Are fresh vegies better?

Frozen vegetables can have higher levels of important nutrients, such as vitamin C, than fresh.
 
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  • Updated:13 Mar 2007
 

01 .Introduction

Fresh vegies with tinned vegies

In brief

  • Frozen and canned vegetables may not have the texture (and sometimes the flavour) of fresh ones, but they can be just as nutritious.
  • Broccoli was the only frozen vegetable in our test that was less nutritious than fresh.
  • When you buy fresh vegies, don’t keep them too long before you use them. Vegetables (especially green ones) continue to lose some of their nutrients while they’re stored in your fridge.

Fresh not always best

Next time you’re in a rush to get dinner on the table, don’t feel bad about serving frozen or even canned vegies.

  • By the time you eat them, fresh vegetables can have lower levels of important nutrients, such as vitamin C, than their frozen counterparts.
  • And while canned vegetables retain less vitamin C than frozen, they still contain as much dietary fibre as fresh, as well as retaining many other valuable nutrients. 

CHOICE investigation

We wanted to compare the vitamin levels in a range of fresh raw, fresh cooked, frozen and canned vegies to see which were more nutritious.

We chose the following vegies for testing because most people use them and you can get frozen or canned, as well as fresh:

  • tomatoes
  • spinach
  • green beans
  • carrots
  • corn
  • broccoli

We tested vitamin levels of the raw and cooked produce because cooking makes vegetables more palatable for most people, but they always lose some nutrients — especially vitamin C.

We also retested the fresh vegies after storing them (uncooked) for one week in the fridge (at 4°C). They lost nutritional value in this time — especially the green vegetables (broccoli, green beans and spinach). So unless you use up your fresh veg quickly you’re better off with frozen.

For more details, see What we found.

Which vitamins?

We picked the following nutrients because some or all of the above vegetables are good sources of them. Here’s why they’re important:

  • Vitamin C This is the most easily destroyed nutrient in vegetables, so it’s a good marker of a vegetable’s overall freshness, as well as an important nutrient in its own right. If you don’t get enough you get scurvy — though these days that’s very rare — but it’s also an antioxidant and may be protective against heart disease and some forms of cancer. It’s one of the water-soluble vitamins (the others are the B vitamins, which include thiamin, riboflavin, niacin, folate, pyroxidine and B12).
  • Beta-carotene is an antioxidant and again may help to prevent heart disease and some cancers. Some of it’s lost during processing and cooking, though it’s not as easily destroyed as vitamin C. In the body, beta-carotene can be converted into vitamin A, one of the fat-soluble vitamins (the others are D, E and K).
  • Lycopene This is the red pigment in tomatoes; there’s now good evidence that tomatoes help prevent heart disease and prostate cancer.

The results show the levels of vitamin C and beta-carotene (and lycopene for tomatoes) per 100 g of vegetable as percentages of the recommended dietary intake (RDI) for adults (vitamin C, 45 mg; beta-carotene, 5.4 mg). As there’s no specific RDI for lycopene we used the value for beta-carotene for comparison (lycopene is regarded as a kind of first cousin to beta-carotene).

The results also show how much of the nutrients fresh vegetables can lose during cooking and over a week’s storage.

How we tested

We bought vegetables from three Coles and three Woolworths (Safeway) stores in different suburbs across Melbourne. The fresh vegetables were the best quality available from each store; the frozen and canned vegetables were top-selling brands.

  • Before testing we combined each set of samples of so we’re reporting average values across both supermarket chains for fresh and across all included brands for frozen and canned vegetables.
  • The fresh and frozen vegetables were steamed for 10 minutes and the canned ones heated before testing.
  • Our lab then tested the vegies for the following nutrients: vitamin C, beta-carotene and lycopene (tomatoes only).
  • We tested the fresh vegies both raw and cooked and then retested them a week later. The exception was corn, which we only tested cooked.
 
 

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The graphs below show percentage of the recommended dietary intake (RDI) for adults of important nutrients that our tests found in fresh (raw and cooked), frozen and canned versions of the six vegetables. They also show how much of the nutrients fresh vegetables can lose over a week’s storage. Find out how we tested.

Green beans

Green beans results tableBeans are a good source of vitamin C. Even after cooking, frozen green beans had twice as much vitamin C as fresh beans.

What’s best? (1) frozen; (2) fresh.

Results table key

 

 

Corn

 
Corn results tableFrozen and canned corn had marginally less vitamin C than fresh but the differences aren’t enough to worry about. We measured beta-carotene but the percentages are too small to show.

What’s best? If you want convenience, go for canned or frozen corn.

Results table key

 

 

Carrots

 Carrots results table
Carrots are a good source of beta-carotene. Canned carrots had the most, probably because different varieties are often used for canning (for ‘baby carrots’ or for better texture) and these may, coincidentally, contain more beta-carotene. The fresh, frozen and canned carrots all had much the same levels of vitamin C.

