Waiting to Eat Fresh Vegetables Means Loss of Nutrients
Mar. 27–CHEYENNE — That bag of spinach that has been sitting in the fridge for a week looks OK. Not too many wilted pieces. Tastes fine too. But guess what? It’s missing a lot of the nutrients it had when picked.
According to research from Pennsylvania State University, a bag of spinach that has been stored at 39 degrees Fahrenheit for eight days has lost half of its folate and carotenoids, compounds known for their importance in preventing birth defects, fighting heart disease and preventing blindness and cancer. And at higher temperatures, the breakdown was even faster. At 50 degrees it took only six days to reach about half of initial levels; at 68 degrees it took four. What’s a consumer to do?
“People should just eat (spinach) fast and not let it sit in their drawers,” said Luke LaBorde, associate professor of food science at Pennsylvania State. “You have to accept the reality that it’s a living plant, and you should eat it while it’s fresh.”
The research also underscores the importance of keeping fresh vegetables cold — experts recommend a refrigerator temperature between 36 and 40 degrees Fahrenheit — and eating them as soon as possible.
Eight days. And that count started from within 12 hours of the time the spinach was packaged. Commercial spinach must be transported from the field — somewhere in the Southwest at this time of year — to the processing plant and to the store. Then it must sit on store shelves until it is purchased. This takes a few days at least, and the clock is ticking.
LaBorde said while fresh fruits and vegetables are becoming popular, not a lot is known about their nutrient loss because much of the early research was done on canned and frozen vegetables.
“We’ve got the fresh vegetables that are so popular right now,” he said.
“When you have a fresh vegetable, it slowly dies. And as it dies, the enzymes take over and slowly degrade it.”
He said the fruits and vegetables most at risk of nutrient loss are those that are crushed or cut. Apples, he said, are not going to change much because they are designed to fall off the tree.
Spinach and most greens are a different story, though.
“In this case you’re ripping it off the plant,” LaBorde said. “(Loss) would be even higher with chopped spinach.”
Broccoli, another cut vegetable, loses about half its total carotenoids after six days at 41 degrees, previous research shows.
The culprits are degrading enzymes that are normally contained inside intact cells but are released and free to cause damage when veggies are wounded. Chopped or peeled versions of fruits or vegetables also are vulnerable to nutrient loss during refrigerator storage.
LaBorde and Suzy Pelican of the University of Wyoming Cooperative Extension agree that fresh veggies are part of a good diet, but a combination of fresh, canned and frozen is the best way to go.
“Don’t assume fresh is best and frozen or canned are not,” Pelican added.
Canned or frozen fruits and vegetables are relatively stable and impervious to nutrient loss. Frozen vegetables are made that way very soon after harvest, preserving almost all of the nutrients. And in canning, the enzymes that break down vitamins in fresh vegetables are inactivated.
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