Frozen and tinned vegetables: are they as good, and how to cook them well

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Fresh vegetables have a healthy reputation, while frozen and tinned ones are sometimes treated as second best. For anyone cooking on a budget that is a pity, because frozen and tinned vegetables are often cheaper, last far longer and cut waste dramatically. The question is whether they are as good for you, and how to cook them so they taste good too.

Do they count?

Yes. The NHS says that fresh, frozen and tinned fruit and vegetables all count towards your 5 A Day, with a portion for adults being 80 grams. For tinned vegetables, it advises choosing those in water without added salt or sugar. Beans and pulses count, but only once a day however much you eat. Potatoes do not count, because they are classed as a starchy food.

How do they compare nutritionally?

Vegetables for freezing are generally frozen soon after harvest, which helps hold on to nutrients. Fresh vegetables, by contrast, may spend days in transport, on the shelf and in your fridge, losing some vitamins along the way. Tinning involves heat, which reduces some heat-sensitive vitamins, but tinned vegetables still provide fibre and many nutrients. The honest answer is that it depends on the vegetable, how it was stored and how you cook it. For practical purposes, the best vegetable is the one you will actually eat. A bag of frozen peas used over a month beats a fresh bunch of broccoli that turns yellow in the fridge.

What to look for when buying

Frozen: plain vegetables with no sauce or seasoning give you the most control. Check the bag for ice crystals or clumps that suggest the pack has partly thawed and refrozen.
Tinned: look for tins in water and labelled no added salt or reduced salt. Avoid tins that are badly dented, especially along the seams, bulging or leaking.
Mixed bags of frozen vegetables, stir-fry mixes and soup mixes are a cheap way to add variety.

Cooking frozen vegetables well

Most frozen vegetables have been blanched before freezing, so they need less cooking than raw ones. Overcooking is the main reason they turn soggy.

Cook from frozen unless the pack says otherwise. Thawing first usually makes them watery.
Roast at a high heat. Spread frozen broccoli, cauliflower or green beans on a hot tray with a little oil and salt and roast until the edges brown. Do not crowd the tray, or they steam.
Stir-fry in a very hot pan in small batches, adding sauce at the end.
Stir peas, spinach and sweetcorn into dishes at the last few minutes: pasta, rice, soups, curries and omelettes.
Steam or microwave briefly with a splash of water rather than boiling in lots of water, which leaches out some nutrients.
Follow the pack instructions, especially for frozen vegetables you plan to eat without cooking. Some frozen vegetables are meant to be cooked before eating.

Cooking tinned vegetables well

Tinned vegetables are already cooked, so the aim is to warm them and add flavour.

Drain and rinse to reduce salt and the tinny taste.
Add them late. Tinned carrots, green beans or sweetcorn only need heating through.
Fry tinned potatoes or sweetcorn in a hot pan until golden for a different texture.
Tinned tomatoes are a cupboard essential: the base of sauces, soups, stews and curries. Cooking them for a while with onion and garlic sweetens them.
Season boldly. Lemon juice, garlic, chilli, herbs, butter or a little cheese make a large difference.

Storing them safely

Keep frozen vegetables frozen and reseal opened bags tightly to avoid freezer burn.
Once a tin is opened, transfer any leftovers to a covered container in the fridge rather than leaving them in the open tin, and use them within the time given on the label.
Check best-before dates. Tinned and frozen foods are usually labelled with a best-before date, which is about quality rather than safety. A tin past its best-before date is not necessarily unsafe if it is undamaged, but quality may decline.

A simple weekly approach

Keep two or three frozen vegetable bags and a few tins in stock at all times.
Buy fresh vegetables for the first half of the week.
Switch to frozen and tinned for the second half, when fresh ones would be wilting.

Do you have a favourite way to cook frozen or tinned vegetables? Share your tips or questions in the comments.