INTERACTIONS OF FOOD MATRIX WITH SMALL LIGANDS INFLUENCING FLAVOUR AND TEXTURE

Obiettivo

GENERAL DESCRIPTION OF THE ACTION

1. INTRODUCTION

1.1. Why a COST Action on this topic?

Flavour is considered one of the most important attributes determining the acceptability of food to the consumer. In particular, consumer demand for healthier foods which contain less fat, sugar and salt has generated in industry a keen interest in basic knowledge regarding the influence of the food matrix on flavour release and perception. As a modification of the formulation of a product induces alterations in the flavour quality, it is necessary for industry to optimize the flavour or the texture by an empirical change in the formulation. The aim of this Action is to increase our understanding of flavour release and perception in relation with texture characteristics and perception. This information will be of great advantage to industry in the formulation of products with acceptable flavour and textural properties. The systematic development of products with acceptable flavouring properties will be possible only when the flavour binding behaviour of food ingredients has been thoroughly elucidated.

Previous investigations have involved studies of interactions between components of simple mixtures, i.e. model systems consisting of water, a volatile substance and a non-volatile constituent have been used. A critical evaluation of the published information shows that most data have been frequently obtained under inadequately specified conditions or that there is such a wide range of conditions used that generalizations are not possible. Moreover, there are few reports regarding the nature of these interactions, even in simple systems, and few studies only have been undertaken on real food systems. All these studies did not take into account the in-mouth situation and the effect of mastication on flavour release.

Very few laboratories have actively worked recently in this field and mostly isolated researchers can be currently found in Europe. It thus appears indispensable to draw up and co-ordinate a European research programme into the INTERACTION OF FOOD MATRIX WITH SMALL LIGANDS INFLUENCING FLAVOUR AND TEXTURE. This topic is also of interest in the USA and one of the symposia to be held at the 208th National ACS Meeting (Washington, DC, 21 to 26 August 1994) is entitled CHEMISTRY OF INTERACTIONS BETWEEN FLAVOR AND NON-FLAVOR COMPONENTS. The laboratory of Dr Reineccius (St Paul, Minnesota) is a very active research group in the USA on this topic.

This type of research requires a real multidisciplinary basis since many scientific fields are involved. We need the collaboration of laboratories working in these different fields of research and offering complementary approaches. The creation of a network through a COST proposal will attempt to realize this scientific goal on the European scale. This will lead to the use of large and expensive equipment in European research centres.

The research topic of the proposed project includes 5 major scientific fields for which state of the art knowledge and possible research approaches are described in the following sections. They are:

1. selection and characterization of suitable models
2. evaluation of existing methods
3. development of new methodologies of investigation
4. measurement of flavour retention and release
5. correlation between sensory and instrumental data.

1.2. Relations with the other European programmes

Because the Action is an open project it is planned to work in close collaboration with any national and international organizations which are involved in flavour release from food. Basically, the objective is not to set up a new structure but, on the contrary, to bring together the existing means and competences, which the organizations concerned will be able to use.

INRA laboratories (France) have already been involved in a European project on the flavour research: Flair Cost 902 RELATING SENSORY, INSTRUMENTAL AND CONSUMER CHOICE STUDIES. AFRC (England) and Istituto di Industria Agraria (Italy) are also involved in this Flair project. This project is at the end. A new proposal for a concerted action will be filed by Norway on MEASUREMENT OF CONSUMER ATTITUDES AND THEIR INFLUENCE ON FOOD CHOICE AND ACCEPTABILITY. Our topic proposed now has not been studied during Flair Cost 902 and will not be studied in the proposal on acceptability. These topics are complementary.

IATA laboratory (Spain) is involved in an AIR project on ESTABLISHING SCIENTIFIC BASIS FOR CONTROL AND IMPROVEMENT OF SENSORY QUALITY OF DRY-CURED HAMS IN SOUTHERN EUROPEAN COUNTRIES. This AIR project does not take into account the flavour release in food.

Exchanges of scientists between INRA and AFRC already exist within the ESN network and a collaboration will begin on the topic "Interactions between macromolecules and flavour compounds". Moreover both Institutes intend to develop a mutual interest and a flavour consortium will probably be supported to facilitate mobility of researchers.

