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Agriculture and Food Title

Flour for Europe

Fifteen organisations from nine countries have collaborated in certifying a standard wheat flour (denoted CRM 563). The flour is characterised by 17 properties measured from eight standard test procedures. Samples of the flour are now available to food manufacturers and laboratories who wish to calibrate their measuring apparatus to common European standards.

A bag of flour in the supermarket may look like any other but, as every bread maker knows, no two batches of flour are the same. Even flours milled from identical varieties of wheat will vary according to the soil in which they were grown, weather conditions, cultivation methods and so on. No farmer can undertake to grow identical wheat two years running, and flour mills cannot guarantee that the properties of their flour will remain the same from one batch to the next.
These differences do not matter much provided that industrial users of flour, such as bakers and other food manufacturers, can check the properties of the flour they buy to maintain good quality control. Some of these properties, such as moisture content, are relatively straightforward to measure, others, such as the 'rheological' properties are concerned with consistency and strength of doughs and require specialised apparatus. While the methods used are agreed by international standards, there can be considerable differences between measurements made in different laboratories. Such differences can have serious financial consequences where large quantities of flour are concerned and may require costly duplication of effort if re-testing is required.
Ideally, laboratories should have access to a 'certified reference flour', whose properties are precisely known. The reference flour can then be used to calibrate the measuring equipment to ensure that tests are compatible between different laboratories. Until now no such flour has been available. This project was set up by the European food industry to remedy that deficiency.

Testing the flour

An ordinary, commercially milled flour was selected by the project's Scientific Steering Group on the basis of its physical and chemical properties. A 400-kg batch was blended and then packed into 1000 vacuum-sealed laminated sachets each containing about 360 g; 50 kg of the batch was blended with a different flour to produce control samples with slightly different properties. In order to ensure stability of the flour characteristics, all the sachets were stored at a temperature of minus 20C.
The partners decided to test the flour for 17 properties measured from eight standard procedures. The work was carried out by 14 different laboratories in nine countries which were sent coded samples of both the flour and the controls.
Apart from standard tests for moisture, protein and ash content, and more specialised industry tests (falling number, Zeleny sedimentation volume), empirical some were in nature. The rheological tests required several different countries to test samples under defined conditions within a short period of time. This provided a wide base of independent tests whose values could then be compared.
The rheological tests were based on three specialised measuring machines used in the food industry:
The Brabender Farinograph records the resistance of a dough to mixing (known as consistency) as it is formed from flour and water. The features of the resulting 'mixing curve' are a guide to the strength of the flour in relation to its water absorption.
A sample from the Farinograph is then moulded into a standard shape. After a fixed period of time the dough is stretched on the Brabender Extensograph and a curve is drawn recording the resistance of the dough to stretching. The size and shape of the curve are a guide to the baking characteristics of the flour.
Another specialised machine, the Chopin Alveograph, records the pressure developed in a dough bubble during inflation. The resulting graph describes the resistance to stretching and the extensibility of the dough. As with the Extensograph, the length and shape of the curve can be related to the baking characteristics of the flour.

Strict protocols

Each participating laboratory agreed to perform a certain range of measurements, depending upon its expertise. In order to reduce as much as possible any variation between laboratories, the tests had to be carried out to a strict protocol over a two-week period. Where the protocol was not followed, the results from that laboratory were rejected. All the results were subject to rigorous statistical evaluation to guard against systematic error.
Certified values were found for each of the 17 properties. Full details are published in the EU Community Bureau of Reference report EUR 16478 EN.
The greatest technical problem was that the partners were working with biological material, where it is much more difficult to achieve consistent results than with a non-biological product.
The project has had two major benefits. First, the partners have produced a common reference material (now denoted CRM 563) which will find applications in a very large commercial market. This is the first time that a suitable reference flour has been available for this range of rheological properties. Although the reference flour is used only on a limited scale at present, its use among European food laboratories and bakeries should eventually become routine.
Secondly, the project has established a very strong network of laboratories across Europe which are now all working to a common set of standards. The result of a test on a food which contains flour in one country will also be valid for any other country in Europe.
(Samples of the flour may be obtained at the Institute for Reference Materials and Measurements, IRMM, Retiescweg, B 2240 Geel, Belgium) When the samples of CRM 563 are used up, the partners plan to certify another batch of flour in the same way to maintain common standards throughout the European food industry.
It should be noted that this project is not an attempt to force European bakeries to standardise the type of flours they use in their products, but only to ensure that their measuring equipment is calibrated to common standards.
The potential market for the product is very large as there are thousands of laboratories, bakeries and food manufacturers in Europe.



Project Title:  
Certification of properties of common wheat flour reference material CRM 563

Industrial and Materials Technologies (BRITE-EURAM/CRAFT/SMT)

Contract Reference: MAT1-CT93-0047

Cordis DatabaseFor more information on this project,
go to the CORDIS Database Record