A special kind of apple is coming to supermarkets in the US: thanks to our research these apples won't turn brown when they're cut, bitten or bruised.
Unlike a conventional apple (on the left) Arctic® apples do not brown when sliced. Photo: OSF
Conventional vs arctic CSIRO

Unlike a conventional apple (on the left) Arctic® apples do not brown when sliced. Photo: OSF

Ever wondered why apples turn brown when you cut them up? It’s all thanks to a naturally occurring enzyme called polyphenol oxidase (PPO). This enzyme is released when the fruit’s cells are ‘broken’ and it reacts with other parts of fruit cells turning the fruit brown. Once this reaction has taken place, nothing can be done to reverse it and quite often the fruit is thrown away.

You can destroy the PPO enzyme through cooking or reduce enzymatic browning by covering the fruit. Another popular way to stop further browning is to put lemon juice on it. This works because the ascorbic acid in lemons delays the PPO enzyme reaction.

We took a different approach to stop browning. First, we isolated the genes that encode the PPO enzyme, then we constructed an anti-PPO gene. Inserting this gene into plants blocks the production of PPO and therefore stops the browning.

War on food waste

Australians are throwing out over 4 million tonnes of food each year. That’s over $1000 of food wasted by the average Australian household. This waste not only hurts our bank accounts, it also hurts our world, with global food loss and waste generating 8 per cent of total greenhouse gas emissions annually. Sounds like a big problem, doesn’t it? And we haven’t even mentioned its impact on global food security and our growing waistlines. As with any complex problem, the solution involves a number of different tactics. One of which is trying to keep food fresher for longer.

This month, a special kind of apple slice will go on sale at select US supermarkets and, thanks to our research, these apples won’t turn brown when they’re cut, bitten, or bruised.

USA getting a slice of the action

Arctic® apples have been developed by an innovative Canadian biotech company, Okanagan Specialty Fruits Inc. (OSF). Their first product will be bags of fresh Arctic® Golden apple slices, with more nonbrowning varieties expected in future years, including Arctic® Granny and Arctic® Fuji. Neal Carter, the company’s founder, began working on the apples in the mid-1990s.

“I came across research from CSIRO that had managed to ‘turn off’ browning in potatoes,” explains Carter. “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 with apples, as nonbrowning apples would be more appealing and convenient. Additionally, we felt this small genetic change could also significantly reduce food waste, as nearly half of all apples produced end up wasted, many due to superficial bruising.”

Arctic® apples will be sold through select US outlets beginning in October 2017; while there is limited supply this year, as plantings mature resulting in increased volume, sales will expand throughout the U.S. and Canada.

While there may be other sliced apple products already on the market, these are often coated with vitamin C and calcium to prevent browning and to preserve crispness, and this can change their taste.

I heard it on the grapevine

Ian Dry and Simon Robinson were our scientists working on this 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,” explained Ian.

“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,” he said.

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.

Waste not, want not

This non-browning technology has potential to reduce waste not only in apples and potatoes but also in other important horticultural crops, such as beans, lettuce and grapes where produce with only small injuries could still be sold.

Interested in using this technology?

14 comments

  1. This is a great way to make more money and reduce waste. I was also woundering what is bad about GMO. There is all of this great advanteges but no bad effects. What are some of those bad effects that are unone, is my question?

    1. Hi Leandra,
      Thanks for your question.
      There have been numerous scientific studies undertaken to ascertain if GM foods have a harmful effect on human health, none of which have found evidence of adverse health effects compared with non-GM foods.

      Regards,
      Kashmi
      CSIRO Social Media team

  2. Yea I tend to agree wtih MW and Tracey on this one. Surely the CSIRO has more relevant and useful discoveries to be talking about in it’s newsletter? Nothing disturbs me more than patenting of ‘new and improved’ food plants. I also love the ‘war on waste’ spin. Surely this kind of product is adding to the perception that fruits and vegetables need to look perfect and hence causing the wastage of millions of tonnes of second rate fruits and veg each year.

  3. Well said MW. Here we go with more stuffing with our food. Thank goodness Australia still has laws which help us to discern where GM foods are involved and we can avoid them like the plague. There is tons of research and evidence of past situations with GM introduced foods in America that tell us how damaging GM foods are for humans and animals. Unfortunately the voice of those with vested interests ($$$$) drowns out those trying to raise the alert for future food disasters if GM foods are allowed to creep into the lives of Australians as it has in America. CSIRO has so much good science but I wish they weren’t involved with this.

  4. Sometimes fruit goes brown on the inside when it has been stored too long at temperatures that are too cold. Is the browning actually due to cell damage? If so, then by stopping the fruit going brown, are we not stopping consumers seeing when fruit is damaged?

    1. This is an interesting question. It is true that just because you can no longer see browning that the cells are not damaged. I think if you bit into a non-browning apple that had significant bruising you would still be able to tell that the apple had been damaged based on the texture of the apple and you would then probably discard (and hopefully compost) the apple. But what the non-browning apple is trying to address is the behaviour that consumers have developed that fruit and veg cannot be consumed unless it is ‘perfect’ to look at such that people will discard fruit that shows a slight tinge of discolouration even when they are probably perfectly safe and nutritious to eat. Hopefully this technology will lead to significantly less food waste.

      Jesse,
      Communications Advisor
      CSIRO

      1. If the whole point of non-browning apple is to reduce food waste due consumer behaviour of wanting “perfect” looking food then I think it’s putting the cart before the horse. We need to educate consumer of what is bruised fruit (edible) and what is rotten fruit (unedible), and indirectly teach them to handle fruit gently so not to bruise them.

        I can see this technology is good for food processing industry such as fruit salad maker and juicing bar where they need to slice fruit in advance. In this case sliced apple products may have deceiving longer shelf life due to non browning gene. Can the scientist tell us is it better for human to consume “perfect” looking slice apple that has been cut for 12 hours in the fridge or sliced apple that been in fridge for one hour?. And comparison of the impact of letting human eat the deceiving perfect looking apple slice and, the impact of dumping the “imperfect” to the landfill and decompose gracefully?

        I am also wondering is there any difference when decomposing natural and non-browning apple? For example length of time it take to decompose and the difference in soil after composing. Non-browning apple may reduce food wastage but to think it will never end up in landfill is naive.

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