Exchanges of students in the framework of Erasmus or Comett projects exist between Ensbana (France) and about 25 universities or industries in Europe, working in the field of food science and technology. IATA (Spain) is active within the Ecceamst (European Consortium for Continuing Education in Advanced Meat Science and Technology).

2. OBJECTIVES

In France, bilateral collaborations exist between INRA and university laboratories, since 1986. The studies already undertaken on this topic in France have been more oriented towards physicochemical interactions in the product. Regarding the need for a better understanding of flavour release in food, a French network on the topic "Interactions texture-flavour" will be constituted, gathering scientists from INRA (Nantes, Dijon, Theix, Poligny, Jouy en Josas) and universities (Bourgogne, Montpellier).

In England, several laboratories in AFRC and universities are working on common projects on flavour release and perception. They quantify the variations in the eating process as a function of food, to be related to structural changes in the food and flavour release. They measure and identify the mechanisms of volatile release from different food structures under eating conditions. They also study the interactions between volatile compounds and receptor protein at the olfactory epithelium.

Collaboration already exists between United Kingdom University Departments which are active in Flavour Research. This is co-ordinated through the United Kingdom Universities' Flavour Research Consortium, which provides a mechanism for discussion and joint research ventures. Research on flavour retention and release is currently being undertaking in 5 universities which will participate in this COST Action, co-ordinated by the Consortium.

In Switzerland (Swiss Federal Institute of Technology), an important work has been conducted on starch-lipid and starch-flavour interactions and their implications on rheological properties and textural qualities.

In Belgium at the University of Louvain la Neuve, spectroscopic methodologies are used and interactions between peptides and ions are studied.

In the Netherlands (Wageningen Agricultural University) sensory attributes of different products and model systems are correlated with release data of volatile compounds.

All these laboratories have therefore complementary approaches to try to understand a general objective on the effect of food formulation on flavour perception.

There is a need for European collaboration in order to avoid duplication of the activities of the different countries in the field.

2.1. Main objectives

The main objectives of the project will be to:

- set up a programme for scientific research and exchanges aiming to study the interactions between food matrix and small ligands influencing flavour and textural properties of food;

- develop appropriate systems for the study of flavour release and provide standard methodologies, taking into account previous experiences of all the participants;

- determine the areas where sensory and instrumental measurements can be used in the study of interaction between flavour and the food matrix.

2.2. Secondary objectives

The secondary objectives are as follows:

- develop and optimize new methods for evaluation of flavour retention and flavour release. The co-operation with European partners will allow the investigation and the critical study of a large number of methodologies on the same models;

- determine relationships between food structure, sensory properties and instrumental measurements of flavour, in order to validate the methodologies;

- establish a European network for flavour analysis which will link with the existing European Sensory Network (ESN). Numerous partners, such as public services, universities and industries, could be requested to become members of such a network;

- promote further research in the area of the interactions between food structure and flavour perception.

3. CONTENT OF THE PROJECT

Research efforts in the participating countries will be co-ordinated through this COST Co-operation to ensure unnecessary duplication of effort is avoided. The COST Action will define a programme of collaboration between the participating scientists, provide guidelines for research and permit comparison of results.

The scientific programmes

A concise synopsis of the different proposals (schemes No 1 and No 2) sent by the different countries is given below:

*1* Selection and characterization of suitable models

All the work related to the interactions between non-volatile and volatile compounds was done on simple model systems very far from the real food product. In every case the authors were not able to explain the change in flavour quality induced by some modifications in the formulation of food products. Our objective is to define explanatory models with non-volatile compounds in the presence of aroma compounds with well defined chemical properties and defined structures.

This first stage will be divided in 2 steps:

1a Selection of representative flavour compounds and food systems which can be used to model flavour retention and flavour release (different formulations and structures)

This choice will be discussed during the first meeting, taking into account the experiences of all the scientists in the field. We will choose compounds with high flavour impact value and belonging to various chemical classes.

The food system will be defined to take into account the nature of the ingredients used in the formulation and the structure of the matrix.

1b Selection of appropriate formulations and processing conditions which can be applied to such studies

The experimental work will be done in the laboratories depending on their capabilities.

