Keep Eating Veggies and Fruit, whether Fresh, Frozen or Canned

If you live in New England, your thirst for fresh fruit and vegetables during the winter months must be satiated with imports from California, from hot houses or hydroponic food producers, or from other countries, mainly those in South America. However, that doesn’t mean you should cut back on vegetables and fruit until your garden’s ready to be harvested or local farm stands open again. Your supermarket offers a wide variety of fresh, frozen, and canned veggies and fruit, and surprisingly, many offer the same nutritional value found in fresh produce …in some cases, they’re even better than fresh!

Most of the produce we buy in a grocery store was picked at least several days ago, likely not at its peak ripeness — if picked too early, it can spoil en route to the store. Fresh produce also degrades and loses some of its nutritional value after picking and during transport. Once fresh fruits and vegetables are harvested, they undergo higher rates of respiration– a physiologic process in which plant starches and sugars are converted into carbon dioxide, water, and other by-products — leading to moisture loss, reduced quality, and susceptibility to micro-organism spoilage. 

Refrigeration during transport helps to slow the deterioration, but by the time we eat a fresh vegetable that traveled across continents to reach us, a substantial amount of its nutritional value may be lost. We can help maximize the nutritional value of our fresh produce by choosing locally-grown produce when in season, refrigerating fruits and veggies to help slow down nutrient losses, and steaming rather than boiling them when cooking to minimize loss of water-soluble vitamins.

Produce destined for freezing is picked at its maximal ripeness, quickly frozen to a temperature that retains its maximum nutritional value and flavor, and kept frozen until it gets to the freezer in your local store. While there is some initial nutrient loss with the first steps in the freezing process — washing, peeling, and heat-based blanching (done for vegetables, but usually not fruits) — the low temperature of freezing keeps the produce good for up to a year on average. Once thawed, it has maintained the majority of its original nutritional value. And depending on how you cook or prepare the food, it may taste quite similar to its fresh counterpart.

The process differs for canned produce and fruit, and though still healthy, there may be some loss of nutritional value.  Similar to frozen, the product is picked at its maximal ripeness, blanched (this time for longer duration and with somewhat increased nutrient loss for heat-sensitive compounds compared to frozen), and then canned.  Oftentimes, sugary syrup or juice is added to canned fruit. Salt also is added to many vegetables to help retain flavor and avoid spoilage. These additions can take a very healthy fruit or vegetable and make it much less nutritionally desirable than its fresh or frozen counterpart. 

But without these additions, in general the nutritional value of canned fruits and vegetables is similar to fresh and frozen.  For fruits, look for canned fruit that is “in its own juice.”  For vegetables, check the sodium content on the nutritional label and aim for vegetables with “no added salt” and without added butter, cheese, or cream sauces.  Because the canned produce is maintained in an oxygen-free environment, canned foods can last for years, but be weary of dented or bulging cans.   

So the bottom line is that by the time they are consumed, most fresh, frozen, and canned fruits and vegetables seem to be nutritionally similar.  Each has the same fat, carbohydrate, and protein content as the pre-harvest fruit. Ultimately you might find that choosing a mix of fresh, frozen, and canned fruits and vegetables will help you and your family to more easily, inexpensively, and creatively enjoy many daily servings of fruits and vegetables without sacrificing nutritional value. 

As a final note, mineral, fiber, carbohydrate, protein, and fat levels are similar in fresh, canned, and frozen fruits and vegetables, but vitamin values will vary. Here’s a brief guide for maximizing nutritional value of your fresh, frozen and canned fruit and vegetables, based on primary nutritional research:

Vitamin C: Vitamin C is sensitive to heat, light, and oxygen.  If fresh produce is stored at the appropriate temperature and consumed in a relatively short period of time, then it is the best source of vitamin C.  However, during prolonged storage, vitamin C degrades rapidly.  It is also lost with blanching (though some fruits with ascorbic acid that undergo freezing may retain more vitamin C than fresh). A large percentage of vitamin C is lost with the initial canning process.

B vitamins:  Most B vitamins are sensitive to heat and light, which leads to significant loss with blanching used in freezing and canning. Thus, fresh tends to be the best source.

Polyphenolic compounds: Water-soluble polyphenolic compounds, found primarily in the skins of peaches, pears and apples, are lower in products that are frozen or canned without the skin compared to fresh.  But, if you keep the skin or if the juice is included, levels are as high or higher in canned versus fresh products.

Fat-soluble vitamin A and carotenoids and vitamin E:  Little fat-soluble vitamins are lost in blanching, so overall, frozen and canned are just as good as fresh.  Nutrient losses depend on the specific fruit or vegetable.  For example, fresh green beans have more beta-carotene than frozen or canned.  However, frozen peas have more beta-carotene than either fresh or canned.  Canned tomatoes have the highest levels of beta-carotene and lycopene, most likely due to heat-induced release of the nutrient with blanching.

Whatever you choose, however, remember that the U.S. Department of Agriculture recommends that you fill half your plate at every meal with fruit and vegetables!

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