions, outside of those created by the bacteria themselves, must diffuse through the matrix to reach these colonies. Temperature has been shown to have a strong influence on the rate of solute diffusion (Floury, Jeanson, Aly, & Lortal, 2010;Floury, Rouaud, Le Poullennec, & Famelart, 2009;Lauverjat, Loubens, D el eris, Tr el ea, & Souchon, 2009;Simal et al., 2001). Simal et al. (2001) developed a mathematical model for salt and water diffusion based on surface mass transfer values, while Lauverjat et al. (2009) outlined fast, inexpensive methods for the determination of diffusion and partition properties for salt and other aroma compounds. ...
... Temperature has been shown to have a strong influence on the rate of solute diffusion (Floury, Jeanson, Aly, & Lortal, 2010;Floury, Rouaud, Le Poullennec, & Famelart, 2009;Lauverjat, Loubens, D el eris, Tr el ea, & Souchon, 2009;Simal et al., 2001). Simal et al. (2001) developed a mathematical model for salt and water diffusion based on surface mass transfer values, while Lauverjat et al. (2009) outlined fast, inexpensive methods for the determination of diffusion and partition properties for salt and other aroma compounds. Floury et al. (2010) reviewed the knowledge of salt diffusion rates and other small solutes in cheese. ...
Article
This review considers the relationship between cheese manufacture process parameters including high heat and high pressure processes and protein standardisation techniques on the resultant cheese microstructure, microbial activity within the cheese matrix and the interactions between the cheese matrix and the entrapped bacteria during ripening. Particular consideration is given to bacterial location, localised ripening and mineral movement within the matrix as well as the effect of processing on milk fat globules and the influence of milk fat globule membrane material on cheese structure and ripening. Further investigation is suggested relating to profiling bacterial growth at protein fat interfaces and curd junctions using flow cell cytometry techniques.
... The release kinetics of aroma compounds was determined experimentally by the Volatile Aroma Stripping Kinetic (VASK) method (Lauverjat, de Loubens, Déléris, Tréléa, & Souchon, 2009). Flavoured products (25 g) were gelled in 0.25 l flasks (Schott, France) and placed in a thermostated vault at 25°C for 12 h to allow a thermodynamic equilibrium to be established between the product and the headspace. ...
... A description of the main mass transfer phenomena occurring in the flask allowed the establishment of a mechanistic model composed of a set of differential equations. The main assumptions were mass balances for each phase, local thermodynamic equilibrium at the interfaces and mass flux conservation through the interfaces at all times (Lauverjat et al., 2009). The apparent diffusion coefficient D app was determined by numerically fitting the mechanistic model to the experimental in vitro release data using the Levenberg-Marquardt algorithm (least squares curve fitting). ...
Article
We investigated the role of both candy texture and eating technique (melting or chewing) on the dynamics of aroma release. One novelty of this type of analysis was the simultaneous application of instrumental and sensory analysis. Four candy textures were established based on their storage modulus at 1 Hz by varying the gelatine content between 0 and 15% w/w. The invivo release of three aroma compounds was monitored using Proton Transfer Reaction Mass Spectrometry and with a trained panel of testers. The gelatine content had no significant effect on the headspace/product partition and diffusion properties of the aroma compounds. The highest invivo release for all aroma compounds was obtained with the 2% gelatine sample. Our findings indicated that aroma release was determined by interaction between the product properties and oral behaviour. Relations between the dynamics of release and perception (method of Temporal Dominance of Sensations) have been established on temporal parameters.Research highlights► This study focus on the effect of candy structure on aroma release and perception. ► The highest in vivo release was obtained with the 2% gelatine sample. ► Release results from interactions between product properties and oral behaviour. ► Relations were established between sensory and release temporal parameters.
... All these species contribute to the conductivity signal. With similar products, Lauverjat et al. (2009) showed that NaCl had mass transfer properties (diffusion and partition coefficients) similar to those of the other solutes. There is therefore no need to distinguish between the different solutes in this study. ...
... The water / product partition coefficients K and initial salt concentrations C 0 p of the four products were determined according to SL-PRV method developed by Lauverjat et al. (2009). The values of K and C 0 p are global and correspond to the total amount of salt present. ...
... PTR-ToF-MS allows the non-invasive real time detection of VOCs with higher proton affinities than that of water (e.g., carbonyl compounds, carboxylic acids, alcohols, esters, sulphur and nitrogen compounds, ammonia) at the low pptv level. Therefore, PTR-ToF-MS can be considered as an efficient technique for the measurement of flavour release studies in complex food systems or in matrices undergoing timedependent transformations, as in the case of dairy gels formation (Fabris et al., 2010;Lauverjat, de Loubens, Déléris, Tréléa, & Souchon, 2009;Soukoulis et al., 2010) or of food mastication (Aprea, Biasioli, Gasperi, Märk, & van Ruth, 2006). ...
... This method was applied subsequently to cheese products [12].  The solid/liquidphase ratio variation (SL -PRV) developed on model cheeses [13,14], which is an adaptation of the PRV method used for volatile compounds [15].  The drawback of the second method is that the associated analytical technique (Conductometric detection) is not specific to sodium chloride. ...
Book
During the eating of food, the in-mouth process leads to food breakdown which induces the release of flavour compounds. Volatile and non-volatile compounds are released into the saliva, and volatile compounds are transferred into the vapour phase to reach olfactory receptors in the nasal cavity. The aim of this chapter is to review the effects of changing the composition of cheeses on the mobility, release and perception of flavour molecules (salt, aroma compounds), and to discuss the results with respect to human physiology. Cheese is a good model because it is possible to vary its composition (in lipids, proteins, salt), in order to comply with nutritional guidelines (less salt, less fat) and to study the effects of these changes in composition on its microstructure and texture, and then on flavour (taste and aroma) release and perception, while taking account of in-mouth breakdown. Papers on this subject have mainly been related to either salt release and perception or aroma release and perception, and few have taken account of the combined effects of cheese composition on both salt and aroma release and perception. Indeed, recent papers from our research group have shown that the salt and fat contents of cheeses induce modifications to texture and microstructure that affect not only salt release and perception but also aroma release and perception and chewing behaviour.
... PTR-MS can perform rapid online monitoring of flavor release, without the need of any sample pretreatment (a critical step in the case of the investigation of the matrix effect on flavor release) and has a sensitivity threshold in the low parts per trillion (ppt) range (Jordan et al. 2009). Moreover, PTR-MS has been established as a reliable technique for the determination of flavor release from many dairy matrices including cheese (Aprea, et al. 2007; Lauverjat et al. 2009), dairy desserts (Aprea et al. 2006), and whey products (Gallardo-Escamilla et al. 2007). Recently, we have shown that PTR-TOF-MS can monitor the complex processes that involve both volatile organic compounds (VOCs) formation and structural changes in lactic acid fermentation of milk (Soukoulis et al. 2010) and that it allows for the detection of VOCs during gel formation without destroying the forming gel during incubation. ...
