Apple Browning

Addressing a key barrier to consumption

Solving the issue of apple browning

In our consumer research, we have found that the majority of apple eaters feel that apple browning is an issue in their apple-eating experience. And, it is clear that browning is a significant deterrent for freshcut apple products, which currently make up just ~2% of apple sales despite rising consumer demand for healthy, convenient snacks.

Currently, most commercial freshcut apple products require anti-browning treatments, such as calcium ascorbate, in order to delay or reduce the enzymatic browning reaction. Unfortunately, these treatments can add up to 40% in processing costs and frequently impart an off-taste to the fruit.

Additionally, sulfites are commonly used to reduce browning in dried apple products. Such sulfite treatments are ideally avoided as, according to FDA estimates, one in 100 people are sensitive to sulfite treatments and can have allergic reactions. And for those with asthma, the likelihood of sulfite sensitivity may be as high as 10%.

Therefore, it comes as no surprise that the majority of consumers have told us they would be more likely to purchase sliced apples that did not require anti-browning treatments!

Arctic apple PPO silencing

Why do apples brown?

There are two types of browning in apples – primary (or, enzymatic) browning and secondary browning. Secondary browning generally refers to the discoloration that occurs when an apple is beginning to decompose due to fungi and bacteria; in other words, when the fruit is rotting.

Primary browning in apples, on the other hand, takes place when the fruit’s phenolic compounds react with oxygen. This oxidation process is driven by an enzyme called polyphenol oxidase (PPO) (which we silence in our Arctic® apples). When an apple’s cells are ruptured – for example, by bruising, biting or cutting – the browning reaction begins when PPO found in one part of the cell is able to react with phenolic compounds found elsewhere in the cell.

Browning variance in apples

Just as different plants have varying levels of PPO, there is a wide range of PPO levels among the 5,000+ apple varieties in existence. Some existing apple varieties turn brown more slowly than others, which can be due to a number of factors:

  • The apple variety may have high levels of certain acids, such as malic and citric acids, which impedes the PPO/phenolic reaction
  • It may be low in phenolic substrate so the reaction just doesn’t happen as intensively
  • It may have stronger cell walls, which reduces the mixing of PPO and phenolics
  • It may have naturally low levels of PPO

But, even slow or low browning apples do experience enzymatic browning; Arctic® apples do not because there is insufficient enzyme to drive the oxidation reaction.

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