Microwave-Rendered Chicken Fat

The microwave oven is a wonder. It can warm up leftovers in minutes; it can make packaged ramen in about the same time; it can turn your vegetable scraps into powder; it can toast nuts; it can fry shallots, garlic; it can boil water; it can defrost things unevenly; it can even warm up your cup of tepid coffee. It is, as someone, somewhere, must say about amazing kitchen gadgets, peak culinary technology.

You might look at that list and think, "What can't a microwave oven do?" Can it make a soufflé? Yes. Can it cook foie gras? Yes! (There's a recipe in a cookbook by the Joe Beef chefs, if you'd like to give it a try.) But there's another application for the microwave oven that's seldom talked about, often ignored, and/or grievously mocked by people like my colleague Sasha, who has for months been saying to me, "Why do you want to do this? Who is it for? Please stop getting the microwave dirty."

Yes, readers, the microwave oven can render the fat from the skins of chickens. And it renders the fat from the skins of chickens very, very well. "What?" I hear you gasp. "Who says?" I hear a few of you mutter. To which I say, "Yes!" and "Real scientists!"

A 2002 study by K.S. Sheu and T.C. Chen, published in The Journal of Food Engineering, compared different methods of rendering chicken fat from chicken skin—boiling, griddling, deep-frying, using an oven, and using a microwave oven—and found that the microwave produced the lightest colored fat, indicative of a lack of oxidization and browning, and the highest yield. In 2013, Liyan Zhang, Bi Yin, and Hanming Rui expanded upon the findings of the 2002 study when they published a study of their own in The Journal of Food Science and Technology, in which they assessed the efficacy of various microwave power levels in rendering fat from chicken skin, and they agreed with the previous study's findings that a microwave is a very efficient rendering-fat-from-chicken-skin device, indeed.

Who Is Microwaving Chicken Skins? (Me.)

I first came across this second study because it was being passed around in the homemade ramen community. Mike Satinover, a homemade ramen enthusiast/quondam ramen chef, posted something about the study on his Instagram, although apparently the research was surfaced by members of a now-defunct Discord server that was run by Ryan Esaki, the man behind the popular The Way of Ramen Youtube channel. (Got all that? Good.) An aromatic liquid fat is an integral component of any bowl of ramen, so it figures that this specific subject would merit investigation for the community.

The method Satinover posted called for nuking chicken skins on high for about eight minutes, which basically tracks with the findings in the second study. The day after I saw it, as I butchered my weekly chicken, I set aside the breast skin and some of the fat from the cavity, cut it all up into rough, one-inch strips, stuck those in a little microwave-safe bowl, and let the machine rip. Eight minutes later and I had a little microwave-safe bowl's worth of chicken fat, with a mini gribenes iceberg floating in the middle of it. Success!

Well, in a sense. Some of the chicken skin cooked (microwaved?) a little faster than the rest and burned, which imparted a small burnt note to the aroma and flavor of the fat, and the interior of my microwave was also a steamy, greasy mess. But the fat was otherwise golden, if a little dark, and seemingly water-free, and it didn't require straining as the process didn't create any errant debris, so I decided to play around with the method, microwaving the breast skins from the chickens I take apart every week, along with any skin and fat I usually would save for the stock pot. Each time, I altered the process a bit, cutting up the chicken skins in different ways, using different quantities of chicken skin, using containers of different sizes and materials and shapes.

And then, about nine weeks in, the chicken skins broke my microwave.

A Flickering Light, an Ominous Sound

Now, I don't know that it was actually the chicken skins that broke my microwave, or whether my microwave just broke on its own, but it was definitely while microwaving a small amount of chicken skins that my microwave broke. About three minutes into rendering the fat from the breast skin of my chicken, my microwave started buzzing and the interior lights started flashing, and it was clear something was wrong. Not one to be cowed by a bit of dumb machinery, I didn't shut it off; I just watched it warily from the other side of my kitchen, which, in New York City, means two feet away. After enduring its constant buzzing and interior-light-flashing for an eternal four seconds more, I admitted to myself I am one to be cowed by a bit of dumb machinery freaking out two feet in front of me, and I shut it off.

But the microwave wasn't really broken, at least not yet. I still used it to warm up coffee and I could use it to steam frozen peas; it just really didn't like it when I tried to use it for chicken fat rendering. So, over the next several weeks, I continued to try microwaving chicken skins in containers of different sizes and materials, cutting up the chicken skin in various ways, from roughly hacked strips to a very fine mince, before sticking it into the microwave. I also tried iterations of each trial with a little ramekin filled with water placed alongside the chicken skin receptacle. In the water-less trials, my microwave would eventually begin bleating and blinking no matter what, although the finer the chicken skin was cut, the longer the machine would go before the bleating and blinking began. The trials with the ramekin filled with water produced none of the bleating and blinking, but I ended up having to extend them for twice as long (or longer, depending on the volume of water) in order to render all the fat from the chicken skin.

After all these trials, one morning my wife tried to warm up some leftovers, and when it started bleating and blinking she told me the chicken-skin thing had to stop. And we needed a new microwave.