Article
Full-text available
In the present study, the effects of milk fat (0.3% and 3.5% w/w), solids non-fat (8.4% and 13% w/w), and modified tapioca starch (0%, 0.5%, 1.0%, 1.5%, and 2.0% w/w) concentrations on the textural and physicochemical properties as well as the concentration of several endogenous flavor compounds in the headspace of set and stirred yogurts were investigated. The novel proton transfer reaction time-of-flight mass spectrometry technique was implemented for the non-invasive determination of the amounts of volatile organic compounds in the samples headspace. Milk fat and skim milk powder supplementation of the milk samples increased significantly the firmness and adhesiveness of yogurts (p<0.001) and improved the stability of the formed gels by increasing their water holding capacity and reducing the amounts of expulsed whey (3.94 and 5.1 g for the milk fat and SNF-fortified samples). Acetaldehyde was significantly (p<0.001) higher in the low fat-unfortified systems (6.15±0.48 and 5.6± 0.60 ppmv, respectively). A similar trend was also reported in the case of 2-propanone (0.91±0.11 and 1.13± 0.07 ppmv), diacetyl (334±37 and 350±34 ppbv), 2,3- pentanedione (54±6 and 55±6 ppbv), and 2-butanone (56± 7 and 68±5 ppbv) for the same systems. In contrast, the concentration of flavor compounds in the headspace with hydroxyl groups (ethanol and acetoin) increased (p<0.001) by solid non-fat fortification of milk base (350±32 and 206±7 ppbv, respectively, for the systems fortified with skim milk powder). Modified tapioca starch addition improved the textural properties and gel stability of yogurts whereas affected only the ethanol concentration (222±16 and 322±55 for the control and 2.0% w/w containing systems, respectively). Our data suggested that the reinforcement of textural and structural properties combined with the protein binding affinity of the flavor compounds seemed to be responsible for the aforementioned observations. In the case of stirred yogurts, the gel breakdown did not provoke significant changes in the headspace concentration of the most compounds, with the exception of ethanol, acetoin, and 2,3-pentanedione being significantly (p<0.05) higher in the stirred yogurts (267±29, 153±11, and 38±1 ppbv, respectively) than set style ones (232±19, 134±9, and 45±3 ppbv, respectively).
... -la méthode Solid/Liquid Phase Ratio Variation (SL-PRV) mise au point sur des modèles fromagers (Lauverjat, 2009c ;Lauverjat et al., 2009a) et qui est une adaptation de la méthode PRV utilisée pour les composés volatils (Ettre et al., 1993). ...
Article
The aim of this work is to understand the effects of changes in the composition of model cheeses on mobility, release and perception of flavor molecules (salt, aroma compounds). Six flavoured model cheeses were formulated (3 lipid/protein (L/P) ratios and 2 salt contents). The microstructure and the rheological properties of the model cheeses were characterized respectively by confocal microscopy and by uniaxial compression test. The mobility of sodium ions was analyzed by 23Na NMR. The kinetics of sodium release was followed in water and then in saliva during consumption of the model cheeses. The retronasal release of aroma compounds was followed by nose-space APCI-MS, simultaneously with the study of swallowing and chewing by electromyography. Then, the sensory properties of the model cheeses (saltiness, aroma, texture) were studied.A decrease in the L/P ratio and a decrease in salt content reduce the fat droplet size and increase the hardness. This leads to a decrease in sodium ion mobility, which results in a decrease in sodium release in saliva and a decrease in salty perception. Moreover, the maximum intensity of aroma release is reached later and the aroma perception is decreased. These effects can be explained by the observed lipid/protein distribution in microscopy, by the later swallowing and by the higher chewing activity
... The mass spectrometry data were collected using a high-sensitive PTR-MS apparatus (Ionicon Analytik, Innsbruck, Austria) in SCAN mode over a mass spectrum of m/z 21 to 150; dwell time was 100 ms per peak. The vial valves were connected to a circuit (Lauverjat, de Loubens, Déléris, Tréléa, & Souchon, 2009), which made it possible to: i) draw in ambient air for 78 s (6 cycles); ii) switch between ambient air and flask headspace; and iii) purge the headspace for 260 s (20 cycles) at a mean flow rate of 28 mL/min. The PTR-MS instrument drift tube had the following parameter settings: P = 195 Pa; T = 60°C; U = 600 V (E/N = 156 Td). ...
Article
The objective of this study was to investigate for the first time the influence of bread structure, volatile compounds, and oral processing on aroma perception. 3 types of French baguette were created using the same raw ingredients but different bread-making processes; they consequently varied in their crumb and crust structures. We characterized the initial volatile profiles of two bread structural subtypes—namely bread crumb and bread crumb with crust—using proton transfer reaction–mass spectrometry (PTR–MS) headspace analysis. Three types of bread were characterized by thirty-nine ion fragments from m/z 45 to 139. We then conducted a study in which 8 participants scored aroma attribute intensities for the different bread types and subtypes at 3 key stages of oral processing (10, 40, and 100% of individual swallowing time). At these 3 time points, we collected boli from the participants and characterized their volatile profiles using PTR–MS headspace analysis. The results suggest saliva addition dilutes volatile compounds, reducing volatile release during oral processing. Thus, a bread with high porosity and high hydration capacity was characterized by a low volatile release above boli. We examined the relationships between 4 aroma attributes of bread crumb with crust and 24 discriminatory fragment ions found in boli headspace. This study demonstrated for the first time that the perceived aroma of crumb with crust was influenced more by volatile profiles than by crumb texture. It thus contributes to our understanding of aroma perception dynamics and the mechanisms driving volatile release during oral processing in bread.
... Other techniques used to determine an effective diffusion coefficient such as infinite cylinder in contact with solution (Floury et al., 2009;Wilde et al., 2001), diffusion cell (Djelveh et al., 1989;Zorrilla and Rubiolo, 1994), solid liquid nonvolatile release kinetic method (SL-NVRK) (Lauverjat et al., 2009), pulsed field gradient NMR (PFG-NMR) (Callaghan et al., 1983;Métais et al., 2004), NMR imaging (Vestergaard et al., 2005), and FRAP (Floury et al., 2012) have certain drawbacks along with their advantages. Infinite cylinder and diffusion cell methods are destructive and time consuming techniques that require a number of analyses for accurate determination of solute concentration. ...
Article
In the cheese industry, mass transfer of small solutes like salt during brining and ripening is extremely important for the quality of final products. In general, effective diffusion coefficient values have been reported in the studies using destructive concentration profile methods. This study aims to monitor NaCl diffusion in cheese by using laser induced breakdown spectroscopy (LIBS) as a nondestructive method to fulfill the requirement of measuring mass transfer properties of solutes in microscopic size complex heterogeneous structures. To this end, spherical shaped white cheese samples were brined in 16% salt solution for 5–210 min and overnight, and Na emission lines were monitored by scanning the cross-section of each sample at 30 points on the radial axis. As was expected, increasing brining time decreased the concentration difference between the center and edge of the cheese samples. Experimental results were fitted to Fick's Diffusion Equation. It was observed that NaCl distribution became uniform and equal at different locations of the cheese sample after 13.8 h. All these results have demonstrated that LIBS can be utilized for optimization of the brining conditions of cheese. Although the use of LIBS in this study was limited to parameter optimization, it can also be applied for real time monitoring of food processes due to its rapid and continuous measurement mode.
... For this aroma compound, only 20% was released in water with films prepared without fat (Table 3) and there was no release in salt medium. With this lipophilic aroma, the release decreased when films were prepared with fat due to an increase of reservoir capacity by the location of aroma in the lipid phase and a decrease of aroma mobility (Lauverjat et al., 2009). In this sense, some authors showed that aroma compounds are retained more easily in matrices with similar polarities (Arora et al., 1991;Reineccius and Risch, 1988). ...
Article
This work analyses the release of n-hexanal and d-limonene from edible films, previously encapsulated in the iota-carrageenan matrix (with and without lipid). Both volatile compounds have different physico-chemical properties. The effect of temperature (25 °C and 37 °C) and dissolution medium (water and 0.9% NaCl) on the release and retention of aroma compounds were studied. Hydrophobicity and wettability properties of active iota-carrageenan films were also studied and they were related with the internal and surface microstructure of films. Results highlight that d-limonene is encapsulated in the lipid phase of the films decreasing the release in the salt medium. d-limonene, the most hydrophobic, was more sensitive to the temperature changes than hexanal. Thus, this work gives an idea of the release of aroma compounds encapsulated in iota-carrageenan films in aqueous media.
