Tuesday 30 January 2001

Pic of the day: Cryopreservation? OK, in a way perhaps ...

Preservatives

I got a leaflet in my physical mailbox. Normally I throw away those that are not adressed, but this was from a large producer of juice and jam. Good things all. I did however frown at the prominent promise of NO PRESERVATIVES ADDED!

They say that as if it were a good thing. But in ages gone by, people ate food without preservatives, and where are they now? Dead all of them. OK, that may not be the only reason, but there are other reasons why you may want a few preservatives in your food. They may indeed preserve not only the food, but your body too!

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I certainly don't applaud the use of preservatives in food as an alternative to first-class raw materials, good hygiene and solid packaging. And some foods, like canned goods, don't need preservatives, as they're supposed to be absolutely free of bacteria and with no influx of oxygen either. But there are many places where preservatives are good and proper.

Basically preservatives fill two different functions. One is to kill off bacteria, fungi or whatever organisms may want to break down the food before we do. A good example of this is salt. Salt is a good thing, according to very reliable sources. For thousands of years, salting has been used to conserve food. It drains fluid from the food, helping to dry it out. (Drying food is also a familiar way of making it last.) But more, it dries out cells, such as bacteria, that try to live in the food. (There are actually salt-loving bacteria around, but they don't eat our food.)

Salt, smoke and some spices kill off bacteria, but are not particularly healthy to us either. Normal humans can handle a fair amount of salt, simply by drinking enough water, but if you suffer from hypertension you should avoid it. But through most of human history, bacteria in food have been more of a danger than too much salt or smoke. To this very day, harmful bacteria in food incur a great loss of productivity even in advanced nations like ours. Many a sick day is due to more or less serious food poisoning.

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The really fascinating preservatives however is another group: Antioxidants. Oxygen, so useful to living things, is also a highly reactive material that happily binds to complex molecules and changes them. Dead food is basically helpless against this onslaught. Like rust on iron, food also changes into an inferior form if exposed to oxygen, even when bacteria somehow are kept off. The molecules that give food its aroma and taste are oxidized, and soon enough the color also changes, often to an unappetizing gray.

Some of the more commonly used additives used to preserve food are actually vitamin C, vitamin E and betacarotene, a precursor to vitamin A. These fill similar roles in our own body, and are heartily welcome in moderate quantities. The quantities used in food present no health risk, and the body is able to get rid of the excess.

Studies only show a moderate connection between intake of antioxidants and longevity, but the connection seems to be positive. And it is worth noticing that the researchers in this field are using more of the stuff than the government-recommended daily intake. (Which is more like a minimum.) You can certainly get too much of the stuff, but not by eating normal food with added preservatives.

Other preservatives are natural. Several berries (cranberries, cloudberries, and not least rowan berries if I remember correctly) contain natural preservatives. This has been used by farmers for a long time. (Don't try this at home if you're clueless on berries. The rowans in particular may be confused with poisonous trees if you're too urban.) Pectin, found in many unripe fruits, is also a preservative. (But a little eager to speed on digestion, as some of us may have noticed.) I guess these natural preservatives may be enough for some of the juices and jams that this supplier offers me; but I for one would not mind a little extra antioxidants, if the price is right.

(Now, artificial sweeteners is another chapter and worse entirely.)