Much fresh farm produce has to be discarded due to contamination. In the dairy industry, waste and the cost to the farmer can be reduced by better detection of contaminants such as aflatoxins. Animal feed contaminated by aflatoxin mould and consumed by cows can be passed on in milk as Aflatoxin M1 — a potent carcinogen in humans that is heat resistant and cannot be controlled by pasteurisation. With dairy ingredients present in a multitude of foods and drinks, early detection and protection from contamination is crucial for both the food industry and human health. Now EU-funded researchers working on the SYMPHONY have developed a desktop system that incorporates sample preparation and the functions of a small laboratory to detect even very low concentrations of aflatoxins in milk and dairy products. ‘The system developed by the consortium brings testing into the dairy. Aflatoxin detection methods currently in use are not very friendly to the dairy — samples must be sent to external laboratories for final confirmation of the analysis,’ says project coordinator Leandro Lorenzelli, head of microsystems technology research at the Bruno Kessler Foundation’s Centre for Materials and Microsystems in Italy. Traditional tests for aflatoxins in milk take two hours to obtain a result, but the method is not accurate and gives many false positives. With strict EU limits on aflatoxins, testing needs to be more reliable. ‘If you want high accuracy you have to assign the test to external laboratories and then you get the answer after several days which is totally unacceptable for the fresh milk market,’ notes Dr Lorenzelli. It is also expensive as it requires specialist personnel, he adds. Swifter results ‘Currently SYMPHONY has demonstrated a result in half an hour. The aim is to reach a time of ten minutes,’ Dr Lorenzelli says. Over the three and a half years of the project, the consortium developed a three-stage process of sample preparation to extract the soluble aflatoxin from the milk, then produced a concentrate that can be analysed, followed by sensing to detect the amount of toxin. Two of the processes developed by the team have been patented. The main purpose of the sample-preparation stage is to clean the milk sample of unwanted components like fats, which may interfere with the following stages and cause clogging of the system, and to concentrate and make the toxin available for detection. The concentrated liquid containing the toxin is then passed over a photonic sensor on a silicon chip coated with antigen receptors to detect and quantify the aflatoxin. ‘Concentrated liquid sticks to the receptors which affects the light travelling through the sensor and this phase shift is measured. The degree of phase shift relates to the amount of toxin present,’ explains Dr Lorenzelli. Multiple detection The targeted cost of the overall system should be some EUR 2 000–3 000 for the hardware, he says, and the cost of each test is estimated at around EUR 5. The system can be useful beyond the dairy industry as an array of sensors can be set up to measure different toxins or target substances. ‘In principle you can expand the system for multiple analyses. The sensor is particularly suited to detect many different molecules at the same time,’ Dr Lorenzelli concludes.
SYMPHONY, dairy, milk, toxins, aflatoxins, sensing