... Their modification or loss caused by fabrication and conservation treat-ment may induce the loss of consumer's perception. There are many ways to enhance their retention in food such as the addition of sugars [1] or of a fat phase [2,3]. However, due to the consumption tendency of reduction of sugar and fat contents to provide better healthier foods, this method gradually declines in food processing today. ...
Article
Yeast cells are efficient microcapsules for the encapsulation of flavoring compounds. However, as they are preformed capsules, they have to be loaded with the active. Encapsulation efficiency is to a certain level correlated with LogP. In this study, the effect of structural factors on the encapsulation of amphiphilic flavors was investigated. Homological series of carboxylic acids, ethyl esters, lactones, alcohols and ketones were encapsulated into the yeast Yarrowia lipolytica. Although, in a single homological series, the length of the molecule and thus the LogP were correlated with encapsulation efficiency (EY%), big differences were observable between series. For instance, carboxylic acids and lactones exhibited EY% around 45%–55%, respectively, for compounds bigger than C8 and C6, respectively, whereas ethyl esters reached only about 15–20% for C10 compounds. For a group of various C6-compounds, EY% varied from 4% for hexanal to 45% for hexanoic acid although the LogP of the two compounds was almost similar at 1.9. In total our results point out the importance of the level of polarity and localization of the polar part of the compound in addition to the global hydrophobicity of the molecule. They will be of importance to optimize the encapsulation of mixtures of compounds.
... PTR-MS can perform rapid online monitoring of flavor release, without the need of any sample pretreatment (a critical step in the case of the investigation of the matrix effect on flavor release) and has a sensitivity threshold in the low parts per trillion (ppt) range (Jordan et al. 2009). Moreover, PTR-MS has been established as a reliable technique for the determination of flavor release from many dairy matrices including cheese (Aprea, et al. 2007; Lauverjat et al. 2009), dairy desserts (Aprea et al. 2006), and whey products (Gallardo-Escamilla et al. 2007). Recently, we have shown that PTR-TOF-MS can monitor the complex processes that involve both volatile organic compounds (VOCs) formation and structural changes in lactic acid fermentation of milk (Soukoulis et al. 2010) and that it allows for the detection of VOCs during gel formation without destroying the forming gel during incubation. ...
Article
Full-text available
In the present study, the effects of milk fat (0.3% and 3.5% w/w), solids non-fat (8.4% and 13% w/w), and modified tapioca starch (0%, 0.5%, 1.0%, 1.5%, and 2.0% w/w) concentrations on the textural and physicochemical properties as well as the concentration of several endogenous flavor compounds in the headspace of set and stirred yogurts were investigated. The novel proton transfer reaction time-of-flight mass spectrometry technique was implemented for the non-invasive determination of the amounts of volatile organic compounds in the samples headspace. Milk fat and skim milk powder supplementation of the milk samples increased significantly the firmness and adhesiveness of yogurts (p p p w/w containing systems, respectively). Our data suggested that the reinforcement of textural and structural properties combined with the protein binding affinity of the flavor compounds seemed to be responsible for the aforementioned observations. In the case of stirred yogurts, the gel breakdown did not provoke significant changes in the headspace concentration of the most compounds, with the exception of ethanol, acetoin, and 2,3-pentanedione being significantly (p
Article
Solid lipoproteic colloid (SLC) foods that consist of an oil-in-water emulsion of lipid and protein such as cheese and sausage contribute a significant amount of sodium to modern diets. This study aimed to correlate the overall saltiness perception to the texture and temporal saltiness perception of SLCs to understand saltiness perception during oral processing. Model SLCs with varying levels of protein and fat were prepared via pressure homogenization of whey protein isolate, anhydrous milk fat, and NaCl, followed by heat-induced gelation. Descriptive sensory analysis (DSA) and time-intensity (TI) method were used to characterize the sensory profiles and the temporal saltiness perception properties of the SLCs, respectively. Principal component analysis (PCA) and cluster analysis of the DSA results showed that the samples were grouped based on the formulation and the homogenization pressures. The maximum saltiness intensity in the TI curves increased with decreasing contents of protein and fat and decreasing homogenization pressures. The PCA and cluster analysis of the taste and texture attributes from the DSA and the TI parameters showed that the nonfat samples were clustered together, characterized by the DSA salty taste, syneresis texture, and the TI initial saltiness intensity. When only fat-containing samples were analyzed, the DSA salty attribute correlated significantly with the texture attributes of fracturable and syneresis. The dependence of saltiness perception on the texture properties of the nonfat and fat-containing samples discovered in this study provided insights for the future development of reduced-sodium products.
Article
The development of food products that may contribute to attenuate issues related to public health in a positive way is a challenge for the dairy industry. Due to its negative effects of salt on health, such as increase in blood pressure and decrease in calcium absorption, high intake of salt derived from food in industrialized nations is an important issue for the modern society. Considering that cheese consumption is increasing worldwide, importance should be given to reducing the contribution of salt as a sodium-carrier without affecting its consumption. Various types of cheese have been developed with reduced sodium content by decreasing NaCl or partial/total substitution of this salt with KCl, MgCl2 and CaCl2. The results are mostly positive; most variety of cheeses is acceptable, but at times there is a sour residual taste resulting from the substitution of NaCl. Further knowledge is necessary regarding the quality of cheese and levels of salt that is acceptable in the production of cheeses with reduced sodium content.
Article
The partition of aroma compounds between a matrix and a gas phase describes the individual compounds specific affinity towards the matrix constituents affecting orthonasal sensory perception. The static headspace phase ratio variation (PRV) method has been increasingly applied by various authors to determine the equilibrium partition coefficient K in aqueous, polysaccharide and dairy matrices. However, reported partition coefficients are difficult to relate and compare due to different experimental conditions, e.g. aroma compound selection, matrix composition, equilibration temperature. As due to its specific advantages, the PRV method is supposed to find more frequent application in the future, this review aimed to summarize, evaluate, compare and relate the currently available data on PRV determined partition coefficients. This process was designed to specify the potentials and the limitations, as well as the consistency of the PRV method, and to identify open fields of research in aroma compound partitioning in food-related, especially dairy matrices.
Article
Eating is a complex process with a range of phenomena occurring simultaneously, including fracture, temperature changes, mixing with saliva, flavour and aroma release. Sensory perception as experienced in the oral cavity has a strong effect on the overall acceptability of the food. Thus in an engineering sense one would want to be able to understand and predict phenomena for different food matrices in order to design more palatable foods through understanding food oral processing without the health concerns of adding salt, fat and sugar. In this work we seek to obtain such an understanding for salt release from food matrices and perception viewing the oral processing as a physical/chemical reactor. A set of equations was developed to account for mass balance and transfer. Data required for the model such as effective diffusivity and mixing times were obtained from the chemical engineering literature. The model predictions compared favourably with published TI data, managing to capture key phenomena including response to pulsed salt release. The model was used to predict response to a range of food matrices and indicated that for solids and thickened liquid food products there is the potential to modulate consumer response by pulsing the release of sodium.
