If someone told me two weeks ago that cockroach milk was even a thing, I would have told them they should probably stop re-watching Aliens.
Enter Barbara Stay, a professor at the University of Iowa, who discovered a protein crystal produced by the female Pacific beetle cockroach, a unique insect that gives birth to live young and feeds them a liquid from her brood sack. This liquid eventually develops into nutrient rich crystals, and both can be extracted from the insects for consumption.
Whether or not the extracted ‘superfood’ is safe for us to drink is still yet to be determined, however. “In principle, it should be fine,” says Subramanian Ramaswamy, a biochemist at India’s Institute for Stem Cell Biology and Regenerative Medicine, “but today we have no evidence that it is actually safe for human consumption.” Only one person so far has tasted it, and it was as a dare -- one of Ramaswamy's colleagues ate a small sprinkling of the crystals because he lost a drinking competition, and noted that “it didn’t taste like anything special.”
So what makes it so intriguing?
As it turns out, the milk produced by the cockroach contains 3 times more energy than buffalo milk pound for pound (which was previously the top contender for producing the protein with the most calories). Additionally, amino acids are one of the key building blocks of the body, and cockroach milk contains 4 times more amino acids than cow’s milk.
Still, there’s something off-putting about drinking a liquid that come out of another organism's body. Also, many argue against the consumption of dairy milk due to it causing spikes in blood sugar levels due to being highly insulinogenic, and consuming too much potassium, calcium, or phosphorus can be harmful to kidneys, resulting in kidney stones or a risk of heart disease. On top of that, dairy milk has been under environmental scrutiny, due to it’s gigantic greenhouse gas creation, while the creation of alternatives like almond milk is famously a water-intensive process. It’s possible that this new product may also fall under similar scrutiny.
However, you can’t deny the value of nutrient dense substances when we live in a culture that encourages quick meals, given the prevalence of other superfoods coming into the market.
“The crystals are like a complete food -- they have proteins, fats and sugars. If you look into the protein sequences, they have all the essential amino acids,” says Sanchari Banerjee, one of the authors of a paper published in the journal from the International Union of Crystallography.
Ramaswamy mentions that they’re looking to use a yeast system to produce these crystals on a scale that would allow it to be consumed by humans.
Another interesting discovery is the natural structure of the crystals, which exhibit characteristics that could be used to design nanoparticles for drug delivery. The crystalline nature allows the proteins to be released at an equivalent rate, which Ramaswamy calls a time-released food.
However, the substance should certainly consider hiring a brand manager. “I don’t think anyone is going to like it if you tell them, ‘We extracted crystals from a cockroach and that is going to be food,’ ” Ramaswamy said.
Now we just need to find out if it comes in chocolate flavor.
Ref: Structure of a heterogeneous, glycosylated, lipid-bound, in vivo-grown protein crystal at atomic resolution from the viviparous cockroach Diploptera punctata. International Union of Crystallography (27 June 2016) | DOI: 10.1107/S2052252516008903 (Open Access)
Macromolecular crystals for X-ray diffraction studies are typically grown in vitro from pure and homogeneous samples; however, there are examples of protein crystals that have been identified in vivo. Recent developments in micro-crystallography techniques and the advent of X-ray free-electron lasers have allowed the determination of several protein structures from crystals grown in cellulo. Here, an atomic resolution (1.2 Å) crystal structure is reported of heterogeneous milk proteins grown inside a living organism in their functional niche. These in vivo-grown crystals were isolated from the midgut of an embryo within the only known viviparous cockroach, Diploptera punctata. The milk proteins crystallized in space group P1, and a structure was determined by anomalous dispersion from the native S atoms. The data revealed glycosylated proteins that adopt a lipocalin fold, bind lipids and organize to form a tightly packed crystalline lattice. A single crystal is estimated to contain more than three times the energy of an equivalent mass of dairy milk. This unique storage form of nourishment for developing embryos allows access to a constant supply of complete nutrients. Notably, the crystalline cockroach-milk proteins are highly heterogeneous with respect to amino-acid sequence, glycosylation and bound fatty-acid composition. These data present a unique example of protein heterogeneity within a single in vivo-grown crystal of a natural protein in its native environment at atomic resolution.