Articles

Zoom – Flying protein sources (engl. version)

February 21, 2020


A greenhouse in Baruth in the German state of Brandenburg. Behind the inconspicuous glass façade you’ll find a highly specialised biotech company: Hermetia Baruth. Founder Heinrich Katz is visiting the site that underpins his success story: fly breeding. In 2006, he was the first in Europe to succeed at building a stable breeding facility for the black soldier fly. From a biological point of view, the fly is very interesting. The adult doesn’t eat any food, but it lives for 12 days. That means that especially during the larval stage, the fly’s protein has to be enriched with enough fat and energy to survive for 12 days. Otherwise they just need a little bit of water. Basically the adults are only there to ensure the survival of the species. Together with biology student Winnie Akara, the breeder inspects the quality of some newly-pupated larvae. Insect biomass largely made up of high-quality proteins and lipids. It’s used mainly to make feed products for farm animals and pets. The black soldier fly originally comes from South America. Adults hatch from pupae after 8 to 9 days. But what makes the insect such a good bet when it comes to commercial breeding? The flies have practically no negative characteristics They don’t transmit diseases and aren’t a nuisance. They don’t eat crops or cause any damage. They’re not an invasive species. And the fly’s larval stage has a very broad enzymatic spectrum. So it can convert a very wide range of substrates. This is how the cycle begins. The adult animals are first lured into cages with the help of particular scents. After mating, the females lay their eggs in honeycombed sheets made from cardboard. The eggs are the insect breeder’s gold. Most of the larvae that develop from them will be used for protein production. A fraction will be allowed to pupate, develop into adult flies, and continue the cycle. The eggs are hatched in boxes. After hatching, the larvae can plunge straight into a nutritious medium. Soldier fly larvae grow quickly, and the conditions are optimal in the breeding plant’s six bioreactors. Temperature and humidity are adjusted to the different stages of their life cycle. A single reactor contains about 4 million larvae. We use the phrase ‘positive factory farming’. Even if you pull them apart, the larvae quickly snuggle back up together. That’s because they generate their own heat, which makes physiological processes take place at a higher temperature. We feed them once, and the amount is calculated to get this number of larvae to the L 4 stage. The final larval stage. The larvae are harvested before they begin to pupate, when the protein they contain peaks. Before long, levels would drop again, since protein is converted into the insect’s exoskeleton during pupation. The mature larvae are automatically sifted out by the system and separated from both food remains and any excrement. We dry them then at 90 degrees. The larvae are about 60% water. After drying, they’re around 40% protein and 35% fat. And we separate that out so that we have a clean protein. That gives us a meal that’s about 65% protein. A number of development factors had to be be researched and improved to make the process more economical. Under what conditions do the larvae grow most rapidly? And what should they be fed? Because the soldier fly has legally been declared a farm animal, Katz has to use certified feed, which is costly, and not sustainably sourced. So he’s looking for alternatives. Hermetia is supported by the Leipzig-based German Biomass Research Centre, or DBFZ. Here, the larvae are test-grown at comfortable temperatures, and are fed various types of organic residues. We’re looking for residues we can use for insect breeding that don’t compete with feed production. For instance, fermentation residues from biogas plants, cattle slurry, agricultural waste or industrial residues from the food industry or possibly from the bioethanol sector or biodiesel production. We’ve achieved the best results with things like spent grains from breweries and bioethanol by-products. There we get yields that are very high. After two weeks, the researchers tot up their results measuring larval growth and weight and analysing the biomass. Project manager Harald Wedwitschka is also interested in what’s left over after the maggots have been removed. The waste contains so much energy it can be used to produce biogas. A potential new circular economy concept. If you combine insect breeding systems with existing biogas plants, the residual heat from the plant can be harnessed for use in insect breeding programs, while fermentation residues from the biogas plant can be used as a substrate for insect breeding. At the same time, residues from the insect breeding can be used as biogas substrates. In other words, different synergy effects would result from these two different plant concepts. As the DBFZ continues to test maggot input and output, Heinrich Katz is already dreaming of expanding his process in Baruth. My vision for the future is that we scale up this pilot plant increasing the number of individual bioreactors from 6 to 480 in the first stage of expansion, with correspondingly higher output. Once we’ve mastered production at that scale, we can multiply it to supply the market with significant quantities.

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