How do consumers know whether the food item they have purchased actually is the product with the desired properties or whether the packaging promises more than the product actually delivers? This is not a judgement that can be made based on the product’s appearance or taste. Only analytical methods can get to the bottom of the molecules inside the food item. Prof. Dr. Walter Vetter at the Institute of Food Chemistry at the University of Hohenheim and his team of researchers work on verifying the authenticity of food.
Prof. Dr. Walter Vetter’s team of researchers specialises in the development of analytical methods and in investigating the structure of unknown compounds. Prof. Vetter is the head of the Institute of Food Chemistry. He teaches food chemistry and is also involved in the organic food management course. “We were looking for a project to work on related to those areas and we came up with the idea of working on the development of methods to verify the authenticity of organic food,” Vetter said.
An organic fraud was discovered in Italy in December 2011 relating to illegal organic products that had been sold in Germany and elsewhere. This discovery revealed that if a label says organic, it does not necessarily mean that an organic product is inside. Analytical test methods that consumers can trust, which uncover products that falsely claim to be organic, are therefore needed. The researchers from Hohenheim have already developed a method for testing milk, which involves the use of phytanic acid, a fatty acid that does not normally occur in the food cows eat. The precursor of phytanic acid, phytol, is however on the menu of cows as it is a constituent of chlorophyll. “Chlorophyll is digested in the cow’s rumen, which leads to the liberation of phytol. Phytol is then converted into phytanic acid which is stored in fats and hence found in milk,” Vetter said. “Phytol can be used to differentiate between normal milk and organic milk.” As organic farming uses a lot more green fodder than traditional farming, organic milk contains higher amounts of phytanic acid than conventionally produced milk. “On one occasion we had a sample where the label said organic. But we were not 100% sure whether this was really true. In practice, in order to substantiate any suspicion, it would mean monitoring the milk producer at shorter intervals,” said the food chemist. However, it is early days yet for the methods being developed and they will have to be tested thoroughly for several years and validated before being approved for application.
Vetter and his co-workers are also developing a test that enables them to verify whether oils are cold-pressed or not. “There are a growing number of cold pressed oils on the market, which all have a higher commercial value than refined oils. It would be good to find a method that would enable us to differentiate between non-refined and refined oils,” said Vetter. In contrast to refined oils, which are heated to 100°C during production, cold pressed oils are produced in oil mills without being heated. This is a comparatively gentle process and the oils retain most of their ingredients and nutritional value. In this case as well, the food chemists have also chosen a chlorophyll component as marker due to its high sensitivity to heat. “Refined oils contain an isomer of this chlorophyll component, cold pressed oils do not,” Vetter said.
Prof. Vetter’s group of researchers also carries out basic research and is particularly focused on natural halogenated compounds and pollutants. “Over the last few years, natural halogen compounds that normally occur in algae and sponges have also been found in fish and other marine animals,” Vetter said. Fish and other marine animals are increasingly bred in fish farms in flat coastal waters, which are the natural habitat of algae and sponges. “We will initially focus on the identification of the natural pollutants, clarify their structure and then issue warnings,” said Vetter. Unfortunately, the compounds have a rather complicated structure and are difficult to synthesise. The initial toxicological investigations were therefore rather difficult. “Little is yet known about the compounds. However, German testing offices have started to collect data and we hope to be able to carry out toxicological evaluations sometime in the next few years,” said Vetter.
In addition to the aforementioned research, Prof. Vetter also focuses on classical pollutants, including flame retardants used in cars and children’s toys. “Compounds are given off by the devices and accumulate in fish, amongst other things,” said Vetter whose investigations take into account the fact that Europeans rarely consume uncooked fish. Vetter and his co-workers are therefore looking into the effect of high temperatures on the pollutants. “This is necessary in order for us to assess whether a certain substance has a negative effect on human health,” said Vetter. The researchers were able to identify compounds that the fish gave off as it was heated, as well as compounds that were converted into compounds that were harmful to human health. The researchers from Hohenheim like to use innovative analytical instruments for their analyses, including a GC/NCI-MSMS (gas chromatography-negative chemical ionisation-tandem mass spectrometry) device, which combines gas chromatography and mass spectrometry and allows the highly selective identification of halogenated compounds.
The Institute of Food Chemistry also deals with the analysis of lipid compounds. The researchers use countercurrent distribution chromatography to analyse butter samples and have identified more than 400 different fatty acids in a single butter sample. “One tends to think one knows what a particular food item contains. In fact, it’s usually quite the opposite,” said Vetter. “The media usually only tell us that butter contains a lot of saturated fatty acids and therefore is bad for human health. This is only half the truth.” Using highly sensitive investigation methods, the researchers are able to identify fatty acids that are only present in minute amounts in butter, but which might nevertheless have a huge effect on the human body. “The media do not usually talk about the effect of the remaining 300 or so fatty acids,” said the researcher. “We hope that our work will encourage other experts to carry out additional investigations. And we are happy to provide them with the tools they need,” Vetter concluded.
Prof. Vetter is a member of the Bioactive Plant Foods network. “The network brings together experts with a broad range of different backgrounds, and this enables us to effectively turn an idea into application,” said Vetter who would like to understand the problems different users – from bakers to food supplement producers – face in order to be able to put his expert knowledge in analysis to good use. “I also believe that it is a good idea to strengthen regional approaches in the food sector, by which I mean the regional production of high quality food,” said Vetter who attaches great importance to people eating a balanced diet and being aware of the composition of foods, in particular with regard to the ingredients present in food items.
Prof. Dr. Walter Vetter
Institut für Lebensmittelchemie
Tel.: 0049/ 711/459-24016
Fax: 0049/ 711/459-24377