Over the past two decades, modified-atmosphere packaging has changed the face of the produce industry, making a wide range of fresh-cut fruits and vegetables everyday fare in homes, restaurants and dining places throughout the world.

Now that the technology has passed its 20-year milestone, researchers and manufacturers are looking at innovative ways to incorporate the concept into new kinds of produce packaging, said Jeffrey Brandenburg, president of The JSB Group LLC, a global consulting firm based in Greenfield, Mass.

“Modified-atmosphere packaging is the fundamental technology for optimizing quality and shelf life in fresh produce,” Brandenburg said.

The technology comes with three fundamental tenets:

1. It reduces the amount of oxygen in a package and slows the respiration rate, putting the produce to sleep, thus extending its shelf life.

2. It minimizes enzymatic browning reaction — or “pinking” — for products that are prone to that condition, like iceberg, romaine and butter head lettuce.

3. It increases the amount of carbon dioxide in a package, minimizing growth of spoilage bacteria.

Modified-atmosphere packaging is “almost mandatory” for fresh-cut fruits and vegetables for optimal quality and shelf life, he said.

“Pretty much every fresh-cut produce package out there is modified-atmosphere packaging in one way or another,” Brandenburg said.


Gone too far?

But Brandenburg cautions that sometimes processors in North America may extend shelf life too far.

Shelf life of 20-plus days for leafy greens is not uncommon, he said.

But Americans found themselves drenching their salads with dressing to make up for a loss of taste in the lettuce, which more and more became a vehicle to add texture rather than flavor to their salads, he said.

As Americans started eating more healthfully and cutting back on dressing, they thought, “maybe we extended shelf life too far,” he said.

“Just because we can get 21 days doesn’t mean we want 21 days.”

Processors now are redefining shelf life, he said.

It’s good to extend shelf life, Brandenburg said, “But you also want to make sure you’ve optimized your quality.”


Handle with care

To optimize quality, it’s important that the atmosphere in packaging be modified correctly.

If the atmosphere isn’t modified enough, the benefit of the technology will not be realized, he said. And if all of the oxygen is removed from the package, quality suffers and the potential arises for a food safety issue.

Another potential problem with modified-atmosphere is the fact that it relies heavily on temperature control.

“If you don’t have proper cold chain management or temperature control throughout the cold chain, you lose a lot of the benefit of modified-atmosphere packaging,” he said.

One of the real growth areas in modified-atmosphere packaging is for whole produce for products like brussels sprouts, green beans, citrus and possibly berries, Brandenburg said.

But whole produce doesn’t necessarily have the same need for modified-atmosphere packaging as fresh-cut, and it often doesn’t need refrigeration, so it can be difficult in some cases to take advantage of the technology, he said.


Never satisfied

It seems that those who work with modified-atmosphere never are satisfied with the status quo.

They are now asking, “What else can we have it do?” Brandenburg said.

They’re asking, for example, if they can add in moisture management – actually managing water in the form of free liquid, water vapor or relative humidity.

Brandenburg believes this could be “the next big breakthrough.”

They also want to know if they can add management of ethylene, the plant-ripening hormone.

And they’re curious to find out if they can add antimicrobials to kill bugs — whether they’re spoilage organisms or pathogenic organisms – and maybe reduce the risk of a food safety incident, he said.

And that’s not all.

Historically, modified-atmosphere has been used primarily by processors for product going to consumers.

“Now, people are starting to look at modified-atmosphere packaging technology farther up the supply chain — more toward the grower,” he said.

For example, some companies are exploring ways to make shipping containers or pallets “giant modified-atmosphere packages,” he said, and they’re seeing some success.