Could ‘milk’ crystals from cockroaches become the world’s next superfood?
Pacific beetle cockroaches produce a highly nutritious substance, studies suggest
The milk crystals of the Pacific beetle cockroach are beautiful. Slice open an embryonic roach under a microscope, and the crystals spill out in a shower of nutrient-dense glitter.
But the flavour of cockroach milk is nothing to write home about. Subramanian Ramaswamy, a biochemist at the Institute for Stem Cell Biology and Regenerative Medicine in Bangalore, India, said as much early Tuesday. As a party dare — he’d lost a drinking competition — one of Ramaswamy’s colleagues once ate a sprinkling of the crystals.
“He said it doesn’t taste like anything special,” Ramaswamy said.
Most roaches lay eggs. Not the Pacific beetle cockroach. It gives birth to live young, sort of like humans if we kept babies by the dozen in fleshy organs called brood sacs. Also like humans, mother Pacific beetle cockroaches produce food for their offspring.
The embryos dine on a liquid substance packed with fats, sugars and protein. You can think of this like cockroach milk. It gets weirder. Insect experts have long known that this cockroach species secreted liquid food. But they thought baby roaches simply digested the stuff.
When Barbara Stay, a zoologist at the University of Iowa, first stumbled upon a cache of crystals tucked inside the embryos, scientists were stumped.
“We didn’t believe these crystals were actually protein crystals,” Ramaswamy said.
Close inspection of the crystals using X-rays proved otherwise. Experiments suggest that cockroach milk is among the most nutritious and highly caloric substances on the planet, according to research published recently in the journal for the International Union of Crystallography, IUCRJ.
Pound-for-pound, cockroach milk crystals contain three times more energy than buffalo milk, according to the analysis by Ramaswamy and his colleagues. Buffaloes, he said, were the previous top contender for producing a protein with the most calories.
“It’s a complete food,” Ramaswamy said of the roach crystals. In the brood sac, the embryos gulp down the liquid. There, the proteins turn to hard crystals in their guts. Nothing is wasted — “the mouth is open and the backside is closed,” as Ramaswamy described the embryos.
Within the sac, the baby roaches rely on these concentrated nutrients to grow large with an alien speed.
The discovery comes at a time when dairy milk is under increasing environmental scrutiny, as cow burps add to greenhouse gases.