The study, published in the journal of the International Union of Crystallography (IUCrJ), investigated the full structura;l properties of a crystalline secretion found in the guts of a particular type of cockroach called known as the Pacific Beetle Cockroach (Diploptera punctate) after previous research identified the crystals to be made from milk proteins.
Now, nearly 10 years after this initial discovery by researchers at the University of Iowa, the full structure of the milk crystals have been determined by an international team of scientists led by Subramanian Ramaswamy from the Institute for Stem Cell Biology and Regenerative Medicine (inStem) in Bangalore.
“It [the milk protein crystals] are like a complete food – they have proteins, lipids and sugars. If you look into the protein sequences, they have all the essential amino acids,” said study co-author Sanchari Banerjee.
According to Ramaswamy and colleagues, the crystal ‘cockroach milk’ is estimated to contain more than three times the amount of energy found in an equivalent amount of dairy milk.
“They’re very st able. They can be a fantastic protein supplement,” commented Ramaswamy – who suggested that the unique crystal structure could also offer advantages for industry.
The inStem researcher also added that the crystalline nature means that the crystal releases protein at the same rate the protein is consumed – and could help to maintain protein levels in liquid solutions.
As the protein in the solution is used up, the crystal releases protein at an equivalent rate, the team said.
“It’s time-released food,” Ramaswamy commented. “Besides this, these crystals have three times the calorific content of buffalo milk. If you need food that is calorifically high that is time released and food that is complete. This is it.”
The lead researcher added that in addition to their potential use as a food supplement, the structure of the milk crystal scaffolds show ‘fascinating characteristics’ that could be used as a novel delivery format for other bioactive compounds – and could potentially be used to design nanoparticle delivery systems for drugs and nutraceuticals.
Now, armed with the gene sequences for these milk proteins, Ramaswamy and colleagues plan to use a yeast system to produce these crystals en masse – which could lead to the large-scale production of the nutritious crystals for use as a dietary supplement.
Indeed, Professor John Carver, the Director of the Research School of Chemistry at the Australian National University recently told news service SBS that while even the idea of cockroach milk sounds "really out there", it has a lot of promise.
"It would require quite a bit of biotechnology to get it into a form that you would harvest and use as a food supplement, but it's eminently doable with the technologies that we have and it's very common for making large dietary supplements that way," Carver told SBS.
"Potentially it could be an additive which is a very high energy source, which people who work out in gyms might be interested in using."
Volume 3, Part 4, July 2016, Pages 282-293, doi: 10.1107/S2052252516008903
“Structure of a heterogeneous, glycosylated, lipid-bound, in vivo-grown protein crystal at atomic resolution from the viviparous cockroach Diploptera punctate”
Authors: Sanchari Banerjee, et al