Reporter: Hellen Wellings
Microwave cooking was discovered way back in 1945, but today there are still serious fears of their safety in our kitchens that powerful microwaves zapping vegetables, meats and liquids are harmful, even potentially deadly.
More than 90% of Australian homes now have a microwave oven. So what are the risks? Tonight; the latest evidence on their safety and the final word on what microwaves actually DO to the nutrients in our foods. Also, with energy bills set to double, how costly are microwave ovens to run compared with conventional oven ranges?
Electrical Engineer John Lincoln says old ovens like this 20 year old can develop loose seals, leaking the high frequency microwave radiation that cooks our food.
"This indicates to me that this oven is leaking very badly. The modern microwave has much better seals, contains the microwaves within the oven, as you can see we are not getting anything registered on our meter."
"Microwave ovens are constructed with a solidly built door and a mesh guard to prevent any energy coming out and to focus it all on the food" says Dr Peter Osman, co-author of the CSIRO's Home Energy Saving Handbook. He is adamant - microwave ovens will not harm us, or our food.
"They have a device in them called a magnetron and that is rather like an old-fashioned radio valve that makes radio waves at a very very high frequency and that's electrical energy it is not ionizing radiation, it's not dangerous at all."
Any cooking will destroy some nutrients in food, but it depends on the type of cooking, how much water's used, how long it's cooked and at what temperature.
"The water will dilute the vitamins, the vitamins will get thrown away when you throw the water away, if you overheat or cook for too long it will destroy the vitamins" tells Dr Osman.
We compared the effect on vitamins and minerals in vegetables between steaming, boiling and microwaving. Broccoli, raw, 34% is vitamin C, but boiling destroyed 11%, steaming 8%, microwaved comes out best, only 7% lost. What happened to the key antioxidants in broccoli? Steaming no effect on some but 11% destroyed for one, boiling killed off 66%, microwaving .. worst, destroyed 94% of the antioxidants.
Carrots containing 4.5% beta carotene are best eaten raw because steaming loses 2%, boiling and microwaving loses 2 and a half percent. Spinach, rich in folate, retains almost all of it cooked in a microwave oven, but boiled on a stove
loses almost 80% of the nutrients. So generally, vegies keep most nutrients when steamed, some when microwaved, and most when boiled. An overseas
study showed microwaved bacon has much lower levels of cancer-causing nitrosamines than stove-cooked bacon.
Cooking accounts for 6% to 10% of total household energy consumption, but if using a microwave oven for meals will slash your yearly cooking bill to one third of the cost of running a conventional oven and stove.
COMPACT microwaves cost from $110 to $240, good for reheating, defrosting, simple cooking. MEDIUM, $180 to $300 also bake and have sensor programs to control the cooking time and power level. COMBINATION ovens with convection mode and grill, $720 to $3000,
"Electric ovens waste a huge amount of energy compared to a microwave oven, 3 to 4 times as much" says Dr Osman.
Operating costs - running ovens at full power for an hour - conventional electric oven 50 cents, microwave 30 cents, gas 13 cents. Cooking a chicken in an electric oven takes 47 minutes costs around 35 cents, gas 47 minutes, 9 cents, microwave 22 minutes 10 cents.
BOOK: The CSIRO Home Energy Saving Handbook: How to Save Energy, Save Money and Reduce Your Carbon Footprint. by john Wright, Peter Osmen and Peta Ashworth. Pan Macmillan Australia, 1 Market Street, Sydney 2000. First published 2009.