So what do you think of irradiation of food? The FDA has just extended the allowed use of irradiation to produce such as lettuce and spinach.

Do you actually know what irradiation of food is?

Everything is naturally exposed to radiation, it comes from space and from the earth. Think of a radioactive substance as something (a source) that sends out (emits) high energy. Different sources send out different amounts of energy. Importantly, this energy can be felt (detected) without touching the radioactive source.

When food is is irradiated it does NOT come in contact with the radioactive source. It placed close too, but not against a source. It gets a dose of short really high energy that may be bad or good (see below) but it does NOT make the food radioactive.

The food being radioactive is used as a scare tactic, the real pros and cons are elsewhere. As always the answer is not totally black and white.

The blast of high levels of ionizing radiation from a radioactive source can slow the ripening of fruits and damage the DNA of microbes so that are unable to divide and grow in foods. UV light also affects DNA and can be used to sterilize things. Radiation is more effective since it can penetrate into things.

Probably the most widespread use of irradiation is for sterilization of health items, particularly for use in hospitals.

Low doses of radiation are used to delay ripening of some fruits and slow the sprouting of some tubers such as potato and bulbs. Higher doses are used to decrease the level of viable microbes so that shelf life is extended. Even higher doses are used to effectively sterilize products so that they can be stored at room temperature for extended periods of time.

Exposing anything to high doses of ionizing energy sources will cause changes in cells including damaging DNA. The main aim for irradiation when being used to stop the growth of microbes, is to cause sufficient damage to the DNA of the microbes that they can no longer grow and divide. (Of course there will some effect on the DNA of the cells of fruit or Vegetable. However, the fruit or vegetable has been harvested, is now dying and so few if any cells will be dividing.) This damage to the DNA of the microbes either slows the rate of, or stops, food spoiling.

It has been legal to irradiate many products for years. Irradiation of spices and herbs controls both any insects and bacteria present. Irradiation of fruit will both control any pests on the fruit and slow the ripening. For instance strawberries will be easier to transport, can be transported further and will not rot in your fridge so quickly. Hamburger patties can be irradiated to reduce the risk of food poisoning from virulent E. coli. The recent addition of spinach and lettuce, makes sense, they are hard to wash effectively and can be accidentally contaminated, while being grown, with run off containing animal waste.

However though there are a wide range of foods that can be irradiated, due to consumer concerns, only a small proportion of the eligible food is irradiated.

So the pros are fruit that will ripen slower, an extended shelf life for foods and a reduction in the likelihood of getting food poisoning.

The cons are a bit less well defined.

What exactly is the effect of the blast of ionizing radiation on food? The radiation and any heat generated will affect the proteins, fats, DNA etc of the cells. Are any of these effects negative? Is the nutritional quality of the food affected? Some people suggest that there may be toxic byproducts. Though there does not seem to any firm idea of what these toxic byproducts might be. Of course it is possible that in some cases the nutritional quality could be improved (like exposing tomatoes to heat makes more lycopene available).

The effect on food is complicated by the fact that there is a wide range of strength of irradiation of food. So there is going to be a range of effects. In a photo credit: Mike Licht, NotionsCapital.com

[tags]irradiation food, DNA, ripening, vitamin K[/tags]