One undeniable fact of life is that most of us don't know the ingredients of our meals. Food is produced on an industrial scale. And as with most commodities food is increasingly bought and sold on international markets. It means that food scandals - when they erupt - can affect consumers all around the world, all at once.

So if you're looking for a place to buy food you can trust, a good place to start might be your local farmers' market.

Thomas Hoppe is one of the regulars at the weekly market in the Altona district of Hamburg.

The freelance art conservator lives and works locally and comes to the market almost every Friday to do his shopping. He's on first-name terms with some of the stall holders - and that's no mean feat in Germany.

"I buy my fruit and vegetables from Willi," says Hoppe. "I've known him for over 20 years and I trust him and his staff."

The same is true for the stalls where Hoppe buys his eggs and meat. Hoppe accepts he may be paying a little more than he would at a supermarket. But in return, he says, he feels his food is safe.

"It's all proper," says Hoppe. "I don't have to research where the food comes from. I can look the seller in the eye."

Undermined sense of trust

But for many consumers a steady stream of food scandals in recent months and years has undermined this sense of trust, especially with supermarkets.

In February, more than a dozen European countries were hit by a horsemeat scandal. Up to five percent of products advertised as beef in supermarkets were found to have contained large quantities of horsemeat. It wasn't seen as a big health threat, but the scandal did reinforce fears about a lack of transparency of food labeling.

Then, in early November, a number of cheese products were recalled from stores in northern Germany because they were contaminated with listeria.

At the University of Hamburg, Professor Markus Fischer is on a mission to restore consumer trust, at least to an extent.

One of the machines Fischer uses at his laboratory is a GCMS.

"MS stands for mass spectrometry," Fischer explains. "We use it to measure metabolites. This is one methodology which can be used to check the origin of food."

Professor Fischer is the director of the School of Food Science at the University of Hamburg.

His team develops methods to determine the geographic origin of food products.

In an increasingly globalized world, Fischer says, the geographic origin of raw ingredients is becoming more important.

A product's origin is often used to market its unique selling point - chocolate, for example, that contains cocoa from a certain region.

"On one level, it's not a health problem," Fischer says. "It doesn't matter if the cocoa comes from Ecuador or Ghana."

But there are cases where the origin can have safety implications

"Take the example of fish," says Fischer. "In this case it does matter if the fish comes from the Fukushima region, or from the North Sea."

Fingerprinting the ingredients

Using a mass spectrometer to analyze the metabolites of a given food sample is one way of determining its geographic origin.

The analysis gives the scientists what they call a metabolic fingerprint. This fingerprint can then be compared to reference samples. A similar fingerprint means that the foods are from the same region. Fischer's team can also analyze samples based on their DNA and proteins.

The aim of the research is to create simple testing methods for the food industry.

"Crude materials are bought on a global market," Fischer says. "And this is also the reason for some problems with food safety. If there is one part in this global food chain with criminal energy, you might get problems. And so you need suitable methodologies."

The Hamburg School of Food Science has just joined a scientific partnership with the American federal food surveillance body, the Food and Drug Administration (FDA).

The FDA is one of the largest food surveillance organizations in the world.

For the first time, it's officially cooperating with a German university. It's a reflection of the increasing global nature of food supply chains.

For Professor Fischer the partnership is an efficient way of sharing knowledge on different areas of expertise.

"The FDA works mainly on microbiology," he says. "Microbiology is very important for food safety - think of the EHEC problem in 2011. And we mainly focus on food analytics. Both are very important for food chemistry."

At the center of the partnership between the University of Hamburg and the FDA will be a transfer of knowledge, including an exchange of students and scientists.

Two PhD students from Hamburg have already conducted research at the FDA.

In return, Professor Fischer expects he'll be welcoming scientists from the US in Hamburg soon.