SYSTEMATIC REVIEW

WORDS BY MAXIM BUCKLEY

One thing that honours has taught me is that science is a field full of weird and wonderful things. I completed my undergrad with the medical faculty and then decided that my honours would best be completed with the science faculty. Don’t ask me why. The medical faculty is fairly focused: science for the betterment of human health.

In a sense the science faculty has a similar idea, but it’s far broader. I met Sam at a faculty tea and cake day, in between stuffing our faces with free pastries, tarts, and doughnuts, we discussed our projects. Sam’s project really blew me away because he was the first person, I’d met who wasn’t directly working on a pathogen of some description, which in retrospect is quite funny because that seems to be a good portion of the building. Sam is from England’s Midlands and grew up in Stoke-on-Trent. After completing his undergrad at nearby University of Nottingham, Sam decided to complete a PhD, specifically a joint PhD with the University of Adelaide. So, while Sam is still a student at Nottingham, he has spent a good portion of his PhD at Adelaide, two and a half years in fact. “In retrospect I’m glad. I was originally going to do another year in the UK but with the pandemic and what my project is on, staying her just made sense”. These programs are available to University of Adelaide students too and Sam highly recommends anyone considering a PhD consider one of these programs.

“So essentially the project is based on global food security. Global populations are getting larger, so we need more protein to feed the world. Animal protein isn’t

very efficient so we’re looking into plant-based options”. In essence, Sam’s project is on common vetch, a plant that’s very similar physiologically to lentils but is incredibly protein rich and drought tolerant, allegedly able to survive up to a month without water. The catch? It produces a very potent neurotoxin called gamma-glytamylbeta-cyanoalanine (GGBC for short) that kills human model neuronal cells and primary mouse neuronal cells with great efficiency. GGBC’s precursor, betacyanoalanine (BC) is actually present in all plants and becomes toxic to them at high concentrations. Vetch, unlike other plants, decides to turn this BC into the neurotoxin GGBC and store it. “You can just boil the stuff away, but unfortunately that kind of defeats the purpose. If you have this really nutritious thing and then you boil it then it’s not as nutritious and you’ve just wasted your time” so Sam’s project is looking into other methods of removing this toxin. He also needs to find out what it tastes like, but we’ll get into that later.

So rather than boiling, Sam is looking at fermentation. Specifically, Japanese nattō, and Indonesian tempeh. “We actually just went down to Chinatown and got some natto, isolated the bacteria (Bacillus subtilis) and got on with the fermentation”. For those who haven’t tried natto before, it does look quite unappetising. Essentially, the soybeans when fermented with B. subtilis take on a pungent cheese smell and produces these sticky strands. It does look a little bit like slime, but I assure you it is quite delicious. “I actually haven’t brought myself to try natto yet, but I really don’t have any excuse at this point”. The other method, tempeh, I’m not so keen on. “You basically make a cooked block of condensed seed, you wrap it in banana leaves or something similar, and then it’s naturally fermented by the fungi Rhizopus oligosporus or Rhizopus oryzae”. Apparently, the tempeh method works extremely well, it does a great job of getting rid of the neurotoxin but also makes the product really digestible. “Fermentation does great things for nutritional content in general. When you have these really long chains of sugars which are quite difficult for us to break down, if you let something else like a bacteria or fungus do the work, then you suddenly have a stack of available nutrients”. Unfortunately, Sam doesn’t know yet how these processes affect the neurotoxin, but work will be done to figure that out eventually.

But how do you find out what a neurotoxin tastes like? For that, you need an electronic tongue. “So basically, you make you sample up, put it in some water, and then you have two probes that go into the water and these test the electrical charge between them. If it’s really salty, you get a certain charge. So, we can test salty, sweet, umami, just about anything. It’s a really cool piece of kit”. Sam has a library of foods with known descriptions, so he compares the electrical charge of GGBC to the library and can approximate the taste.

When asked what’s next, the future becomes less clear. “I’m heading back to England soon. I haven’t been back in over two years. I want to see my partner and my family. Beyond that it’s a bit up in the air. The opportunities are seemingly endless for food science”. Sam also hopes to continue and eventually finish the Heysen Trail, something he’s been chipping away at over many weekends.