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This study (open access) tested 119 commercial products of insect flour, composite food and animal feed using two DNA-based methods, real-time PCR and metabarcoding, to check whether the insects claimed on the packaging were actually present.

The headline result is that 50% of the products contained insect species not listed on the label, or lacked the species that were declared. The detailed results are explained within the article and there are not always clear-cut interpretations (particularly for feed, where – for example -  it is not illegal to fail to declare all protein species within a pet food recipe).  However, some trends were clear.

• Many producers are unspecific about species identification, using general terms such as “cricket” which do not differentiate between legal and non-legal species
• Cross-contamination between different insect species is endemic
• Regulatory test methods (PCR) are not fit to tell whether the banned practice of rearing insects on substrate containing meat/bone has been used (because the method will also detect, for example, permitted animal-derived substrates such as egg shell)

The authors conclude that traceability and cross-contamination control needs to be improved in this nascent industry, before insects become mainstream, to avoid loss of public trust.

This study (purchase required) evaluated two portable NIR spectrometers (900–1700 nm and 1450–2450 nm) and a benchtop FTIR device (4000–550 cm⁻¹) for authenticating edible insect flours. The reference data were constructed from flours produced in-house from insects or larvae purchased online: mealworm (Tenebrio molitor) larvae (23 samples), buffalo worm (Alphitobius diaperinus) larvae (28 samples) and crickets (Acheta domesticus) (28 samples).  Data-Driven Soft Independent Modelling Class Analogy (DD-SIMCA) and soft Partial Least Squares Discriminant Analysis (sPLS-DA), were used on the spectral data.

Principal Component Analysis (PCA) showed that spectral data of pure insect flours were clustered in the scores plot. DD-SIMCA achieved 100 % sensitivity (SNS) in the test set using FTIR for all insects. NIR Spectrometer in the range of 1450–2450 nm reached 100 % SNS and 100 % specificity (SPS) for buffalo worm and mealworm flour. sPLS-DA showed class sensitivity (CSNS) between 75 % and 100 %, for all three devices tested, with spectrometer in the range of 1450–2450 nm reaching class efficiency rate (CEFF) and total efficiency (TEFF) values ranging from 93 % to 100 %. Also, PLSR achieved RMSEP values as low as 0.44 %, demonstrating its robustness as a tool.

The authors conclude that IR spectroscopy with soft modelling is a non-destructive solution for authenticating insect flours, filling the current gap in rapid and reliable analytical tools for this emerging industry.

Photo by Olga Kudriavtseva on Unsplash

There is a growing market for the use of insect protein in feed.  The cricket species Gryllus assimilis. is approved in the EU for feeding farmed animals whilst the closely-related G. locorojo is only permitted for pets. The two are difficult to distinguish analytically in a highly processed product.

This paper (purchase required) reports a method developed on the basis of the cytochrome oxidase I gene, (COI), which was sequenced with thoroughly characterised G. locorojo and G. assimilis samples. The method is highly sensitive, detecting 0.8 pg G. locorojo-DNA or 0.1% G. locorojo incurred in feed, respectively. Authentic G. assimilis specimens were used to ensure that the G. locorojo method (Gloco-PCR) discriminates this closely related sister taxon, with a comfortable Ct-difference of 10-15. For cross analysis of true G. assimilis, similar primers with another probe were employed (Gassim-PCR) and the annealing temperature was increased from 60 °C to 62 °C.

Under these conditions, authentic G. assimilis crickets were detectable with Ct-values around 20, while G. locorojo samples showed a low detection at cycles around Ct 35. An investigation of ten ‘G. assimilis’ samples collected from Germany and four other European countries revealed that all of them were of the G. locorojo type.

The authors conclude that this small preliminary survey proves the usefulness of the method and supports the assumption that many G. assimilis crickets marketed in the EU indeed belong to the species G. locorojo. Consequently, European legislation, currently based on a white list of allowed insect species, is critically questioned.

Photo by Ivan Ivanovič on Unsplash