2 Evaluation of existing methods

A critical study of all the techniques already used in the laboratories will be done:

chemical analyses
- measures of diffusion, headspace analysis (England, France, Hungary, Italy, Norway, The Netherlands)
- exponential dilution, equilibrium dialysis (France, Italy, The Netherlands)
- sorption measurements (France, England)
- image analysis (Sweden)

sensory analyses
- profile analysis (France, England, Finland, Norway, Czech Republic, Sweden)
- time intensity (England, Czech Republic, The Netherlands)

2a In a first step, the limits of applicability of these methods will be defined.

2b In a second step, after the preparation of the models, their suitability will be checked for this study with these existing methods.

3 Develop new methodologies of investigation.

3a Methods used in other fields will be transposed for our task. They are for example:

- diafiltration (France)
- HPLC on bound columns (France, Hungary, Czech Republic)
- spectroscopic methods (Belgium, Switzerland, Sweden, England)
- circular dichroism, fluorescence, microcalorimetry (France, England, Norway)
- photoaccoustic analysis (The Netherlands)
- capillary electrophoresis (Norway, Spain)

These methods will be checked in comparison with the existing methodologies.

3b Optimization of the models and of the performances of the methods

For this optimization we will use radioactive ligands, if available (France).

3c Evaluation of the repeatability and reproducibility of the sensory and instrumental methods on the models

4 Measurement of flavour retention and release in models with differing formulations and structures and relate to real food systems

At this point of the action, the models will be well defined and the methods validated. Flavour retention can be important even with highly volatile compounds. The main factors which could influence the interactions between non-volatile constituents and small ligands are especially the concentration of the compounds and the temperature. The effect of temperature, in some cases, can give information on the nature of the interactions, as other techniques like spectroscopy.

The interactions will be discussed with the aid of molecular modelization (France, England).

4a Measurement of flavour release in the mouth

This could be investigated by the measurements of nose space and mouth space (England, The Netherlands). In this case, extra factors like pH and saliva could also influence the release of aroma.

4b Measurement of the sensory consequences of these variations

Sensory analyses experiments could be conducted in parallel in different laboratories, as well as extract dilution analysis and sniffing panel (France, England, Italy, The Netherlands).

5 Correlation between sensory and instrumental data

To establish correlations between the obtained data, we will use the same statistical packages as the laboratories belonging to the Flair COST Action 902 RELATING SENSORY, INSTRUMENTAL AND CONSUMER CHOICE STUDIES (France, England, Norway, Hungary, Czech Republic, Spain).

4. SCHEDULE

A four-year programme is proposed for this Action. The numbers refer to those in section 3.

Starting point First meeting:
definition of the working groups
allocation of the scientists in working groups.
Discussion of point 1.

Points 2a and 2b

1,5 year Second plenary meeting:
workshops
general synthesis
first reports

Points 3a, 3b, 3c

3 years Third plenary meeting:
workshops
general synthesis
second reports

Points 4a, 4b

3,7 years Point 5

4 years Fourth plenary meeting:
workshops
final synthesis
final report
publication and diffusion of the results

5. ORGANIZATION, MANAGEMENT AND RESPONSIBILITIES

The co-ordination of the Action will be carried out by the Management Committee, in accordance with Annex I to the Memorandum of Understanding. The following activities will be realized:

The Management Committee will assign working group co-ordinators. Co-ordinators will organize the co-operation within and between the working groups, organize sessions on topics within the objectives of their working group during COST workshops. People working in each group will meet when necessary and at least 4 times a year, at the meetings organized within the working groups. Short reports of these meetings will be given to the Management Committee and diffused to all the participants of this Action. The results will be presented for the plenary meetings. Annual reports will be written by the participating scientists, describing their results obtained through this concerted action.

At the beginning of this Action, a bibliographic review on the work already done in the field could be realized and submitted for publication.

The joint exploitation of the research potential shared by the participants will be realized by exchange of experts, postdocs and postgraduates between the laboratories financed from available national and international sources and by exchange of information through workshops. These workshops will be a forum for the distribution of results and improved or standardized protocols and techniques.

