CSIRO data used for ‘non-browning’ apple
CSIRO research leads to non-browning apples
RESEARCH by Australia’s peak scientific body, the CSIRO, has led to the production of apples that will not turn brown after they have been cut.
The findings have been taken into the North American marketplace with a variety named Arctic Golden apples, with further varieties expected in coming years. They will also have an impact on the amount of “imperfect” food being thrown out.
The non-browning technology also has the potential to reduce waste in potatoes and other important crops – such as beans, lettuce and grapes – where produce with small injuries could still be sold.
Apples turn brown when they are cut thanks to a naturally occurring enzyme called polyphenol oxidase (PPO). This enzyme is released when the fruit’s cells are “broken”. It reacts with other parts of fruit cells, turning the fruit brown. It can’t be reversed and often fruit is thrown away.
The PPO enzyme can be destroyed through cooking or reduced by covering the fruit. The ascorbic acid in lemons will also delay the PPO enzyme reaction.
The CSIRO reports that it took a different approach. First, its researchers isolated the genes that encode the PPO enzyme, then they constructed an anti-PPO gene and inserted it to block production of the enzyme.
Keeping food fresher for longer is a major tactic in the war against waste, which sees more than four million tonnes of produce thrown out each year – about $1000 for the average Australian household.
This month, a special kind of apple slice will go on sale at some US supermarkets.
The Arctic apples were developed by Canadian biotech company Okanagan Specialty Fruits, whose founder, Neal Carter, began working on the apples in the mid-1990s.
“I came across research from CSIRO that had managed to ‘turn off’ browning in
I was aware apple consumption had been declining...
— Neal Carter
potatoes,” Mr Carter said. “As an apple grower, I was very aware that apple consumption had been declining for decades while obesity rates had simultaneously been sharply rising. My wife and I felt that we could help boost apple consumption through a similar biotech approach.”
The CSIRO’s Ian Dry and Simon Robinson worked on the project in the 1990s.
“We heard about a naturally occurring sultana grapevine mutant that produced sultanas that were light golden in colour instead of dark brown and we tried to find out why,” Dr Dry said.
“We discovered the sultana was light in colour because of a mutation in the grape PPO gene.
“It was then that we realised the potential of this discovery to be applied to other fruits and vegetables. We tested anti-PPO technology on potatoes and managed to produce Australia’s first non-browning potato.”
The anti-PPO gene in the apples does not come from another species. It is made from DNA sequences from four of the apple’s own genes, and insertion of this anti-PPO gene is aided by commonly relied upon biotech tools.
FRESH: But cut them and they will go brown. Science is helping save such fruit from being wasted.