Chapter
During food eating, flavour compounds are progressively released in the mouth while the food bolus is progressively formed from food particles issued from food submitted to mastication, and from saliva. Among these compounds, the taste compounds fraction is mainly constituted of poorly- or non-volatile compounds generally soluble in water. During food oral processing, they are extracted from the food matrix and dissolved in saliva. The delivery of these tastants to the receptors located on the tongue is one of the key factors determining the perceived taste of foods. However, food texture and composition and oral physiology modulate the release kinetics of these tastants and consequently modulate taste perception. This chapter presents the main physico-chemical and physiological factors involved in the release of tastants in the mouth when eating food, in relation with perception.
Article
A major problem when assessing in vitro the toxicity of volatile organic compounds is the loss of the tested chemicals during the course of experimental studies. This work presents a novel device for the experimental study of cell culture exposure to volatile compounds. The device is formed by different compartments separated by a porous hydrophobic membrane and allows for lengthy experiments without restricting cells from breathing. A mathematical model taking into account the mass and momentum conservation between the different device compartments has been built in order to predict the evolution of the volatile compound concentration. Theoretical results revealed a good match with experimental data and showed that the membrane surface, the volatile compound transfer properties and the operating conditions have a significant influence on the evolution of the volatile compound concentration in the liquid phase. Finally, the model proposed here is used to choose the best parameters related to both membrane structure and enclosure design so that the volatile compound can be maintained at a higher concentration for a longer period of time in the exposure chamber.
Article
A dynamic, three dimensional (3D) computational model that predicts the breakdown of food and the release of tastants and aromas could enhance the understanding of how food is perceived during consumption. This model could also shorten the development process of new foods because many virtual foods could be assessed, and discarded if unsuitable, before any physical prototyping is required. The construction and testing of a complete 3D model of mastication presents many challenges including an accurate representation of: the anatomical movements of the oral cavity (including the teeth, tongue, cheeks and palates), the breakdown behaviour of the food, the interactions between comminuted food and saliva as the bolus is formed, the release and transport of taste and aromas and how these physical and chemical processes are perceived by a person. These challenges are discussed in reference to previous experimental and simulation work and using results of new applications of a coupled biomechanical-smoothed particle hydrodynamics (B-SPH) model. The B-SPH model is demonstrated to simulate several complicated aspects of mastication including: (1) the sensitivity of particle size to changes in the movements of the jaw and tongue; (2) large strain behaviour of food due to softening by heating; (3) interactions between solid and liquid food components; (3) the release of tastants into the saliva; and (4) the transport of tastants to the taste buds. These applications show the possibilities of a model to viably simulate mastication, but highlight the many modelling and experimental challenges that remain.
Article
Excess sodium as salt (NaCl) added to foods may be harmful to humans. Most salt intake comes from processed foods, therefore salt reduction strategies should be developed by the food industry. One strategy seeks to optimize the delivery of salt ions inside the mouth. To accomplish this purpose, the dissolution characteristics of salt crystals in saliva must be understood. However, relatively scarce information is available on this topic. This study compares the dissolution of five commercial salts in deionized water and two formulations of artificial saliva, at four temperatures and in the absence of agitation. Salt dissolution was quantified in vitro by analysis of video-microscopy images taken at different times. Higher dissolution rates of salt crystals were found in water than in artificial saliva, and at higher temperatures. Video-microscopy was instrumental to reveal that some crystals were fragmented during dissolution while others remained as a unit of decreasing size until complete solubilization. Increased surface area after fragmentation led to pyramid-shape crystals having the highest dissolution rates. Hence, significant changes can be achieved in the dissolution of salt depending on the crystal structure and its dissolution pattern.
Article
In vivo aroma release during solid food consumption is a complex phenomenon that depends on food structure and composition, as well as on oral processing (combination of mastication and incorporation of saliva into the food product). The objective of this study was to understand and to predict the physico-chemical properties of aroma compounds through the dynamics of flavor release during in-mouth oral processing of food before bolus swallowing. Within this context, the evolution of two aroma compounds during bolus formation was explored by studying the two main properties that account for mass transfer: air/ bolus partition and mass transfer coefficients. Four types of industrial cheese products (varying in fat and firmness) flavored with ethyl propanoate and 2-nonanone were chosen. Each matrix was mixed with various amounts of artificial saliva to mimic boluses at different stages of mastication. The air/bolus partition coefficient was determined by the static phase ratio variation method (PRV), while the mass transfer coefficient was obtained by non-linear regression from dynamic headspace experiments. Results showed that there is a dilution effect on the air/bolus partition coefficient and both a dilution and a product effect (firmness) on the mass transfer coefficient of ethyl propanoate in the bolus. These results were also validated with 2-nonanone for the low-fat cheeses.
Article
Full-text available
Interaction between poly(ethylene glycol) and two surfactants investigated by diffusion coefficient measurements Abstract Dynamic light scattering (DLS) and fluorescence recovery after pattern photobleaching (FRAPP) were used to study the interaction of low molecular weight poly(ethylene glycol) (PEG) with micelles of two different surfactants: tetradecyldimethyl aminoxide (C 14 DMAO, zwitterionic) and pentaethylene glycol n-dodecyl monoether (C 12 E 5 , non-ionic). By using an amphiphilic fluorescent probe or a fluorescent-labeled PEG molecule, FRAPP experiments allowed to follow the diffusion of the surfactant–polymer complex either by looking at the micelle diffusion or at the polymer diffusion. Experiments performed with both fluorescent probes gave the same diffusion coefficient showing that the micelles and the polymer form a complex in dilute solutions. Similar experiments showed that PEG interacts as well with pentaethylene glycol n-dodecyl monoether (C 12 E 5).
Article
Full-text available
Model jam-like systems at increasing High Methoxylated Pectin content were developed in order to observe flavour release from gelled matrix at very low hydrocolloid concentration. The addition of pectin modified the release of the most volatile and hydrophobic aroma compounds. This phenomenon was strictly related to the formation of a gel network that, even at a concentration of 0.1% pectin, led to a decrease of volatile mobility. No specific molecular interactions were found between flavour compounds and pectin in water solution without sugar; moreover no significant difference was observed in diffusion coefficient values for all aroma compounds at the pectin levels used (0.1% to 0.4%). The predominant cause of aroma retention in gelled systems might thus be due to a hindered molecule migration through the three-dimensional structure.
Article
Full-text available
Salt transport in white cheese was investigated at two brine concentrations (15 and 20% w/w) and at three temperatures (4, 12.5 and 20°C) for each brine concentration. Two mathematical models were developed based on treating the cheese samples as finite or semi-infinite bodies. Theoretical and experimental salt concentration profiles were in good agreement. The semi-infinite model was valid only for low Fourier numbers, i.e., Fo≤0.07. Effect of convectional flow was insignificant. Salf diffusivity remained constant with time, and an Arrhenius-type equation described its variation with temperature. Salt diffusivity in white cheese was estimated as 0.21 × 10−9 m2/sec at 4°C and 0.31 × 10−9 m2/sec at 12.5°C for both brine concentrations and as 0.39 × 10−9 m2/sec for brine concentration 15% (w/w) and 0.34 × 10−9 m2/sec at 20°C for 20% (w/w).
Article
Full-text available
Liquid–gas partition coefficients (HLC) of volatile organic compounds (VOCs) in water–air systems are determined using a novel dynamic approach by coupling a stripping cell directly to a proton-transfer-reaction mass spectrometer (PTR–MS). Two complementary set-ups are evaluated, one suited for determining HLCs of highly volatile compounds (<10 M/atm), the second adapted for medium to low volatile compounds (∼10–1000 M/atm). We validated the method using 2-butanone, investigated the temperature dependence of various HLCs and applied the stripping technique to a series of VOCs. Compared to alternative state-of-the-art techniques the present approach has the advantage of being simple, fast and less prone to artefacts. Furthermore, it allows to quantify volatile compounds in the headspace without calibration or addition of standards.
