Tackle mycotoxins early in value chain - Bühler

Picture: ©iStock

A European project and practical experience has shown cleaning and optical sorting can reduce mycotoxin levels, according to Bühler.

Mycotoxins are chemical compounds produced by fungal moulds that grow on raw materials and most food crops can be affected. They are toxic for humans and animals.

A quarter of the world’s agricultural produce are contaminated, according to the FAO.

Mycotoxins rank as the third most important threat after bacteria and pesticides, which is why maximum tolerance levels in food and feedstuff are crucial for producers.

Aflatoxin, zearalenone, fumonisin, deoxynivalenol and ergot alkaloids are mycotoxins.

Reducing burden

Dr Béatrice Conde-Petit, food safety officer at Bühler, said the burden of aflatoxin is very high.

“There is an estimation from the literature that up to 155,000 liver cancer cases occur per year due to consumption of maize, peanuts and other goods which are contaminated with aflatoxin. WHO has also published concerns regarding aflatoxin and other mycotoxins in connection with stunting in children," she told FoodQualityNews.

“Finally, it is around post-harvest losses so once you have the fungal growth on the raw materials the quality starts to go down and you have spoilage and it is part of the reason for the high losses that we still have.”

Extreme environmental conditions such as drought and rising temperatures have triggered an upsurge in toxic crops with climate change increasing the prevalence of aflatoxin.

Previously more prevalent in tropical and sub-tropical regions, mycotoxin contamination is on the rise in temperate regions – meaning it will increasingly become an issue for Europe.

“Aflatoxin used to be a problem of hot and humid climates, Europe was less affected but we were always aware of this because of imported materials,” said Conde-Petit.

"Today, Europe is also affected because of climate change. There are interesting predictions how this will increase contamination of the crops in southern Europe due to increased temperature and this is what we are already seeing with our customers in Italy, Spain and Hungary where the contamination of aflatoxin on maize is increasing.”

Hotspots and geographical incidence

Work to contain and reduce mycotoxins needs to start as early in the value chain as possible, said Conde-Petit. 

“There is no silver bullet, in contrast to bacteria these mycotoxins cannot be eliminated by heat for instance, they are quite stable,” she said.

“So ideally you have good agricultural practices, the next important step is to have a good post-harvest stabilisation. This means quick drying of the raw material because if it is not dried, the fungus starts to grow and mycotoxin is built. The same is true for good storage, so silos were you can maintain the safe moisture level and temperature so that the fungus does not start growing.

“If you still have mycotoxin in the raw material, there is the option to reduce the level by cleaning and this works because today we understand better which fractions are highly contaminated.”

Dr Conde-Petit said it is known that aflatoxin occurs as hotspots so usually a lot would not be homogeneously contaminated.

Schapfenmühle mill in Ulm, Germany

The family-owned mill is a business with three production sites and more than 200 employees.

Schapfenmühle uses the Ridaquick lateral flow tests by R-Biopharm.

The mill grinds wheat, barley, rye, oats and spelt as well as amaranth, quinoa, rice, teff or canihua. During peak harvest time, up to 100 truck deliveries per day have to be handled.

In Europe, the last year has been unusually warm and moist and beneficial to the growth of mould.  

Particularly deoxynivalenol (DON) has been a major problem. Many farmers lost parts of their harvest due to high mycotoxin concentrations.

Schapfenmühle performed more than 1,100 tests during the 2016 harvesting season. Almost 15% of samples showed increased DON levels and a further 10% exceeded the permitted limit value.

“Typically if two out of 10,000 grains are highly contaminated this can already mean the whole lot cannot be used,” she said.

“So it is about identifying these few highly contaminated grains and the fungus leaves a signature on these grains. It is a slight discolouration it can be darker, it can be greenish and that is why optical sorting works so well to identify these grains and remove them from the value chain.

“So a good cleaning solution would be a combination of air cleaning, mechanical cleaning, remove the grains which have a lower density and combine it with optical sorting.”

The ‘pain’ in developing nations is higher, said Dr Conde-Petit.

“If you don’t have good post-harvest stabilisation or poor logistics, in these regions we see the pain is bigger, definitely. On the other hand, those who have the awareness and make sure all the actions are taken can produce grain fulfilling all the compliance regarding food safety,” she said.

“In Europe we have good controls, quite a high awareness but the issue we have, especially in Southern Europe, is aflatoxin and there is a specific problem for feed. Feed receives typically the side-streams of grain processing. So for instance the bran, wheat or other by-products from grain processing are typically higher in contamination as the fungus and the mycotoxin sits mainly on the surface.” 

