Max Rubner-Institut International Green Week 2018: Fermenting food and Food falsification

At a long counter, scientists will present four food groups in the context of fermentation. Sourdough will be leavened and displayed in a proving cabinet. The results of the bacterial activity can be tasted: visitors can try rye bread with and without sourdough. Spreewald gherkins are typical for the Berlin area. Under a microscope you can see the bacteria moving around in the pickling brine; the agents of fermentation become tangible. Perhaps the most famous product of fermentation is yoghurt. Here it can be shown how easy it is to make yoghurt yourself – and why the result looks rather different from what you get at the supermarket. Processed meat, like “Wurst”, is also a good example for demonstrating and tasting the technological function of microorganisms in relation to texture, aroma, taste, conservation (safety) and shelf-life. It is, however, not recommended to ferment meat yourself. At the stand we will demonstrate why it is better to use well-characterised, selected microorganism cultures when producing processed meats and not take any chances with the fermentation.

Background:

Small-scale biodiversity:
Not many people realise that the diversity of certain foodstuffs is linked to the diversity of microorganisms. Whether we think of sourdough, cheese or salami – bacteria (and moulds) have an impact on the variety of tastes. Which bacteria do what and who makes sure certain bacterial cultures do not decline?

Good bacteria?
Even small children know that you should not eat food that has fallen on the floor. The world of bacteria is invisible, but dangerous, they have been taught. Consequently, young people are often unsure how to handle food and even throw things away before they have reached their best before date “just to be on the safe side”. But there are also genuinely “good bacteria”. In our world in which milk no longer goes sour, food is often bought on a daily basis and methods like lactic fermentation are dying out, these young people miss out on interesting experiences.

Fermentation to combat spoilage:
Some foodstuffs and dishes only exist because they were the result of trying to prolong the life of raw foodstuffs. Sauerkraut, for example, or a whole raft of curds and sour milk varieties. Why does fermentation increase the shelf-life of a foodstuff, what happens to it in the process – and are fermented foods really healthier?

2. Topic: Food falsification: “False fish”

As demonstrated by the EU project “Labelfish”, in which MRI was involved, the fish served up in restaurants is not always what the customer has ordered. Particularly in the case of processed fish products, the exact species cannot always be determined with the naked eye. This is where DNA analysis comes into play to determine the real animal species. The gold standard for such testing involves sequencing the PCR products of appropriate genetic markers and then comparing the DNA relevant sequences with international databases. This method is very time-consuming and cost-intensive. In the project “Rapid DNA chip-based test for qualitative fish species differentiation”, the Max Rubner-Institut is developing a fast analytical method for verifying ten fish and two shrimp species. At the stand, we will explain about the chip and the different steps in identifying a fish as well as presenting the various ways of uncovering fraudulent fish labelling.

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