Your risk of being poisoned by a glass of wine or a bottle of beer is very low, but some of the chemicals found in alcoholic drinks are toxic and, if not removed, potentially dangerous.
For example, mycotoxins produced by fungi that can grow on grapes and grains can be carcinogenic. Some consumers are also unhappy about pesticide residues in wine, while others have an allergy-like reaction to sulphites used in the fermentation process.
Solving this problem is not as straightforward as you might guess. Simply 'cleaning' or filtering beer and wine can change its colour and taste. Indeed, industrial filtration processes themselves are not without risk: Kieselguhr, a soft powdery rock used in wine filtration, can be harmful to the lungs of people working with it for long periods.
What is needed are methods for detecting toxins, tools for selectively filtering liquids, and methods for preserving products without changing the taste or introducing health risks.
One of the most feared toxins produced by fungi is Ochratoxin A (OTA). It is made by Aspergillus carbonarius, a fungus which has been found in wine and beer. OTA can cause cancer and kidney problems.
The European Food Safety Authority says that a certain degree of contamination by OTA seems unavoidable in many foodstuffs, and under EU regulations, wine must include no more than 2 micrograms per kilogram.
How can beverage producers check that their products are safe for consumption? 'Normally, analysis of mycotoxins can be done by sending samples away for sophisticated chemical lab analysis,' explained Fabrizio Pavanello of Automation Advanced Lab Solutions in Milan, Italy.
Analytical chemists can use high-performance liquid chromatography (HPLC) and high-performance liquid chromatography mass spectrometry (HPLC-MS) to separate the components of a mixture and identify each component. If OTA is in the product, experts will alert the producer and advise them on how much of the toxin is present.
However, for Europe's burgeoning microbrewery sector and the enormous network of family-run winemakers toiling in vineyards from France to Hungary, this is a slow and expensive option. It can take two weeks for this kind of detailed analysis and running the tests in-house are not an option for small- and medium-sized enterprises (SMEs). HPLC equipment costs around EUR 40 000 while HPLC-MS instrumentation can cost EUR 100 000. Then there are the costs of running a lab and recruiting people with the skills to run the tests.
‘Our technology acts like a molecular sieve for wine.’
Ludovic de Meeûs, Realdyme SA, France
Researchers believe they have found a way to screen wine and beer for OTA which would give almost instant results without racking up lab bills.
'Our aim is to have a low-cost instrument which is easy for producers to use themselves,' said Pavanello, who is working with the EU-funded Demotox project. 'They should be able to check whether their product is contaminated or not. If it is, then they could send a sample away to analyse the level of toxicity.'
Demotox is working on two separate technologies which were developed by SMEs as part of another European project known as OTASENS.
One of the systems is a portable version of a commercial thin-layer chromatography plate which separates a sample of wine into its component parts. Photosensors are used to detect the fluorescent signal for the OTA toxin and this information is shared via a USB connection to the user's computer. Purpose-built software is used to analyse the data.
The second system reacts with antibodies on the surface of the testing kit. The user connects the tool to their computer to check the results.
'The next step is commercialisation of these technologies,' said Pavanello. 'It's not just for wine – it can be used on feed and cereals too. Beer is made from cereals so these systems can be used to directly analyse the raw materials to check for OTA before the beer is brewed.'
Most beers, wines and fruit juices contain trace levels of contamination. Even when the amount of toxin, pollutant or pesticide is deemed to be so low that it poses no threat to human health, consumers may be dissatisfied.
'Wine growers don't like it either,' says Ludovic de Meeûs of Realdyme SA in France. 'Even though wine and beer are safe, producers would prefer the levels of pesticides to be even lower than the limit of detection. There is demand from industry and from the consumer to minimise the level of contaminants.'
He is working on the EU-funded Adfimax project which is focused on commercialising innovative filtration technology developed by Realdyme during an earlier project known as DEMYBE.
'Filtration today is based on particle size. It's essentially a sieve – but you cannot mechanically sieve molecules,' he explained.
Realdyme has come up with a method that selectively removes toxins. The toxins stick to the surface of the filter by adsorption. 'This allows us to selectively remove specific molecules while leaving others,' said de Meeûs.
The big challenge is to do this in a way that does not change the colour or taste of the wine.
'We are using a natural fibre from a normal farm raw material but it has been purified. It acts like a molecular sieve for wine, taking out molecules we don't want but keeping those that we need to keep.'
The technology is currently being evaluated by several companies and it has been shown that any impact on the taste of products is short-term. It has potential to be taken up by the beer, wine and fast-growing fruit juice sectors.
Read the label of a bottle of wine and there is a good chance you will see the words 'contains sulphites'. This labelling is required in the EU because sulphites dissolved in wine have been linked with allergic reactions and asthma.
Sulphites are a result of adding sulphur dioxide to wine in order to reduce the risk of spoilage. They inactivate microorganisms such as excess yeasts and bacteria, and they act as antioxidants – protecting the wine's unique flavour.
Scientists participating in the EU-funded project PreserveWine-DEMO have been exploring ways to produce wine with a suitably long shelf-life without adding sulphur dioxide.
One promising alternative to sulphites is known as cold pasteurization. Rather than rely on high temperatures – which might destroy heat-sensitive ingredients – this method uses high pressure to halt the growth of microorganisms and inactivate enzymes.
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