Melanoïdins in food and health

Objetivo

A. BACKGROUND

What are melanoidins?

Melanoidins are materials formed primarily by interactions between carbohydrates and compounds possessing a free amino group, such as free amino acids and the free amino groups of peptides. The complex network of interactions, resulting in melanoidins as the final reaction products, are commonly referred to as the Maillard reaction. This reaction occurs readily during many heat treatments applied to foods. Much of the colour that develops when foods, e.g. coffee, bread, are heat processed, is due to the melanoidins formed by reactions between carbohydrates and amino compounds. Melanoidins with phenolic sub-units are also present, e.g. in coffee.

Structures of melanoidins and related materials

The structures of melanoidins and related materials are poorly defined. They are reported to possess molecular masses of up to 100 000 Da and to possess a C:N ratio that varies with the conditions of preparation (temperature and time of incubation). The degree of aromaticity also varies with temperature and time of heating. No single melanoidin has been isolated and characterised, and enormous difficulties have been experienced in separating individual structures. Current thinking is that melanoidins are likely to comprise a complex mixture of closely related structures with very similar charge: mass ratios. The formation or separation of melanoidins of uniform structure and mass is an essential prerequisite to their successful characterisation. Only in recent years have techniques become available to allow the structural characterisation of melanoidins, e.g. certain methods of ionisation for mass spectrometry (MS) and advanced multidimensional nuclear magnetic resonance spectroscopy (NMR) experiments.

Why are melanoidins important and what in their role?

Melanoidins are likely to comprise a substantial proportion of some foods, e.g. coffee, roasted malt, breakfast cereals, bread. For example, in coffee, about 35% of roasted coffee comprises unidentified material, including melanoidins. Malts are used to prepare beers and whiskies and are also used to modify the colour of a range of foods and beverages. Breakfast cereals and bread are consumed widely, especially in northern Community Member States. Thus, melanoidins are widely consumed dietary components. In addition, melanoidins possess antioxidant activity (assessed by physicochemical techniques), are responsible for much of the colour that develops when most foods are heat-processed, may contribute to food texture and beverage viscosity, are reported to possess desmutagenic activity and are likely to play a role in the binding of nutritionally important metals, potentially undesirable dietary components, e.g. heterocyclic amines, and of bile acids (related to cholesterol metabolism) and flavour molecules. Thus, they will contribute to the stability (increased shelf-life) of foods through their antioxidant properties and they play an important role in the acceptability of foods through their colour properties. Their contribution to food choice, in terms of flavour binding and texture properties has not been reported.

Although melanoidins are known to possess antioxidant properties and to bind nutritionally important metals, such as copper and zinc, the effect of melanoidins on the health status of the human organism is unknown. The degradation of melanoidins in the gut and the subsequent absorption and function of any degradation products has not been reported. Also, the role of unabsorbed melanoidins on human health, e.g. ability to reduce absorption of undesirable components in the gut, followed by excretion, is unknown. There is a need to investigate the possibility that modifying the quantity and/or profile of melanoidins formed at different food processing conditions and subsequently consumed, can improve human health status.

We recognise the importance of sensory and consumer science in assessing the acceptability of new or modified foods, but this aspect will not be part of this proposed COST Action.

Synergies with relevant areas of Framework Programme V (FPV)

The document "Fifth Framework Programme for Research and Technological Development (1998-2002) Commission Working Paper on the Specific Programmes: Starting Points for Discussion" includes objectives and RTD priorities in the key action "Health and Food". The document emphasises the economic importance of the Community food and drink industry, which accounts for 16,5% of the Community's total industrial value. Most European citizens have access to sufficient quantities of food. Therefore, health issues related to food lie in optimising the intake of amounts and types of dietary components and in ensuring that food is attractive to the consumer. There is a need to provide knowledge to assist the production of health-promoting foods by the industry. This could involve, e.g. producing foods containing enhanced levels of antioxidants which improve the health status of the individual (without the use of artificial additives), or developing foods containing increased levels of components with the ability to interact with nutrients and undesirable materials

Why a COST Action on melanoidins?