6. ECONOMIC AND FINANCIAL MATTERS

6.1. Economic importance

A better knowledge of the flavour which could be released during the mastication will allow a better use of the flavouring molecules. Between 12 000 and 15 000 tonnes of flavour molecules are used in the industry, among them 15 to 20% are natural molecules. The cost varies between 14 to 57 ECU/kg for synthetic molecules and reaches the amount of 210 ECU/kg for some natural molecules. For example in the case of yoghourt, the cost for the aromatization is between 0,1 and 0,2 ECU/kg for natural flavour and between 0,01 and 0,02 ECU/kg for nature identical flavour.

The use of judicious supports for the aromatization could reduce the costs if these supports allow a better incorporation in the food matrix and a good release during the mastication. Moreover, an increase in the efficiency of the aromatization could lead to a decrease in the use of non-substantial additives such as sugars, sweeteners, salt or fat, and thus induce a decrease in the cost of the final product.

6.2. Research efforts

Setting up a COST Research Action on the topic INTERACTIONS - NON-VOLATILE COMPONENTS - SMALL LIGANDS should allow the abovementioned objectives to be met, thus leading to a better understanding of the FLAVOUR RETENTION AND RELEASE IN FOODS WHEN FORMULATION AND FOOD STRUCTURE VARIES.

An estimation of the costs could be made when we know how many people will be concerned in the research programmes, on the basis of:

60 000 ECU/man-year for scientists
40 000 ECU/man-year for technicians
25 000 ECU/man-year for secretaries.

Considering the answers given by the 30 laboratories (12 countries) which are interested by this Action, the overall value of the activities of the Signatories could be estimated approximately at ECU 13 million.

6.3. Co-ordination costs

Research costs will be taken over by the participating countries according to their respective involvement.

Current status
In 1995, a review of all the methodologies used and available in the different laboratories was established together with a list of the models experimented.

In 1996, four Working Groups were established:

Working Group 1 (kinetic and thermodynamic constants): Prof. Andrée VOILLEY (F)
The first objective of this working group is to carry out a critical review of the thermodynamic and kinetic data and to demonstrate their interest in developing physico-chemical models in flavour release.
The second objective is to define a simple methodology to measure the constants:
an interlaboratory study will begin on vapour-liquid equilibrium in the same conditions, in water with and without (-lactoglobulin. The aroma compounds chosen are isoamyl acetate and 2-nonanone;
experiments will be done in the different laboratories with the same protein but with their own ligands and methodologies;
the last objective is to collate the data from the literature.

Working Group 2 (theoretical modelling): Dr. Brian HILLS (UK)
Development of theoretical models for flavour release, including experimental data, in order to predict breath-by-breath time-intensity flavour release.

Working Group 3 (Dynamic sensory methods): Dr. Garmt DIJKSTERHUIS (NL)
Some background information on time-intensity studies and the analysis of time-intensity data were given. The work planned is to collect time intensity data in different laboratories, and attempt to standardised the way to collect and handle such data. As time-intensity studies are a good tool to study the perception of flavour release, the harmonisation of time-intensity methodology will aid in understanding flavour release and its perception by human subjects.
Data from a combined breath-by-breath analysis and mastication study and also time-intensity data are available to all participants. Each participant will present its way of analysing and interpreting these data during the next meeting in The Netherlands.

Working Group 4 (instrumental measurements): Prof. Michele DEBATTY (B)
In this working group the different methodologies used by the participants have been presented with their possible applications to the understanding of flavour binding and flavour release. This working group will now focus more on the instrumental methods which could give a better understanding of the structure and texture of the matrix and on its influence on the binding or release of aroma compounds. Thus three categories of matrix were defined, proteins, polysaccharides and neutral polymers. A special effort will be put to analyse to what extent some common key features could be defined with a view to describing on a common basis the different matrices and their binding or release properties.

Short term scientific missions
Many exchanges of scientists were realised within this Action, allowing the experimentation of different methodologies.
Eight missions were realised in 1995, 10 in 1996 and 10 are planned for 1997.

Programma(i)

IC-COST - European cooperation in the field of scientific and technical research (COST), 1971-

Argomento(i)

5 - Food Technology

Invito a presentare proposte

Data not available

Meccanismo di finanziamento

Data not available

Coordinatore

CEC

Contributo UE

Nessun dato

Indirizzo

Rue de la Loi, 200
1049 Brussels
Belgio

Costo totale