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New methods for feed control in a circular economy

Brown and black insect larvae in a box.

Black soldier fly is one of the insect species currently authorized for use in fish feed.

Photo: Ikram Belghit / IMR

Insect farming for fish-feed production offers interesting opportunities in aquaculture, but it also raises new challenges for food and feed safety testing. Researchers have now developed and tested new methods for detecting and tracing prohibited ingredients in insect meal.

Insect meal has increasingly drawn attention as a sustainable alternative to traditional ingredients like fish meal and soybeans in fish feed for aquaculture. 

Because insects can be reared on resources that would otherwise go to waste, insect farming also offers interesting opportunities from a circular economic perspective.

However, under current food safety regulations, feed-grade insects must comply with legislation on processed animal proteins (PAP). This means, among other things, that they are not allowed to be fed with meat or blood products from cattle.

Tested new methods to detect bovine blood

In a new study, researchers at the Institute of Marine Research (IMR) tested new analytical approaches for detecting these prohibited materials.

The study, led by researchers Josef Rasinger and Ikram Belghit, was done using black soldier fly larvae – one of seven insect species that are currently authorized for use as ingredients in fish feed in the EU.

Researchers reared insect larvae on a diet based on standard chicken feed. In different experimental groups, varying amounts of bovine blood was added to the feed.

Samples of both insect feed and harvested insects were sent to laboratories in Norway, Belgium and Germany and were analyzed using a total of six different analysis methods – including a new method currently being developed at IMR.

All the methods detected the blood

“We found that all the methods detected and traced the presence of prohibited bovine material,” says Madhushri Shrikant Varunjikar, a PhD scholar at IMR and the University of Bergen who contributed to the study.

“To ensure efficient feed control of novel insect meals in aquaculture, we must use different molecular tools in tiered approaches,” Varunjikar adds.

 “We found that each method we tested had its inherent strengths, but each approach also suffered from shortcomings in the detection of prohibited material; these can however easily be overcome if complementary tools are used in union.”

New method developed at IMR

Varunjikar, Rasinger and Belghit, together with Magnus Palmblad at the Leiden University Medical Center, have been developing one of the novel methods that were used in the study, called spectral library matching.

This method uses mass spectrometry (MS) – a tool for detecting the chemical signature of different molecules by their mass spectra – to identify proteins.

“We can create a library of spectra, which can then be used to find a match for the unknown analyzed materials,” explains Varunjikar.

“This method has been used to detect prohibited material in the insect food chain, but it can be used as well for differentiating species and tissue origin of any other PAP-based fish feed ingredient or the detection of feed and food fraud in general.”

Standard PCR method is not tissue specific

The method currently used for detecting prohibited ruminant PAP in feed in national reference laboratories for animal protein such as the IMR, is based on polymerase chain reaction (PCR); essentially the same method that used for detecting coronavirus.  

“Even though PCR is rapid and sensitive, this method is not tissue specific. For example, authorized milk powder cannot be differentiated from prohibited animal proteins or blood products from the same species. While with the spectral library method we were able to say what is legal and illegal material,” says Varunjikar.

Other ruminant PAP product such as collagen and gelatin will be soon allowed as feed ingredients, where this new method will be more useful to differentiate animal products. 

Promotes safe and sustainable seafood production

The new study provides valuable new knowledge about how food safety standards can be maintained in circular economies when introducing new and more sustainable feed resources into aquaculture.

“To the best of our knowledge, this is the first study to compare the suitability of different tools for the detection of prohibited blood products in insect feed and insect larvae,” says Ikram Belghit.

The work is a result of a project funded by the Norwegian Research Council (ENTOFOR). It is one example of how molecular tools can be used for tackling future feed and food authenticity challenges.

“At the IMR, method development for food and feed safety analyses continues in close collaboration with national and international food safety authorities” says Kai Lie, who is leading the national reference laboratory at the IMR, and Josef Rasinger, project leader of the MultiOmics project.

Reference

Belghit, Ikram, Varunjikar, Madhushri et al. (2021). "Future feed control – Tracing banned bovine material in insect meal". Food Control 128:108183.