Hitherto, scientists have worked on melanoidins isolated from different systems and prepared in different ways. Studies have been uncoordinated, leading to different sets of data that cannot be easily compared with each other. Therefore, it appears essential to establish a coordinated European network in order to facilitate progress in the area and to make efficient use of scarce resources, particularly state-of-the-art instrumentation. Work on melanoidins is conducted in several

Community Member States, as well as other European countries, including Bulgaria, the Czech Republic, Norway and Romania. The aim is to bring together scientists who already have experience of melanoidins and related molecules and who already have, or expect to have, such research funded. A COST Action on melanoidins will promote work in the field by exchange of ideas and access to expensive resources. It will provide a conduit to establish a European network of scientists in a key action of FPV (Health and Food).

This proposed COST Action will help industry produce foods with superior health properties and sensory quality attributes. Increased knowledge of e.g. the flavour binding, colour, texture and antioxidant properties of melanoidins, is of tremendous interest to food manufacturers in terms of food choice and shelf-life, and thus has important implications for the economic competitiveness of the European food industry. The topic is also of interest in Japan and in the US. In Japan, most work on melanoidins has concerned their function rather than their structure. In the US, most effort has been devoted to in-Maillard reaction in vivo (advanced glycosylation endproducts (AGEs)).

Several laboratories which are interested in melanoidins also participate in FAIR project CT96-1080 "Optimisation of the Maillard Reaction. A way to improve quality and safety of thermally processed foods". Although melanoidins are products of the Maillard reaction, their structure and functions are not addressed by that project. Thus, this proposed COST Action on melanoidins is entirely complementary to CT96-1080. Some laboratories interested in melanoidins participate in COST Action 96 "Interaction of food matrix with small ligands influencing flavour and texture". That Action is not concerned with melanoidins although some of the findings concerning flavour binding to other macromolecules may be relevant to it. There is no overlap between COST Action 96 and this proposed COST Action.

B. OBJECTIVES AND BENEFITS

Main Objective

The main objective of the Action is to increase knowledge regarding the structure of melanoidins and related molecules in different food systems and to develop knowledge concerning the function (quality related to food-acceptability and quality related to health aspects) of melanoidins and related molecules in food, especially: capacity to bind ligands, e.g. flavour compounds, role in colour and texture, antioxidant and other properties related to the shelf-life of food, and role in health, as assessed by in vitro and in vivo studies.

Secondary Objectives

The secondary objectives are:

- to optimise procedures for the separation and characterisation of melanoidins and related macromolecules;

- to develop and optimise methods for evaluating the flavour binding, colour, texture and antioxidant properties of melanoidins and related molecules in food;

- to determine relationships between the character of melanoidins and related molecules and their functional properties related to food-acceptability;

- to investigate the physiological effects and fate of melanoidins using in vitro and in vivo studies (animals and humans);

- to exchange and apply expertise and methodology used by scientists working with different types of macromolecules (melanoidins and AGEs);

- to promote further research in the area of melanoidins in food and health in a synergistic way, to optimise the efficient use of scarce resources and to maximise progress.

Benefits

It is expected that the project will result in a much clearer understanding of the chemical nature of melanoidins and related structures formed under different food processing and other conditions. This understanding will be related to the various functions of melanoidins in foods and beverages, and in the human body. Thus, the findings from the project will indicate the sub-structures of melanoidins and conditions required to optimise the following properties of foods and other biological systems, i.e.

- flavour-binding capacity;

- colour and textural characteristics;

- antioxidant activity, related to food stability and shelf-life;

- physiological properties of melanoidins and role of melanoidins in human health.

C. SCIENTIFIC PROGRAMME

The scientific programme has been developed with input from different countries. The scientific programme addresses the objectives set out in Section B.