Troubleshooting Microwaved Chicken Fat Troubles

While I waited for my new microwave to arrive in the mail, I considered what could have possibly gone wrong. Scientists had completed whole studies showing the microwave renders fat from chicken skins quite well; they made no mention of bleating, blinking, or any other adverse effects to their microwave devices. I polled my followers on Instagram to see if they had tried this method and if anything had gone awry, and no one reported anything out of the ordinary (although a few complained about the greasy splatter the process makes). In order to receive some affirmation that I'm not incompetent, I did what everyone else does and searched Google for similar experiences, and found a couple of comments on recipes for rendering schmaltz in the microwave that reported that the container in which the skins were being microwaved became very hot, which tracked with my trials. (Granted, there's one report of a fire.) At a loss, I decided to contact someone who knows something about microwaves.

About a year ago, Chris Young, the chef, co-author of Modernist Cuisine, co-founder of ChefSteps, and now founder of Combustion, Inc., wrote an edifying Twitter thread on microwaves and bacon. I reached out to Young and described my dilemma, and he quickly pinpointed the small quantity of chicken skin, as well as the way in which I'd been cutting it up, as a potential issue. "The basic issue is your food is an antenna in a microwave," Young wrote, "and for smaller amounts, it’s acting as a bad antenna. Your microwave senses how much energy is being reflected or absorbed, and if the quantity of skin is too small, it doesn’t absorb microwave energy, and instead that energy is reflected around the cavity of the microwave and eventually shuts the magnetron off."

The bleating and the flashing of lights, then, was just my microwave telling me, its hapless owner, that he has, once again, turned on the microwave without putting anything inside. I hopped on the phone with Young and after a few pointed questions, he noted that while the study used 250g of chicken skin that was frozen, run through a grinder, and then microwaved, I was microwaving about 35g of fresh chicken skin that had been haphazardly hacked up. Young noted that both the freezing and grinding of the chicken skin would release a fair amount of water by ripping open the cells in the skin, and consequently "the extra wetness helps [the ground up chicken skin] absorb the microwave energy, making it a better antenna."

Young had a straightforward suggestion: Save up chicken skin in the freezer until I had about 250g worth, and then run it through a meat grinder before putting it in a microwave. Which was all well and good, and sounded perfectly reasonable to me, but I didn't think my betters here at Serious Eats would think it reasonable for our readers. I had had hopes of producing a foolproof method for any quantity of chicken skin you might have on hand, whether it's skin scraps from cutting up a single chicken or a wad of frozen skin scraps collected from many, many chickens.

When I said this to Young, he suggested an even more reasonable solution: Just lower the power setting on my microwave. He noted that the power setting on most microwaves, rather than literally adjusting their power output, simply cycles the machine's magnetron on and off. For the chicken skin, which apparently was absorbing some but not all of the energy emitted by my microwave, turning down the power setting would allow more time for absorbed energy to diffuse and evenly heat the chicken skin to render out the fat.

Patience Is a Virtue

When my new microwave arrived, I once again began microwaving the chicken skin scraps from my weekly chicken, but this time using a power setting of "3," which roughly translates to about 30% of full power. And I found, no matter what I did with the chicken skin, whether I cut it up quite finely, or ground it up, or cut it into one-inch-long strips, the lower power setting rendered fat quite efficiently. And while it it took about 25 minutes to fully render the fat from the skin, I found I didn't have to watch the process at all and I have yet to once experience anything like the burning that sometimes occurred during the full-power trials. (The time of about 25 minutes held true, too, for the microwave in our test kitchen, which is more powerful than the 700W one in my home.)

There was another unexpected benefit: Using a lower power setting made far less of a mess, no matter what Sasha had to say about the negligible amount of condensation the process produced in the work microwave oven; there's far less sputtering, which means you don't have to use a cover for the bowl you're microwaving the skin in. For cleanup, all you need to do is give the interior of your microwave a wipe-down to get rid of a little condensation. (And, of course, you need to clean up the bowl.)

However, for the absolute best results, and most efficient fat rendering, and if you'd like to really enjoy snacking on the crispy float of gribenes this method can produce, I highly recommend grinding or mincing the chicken skin as finely as you can. It is much easier to do this when the skin is cold, and, since freezing ruptures cell walls, it doesn't hurt to freeze your chicken skin first. But given that that's a lot of preparation for rendering chicken fat, I can also assure you that if you do a haphazard job of cutting up a little bit of chicken skin and throw it in a microwave-safe container, set the power setting to 30%, and microwave it for 20-25 minutes, you produce a small quantity of beautifully golden chicken fat.

If you are absolutely intent on eating that float of crackling but don't want to go through the effort of mincing or freezing or grinding, just stop the process about halfway through and flip the little gribenes iceberg over in the pooled fat, otherwise the top will be soft and leathery instead of crisp. (You also may need to zap it for a little longer.) Needless to say, this is essentially a deep-fried edible thing, so it must be salted immediately after you remove it from the fat, if you plan on eating it. (Eat it with pickles, and/or kimchi: it's a really good combination.)

So now that you have a bunch of liquid chicken fat, what do you do with it? (Or, as Sasha puts it so poetically, "Who wants this?") Well, you can use it for ramen, of course, which is where this all started. But chicken fat, like any other oil, can be used where most any other oil can. Use it for making fried rice, brown potatoes in it, warm it up and use it in a vinaigrette, or, I don't know, fry some chicken cutlets in it—it's not quite as good as cutlets fried in clarified butter, but it's quite good. If you amass enough (it keeps quite well in the fridge, but keeps indefinitely in the freezer), you could even make a confit.

Like a microwave, there isn't much you can't do with it.