02.What we found
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
Beans 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.
Corn
Frozen 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.
Carrots
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.
Broccoli
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.
Spinach
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.
Tomatoes
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.
