Insect meal as feed: discrimination of particles issued from authorised and unauthorised species using Near Infrared Microscopy (NIRM)

Since 2017, insect meals have been authorised for animal feed in the European Union, but only eight insect species can be used to produce these meals. This legislation brings with it new analytical challenges, such as the need to identify the insect species processed in the meal. This paper investigated the ability of Near Infrared Microscopy (NIRM) to discriminate meal particles from authorised insect species and differentiate them from unauthorised species. The spectral data was analysed using chemometrics, enabling the assessment of classification specificity and sensitivity for each species to be discriminated. Using Partial Least Squares Discriminant Analysis (PLS-DA), insect species could be efficiently discriminated with specificity and sensitivity values generally above 0.90. However, the discrimination between particular species appeared more difficult. Most of the observed confusion is probably due to the chemical composition of the insects, which can be very similar between closely related species. These results were encouraging, but also indicated that the use of the NIRM technique alone in case of fraud or natural contamination should be complemented by other techniques such as RT-PCR or mass spectrometry.