Help me adapt Barbara Kafka's microwave risotto recipe to my new oven.

April 11, 2010 3:46 PM

Help me adapt Barbara Kafka's microwave risotto recipe to my new oven. Her timings are for 650-700 watts. My new Sharp R-305KS is nominally 1100 watts, but testing shows it's actually 900 watts. That's still too much power for Kafka's timings. Have you adapted the recipe for this oven, or are you so incredibly bright that you can transpose? (Remember, there is no straight-line relationship between microwave power and times, so please don't tell me to multiply by .636. Even I'm smart enough to do that, but it doesn't work.)
posted by markcmyers to Food & Drink (7 answers total)

Is there a high, medium, low setting on the microwave? And does the manual give an indication of how much the power is cut for each? When I cook in other people's microwaves (motels and stuff) I always use the medium or medium-low setting as it's closer to the old 600 watt microwave I have at home so behaves how I expect. Means things take longer but I don't overheat them. If you can figure out which setting on yours gives closer to 650-700 watts (or at least behaves similarly) then you can just use that setting and follow her instructions as is.
posted by shelleycat at 3:57 PM on April 11, 2010

cooking is very rarely about high-tolerance precision...set at 75% power and check it regularly...
posted by sexyrobot at 3:59 PM on April 11, 2010

Don't get too mad that I'm not answering the question, but I think the best easy risotto is Sam the Cooking Guy's Baked Risotto
posted by wrnealis at 4:41 PM on April 11, 2010

Is this it? From Barbara Kafka's site:

This is a simpler version of the dish in my book, Microwave Gourmet, and it is adapted to today’s more powerful ovens. In the spring, use the wonderful peas. In other seasons, use edamame which can be pought peeled and refrigerated or frozen. The recipe was tested in one of the newer, more powerful 1,200-watt ovens.

posted by geoff. at 5:55 PM on April 11, 2010

maybe you could try to figure out a reference? so see if she says how long it will take to boil water, then do it yourself to come up with some kind of time ratio?
posted by refractal at 7:03 PM on April 11, 2010

maybe you could try to figure out a reference? so see if she says how long it will take to boil water, then do it yourself to come up with some kind of time ratio?

Water has a specific heat capacity of 4.1813 J/(g·K) so to heat 1 litre of water from 25 degrees centigrade to 100 degrees centigrade would require 4.1813 *1000 * 75 = 313 597.5 joules of energy. A watt is a joule per second, so a 1100 watt microwave would take 4.75 minutes to perform that operation; a 900 watt microwave would take 5.80 minutes; and a 700 watt microwave would take 7.46 minutes.

In other words, using that calculation would imply a scaling ratio of 5.81/7.46=0.78 (for 900 watts) or 4.75/7.46=0.637 (for 1100 watts) - which markcmyers reports doesn't work.

It is sometimes the case in cooking that you are not just trying to raise something to a given temperature, but to raise it to that temperature slowly, or quickly, or to give water time to absorb, or to heat the outsides only, and so on. Therefore, scaling might work for reheating things that are already cooked, but it won't always produce good results for more complicated cooking processes.
posted by Mike1024 at 12:53 AM on April 12, 2010

Newer microwaves (usually with "Inverter" branding) on fractional power really do turn the power down, but older microwaves just turn it on and off once every few seconds. So for 75%, you might be getting 12s on and 4s off, which is not quite the same as running at 75% because the heat will fluctuate in hotspots and not diffuse quite so quickly to the cooler spots. But it ought to be pretty close and it's a much better solution than scaling the cooking time.
posted by polyglot at 5:13 AM on April 12, 2010