Produce Keepers

A new wave of “produce keepers” is cramming supermarket shelves, promising to extend the life of fresh produce. We tested five such products: two bags, two plastic containers, and one device designed to neutralize ethylene, a gas that accelerates ripening and spoilage. We filled the bags and containers with a pint of strawberries or 15 ounces of baby spinach, then placed them in the refrigerator (middle shelf for the berries, bottom shelf for the spinach) along with the same items left in their original packaging. We put the ethylene neutralizer in a drawer in a separate refrigerator with more strawberries and spinach in their original packaging. We checked the produce every other day for two weeks and recorded any signs of decay.

All the “protected” produce, it turned out, spoiled at relatively the same rate as that in the original packing (4 to 10 days)—and in some cases even faster. Why?

Fruits and vegetables are composed mostly of water and need a humid atmosphere to avoid drying out. But this presents a storage problem: While airtight containers keep that vital moisture in and limit oxygen exposure, thus slowing the plant’s metabolism and prolonging its life, they also create ideal conditions for mold and bacterial growth. (Moisture tends to condense on the surface of the produce, trapping ethylene gas, which causes the produce to deteriorate.) The products we tested either kept in moisture but also trapped ethylene (but didn’t “neutralize” its adverse effects), or let moisture escape along with the ethylene. Overall, the original packaging did a comparable (and occasionally better) job controlling the degree of moisture and oxygen exposure.

You’re better off controlling refrigerator temperature than buying any of these products. Green leafy vegetables should be stored in the lowest shelves of the fridge, where it’s the coldest, while berries should be kept in the middle shelves, where the temperature is slightly higher.