What’s best? Fresh raw and canned carrots contained more beta-carotene than the other types, but for vitamin C there’s little difference between fresh, frozen and canned carrots. You might prefer the flavour and texture of fresh.
Results table key

 

 

Broccoli

Broccoli results table

Broccoli is a good source of vitamin C, but after a week in the fridge it had lost around one third. Frozen broccoli, though, had 92% less vitamin C than fresh.

What’s best? (1) fresh; (2) frozen.

Results table key

 

 

Spinach

 Spinach results table

Spinach (that’s English spinach, as opposed to silver beet) is an excellent source of vitamin C and beta-carotene. Frozen spinach had slightly more of both than cooked fresh spinach. And after a week in the fridge, the ‘fresh’ spinach had lost nearly half of its vitamin C.

What’s best? (1) frozen; (2) fresh.

Results table key

 

Tomatoes

Tomatoes results table

Canned tomatoes have a lot more lycopene than fresh, and only a little less vitamin C than cooked fresh tomatoes. They’re usually canned in tomato juice, which boosts the lycopene content, and the varieties used for canning may have more lycopene than those grown for fresh tomatoes.

What’s best? (1) canned; (2) fresh. Obviously this only applies to cooked tomatoes for pasta sauces, etc — we’re not suggesting you use canned tomatoes in a salad.

Key

03.Frozen and canned facts

 

Freezing and canning

  • Freezing and canning factories are usually close to where the vegetables are grown. This means that the inevitable loss of nutrients during processing is partly offset by the vegies starting off in a fresher state than you can buy them "fresh" from the supermarket.
  • Although canning is definitely not a vitamin C-friendly process, canned vegetables only have to be heated through. So there’s less loss of this nutrient than with fresh or frozen vegetables that take longer to cook.
  • On the downside, canned veg often have salt added. It’s not necessary for processing and is best avoided — so check the label and choose brands without added salt.

In contrast, the fresh veg in your local supermarket may not be as fresh as you might think. Advances in technology have made it possible for growers and distributors to keep vegetables looking good for at least a couple of weeks — but they’re not really fresh. 

Frozen and canned storage

  • Frozen vegies retain most of their nutritional value for up to a year if your freezer is at the right temperature (–18°C) but if it’s not so cold (say –12°C) they lose quality much more rapidly. So check your freezer temperature.
  • When you’re buying frozen veg avoid any that are iced together in clumps (they should be free-flowing), as this means they haven’t been handled correctly during distribution.
  • It’s also a good idea to take your frozen food home in an Esky or cold bag, and get it into the freezer at home as soon as possible. Treat it as you would ice cream.
  • Canned vegetables also gradually lose their vitamins, even when stored under cool conditions; again, they shouldn’t be stored for more than about a year.
  • Unfortunately most canned food isn’t required to have a best-before date so the only way to really keep track is to write the date on the can when you buy it — although you still won’t know how long it was sitting on the shelf before that.

Canned greener than frozen

When you use canned vegetables you use less energy and create fewer greenhouse gas emissions than when you use frozen veg.

  • It takes more energy to make the can than the plastic or cardboard packaging.
  • But frozen foods require more energy for processing and distribution.

Know what to pick

  • Follow the seasons
  • Now that so much is available for most of the year it’s easy to lose track of the seasonality of fresh produce. See Fruit in season.
  • Choose ripe fruit
  • Good colouring with a bright and ‘fresh’ appearance is a good indication of fruit still in good condition.
  • Feel for a tender texture -- gentle pressure between your fingers and palm won’t cause bruising.
  • Smell the stem end for stone fruits and the blossom end for apples, tomatoes and melons. Only buy fruit that has a full, fruity aroma.
  • Take a close look at your veg
  • Green vegetables should be crisp and really green – not shriveled or yellow.
  • With broccoli and lettuce, check there’s no rot at the end of the stem.
  • Avoid carrots whose tips are going brown – and while leaves on carrots look lovely, they’re best cut off because they can dry the carrots out.

It’s best to buy fruit and veg in small lots, once a week or more often, and use them quickly. If you don’t like the look of what’s on offer in the fresh produce section you’re probably better off buying frozen or canned.

Farmers’ markets

While there’s no guarantee, you’re more likely to find really fresh fruit and veg at your local farmers’ market. Farmers often get a better return than from selling through the big supermarket chains, but of course there’s a more limited range of produce available, especially during the winter months.

Visit www.farmersmarkets.org.au to find your nearest market.

How fresh is fresh?

Getting fresh produce from the growers to your local supermarket or green grocer often involves loading and offloading from trucks and transporting over long distances. So what’s available might not be as fresh as you think. For example:

  • Apples can be up to a year old when you buy them.
  • Grapes can have been stored for over two months.
  • Even highly perishable fruit like strawberries might have been picked up to three weeks previously.

Buy in season to improve your chances of getting the freshest fruit.

Apples (best Mar – Aug)

Green applesStorage time before sale: 3 –12 months

Look for
Firm, well-coloured fruit. Check for a full apple aroma by sniffing the non-stem end.