Chapter
The interactions between aroma compounds and other components of a wine matrix : colloids, fining agents and ethanol were investigated in model systems and with instrumental methods. The physico-chemical interactions between aroma compounds and other components depend on the nature of volatile compounds. The level of binding generally increases as the hydrophobic nature of the aroma increases. The interactions also depend on the nature of the macromolecules such as yeast walls, mannoproteins, bentonite or smaller molecules such as ethanol. As a function of the nature of non-volatile component, the increase or decrease in the volatility of aroma compounds can influence largely the overall aroma of wine. The effect of ethanol on the volatility of aroma compounds is understood and it clearly appears that ethanol leads to modification in macromolecule conformation such as protein, which changes the binding capacity of the macromolecule. This review enables to develop some hypotheses on the possible sensory contribution of some non-volatile compounds of wine on the overall aroma.
Article
The interactions between model wine aroma compounds—limonene, isoamyl acetate and ethyl hexanoate—and several polysaccharides—modified corn and waxy corn starches, dextrine, dextrans, hydroxypropyl celluloses and galactomannans—were studied using the exponential dilution technique. Information concerning the nature and the intensity of these interactions were obtained from the study of the variation in the reduced infinite dilution activity coefficient γi∞Gamma; as a function of the polysaccharide weight fraction. Retention of aroma compounds was detected for all the compounds studied except for dextrans, and in this case a salting-out effect was developed. The biphasic curve obtained for modified starch agrees with the presence of two binding modes corresponding to the formation of amylose and amylopectine inclusion complexes. A rapid decrease in the volatility of ethyl hexanoate and limonene (30 to 80%) was obtained at 0.01 weight fractions for galactomannans and hydroxypropyl cellulose; the study of interactions between volatile compounds and these polysaccharides were limited by the strong viscosity of their solutions. In the case of dextrin, the linear decrease in γi∞Γ agrees with the existence of hydrophobic interactions. A 50% decrease in γi∞Γ was obtained for a 0.04 weight fraction of this compound which was selected for the synthesis of a model glycopeptide.
Article
A model for a multicomponent system using the cell for determining apparent diffusion coefficients in gels and foods was developed. In this case, the generalized Fick's law form was used as a constitutive equation for the diffusive molar flux of solutes. Using the method of eigenvectors and eigenvalues, the mass transfer equations were rearranged to simplify the mathematical treatment. Simple expressions for determining the diffusion coefficients of two or more solutes which diffuse in a rigid medium were obtained. In this case, experiments to study the diffusion of NaCl and KCl in cheese were shown and the corresponding effective diffusion coefficients were obtained.
Article
A system for on-line measurements of trace components with concentrations as low as a few pptv has been developed on the basis of proton transfer reactions. Medical applications by means of breath analysis allow the monitoring of metabolic processes in the human body, and examples of food research include investigations of volatile organic compound (VOC) emissions from fruit, coffee and meat. Investigations of VOC emissions from decaying biomatter and on-line monitoring of the diurnal variations of VOCs in ambient air are typical examples of environmental applications.
Article
Concentration profiles obtained by slicing a cylindrical gel were used to measure diffusion of volatiles in viscous aqueous dextrose solutions. The column length, slice thickness and diffusion time were optimized to maximize the repeatability of measurements, the results being very sensitive to small changes in variables. Coefficients of variation between 5 and 10% were obtained. In the presence of different concentrations of dextrose, the diffusivity of acetone decreased markedly as dextrose concentration increased. However, when the acetone concentration was varied within the range 0·6 to 13·7%, at a constant 50% (w/w) dextrose concentration, its diffusivity did not change significantly. The sliced gel system gave values of diffusivity in close agreement with those obtained by other techniques.
Article
A system for on-line measurements of trace components with concentrations as low as a few pptv has been developed on the basis of proton transfer reactions. Medical applica- tions by means of breath analysis allow the monitoring of metabolic processes in the human body, and examples of food research include investigations of volatile organic compound (VOC) emissions from fruit, coffee and meat. Investigations of VOC emissions from decaying biomatter and on-line monitoring of the diurnal variations of VOCs in ambient air are typical examples of environmental applica- tions.
Article
Interactions between flavor compounds and food ingredients are reviewed and their influence on flavor perception is discussed. Proteins are known to bind flavor compounds. For β-lactoglobulin, the most-studied example, hydrophobic interactions with volatiles are described. The effect of the medium on the conformation of the protein and its ability to bind flavor compounds is discussed. In general, the retention of volatiles by protein is much lower than that by fat. In emulsions, however, the presence of protein at the oil/water interface induces a significant effect on flavor release and flavor perception of hydrophobic flavor compounds. For starch, an extensively studied hydrocolloid, amylose has been shown to form complexes with aroma compounds. The physical state of carbohydrates is one parameter influencing flavor retention. However, the major effect of hydrocolloids seems to be a limitation for the diffusion of aroma compounds due to changes in viscosity. Addition of fat induces significant retention of hydrophobic flavor compounds resulting in noticeable effects on flavor perception. Changing the fat content modifies the overall perception of a mixture of flavor compounds from different chemical classes. The melting point of the fats influences the solubility of aromas and thus the flavor release. Emulsification and droplet size also affect flavor release and perception. More research is required on the effects of real food samples containing mixtures of different flavor compounds.
Article
ABSTRACTA diffusion cell was designed to study the apparent diffusion coefficient of solutes through foodstuffs. The mathematical model corresponding to the experimental setup did not assume quasi-steady state diffusion within the slice of food. It was used to obtain the effective diffusion coefficient of NaCl through 3% Agar gels. The results were compared to those obtained by using two agar gel cylinders at different concentrations. The diffusion coefficient of Cl− in gel at 25°C was obtained with at least the same precision (D = 1.30 × 10−9 m2/sec, SD= 0.03 × 10−9 m2/sec) within less than 110 min compared to a few hours with the two cylinder technique. With the mathematical model used to determine diffusion coefficients, the equilibrium ratio between solute concentration in solution and at the interface of foodstuff can be determined.
Article
The diffusion of NaCl and isopropanol was studied in a matrix of pure gel and one containing either carbohydrates, proteins or fat using the concentration-distance method. Concentrations of NaCl were measured by conductivity, those of isopropanol by gas chromatography. Diffusion experiments have shown that the temperature dependence of the diffusion coefficient is in accordance with an Arrhenius approach. Experimental and predicted diffusion coefficients didnot agree satisfactorily when only models of mere obstruction were considered. Including the effect of hydration by values obtained from pure gels, experimental diffusion coefficients range throughout between the calculated values of mere obstruction and those obtained from a mathematical combination of obstruction and maximum hydration.
Article
Salt levels in cheese range from ∼0.7% (w/w) in Swiss-type to ∼6% (w/w) in Domiati. Salt has three major functions in cheese: it acts as a preservative, contributes directly to flavour, and is a source of dietary sodium. Together with the desired pH, water activity and redox potential, salt assists in cheese preservation by minimizing spoilage and preventing the growth of pathogens. The dietary intake of sodium in the modern western diet is generally excessive, being two to three times the level recommended for desirable physiological function (2.4 g Na, or ∼6 g NaCl per day). However, cheese generally makes a relatively small contribution to dietary sodium intake except if high quantities of high-salt cheeses such as Domiati and feta are consumed. In addition to these functions, salt level has a major effect on cheese composition, microbial growth, enzymatic activities and biochemical changes, such as glycolysis, proteolysis, lipolysis and para-casein hydration, that occur during ripening. Consequently, the salt level markedly influences cheese flavour and aroma, rheology and texture properties, cooking performance and, hence, overall quality. Many factors affect salt uptake and distribution in cheese and precise control of these factors is a vital part of the cheesemaking process to ensure consistent, optimum quality.
