It’s the future: Non-browning apples

Today I learned about polyphenol oxidase, an enzyme apparently responsible for the browning of lettuce and apples upon exposure to oxygen.

Then I learned about a set of Golden Delicious apples that have been genetically modified to reduce their production of polyphenol oxidase, allowing them to go three weeks in exposure without browning–an industry standard previously met with additives.

Carter reduced the enzyme polyphenol oxidase to prevent browning when apples are sliced, bitten or bruised. The apples match the industry norm of not browning for three weeks after slicing but without using flavor-altering, chemical additives that the rest of the fresh-sliced apple industry uses.

Golden Delicious, Granny Smith and Fuji varieties have been approved by the USDA and Canada. An Arctic Gala could be approved in 2018. Only Goldens and Granny Smiths have been planted long enough to produce fruit in commercial quantities by next fall.

Read about the summary here or the full post here.

It’s the future! Do me next!



  1. Pierce R. Butler says

    What function(s) do(es) polyphenol oxidase serve in apple metabolism? (The links don’t say.)

    Will the reduced p-o apples need super-strong fungicides or suchlike to compensate?

  2. Siobhan says


    Wikipedia says the function is disputed, though I’ve located a paper that supports the hypothesis of “bug defense.”

    I suppose the question, then, is whether PPO apples are still sprayed with insecticide. Most plants have some defenses from infestation but I don’t think many industrial farmers ever find those defenses good enough.

    Bear in mind that any feasible claim to knowledge I might have in this area is buried under hazy and distant recollection. I only kind-of understand the process to begin with.