Apricots (best Feb – Mar)

Apricots Storage time before sale: 2 weeks

Look for
Plump and juicy looking fruit with a uniform golden-orange color. Ripe apricots yield to gentle pressure on the skin.

Avocados (best all year round)

Avacado Storage time before sale: 4 weeks

Look for
Unblemished skin. Pick it up and make sure it feels heavy. Ripe ones should be just a little soft when squeezed gently.

Bananas (best all year round)

Banana Storage time before sale: 2 weeks

Look for
Firm, bright, unbruised fruit. For most people, taste is best when the skin is speckled brown. Bananas with green colouring haven’t developed their full flavour, but will continue to ripen.

Cherries (best Dec – Jan)

Cherries Storage time before sale: 4 weeks

Look for
Bright, glossy, plump-looking surfaces, stem should be green.

Grapes (best Dec – Mar)

A bunch of grapes Storage time before sale: 6 weeks

Look for
Well-coloured, plump grapes firmly attached to a green, plump stem. White or green grapes are sweetest when they have a yellowish hue, with a tinge of amber.

Honeydew melon (best Feb – Mar)

Slice of honeydew melon Storage time before sale: 4 weeks

Look for
A soft velvety texture, slight softening at the non-stem end, a faint fruity aroma and a yellowish-white to creamy rind colour.

Kiwifruit (best Mar – Jun)

Kiwifruit Storage time before sale: 3-9 months

Look for
Plump, unwrinkled fruit, either firm or slightly yielding. It’s ripe when it gives to the touch but isn’t soft. A ‘water-stained’ exterior doesn’t affect taste. Skin is edible.

Lemons (best Jun – Jul)

Lemons Storage time before sale: 4 weeks

Look for
Green, healthy calyx (where the blossom was attached). Heavy, firm fruit with a rich yellow colour and reasonably smooth skin with a slight gloss. Pale or greenish-yellow lemons are very fresh with slightly higher acidity. Course skin means not much juice.

Mandarins (best May – Oct)

Half peeled mandarin Storage time before sale: 4 weeks

Look for
Deep yellow or orange colour and a bright lustre.

Mangoes (best Dec – Feb)

Two mangoes Storage time before sale: 2 weeks

Look for
Plump with smooth skin that has at least begun to turn from green to orange/yellow or red, and a slight softness. Look for round ‘shoulders’ at the stem end, especially early in the season.

Nectarines (best Nov – Mar)

Nectarine Storage time before sale: 2-3 weeks

Look for
Rich colour and plumpness, and a slight softening along the ‘seam’. Some varieties are orange-yellow between the red areas, others are greenish. Hard, tan stains on the skin don’t affect taste.

Oranges (best all year round)

Orange Storage time before sale: 6 weeks

Look for
Firm, heavy fruit with fresh, bright-looking skin that’s smooth for the variety. Healthy, green calyx. There are two main varieties – navels (best May to October) and Valencias (best November to April). Navels tend to be sweeter and better eating.

Peaches (best Dec – Feb)

A peach Storage time before sale: 2-3 weeks

Look for
Fairly firm or a little soft. The skin between the red areas should be yellow, or at least creamy. The amount of red blush doesn’t indicate ripeness.

Pear (best Mar – Jun)

Brown style pear Storage time before sale: 2-9 months

Look for
Fruit that has begun to soften (that increases the odds that it will ripen properly).

Pineapples (best Dec)

A pineapple Storage time before sale: 3 weeks

Look for
Bright yellow-orange colour, fragrant pineapple aroma, and a very slight separation of the eyes (berry-like fruitlets that run in a spiral pattern on the skin).

Plums (best Feb – Mar)

Three plums Storage time before sale: 2-6 weeks

Look for
Plump fruit that's fairly firm to slightly soft and smells like a plum.

Rockmelon (best Feb – Mar)

Half a rockmelon Storage time before sale: 2 weeks

Look for
Ripe rockmelon has a yellowish rind, a fruity smell, and yields slightly to light thumb pressure on the non-stem end. Melons with bits of attached stem were harvested too early. Small bruises don’t normally damage the fruit.

Strawberries (best Dec – Mar)

A strawberry Storage time before sale: 2 weeks

Look for
Full red colour and bright luster, firm flesh, the stem still attached and a strong aroma. Medium to small strawberries usually taste better than larger ones. Variety is not often displayed. Camarosas are specially good.

Watermelon (best Feb)

Wedge of watermelon Storage time before sale: 3 weeks

Look for
Firm, juicy flesh with a good red colour and dark brown or black seeds (immature melons have whitish seeds). With uncut watermelon, look for a smooth, slightly dull surface. The ends should be filled-out and rounded and the underside that rests on the ground should have a creamy colour.

Table notes

The table shows when you can expect different fruit to be at its best. The dates are only an approximate guide because they'll vary from year to year depending on weather conditions. And with fruits like apples, for example, there are differences between varieties.

The storage time shows the maximum length of time for which fruit can be stored under controlled conditions. They're not necessarily stored for this long.