Not a bento post, but this is something I’ve always wanted to post on my blog.
“Oil hardening” products are very common in Japan. A couple different companies make them, but they’re pretty much the same thing.
You put the oil hardening powder into hot oil, leave it until it cools down, and voila! Oil becomes solid so you can throw it away as regular trash!
The powder is made with natural vegetable oil so it’s very environment friendly.
When I came to the U.S. 15 years ago, I didn’t think the “oil hardener” was anything special. Whenever I had a large amount of oil to discard, I always looked for an oil hardener in a supermarket in the U.S. but I could never find one. So I looked for it online, but came up with nothing except the Japanese one I’m talking about. I was asking my boyfriend if he’s heard of something like that in the U.S., but he couldn’t think of one either. So I showed it to him one day, and he thought it was really cool.
I had a large amount of rather old oil (I’ve been using it for frying croquettes), so I decided to take pictures of how this Japanese oil hardener works.
The one I used is called "Yukko" by a company called Lion. It's about $5.50 and comes with 5 packets of oil hardening powder.
Ingredients: Natural oil (very vague, but that's also what the Japanese package says)
Right after you use the oil, pour the powder into hot oil and stir. The package suggests using one package (20g) of powder for 600 ml (about 20 ounce) of oil.
The oil must be hot.
Stir it very well...
Leave it until the oil cools down. I usually leave a chopstick in, so I can tell when it hardens. The package also suggests leaving the little bag that powder comes in into the oil. (So you can pull it to see if the oil is hard enough later.)
I left it overnight. Ladies and gentlemen, the oil has been hardened.
Scrape around the edge, and remove the oil with a chopstick or spatula. It’s actually easier to remove the oil from a frying pan or wok like the picture on the box, but I use a pot for deep frying.
It looks messy here, but if you do this with a frying pan or wok, it's not as messy.
Once the oil is hardened, it doesn't melt, unless you try to melt it by putting it into heat. You can throw it out with regular trash.
After scraping all the oil off from the pot.
There are a couple of Japanese oil hardeners with different names (Yukko, Temple, etc…), but they’re pretty much the same.
I buy it from a Japanese supermarket in NYC, so it’s not something you can get it at a local supermarket, but you can still buy it online.
J-list/Jbox sells ”Katameru Temple” (tenpuru)
“Japanese oil hardener” set on Flickr
I was born in Japan, lived in New York for a while and now living in San Diego, California. I love creating things with my hands in my free time whether it’s making character bento or stuffing stuff! And now I'm working for 
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This is awesome! Now that I’m near more japanese groceries — I will need to look for this!
That is brilliant. I wonder if they would sell it at a Korean market. We have a few of those. Thanks for sharing.
My mother puts oil in the freezer for a similar effect.
Wow, that’s so neat! I’ll have to go look for it now at Mitsuwa Marketplace (@ River Edge, NJ – ever been there?). It’ll really come in handy after we use the Fry-Daddy. :3
woah. i need to get my hands on these
I have been wanting to try this product out — saw it in the online (now closed) Ichiban Kan shop – but never had the nerve to try it
Thanks for going over it!
Oh my goodness, I need to find this! No more rancid oil in the mushroom can until it hardens!
That is actually amazing. Why don’t we have this here?!
This looks like a cool product. Any idea whether or not it’s environmentally friendly? (compared to throwing out liquid oil of course!).
Well, it’s made of oil, and you’re still throwing out oil rather than recycling it like motor oil.
I suppose if you put it in a bag, it would be ok. In hotter climes I would think the oil would just re-melt when it gets to the dump anyway.
I just don’t use a fryer, partially because of the problem of throwing out the used oil….
More experiments are needed!
I can honestly say that I have never thought of throwing away oil. We just strain it into a jar and use it for popodoms.
Hi Virginia,
I don’t throw away oil after just one use! This is jut an alternate method to get rid of old, used and dirty oil.
(Oil can go bad even if it’s thoroughly strained after each use.) The most ideal way is to never waste anything, of course, but this post was to show such a product exists in Japan, but not in the U.S.