Non-invasive allergen testing: research

Food allergies result in numerous hospitalisations every year, with even trace amounts of allergens triggering severe reactions. During the production process, it’s vital to have reliable methods of allergen testing in place as cross-contamination can occur easily.

A study conducted at the University of Illinois has explored the application of near-infrared (NIR) spectroscopy to detect three types of allergens in quinoa flour. According to the researchers, the method is fast, easy, non-invasive, inexpensive and accurate.

Qianyi (Lisa) Wu, undergraduate student in the Department of Agricultural and Biological Engineering (ABE) and lead author of the paper, said this could benefit millions of people.

“We use an NIR device to measure spectral information through the reflectance of light in the samples. We tested models with different wavelengths to determine the best NIR system for allergen detection,” she said.

NIR spectroscopy was used to identify three common allergens — peanut, sesame and wheat — in quinoa flour, a gluten-free grain often used as a wheat substitute. It is crucial to find any presence of allergens in quinoa as it could be dangerous for people with allergies when contaminate or adulterated.

Typically, allergen detection involves complex DNA analyses that require costly equipment and specialised personnel. These methods are time-consuming, involve the use of chemicals and often result in the destruction of the sample.

“NIR spectroscopy offers numerous advantages. It is non-destructive, non-invasive and doesn’t use chemicals. It provides results in real time, and with a short training period, anyone can perform the analysis,” said Mohammed Kamruzzaman, assistant professor in ABE and Wu’s faculty advisor.

“Each material has a unique ‘fingerprint’ of light absorbance. When allergens are present in the quinoa flour, the NIR instrument can detect them. Then we use machine learning to analyse the gathered information, allowing us to identify the allergens and quantify their concentration,” he said.

As an indirect method of analysis, NIR spectroscopy is not 100% accurate but comes very close. It will identify whether an allergen is present in food, even if it doesn’t capture the exact amount of contaminants present.

This method can detect multiple allergens simultaneously, whereas other techniques usually focus on a single allergen. It can also be modified to detect additional allergens and test other products than quinoa.

According to the researchers, it will not be difficult to develop low-cost miniature sensors based on their methodology. The sensors can be used in various settings, including industry facilities, restaurants and even homes. It may even be possible to develop a mobile phone app that can detect food allergens on the spot.

The paper, “Reagent-free detection of multiple allergens in gluten-free flour using NIR spectroscopy and multivariate analysis”, is published in the Journal of Food Composition and Analysis. In addition to Wu and Kamruzzaman, authors are Marciano Oliveira and Eva Achata. The research was supported by the University of Illinois Office of Undergraduate Research and the College of ACES.

Lisa Wu, undergraduate student in Agricultural and Biological Engineering at the University of Illinois, conducted research on detecting food allergens with near-infrared spectroscopy.