Article
In the first part of the paper (Floury, J., Camier, B. Rousseau, F., Lopez, C., Tissier, J. P., & Famelart, M. H. (2009) Reducing salt level in food: Part 1. controlled manufacture of model cheese systems and their structure-texture relationships. LWT – Food Science and Technology 49(10), 1611–1620), a model cheese matrix presenting different textural properties was developed in order to further study the factors implied in the salt release in mouth during food chewing. The present work consists in physical and modelling approaches to better understand the mass transfer phenomena occurring in the product during its consumption in the mouth. Concentration profiles of several ionic species were measured during the release of salt from the different model matrices into artificial saliva. Apparent diffusion coefficients of the sodium chloride were determined by fitting the experimental data to the second Fick's law. Apparent diffusion coefficients were included between 2.81 and 3.43 × 10−10 m2 s−1 at 15 °C and 75% HR. D-value decreased strongly when the dry matter content decreased. Microstructure of the matrices with the lower protein concentration was coarser and fluffier, facilitating the diffusion of the solutes. The D-value increased with the pH at renneting, probably because of the chemical changes of the structure of the casein micelles and significant differences in textural characteristics of cheeses. The diffusion coefficient also significantly decreased with the initial salt concentration, due to the tightening of the matrix microstructure.
Article
High humidities of drying medium lead to lower drying rates, and both external or internal conditions determine the drying rate. Thus, a diffusional model has been developed assuming that the external resistance to mass transfer could not be neglected in these cases and solved by a finite difference method. The external mass transfer coefficient was estimated from the literature. This mathematical model was used to identify water and salt effective diffusivity coefficients by using experimental data of ripening experiments carried out on parallelepipedal Mahon cheeses of edges kept at 12°C and 85% RH. Using these identified values, for moisture diffusion and for salt diffusion, average moisture content and water and salt profiles during the ripening of cheeses ripened at 12°C and two different relative humidities, 70% and 80% RH, were accurately simulated.
Article
The simultaneous diffusion of NaCl, lactic acid and water in cheese during brining, were experimentally and theoretically evaluated using multicomponent and pseudobinary mass transport models. The average concentration data of each solute in the solid at different process times were correlated with theoretical models determining the diffusion coefficients values for each solute. Applying a ternary model, main and cross diffusion coefficient values for NaCl and lactic acid showed a non-reciprocal flux interaction. The NaCl diffusion rate resulted independent of the lactic acid concentration gradient, while the lactic acid diffusion rate was increased 12 times due to NaCl concentration changes in the cheese. The results established the importance of using multicomponent mass transport models to evaluate the flux variation of solute in the global flux value.
Article
The prediction of infinite dilution volatilities (Henry's law constants) of aroma compounds is examined. At 25 °C, the Bond Contribution model is recommended. At other temperatures where the Bond Contribution model cannot be used, the Kow-UNIFAC group contribution model, coupled with either experimental or predicted by the Antoine-Grain model vapor pressure values, provides estimates only of the volatilities with errors in the range of 20% to 40%. Finally, the effect of a cosolvent (ethanol) on the infinite dilution volatilities of some aroma compounds is examined.
Article
The solubility of nine aroma compounds (acetone, 2-butanone, 2-hexanone, 2-octanone, ethyl acetate, ethyl butanoate, ethyl hexanoate, n-hexanal, and n-hexanol) in both water and various aqueous solutions was measured at 25 °C using the mutual solubility method. The aqueous solutions consisted of sucrose, glucose, sorbitol, glycerol, polyethylene glycol 200, or maltodextrins at different concentrations. Aroma solubility in water decreased with increased hydrophobicity. For aroma molecules which have the same number of carbon atoms in their structure, aqueous solubility decreased as follows: aldehyde > methyl ketone > alcohol > ethyl ester. When using a group contribution method, the estimated solubility of ethyl esters and methyl ketones in water was, respectively, underestimated and overestimated. Compared to water, the solubility of the volatile molecules in aqueous solutions was higher in the aqueous polyols solutions than in the carbohydrate solutions, although solubility decreased as substrate concentration increased. Aqueous solutions properties, such as water activity, also influenced aroma compound solubility. Copyright © 2004 John Wiley & Sons, Ltd.
Article
The new phase ratio variation method is described which represents a convenient way for the determination of gas-liquid partition coefficients for practical purposes, utilizing equilibrium headspace-gas chromatography (EHS-GC). This method is based on the relationship between reciprocal peak area and the phase ratio in the vial containing the sample solution; it involves regression analysis of the EHS-GC measurements of a number of sample vials containing the same sample solution but with a wide variation of phase ratios. Examples are given for both aqueous systems and systems consisting of a stationary (liquid) phase used as the solvent; comparison of the measured values with results obtained by other methods shows satisfactory agreement. A critical discussion of the conditions influencing the accuracy of the analytical results is given.
A system for trace gas analysis using proton transfer reaction mass spectrometry (PTR-MS) has been developed which allows for on-line measurements of components with concentrations as low as 1 ppb. The method is based on reactions of H3O+ ions, which perform non-dissociative proton transfer to most of the common organic trace constituents but do not react with any of the components present in clean air.Examples of analysis of breath taken from smokers and non-smokers as well as from patients suffering from cirrhosis of the liver, and of air in buildings as well as of ambient air taken at a road crossing demonstrate the wide range of applicability of this method.An enhanced level of acetonitrile in the breath is a most suitable indicator that a person is a smoker. Enhanced levels of propanol strongly indicate that a person has a severe liver deficiency.
Article
The characterization of aroma mobility within foods is an important challenge for a better understanding of aroma release in relation to product structure and perception but is difficult to achieve. An experimental device, based on the diffusion cell concept, was used to determine the apparent diffusivity of aroma compounds within complex food products using gaseous measurements. The originality of our approach was based on a mechanistic description of the system and on the early integration of modeling, leading to an apparatus especially adapted for complex matrices and easy to use (direct analysis and no sample storage).The impacts of the operating conditions and of the data treatment analysis on the accuracy of the determination of apparent diffusion properties were evaluated for three aroma compounds in model agar gels. The comparison of these diffusion results with data found in the literature demonstrated the reliability and the robustness of the system. Its suitability for the characterization of mobility properties of aroma compounds in real food matrices was achieved using dairy gels.
Article
The partition coefficients (K) of aroma compounds (a homologous series of ketones, hexanal, t–2-hexenal, ethyl butanoate and 1-hexanol) in polysaccharide solutions were determined by the phase ratio variation method (PRV method) using a headspace autosampler. This method enabled easy determination of the partition coefficients of volatile compounds in a gas/liquid system without external or internal calibration, and the results agreed well with published data obtained by direct method. Measurements of K at different temperatures enabled the investigation of aroma compound retention by maltodextrin and β-cyclodextrin during heat treatment. In a maltodextrin solution, retention depended on the hydrophobicity of aroma compounds and it was favoured by the increase of temperature (from 60 to 80 °C). In a β-cyclodextrin solution, temperature variations produced different effects on the retention of aroma compounds and could reveal differences in the nature of the interaction with β-cyclodextrin.
