Monika Pischetsrieder and Rainer Baeuerlein from the University of Erlangen-Nuremberg, Germany, look at how the safety of GM food can be assured before it reaches supermarket shelves

Fifty-five genetically modified (GM) food or feed items are currently awaiting authorisation by the European Union. Evaluating the safety of GM organisms, which is carried out by the European Food Safety Authority, usually takes more than three years and includes a rigorous risk assessment. In order to simplify the process, the concept of substantial equivalence has been introduced. This means that a GM tomato, for example, is regarded as safe if it has the same composition as a traditionally produced tomato. But what does 'the same composition' mean? Usually, analysing substantial equivalence focuses on the main components, such as sugar and protein concentrations as well as critical nutrients and anti-nutritional factors, such as vitamins or solanine (a toxic tomato component). However, it has been argued that genome modification may lead to unexpected random effects with unknown consequences for the consumer. And these random effects may be overlooked if it is only the main components that are analysed. To combat this, untargeted analytical methods, which promise to give a systematic view of food composition, were introduced into the safety assessment of GM food. The most promising approaches for this purpose are omics-methods.

 

Proteomics researchers have the methods and techniques for understanding our food, the challengeis to find a way to handle and interpret the complex data generated

 

Proteomics, or proteome analysis, was originally developed for biomedical research to search for diagnostic markers (indicators of disease) or new drug targets, for example. The proteome is the entire complement of proteins in a biological sample such as a cell. Since proteins are the primary products of gene expression (where information from a gene is used to make a protein), a random effect caused by genetic modification of a plant should be reflected in the proteome. So proteome analysis could indicate if a new GM food is indeed substantially equivalent to a traditional food and can be regarded as safe without further evaluation. The goal of proteome analysis is to depict the composition and concentrations of all cell proteins or other biological samples as completely as possible. Since a cell contains several tens of thousands of different proteins, sophisticated methods for protein separation must be applied. This is achieved either by two-dimensional gel electrophoresis (gel-based methods) or by two-dimensional liquid chromatography (shotgun methods). After separation, proteins are usually identified by two-dimensional mass spectrometry. However, taking into account that one shotgun experiment can generate up to 100,000 mass spectra, it is obvious that with this method, data interpretation, evaluation and management cause a bottleneck.

In other areas of food science, researchers have also used proteome analysis to give an overview of protein composition in biological samples. To study a particular food's effect on the body-physiological or nutritional activity-the food item is traditionally administered to cultured cells or animals and the response of selected diagnostic markers is recorded. Alternatively, any changes to the whole proteome that can be seen as a reaction to the treatment reduce the chance to overlook any unexpected beneficial reactions or toxic side-reactions. As a result, the process of identifying bioactive food items or components, which affect metabolism and health, should be largely accelerated.

Another hot topic in food science is authentication. With the growing global market, food adulteration is an emergent problem. In some cases, detecting the replacement of valuable ingredients or whole foods by cheaper substitutes can be difficult for food control. Particularly if a new food adulteration problem is arising, there is the need to react quickly and to create a reliable analytical solution. By comparing the proteome of the original ingredient with the substitute, the proteins that are only expressed in the substitute can be quickly and efficiently identified and further used as markers for food adulteration. Finally, proteome analysis is applied in food science to systematically reveal the effect of food processing on food proteins, to identify food allergens and to develop a means to improve food quality. 

To understand complex interactions between food production, composition and their effects on the human body, it seems that proteomics researchers have the method and technique bases covered. Now, the challenge for scientists is to find a way to handle and interpret the complex data generated.

Read more in Monika Pischetsrieder and Rainer Baeuerlein's tutorial review 'Proteome research in food science' in issue 9, 2009 of Chemical Society Reviews.

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