On Nutrition

For local produce, March and April are like the hours between dusk and dawn. The remains of the fall harvest (apples, pears, root vegetables, sturdy winter greens) are waning, but the fresh produce of late spring and early summer (berries, stone fruits, tender leafy greens) has yet to burst forth.

When you enjoy eating an abundance of vegetables and fruit, how do you bridge the gap between the seasons? Should you buy fresh produce that has traveled thousands of miles from the Southern Hemisphere? Or should you step over to the freezer case?

Vegetables and fruits chosen for freezing are picked at the peak of ripeness, when they are at maximum flavor and nutritional value. Within hours of harvest, they are blanched with hot water or steam to kill any bacteria and halt further ripening, then flash frozen. The freezing process slightly lowers levels of some of the water-soluble vitamins, such as vitamin C and the Bs. However, fresh produce shipped long distances fares much worse.

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Vegetables and fruits picked for fresh shipping tend to be picked before they are ripe so they can reach their destination before becoming overripe. Unripe produce also tends to be firmer, reducing damage in transit.

Unfortunately, unripe produce has not fully developed its vitamins, minerals, phytochemicals and flavor. Exposure to heat and light during shipping degrades nutrients further. Even if this produce looks ripe by the time it reaches your store’s produce section, it fails to live up to its full potential.

For top nutrition and flavor, fresh and ripe produce grown locally, or at least regionally, is your best bet. When local isn’t an option, frozen produce will give you more nutrient bang for your buck.

Another advantage of keeping a supply of frozen veggies and fruit on hand is that they have a longer “shelf life” than fresh. That’s particularly handy if you only have time to grocery shop once a week (or less often) and frequently find yourself running out of fresh produce — or staring at wilted, rotting produce that you couldn’t use up in time.

Simply use your fresh produce for the first part of the week, then transition to frozen. And if your next grocery run gets delayed, you have a backup. Frozen foods are already washed and often sliced, reducing kitchen prep time. That’s handy when you need to get a nutritious meal on the table — fast.

Keep in mind that frozen food doesn’t last forever. Even in a frozen state, nutrients and overall quality will start to degrade. Try to keep track of what you have and use things up within a few months, ideally. Most commercially frozen produce lasts for a year in the freezer, maximum.

What about canned produce? One advantage is that they are already cooked and recipe-ready. However, canning does deplete more nutrients than freezing, with the exception of canned tomatoes and pumpkin, which seem to hold up. You also need to watch out for added sodium in canned vegetables and added sugar (aka syrup) in canned fruits.

Next time: Should you shun sodium?

Carrie Dennett: nutritionbycarrie@gmail.com. Dennett is a graduate student in the Nutritional Sciences Program at UW; her blog is nutritionbycarrie.com.