Benefit of EU project

Bühler is a member of MycoKey, an EU funded project to the tune of €6.4m, which has 32 partner organizations from 14 countries in Europe, Asia and Africa.  

“Together with them we have been able to do large scale testing, so field tests of these solutions, which are today also applied by different players in Europe but also around the world,” said Conde-Petit.

“We were able to show how far this reduction can go – it is between 50 and 80% of the mycotoxin level can be reduced. This also means rejecting part of the material which is the downside. So this might mean you reject between 1.5 of the material to 6% depending on the level of contamination.

“But we also see some build a business case around this. For instance, they take poor quality material or material that is biomass quality, go through this cleaning and can still recover 75% as feed quality fulfilling the quality requirements and only then discarding 25% as biomass quality.”

Bühler said academic studies within MycoKey and practical experience show an effective way to reduce mycotoxin level is via cleaning and optical sorting processes.

The European Horizon2020 project, started in mid-2016, has run multiple, large-scale field tests to collect data on the performance of grain cleaning systems.

Dr Conde-Petit said it uses the same approach for grain cleaning of wheat where deoxynivalenol (DON) is the main problem.

Today, a state of the art mill has this already included in their cleaning. Optical sorting 20 years ago was used mainly in the rice industry for quality sorting but found its way into grain milling and is today part of a state of the art mill in wheat cleaning.

In 2013 Italy had a lot of aflatoxin in maize.

“We went and with MycoKey we did testing of these materials on how we could reduce mycotoxin by cleaning,” said Conde-Petit.

“One year later they did not have a big aflatoxin problem but DON, zearalenone (ZON) and fumonisin so we did another test and looked at these different mycotoxins. Very often you can have the co-occurrence of many mycotoxins coming together and we did the tests again and quantified the results and we saw also that it works for the other mycotoxins.

“This is one of the things we have learned, that every year can be different but the solution is rather generic, it works for grains where contamination is sitting on the surface like wheat and maize.”

In a different EU project which runs until February 2020, RIKILT Wageningen University & Research is developing an electronic toolbox that can predict mycotoxin contamination in grain at an early stage.

Early prediction can help farmers make effective choices regarding use of fungicides and the best harvest time.

The e-toolbox is part of MyToolBox being developed by scientists, engineers and IT specialists from 23 government agencies, scientific institutions and industrial organizations from 11 countries.

Real time risk analysis

Dr Conde-Petit said testing and analysis in the lab can be quick but sampling is the time-consuming part.

“Aflatoxin appears in hotspots, it is not homogenously distributed. If you want to have a reliable result you need to apply a protocol taking enough samples so that you have a representative sample,” she said.

“At the end if you collect from 100 tons of material 10kg of sample which you have taken from different places you still need to grind all of this, do proper portioning and then at the end you do the test.

“The problem is the result always comes too late, there is a truck waiting or you are doing a grain cleaning in your plant. There is no good solution for an in-line sensing and analysis of mycotoxin, this does not exist yet also because of the inhomogeneous distribution.”

The future will be in having real-time risk analysis, said Dr Conde-Petit.

“For instance, if you are a grain handler or are doing a grain cleaning, that you collect data that combines the predictions which exist today as data, because depending on the weather condition, one already knows if there will be more or less mycotoxin, combining the food and feed safety alert data, the harvest data but also connecting it to the silo conditions,” she said.

Today there are monitoring systems to assess what is happening in the silo and you can identify very early biological activities like growth of fungus.

“Using all this data together, depending on the risk level, you would then adapt your process to this rather than chasing an absolute number from the lab which always comes quite late. This does not mean no quantification will be done, this will still be the case but more for monitoring purposes.”

Bühler has high-end sorters that come with AnywarePro – a service where data from the sorter can be extracted and used in connection with other data on production.

Dr Conde-Petit said the optical sorter can be used in different ways than it has been traditionally.

“It is using the optical sorter not only to do the job which is optical sorting and reject the material which is not good but also using the data of this optical sorting as part of the risk analysis,” she said.

“One thing is data the other thing is how to convert this into valuable information. So this data needs to be linked to other meta-data, processing conditions and lab results so at the end we need to extract value out of data and that’s what we do with the players in industry.

“At the end it means a combination, the pain is biggest for the end consumer, for the animal or for humans, but the impact of a solution is biggest in the early value chain. It is different actors that need to play together and it is not only for food safety it is also for food security and sustainability. Safe food means also saving food so less losses.”

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