Main Objective One

To increase knowledge regarding the structure of melanoidins and related molecules in different food systems

Research Tasks (milestones)

1. Define the standard melanoidins to be analysed by different laboratories.

2. Develop and optimise procedures for separating of melanoidins and for isolating melanoidins from foods.

3. Develop and optimise spectroscopic procedures for the characterisation of melanoidins.

4. Characterise the standard melanoidins formed in model systems.

5. Acquire information regarding the structure of melanoidins isolated from different foods.

In order to compare meaningfully different characterisation methods, it is essential that melanoidins of the same composition prepared from well-defined model systems are used by the different laboratories. A selection of model systems will be discussed and the final choice will be made at the first meeting of the COST Action.

In addition, participating laboratories will prepare melanoidins of different composition, from various precursors and intermediates under different conditions (depending on their capabilities) for analysis by techniques available in the laboratories of other participants.

Main Objective Two

To develop knowledge concerning the flavour binding properties of melanoidins and related molecules in food

Research Tasks (milestones)

6. Develop methods and evaluate the flavour binding properties of standard melanoidins and melanoidins from selected foods (particularly beer and coffee).

7. Elucidate the interactions between standard melanoidins and melanoidins from selected foods with representative flavour compounds.

8. Define the nature of the binding between melanoidins and flavour compounds.

9. Determine relationships between the nature of melanoidins and their flavour binding properties.

For flavour molecules, when binding is reversible, release can occur during mastication, whereas, in the case of irreversible binding, the flavour perception is considerably lowered. Melanoidins are probably involved in the retention of aroma in beers and coffees, leading to a distorted flavour. The work proposed in this task will help industry to understand and improve the sensory profiles of foods containing melanoidins.

Main Objective Three

To develop knowledge concerning the thermomechanical properties of melanoidins and related molecules in food

Research Tasks (milestones)

10. Develop methods and evaluate the thermomechanical properties of standard melanoidins and melanoidins from selected foods.

11. Measure the effect of melanoidins on the texture of food.

12. Measure the colour properties of standard melanoidins and of foods containing melanoidins formed under different processing conditions (coffee, malt, bread).

13. Determine relationships between the structure of melanoidins and their thermomechanical and colour properties.

The colour and textural properties of heated sugar-amino acid model systems will be determined as a function of their melanoidin content. Selected beverages and foods (e.g. beer, coffee, cereal products) will also be examined.

Main Objective Four

To develop knowledge concerning the antioxidant properties related to shelf-life of foods

Research Tasks (milestones)

14. Evaluate methods for determining the antioxidant properties of standard melanoidins and melanoidins from selected foods, and select the best method.

15. Measure the antioxidant properties of standard melanoidins and melanoidins from selected foods and examine the relationship between antioxidant properties and processing conditions.

16. Evaluate the antioxidant potential of different melanoidins in fats and other oxidisable components of foods.

17. Draw conclusions about the chemical features of melanoidins responsible for their antioxidant properties.

Compounds with antioxidant properties play a role in food stability and their presence can increase the shelf-life of foods. For example, optimising the antioxidant properties of melanoidins in beer could help the brewer to improve beer flavour stability.

By comparing the oxygen consumption data, radical scavenging ability and reducing power, the mechanism of fat spoilage inhibition by melanoidins should be elucidated

Main Objective Five

To develop knowledge concerning the effects on physiological and health properties of melanoidins and related molecules in food, using in vitro and in vivo studies

Research Tasks (milestones)

18. Assess the degradation of melanoidins and the binding properties of melanoidins under in vitro physiological conditions.

19. Assess the mutagenic/desmutagenic properties of melanoidins.

20. Examine the fate of melanoidins in the gut using in vivo experiments.

21. Examine the effect of melanoidins on the antioxidant status using in vivo methods.

22. Examine the effect of melanoidins on biotransformation systems using in vivo experiments.

23. Examine the ability of melanoidins to bind dietary and other components in the gut using in vivo experiments.

Work will begin with in vitro studies. Where these yield promising results, animal experiments will follow, where appropriate. In selected cases, where animal data indicate their usefulness, human studies will be performed, where feasible.