Article
Experimental data concerning NaCl concentration profiles for industrially processed Emmental cheese were determined with cylindrical samples ensuring semi-infinite unidirectional mass transfer with saturated brining aqueous solutions for different temperature conditions in the range between 4 and 18 °C. Considering a binary diffusion system constituted by the cheese water and the NaCl solute, the NaCl diffusion kinetics were analyzed at each investigated temperature by three different approaches: firstly, using the second Fick’s law with a constant NaCl diffusivity, which gave a poor interpretation of the experimental data; secondly, using the Boltzmann’s method with a concentration dependent NaCl diffusion coefficient and thirdly, by numerical identification from the diffusion equation with an empirical variation of the NaCl diffusivity with the salt concentration (2nd order polynomial) and a boundary condition expressing the mass flux continuity at the interface. As a whole, the derived diffusivity values were found to be in good agreement with the previous published data concerning different cheese types. These two last analyses clearly indicated a decrease of the NaCl effective diffusivity with the salt concentration and, secondly, an increase of this diffusivity with the temperature. Finally, the last modelling, based on a quadratic reduction in the salt diffusivity with the salt concentration and on a Dirichlet (type II) limit condition lead to the best fitting between the measured and the predicted NaCl concentration profiles.
Article
A theoretically based model was developed using the Maxwell–Stefan equation to predict the salt gain and moisture loss of cheese during brine salting. The model was used to predict changes in the salt and moisture profile, and dimensions of the cheese. The best solutions were obtained when the diffusivities were made functions of porosity and salt concentration. For Gouda cheese the predicted moisture and salt/moisture profiles were within 0.6% moisture and 0.3% salt/moisture of published experimental data. The model predicted an overall gain in salt of 1.55% by weight, an overall reduction in moisture from 43.4 to 41.0%, a mass loss of 1.5% and a volume reduction of 2.6% after 8 days of brining.
Article
The influence of mannaproteins released from yeast cell walls during alcoholic fermentation on the volatility of aroma substances was investigated in a model wine. After the characterization of macromolecules (substrates), two techniques have been used to study the interactions with aroma compounds: headspace analysis and an equilibrium dialysis method. The assumed effects of these macromolecules from yeasts on the fixation of volatile compounds were demonstrated. The physico-chemical interactions between aroma substances and mannaproteins depended on the nature of volatile compounds. Protein concentration in substrates was an important factor in their binding capacity. The retention of aroma compounds (β-ionone, ethyl hexanoate) was attributed to mannaproteins having a high proportion of proteins.
Article
Interactions between lipids and several aroma compounds (aldehydes, methylketones, esters, and dimethyldisulfide) were studied in a real food system composed of fresh cheese, triolein, and water. The concentration of ‘free’ ligands was measured with a dynamic headspace-gas chromatographic system. From our results, we conclude that retention of all flavouring molecules increases with the amount of triolein. This phenomenon is highly influenced, however, by the structure of the aroma compound, as demonstrated by RP-HPLC lipophilicity determinations. Within the same chemical family there exists a linear relationship between the lipophilicity index kw and retention, indicating that this physicochemical property should be taken into account in choosing the best internal analytical standard.
Article
To better understand which composition levers are available to reduce salt content in food without altering flavour perception, this paper aimed at quantifying the impact of texture and composition (salt, fat and dry matter) of a model cheese: (i) on salt and flavour perception, and; (ii) on profile texture and flavour release.Variations of salt, fat and dry matter highly influenced texture perception and instrumental texture parameters. Differences in aroma release and olfactory perception (“blue cheese” odour perception) between different model cheeses were highlighted when salt and fat content varied. However, a major result of this study showed that salty perception was not influenced by texture characteristics of model cheeses. Furthermore, olfactory perception modified texture perception but only for model cheeses with low fat and low-dry matter contents. Variations in salt content and sensory interactions therefore seem to have a greater impact on products with low fat content than on those with high-fat content.
Article
The growth and survival behaviours of Bifidobacterium lactis and Lactobacillus acidophilus in a semi-hard Gouda cheese at various axial locations during 9 wk of ripening at 13 °C were assessed using non-linear regression analysis. The final average salt levels ranged in 2–4%(w/w). Viable numbers of both probiotic strains underwent a slow decline during the first 3 wk followed by a sharper decrease towards the end of ripening; such decrease was more substantial for the outer than for the inner cheese portions. Salt transport was successfully described by Fick's second law of diffusion, and the cheese was considered as a finite slab for modelling purposes. Salt diffusivity remained constant with time and was estimated to be 0.2 cm2/day. Theoretical salt concentration profiles were in good agreement with experimental data. The mathematical models postulated and fitted to the microbial viability data encompassed both a linear relationship between specific death rate and salt concentration and a constant death rate, following a methodology of increasing model complexity. Decision on the better model was taken based on a F-test of the ratio of incremental sum of squares of residuals to sum of squares of residuals of the more complex model, and it was concluded that viability of the probiotic strains was better described by a first order process independent of local salt concentration. Prediction of profiles of viable numbers of B. lactis and L. acidophilus in cheese with respect to both ripening time and axial location for several overall salt concentrations is useful in attempts to predict potential viability by the time of consumption.
Article
A model study on movements of sodium ions in pork loin during brining was carried out using (23)Na-magnetic resonance imaging ((23)Na-MRI). Samples of different pH and post-mortem age were mounted in Plexiglas(®) cylinders with built-in phantoms and cured in 18.9% and 18.1% NaCl (w/v), respectively. One-dimensional (23)Na-MRI and apparent diffusion coefficient (ADC) profiles were obtained over 5 days with intervals of 24 h. On day 5 the meat was cut into 1 cm slices and analyzed for chloride content. (23)Na-MRI and ADC profiles of meat provided detailed non-destructive information about salt and water movements during brine curing. Quantification of salt concentration in meat by one-dimensional (23)Na-MRI profiling proved successful at values above 0.9 g NaCl/100 g sample in the meat. (23)Na measurements were calibrated against chemically determined chloride, yielding a linear relationship. (23)Na-MRI profiles suggested that the diffusion of salt into whole meat cuts cannot be described by simple ordinary Fickian diffusion with a constant diffusion coefficient. The diffusion coefficient is suggested to be affected by changes in NaCl concentration, swelling and degree of dehydration.
Article
Several experimental methodologies exist for measuring volatilities; however, results show great dispersion and sometimes lack of agreement between different methods. The aim of our study was to compare the performance of three static headspace methods (vapor phase calibration, VPC; phase ratio variation, PRV; and liquid calibration static headspace, LC-SH) for determining gas/liquid partition coefficients of two aroma compounds in hydroalcoholic multicomponent solutions at infinite dilution. Comparison with literature data based on static and dynamic methods showed that PRV is simpler than VPC and LC-SH and that VPC and PRV are more accurate than LC-SH, which presented a significant bias (50% lower values).
Article
Self-diffusion measurement of solutes in polymer gels has been investigated using pulsed gradient spin echo NMR spectroscopy. However, few data are available on the self-diffusion of small solutes in natural polysaccharide polymers used as thickeners in the food industry. Since aroma diffusion in food matrices could have an impact on flavor release, this is an interesting and economic challenge. Diffusion ordered spectroscopy (DOSY) resolves diffusion data for each component in complex mixtures. We used DOSY with the inverse Laplace transform approach with the maximum entropy algorithm to investigate diffusion of two aroma compounds, ethyl butanoate and linalool, in an iota-carrageenan matrix as the food model. We showed that the self-diffusion coefficient values of small molecules in a polysaccharide matrix could be easily extracted using this method. We then investigated the impact of the gelling state of iota-carrageenan matrices on the self-diffusion of ethyl butanoate.
