`Freezing the freshness in'
Freezing is one of the most commonly used methods and its big advantage is that it gives the consumer a year-round availability of what might be a short-season crop. In general, after cooking, most frozen food has the same nutritional value as the identical cooked product using fresh produce. Vegetables are harvested while vitamin C levels are still high and the delay incurred between harvesting and blanching is so short that there are negligible changes in nutritional quality.
A recent report from Britain (the Chipping Campden Report), evaluated fresh versus canned versus frozen peas and came up with some interesting results. For example, it was found that frozen peas do not lose protein, fat, fibre or iron through processing, storage or final cooking. Canned peas are produced from less tender peas and naturally have a slightly higher protein and fibre content. Processing had no effect on zinc levels, but both frozen and canned storage reduced these by about 25%. As regards calcium, cooked frozen peas have a higher level than cooked fresh ones, but they have only about half as much potassium - although this is not a cause for concern since potassium is present in many foods and a deficiency of it is very rare.
What about the all-important vitamin C? Cooked frozen peas have a slightly lower content than cooked, freshly picked ones, but more than cooked, fresh 7-day-old peas. The report concluded that the vitamin C level of cooked frozen peas was about equivalent to cooked fresh 3- to 4-day-old peas, probably about the age they would be if you bought them from your local supermarket for supper the next day. In other words, you can assume that frozen peas are not only convenient but nutritionally as worthwhile as the fresh variety - if somewhat more expensive. If we apply roughly the same results to most frozen vegetables, we can see straight away that they do provide us with a very good out-of-season option.
What's in a can?
Itis probably because frozen fruit and vegetables are raw and canned produce is cooked during the canning process that you may be more likely to regard the former as 'fresh' and the latter as 'processed'. Yet it is interesting that the nutritional value of freshly cooked produce differs very little from the canned variety. This is mainly because with canning, although the cooking period may be a little longer than for home-cooked vegetables, the fact that all air is excluded carries enormous nutritional advantage over our domestic cooking pots. By heating, which destroys any micro-organisms, and excluding air, food is preserved without additives. Apart from the fact that you may simply prefer the taste of fresh vegetables, the only disadvantage of the canned variety is that you don't have any say over the amount of salt and/or sugar added in the canning process.
Fresh from the sea
Fish is another popular frozen food and for many city and country dwellers who fancy something marine on the menu the frozen variety is really the only practical choice. Those who live near fishing ports and harbours (or have keen fisherfolk in the family) are lucky indeed as they will have the chance to enjoy that almost sweet, seaweedy flavour that is the hallmark of truly fresh fish. For the rest of us, frozen fish from one of the big producers is a very acceptable alternative. The fish is caught out at sea and either frozen almost instantly on the fishing vessel itself, or else packed on ice and frozen as soon as it is landed. In this way, optimum nutritional content is maintained and flavour impairment kept to a minimum.
If you are lucky enough to buy fresh fish, check whether it really is fresh, or has been shipped in a frozen state and then defrosted to be laid out on a slab in the supermarket. There's no major difference if you are going to eat it straight away, but if you intend to refreeze it for later use, you would do better to buy commercially frozen fish instead. Not only will the flavour and texture be better, but you will avoid the risk of deterioration attached to freezing, thawing and then refreezingfood.
As with vegetables, most of us would probably like to buy our fish fresh but if you have to settle for frozen, as a bonus you'll be getting consistently high quality. In the case of fresh fish, quality may be erratic, all the more so the further away you are from the maindistribution centres.