Success is in the air

Dr Andrew Kralicek, Plant and Food Research, Auckland

Andrew Kralicek’s dream is in view.  A portable, affordable, accurate device to detect tiny concentrations of volatile organic compounds.  Such a biosensor could be used to indicate:

  • the ripeness and firmness of fruit
  • precursor compounds for the critical flavours in wine
  • the presence of pathogens
  • algae in drinking water
  • biosecurity threats such as the dreaded Queensland fruit fly
  • a variety of human diseases – there are 2000 compounds on our breath and characteristic healthy vs disease profiles
  • the provenance of a food

Andrew is getting ready to build a prototype of this sensing device and there is great interest in it from consumers, and therefore marketers, who are becoming more and more concerned about the quality, safety and provenance of food.   He was the first to receive a $20,000 development grant from Callaghan Innovation’s KiwiNet Emerging Innovator Fund.

The idea for the sensor is based on biochemistry borrowed from nature - the phenomenal ability of insects to smell, which has evolved over 2 million years. Unlike humans, insects have receptors on their antennae, so they can smell on the fly, as it were.  We all know how fast blowflies arrive at the pot of mince on the stove.  Their sense of smell is exquisitely sensitive – they can pick up one part in a million billion (one followed by 15 zeros). This is essential for their survival in a competitive world to find food and mates and warn them of danger.  Bees can be trained to smell and locate ant pheromones miles away, given sugared water rewards.

Our own sense of smell is greatly diminished - only a third of our olfactory genes are active. We cannot smell food contaminants, such as salmonella.  We have only 350 working receptors compared to a dog, which has about 1000.  Smell, like sight, differs among individuals and related groups, accounting for different tastes in food, drink and perfume.   Understanding these preferences is very important for food exporters. 

The adult fly has only 24 receptors, but in different combinations they can detect and differentiate hundreds of volatile organic compounds.  Insects can recognise a whole suite of compounds – alcohols, esters, ketones, aromatics and aldehydes.  There is a size limit on the molecules they can detect, simply because heavy molecules cannot fly.  The compounds bind to the protein receptors, which changes the electronic signal to the brain.  How they register that signal in the brain as a “smell” we are just beginning to understand.

NZFSSRC is excited about the possibilities for such a powerful way of protecting and enhancing New Zealand’s reputation for safe, high quality produce.   Currently, it takes days to get results by the time you send samples to the lab and analyse them using traditional methods such as growing cultures in petri dishes.  What we need, especially where there is a biosecurity or health threat, is the immediate, portable on-site monitor that Andrew’s work promises. 

About Andrew

Andrew was born in Waihi.  He went to McLean’s College in Auckland, where he became interested in how life works at the molecular level.   “Proteins are the workhorses,” he says.  Andrew studied proteins involved in DNA replication for his PhD at Auckland University and first postdoc at the Australian National University, followed by cell division during his second postdoc at the Centre of Biological Investigation in Madrid, Spain. He is now leader of the Molecular Sensing Team at Plant and Food Research.

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