Emphasis will be placed on ligands which are, or may be, nutritionally limiting in some human population groups and on (a) dietary components with reported adverse health properties in humans, e.g. components that are formed during normal food processing operations, but which are undesirable, e.g. heterocyclic amines and pesticide residues and (b) components which affect the metabolism of nutritionally significant compounds, e.g. bile acids. Melanoidins could have beneficial effects by minimising the absorption of some potentially harmful food components.

Thus, the relationship between processing conditions used to produce food melanoidins and their effect on binding of both selected beneficial and potentially undesirable dietary components will be obtained.

We recognise the importance of performing sensory and consumer experiments to assess the acceptability of foods with modified melanoidin profiles, but this will not be part of this COST action.

D. ORGANISATION AND TIMETABLE

D.1. Organisation

The COST Action will be organised as described by document COST 400/94 "Rules and Procedures for Implementing COST Actions". The COST Action will be coordinated by the Management Committee (MC). The scientific work will be organised into Working Groups (WG) as follows:

- WG One: Choice of model systems. Separation and characterisation methods (Main Objective 1).

- WG Two: Flavour-binding properties (Main Objective 2).

- WG Three: Colour and Texture properties (Main Objective 3).

- WG Four: Antioxidant and other properties related to shelf-life of foods (Main Objective 4).

- WG Five: Effects on health as assessed by in vitro and in vivo studies (Main Objective 5).

The MC will appoint WG coordinators (WGCs) who will be responsible for coordinating the work in their WG and for producing reports for their WG.

The five WGs will operate in parallel. A general discussion (GD) of all participants of the COST Action will take place twice a year, in close connection with WG meetings in which the WGs will discuss and agree upon the work to be carried out over the next six months and to report on work carried out over the previous six months. The GD sessions will be coordinated by the Chair of the COST Action. They will provide the essential means to present key findings from the WGs to all COST Action participants, to facilitate transfer of knowledge between the members of each WG and to provide a forum for "lateral thinking" and synergy. Written reports of each WG and the GD will be distributed to all COST Action participants through the Chairperson. It is anticipated that suggestions for possible short scientific missions (STSM) will be made during WG meetings and that further suggestions will arise from the GDs. It is anticipated that companies will wish to host some students undertaking STSMs. Decisions on applications for STSMs will be made by the MC.

At the end of the COST Action, it is intended to hold a major pan-European conference at which presentations of the results of the COST Action will be made. This conference will be widely advertised, and it is planned that many industrial companies will wish to sponsor the meeting. The proceedings of the conference will be published. The existence of the COST Action, its aims and objectives and results from it will be published on the internet by establishing a home page which will be updated at least every six months.

D.2. Timetable

A five-year programme is proposed for this Action. Meetings of each WG will be held in series over three days (enabling all Action participants to attend meetings of each WG). In addition, there will be a GD, to allow for interaction between members of each WG and discussions of future work. The MC will also meet at these six monthly meetings. All the WGs are related to each other, but only the main interactions between the WGs are shown in Fig. 1. Assignment of scientists to WGs is shown in Table 1. A milestone chart is shown in Table 2 (see Part C for description of milestones). If any of the in vitro experiments planned do not indicate that in vivo work should follow, further in vitro studies will be performed instead.

Fig. 1. Main interactions between WGs for the proposed COST Action on melanoidins

On the basis of the national estimates provided by representatives of the fourteen countries and taking into account the coordination costs to be covered over the COST budget of the European Commission, the overall cost of the activities to be carried out under the Action has been estimated, at 1998 prices, at ECU 18,9 million.

Another way of providing an idea of the national effort to be devoted to the project is the number of person-years expected to be involved in the Action. This figure is estimated at 68 person-years per year (340 person-years over the 5 year project) in total for the fourteen countries mentioned above.

These estimates are valid under the assumption that all the laboratories consulted from these fourteen countries, but no other laboratories and no other countries, will participate in the Action. A departure from this is expected and will change the cost accordingly.