Article
This study deals with the release kinetics of nonvolatile compounds (NVC) (leucine, phenylalanine, glutamic acid, citric acid, lactic acid, propanoic acid, sodium, potassium, calcium, magnesium, chloride, and phosphates) during the eating of a model cheese and the relationships to some oral (salivary and masticatory) parameters. The aroma release has previously been characterized in similar conditions [Pionnier, E.; Chabanet, C.; Mioche, L.; Le Quéré, J.-L.; Salles, C. J. Agric. Food Chem. 2004, 52, xxx-xxx (1)]. Saliva samples were collected from the tongues of eight assessors at different times during and after the chewing sequence. Atmospheric pressure ionization-mass spectrometry and/or high-performance liquid chromatography analyses have been performed on these samples in order to quantify the 12 NVC released in saliva. The maximum concentration (C(max)) in saliva varied significantly according to the compound. However, there was no significant effect of the compound on the time to reach maximum concentration (T(max)). Interindividual differences were observed for most of the parameters and for all of the NVC studied. The parameters extracted from the release profiles of the NVC were closely correlated. High T(max) and AUC (area under the curve) values could be related to high chewing time and low saliva flow rates, low chewing rates, low masticatory performances, and low swallowing rates.
Article
Diffusion-ordered spectroscopy (DOSY)-pulsed field gradient (PGF) nuclear magnetic resonance (NMR) spectroscopy was used to measure self-diffusion coefficients of aroma molecules in model fruit preparations. The impact of the sucrose content on aroma diffusion was specifically investigated, and the relationship with viscosity, water activity, and dry matter parameters was evidenced. DOSY-PGF NMR spectroscopy was found to be a relevant and accurate technique to follow self-diffusion of aroma compounds at low concentrations in a complex food matrix and to obtain information on diffusion of the sucrose and of the water molecules. We showed that aroma self-diffusion was strongly decreased in fruit preparation because of the high sucrose content, which induces the formation of a network through hydrogen bonds with water. Self-diffusion coefficients were determined for aroma molecules of different natures, and values are related to the physicochemical properties of the molecule.
Article
The phase ratio variation (PRV) method is widely used for the determination of partition coefficient values (dimensionless Henry's law constants) by headspace gas chromatography. Traditional data processing by linear regression has several drawbacks: potential bias introduced by linearization, absence of quality indicator of the resulting value and, in case of replicate determinations, poor utilisation of the existing measurements leading to unnecessarily large confidence intervals. The paper compares existing PRV data processing methods (linear and nonlinear regression, parametric) and derives confidence intervals for the resulting partition coefficient values. The possibility of using several series of measurements to derive a single partition coefficient value with tighter and more reliable confidence intervals is presented for all three processing methods. The methods are tested on published literature data and new experimental data for 12 volatile organic compounds in water at 25 degrees C. The nonlinear regression based on several series of measurements appears to be the method of choice.
Article
Dynamic light scattering (DLS) and fluorescence recovery after pattern photobleaching (FRAPP) were used to study the interaction of low molecular weight poly(ethylene glycol) (PEG) with micelles of two different surfactants: tetradecyldimethyl aminoxide (C(14)DMAO, zwitterionic) and pentaethylene glycol n-dodecyl monoether (C(12)E(5), non-ionic). By using an amphiphilic fluorescent probe or a fluorescent-labeled PEG molecule, FRAPP experiments allowed to follow the diffusion of the surfactant-polymer complex either by looking at the micelle diffusion or at the polymer diffusion. Experiments performed with both fluorescent probes gave the same diffusion coefficient showing that the micelles and the polymer form a complex in dilute solutions. Similar experiments showed that PEG interacts as well with pentaethylene glycol n-dodecyl monoether (C(12)E(5)).
Article
Using atmospheric pressure chemical ionization-mass spectrometry, aroma release was investigated in vivo and in vitro from three cheese-like gels with different hardnesses. In vivo, nosespace experiments were performed with 14 subjects. Results showed that the harder gel induced a greater and a faster release of all aroma compounds. In vitro, aroma release was followed in a mouth simulator where breakdown was mechanically produced. The same rate of stirring was applied to the three gels. In these conditions, we found that the amount of aroma released from the three gels was not discriminant. Thus, modification of gel structure had a strong impact on in vivo aroma release, but structural variations alone were not sufficient to induce a greater release. Natural breakdown provided by panelists during food consumption and adapted to the texture of the food was proposed to be the key parameter affecting in vivo aroma release.
Article
Aroma compound properties in food matrices, such as volatility and diffusivity, have to be determined to understand the effect of composition and structure on aroma release and perception. This work illustrates the use of mass transfer modeling to identify diffusion and partition properties of ethyl hexanoate in water and in carrageenan matrices with various degrees of structure. The comparison of results obtained with a diffusive model to those obtained with a convective model highlights the importance of considering the appropriate transfer mechanism. Modeling of the preliminary experimental steps ensures correct estimation of the conditions for the main aroma release step. The obtained values of partition and diffusion coefficients are in agreement with those found in the literature (either experimentally determined or predicted by theoretical equations) and demonstrate that the structure level of carrageenan matrices has little influence on diffusion properties of ethyl hexanoate (less than 20%).
Flavor – matrix interactions in wine In: Abstracts of Papers of the Prediction of infinite dilution volatilities of aroma compounds in water
  • A Voilley
  • S Lubbers
Voilley, A., Lubbers, S., 1997. Flavor – matrix interactions in wine. In: Abstracts of Papers of the American Chemical Society, San Francisco, USA. Voutsas, E.C., Andreou, C.I., Theodorou, D.G., Tassios, D.P., 2001. Prediction of infinite dilution volatilities of aroma compounds in water. Journal of Food Sciences 66, 447–452.
Etude des interactions entre la β-lactoglobuline et les composés d’arôme
  • E Jouenne
Jouenne, E., 1997. Etude des interactions entre la b-lactoglobuline et les composés d'arôme. Université de Montpellier.
Influence des caractéristiques physico-chimiques d’un fromage frais sur son aromatisation par des composés volatils de l’ail
  • C Dubois Barbier
Dubois Barbier, C. 1994. Influence des caractéristiques physico-chimiques d'un fromage frais sur son aromatisation par des composés volatils de l'ail. PhD Thesis. University of Burgundy.
23 Na DQF NMR studies on a model system
  • H Dosy
H DOSY and 23 Na DQF NMR studies on a model system. In: The 8th International Conference on the Applications of Magnetic Resonance in Food Science, University of Nottingham, UK.
Diffusion Mass Transfer in Fluid Systems An experimental device to determine the apparent diffusivities of aroma compounds
  • E L Cussler
Cussler, E.L., 1997. Diffusion. Mass Transfer in Fluid Systems, second ed. University Press, Cambridge. Deleris, I., Atlan, S., Souchon, I., Marin, M., Trelea, I.C., 2008. An experimental device to determine the apparent diffusivities of aroma compounds. Journal of Food Engineering 85, 232–242.
Aroma diffusion and salt interactions in food
  • M Gobet
  • M Mouaddab
  • E Guichard
  • Le Quéré
  • J L Moreau
  • C Foucat
Gobet, M., Mouaddab, M., Guichard, E., Le Quéré, J.L., Moreau, C., Foucat, L., 2006. Aroma diffusion and salt interactions in food.
Aroma diffusion and salt interactions in food. 1H DOSY and 23Na DQF NMR studies on a model system
  • M Gobet
  • M Mouaddab
  • E Guichard
  • J L Le Quéré
  • C Moreau
  • L Foucat
Gobet, M., Mouaddab, M., Guichard, E., Le Quéré, J.L., Moreau, C., Foucat, L., 2006. Aroma diffusion and salt interactions in food. 1 H DOSY and 23 Na DQF NMR studies on a model system. In: The 8th International Conference on the Applications of Magnetic Resonance in Food Science, University of Nottingham, UK.