Health and Fitness Tips

Is There Any Health Benefit In Eating Frozen Food Rather Than Tinned?

frozen foodFrozen food has long had a reputation for being inferior to fresh, on a par with canned. But this is now largely undeserved. Frozen fish is a good example of how freezing has come a long way.

Back in the Seventies and early Eighties, when we weren’t so picky or knowledgeable, frozen fish consisted mainly of fish fingers made from the tail ends of poor quality fish, and freezing techniques meant they were often mushy when defrosted.

But freezing technology has improved vastly since then – today fish is frozen within minutes of being caught out at sea.

It’s cleaned and popped into the freezer and transported in this frozen state, so that when you defrost it, it is almost as good as it would have been had you eaten it straight from the net.

If the food is properly cleaned and wrapped – to prevent ice crystals coming into contact with it, causing freezer burn – freezing is rather like suspending the food in a nutritional time-warp.

This means levels of nutrients such as vitamin C in fruits and vegetables, which were at their highest when picked, stay virtually the same.

Then if you defrost the food properly and cook it minimally, such as in a stir-fry or steaming, the vitamin C levels (and those of other water-soluble vitamins such as B vitamins) can be higher even than in some fresh produce.

As there isn’t any legal definition over the use of the word ‘fresh’, the fruit or vegetable on the supermarket shelf could have been picked a long time previously.

Some apples and pears have been picked up to five months before we buy them, so
the time and heat-sensitive vitamins, as well as the water-soluble ones, could be lower than in the frozen version.

Freezing can affect the cell structure of fruits and vegetables (the water expands as it freezes and can damage the cell walls of the plant); as a result, vegetables with a higher water content, such as broccoli and courgettes, can be mushy when you eat them. So texture-wise, freezing can affect food, but not as much as canning.

Canning is an old preservation technique that involves heating food to high temperatures in the tin to make it safe enough to eat (the heat destroys any bacteria that might spoil the food).

So whether it’s canned fruit, fish or vegetables, it’s all been cooked in the can – this is what alters the texture so much.

As well as texture, there are other downsides to canning. With some canned food, manufacturers use brine – salt water – or vinegar to ensure that bugs don’t grow in the tin – this can lead to high levels of salt in your diet, which can have negative effects on blood pressure. Some of the nutrients will also be lost in the cooking process.

Other foods may be canned in oil, to help make them palatable. This isn’t necessarily a bad thing; tuna in oil, for instance, can provide a useful healthy type of unsaturated vegetable fat.

It’s also cheaper and more convenient to use canned fish such as salmon, mackerel and sardines if that’s the only way of getting them in your diet. But if you’re trying to reduce your fat intake, watch out for canned foods.

Sometimes vitamin C is added to canned food once it’s been processed, which can help make up for the loss of vitamins in the heating process.

Look for the words E300 or ascorbic acid on the label of canned fruits – this is just as good as the naturally occurring vitamin C from fresh food.

But make sure you rinse vegetables to get rid of any salt, and, in the case of fruit, try to buy it canned in water or no-added-sugar juices, rather than syrups, which can make the sugar content high.

To sum up, I would opt for frozen food over canned, but there’s always exceptions – I love baked beans on toast, so make sure there are always a couple of tins in my cupboard.

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Filed under: Diet, Health, Nutritions
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