F. OUTPUTS AND DISSEMINATION AND EXPLOITATION PLAN

F.1. Outputs

The COST Action will result in outputs that will not otherwise be realised. These can be summarised as follows:

- a rationale for the choice of specified analytical procedures for the separation and characterisation of specific melanoidins, based on the analysis of standard melanoidins using a wide range of techniques by different laboratories;

- a clear understanding of the advantages and disadvantages of a wide range of physicochemical methods for the assessment of:
= the antioxidant properties of melanoidins
= the flavour-binding properties of melanoidins;

- optimised in vitro methods for the assessment of the fate of melanoidins and their function in the gut;

- information concerning the effects of melanoidins on health using animal and human studies;

- data obtained by applying the most appropriate methods to food systems for:
= the antioxidant properties of melanoidins isolated from foods and model food systems;
= the binding properties of melanoidins for selected ligands (especially key flavour compounds);
= the effect of the conditions (e.g. food processing conditions) used to prepare melanoidins isolated from a range of foods and model systems on their colour, texture and antioxidant properties;

- information regarding the conditions used to prepare melanoidins and their physiological and health effects;

- a rationale for the selection of food processing conditions for the production of melanoidins with optimum functional properties for a particular food or population group, e.g. ranges of health-promoting coffees or beers.

F.2. Dissemination and exploitation plan

In order to disseminate the COST Action (aims, objectives, progress and outcomes) to a wide audience, the following are planned:

- an open web site on the internet for dissemination to COST participants and a wider audience;

- papers in leading publications in each of the working group areas;

- a pan-European conference at the end of the project, at which presentations of the results of the COST Action will be made to an audience including representatives of many food companies. This conference will be widely advertised and the proceedings will be published.

Pan-European conference

This conference will be different from many scientific conferences in the following respects:

- the emphasis of the presentations will be to present the results from the project in ways that industry can understand and relate to their needs;

- companies will have stands to communicate information concerning their products, processes and interests to the scientific community;

- there will be talks explaining schemes facilitating industrial-academic collaboration, including Eureka, CRAFT, TMR and Teaching Company Schemes;

- both confidential and open sessions, involving both industry and academia, to discuss possible collaborative projects aimed at exploiting the results of the project, will be an important part of the conference.

Based on the experience of Dr Ames (Proposer) as a main organiser of the Sixth International Symposium on the Maillard Reaction held in London, July 1997, it is anticipated that the cost of secretarial support, stationery, printing, postage and advertising, for one hundred participants attending a three-day conference will be around ECU 25 000. Costs associated with room hire, audio-visual aids, hire of poster boards, food and accommodation will be additional to this.

Further dissemination

Participants of this proposed COST Action intend to contribute strongly in the following international meetings:

- Ninth Weurman Symposium on Flavour Research, to be held at Garching, Germany, June 1999, organised by Professor Schieberle and Dr Hofmann

- Seventh International Symposium on the Maillard Reaction, to be held in Japan, 2000.

In addition, the American Chemical Society Agricultural and Food Chemistry Division organises national meetings twice a year, often on aspects of flavour chemistry. It is anticipated that results from Task 2 (Binding of flavour compounds by melanoidins) will be appropriate for some of these meetings.

International conferences on the Maillard reaction are normally held every four years. The venue tends to rotate between Europe, Japan and the USA, the organisers being local. The sixth conference was held in London in 1997 and the seventh will be held in Japan in 2000. The eighth conference is likely to be held in the USA in 2004. It is likely that the ninth conference will be held in Europe in 2008 and, if so, it is probable that participants of this COST Action will be involved in its organisation.

Intended use of STSMs

These are most likely to be used by scientists and young co-workers to learn about and use techniques and equipment to which they do not normally have access but which are available in other participating laboratories, including those of industry. Twenty-nine laboratories in fourteen countries have been involved in drafting this proposal. At this level of participation, it is expected that there will be at least seven exchanges per year for each of the five years of the COST Action, funding permitting.

Programa(s)

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

Tema(s)

5 - Food Technology

Convocatoria de propuestas

Data not available

Régimen de financiación

Data not available

Coordinador

N/A

Aportación de la UE

Sin datos

Dirección

Reino Unido

Coste total