Instructables

Microwave Canning. (Metal in the Microwave)

video Microwave Canning. (Metal in the Microwave)

This is my first Instructable, And still a work in progress.  The steps to preparing and putting glass canning jars with metal lids in the Microwave oven and create enough heat to sterilize and vacuum seal the jars. 

I wonder if you could use a microwave pressure cooker like this one. They reach the 212 degree temp and would be safer, granted, the big jars might not fit:

http://www.qvc.com/CooksEssentials-4.5qt-Microwave-Pressure-Cooker.product.K40490.html?sc=TSV&UDC=TSV&MSG=TSV_OTO_INSTOCK

rhinostas (author)  joyce.davis.18488124 days ago
I think it would be fantastic! What a great idea.
rhinostas (author) 1 month ago
Great idea kahakura!
kahakura6 months ago

May I suggested an improvement on this process: That you sterilize the jars and lids as part of the cooking process is great. Instead of screwing the lid on, leave it just sitting on top. Then, when you remove it from the microwave, overflow the jar with hot water, just boiled). Replace lid and screw down. This eliminates the possible danger of cooking with pressure in a glass container.

kahakura kahakura6 months ago

Microwave preserving is described in detail at

http://www.providentliving.org.nz/microwave-oven-bottling-and-preserving/

suttonpl1 year ago
I am sorry this is a bad suggestion. USDA canning recommendations have been tested for safety. Your test, is that you haven't died yet. The fact that you have a seal doesn't mean the food achieved the proper temperature to be safe. When you have the potential of reaching thousands of people with advice; then bad advice such as this is just dangerous.
Amyrosie suttonpl10 months ago
I agree. I don't want to be disrespectful... But even though it sealed, it doesn't mean the bacteria was killed. I'd be more scared of the jars exploding in my face, though.
bcohorn3 years ago
So did it seal?
rhinostas (author)  bcohorn3 years ago
It totally sealed.
Pressing the lid in can cause a false seal. Even with sealing when boiling you can have seals fail but you don't know unless you don't touch.

If this is the first time, please give us an update on the shelf life. Cause it does make me wonder if you cooked it long enough. Cause you sounded like you were guessing on the time and power and would like to know if you've found a more exact number for time and power. Because from my own experience undercooked can still seal but have a shorter shelf life.
jeffmika2 years ago
I have been experimenting and researching this idea for a few weeks now.
I canned jars of numerous foodstuffs to test. Food is edible and seems to be sterile.I don't trust beef or pork.Salmon worked well.Chicken seems to work OK too..all vegetables worked good..fruits the same..Here are the concerns I am wrestling with.1. Even though it is vacummed sealed I don't know with absolute certainty that the product is FREE of latent microorganisms that could culturize over time,say three months. I left my test samples for seven days without refrigeration. 2. my next concern is that the pressure that builds from processing in the microwave bleeds out during the sterilazing process and carries minute particles out across the seal surface.even though it effectively seals I am not sure that a culture would not build under the seal over time from the contamination during the original processing..food needs to be tested for longer then the one week that I allowed for this test to see what happens.
With the pressure canning method there is pressure on the outside and eventually on the inside of the canning jar..the pressures balance each other and therefore NO residual contaminant is carried across the sealing surface..A great big difference the way I see it...My conclusion SO FAR:...the micro method can be used safely on a short term basis..prepare the food for the upcoming week and CAN it to save time later in the week..for serious long term use it is best to use a pressure cooker ..I have a digital one with timers and auto shut off functions that make canning easy...If I find out anything else I will post it here...jeffmika@gmail.com
This is the best idea ever. I hope to try it. Our Mothers and Grandmothers would not believe this!!! I just picked a lot of tomatoes.
dshlabotnik3 years ago
The only way metal has any adverse affect on a microwave is if the metal touches any of the sides or bottom. I've been canning for years in mine (no vegetables though) and it works quite well. After I get the stuff boiling, I let it set in there for two minutes for the heat to penetrate through everything, then I bring it back to the boil again.

If you want to test the metal issue, just leave a teaspoon in a coffee cup when reheating your coffee or heating water.. There is no ill effect. But don't let any metal touch any of the sides!
saj1003 years ago
I am so glad I saw your video!! I recently purchased a book about microwave canning by Rachel Webb and it suggested using recycled jars and lids -- something I am not comfortable doing. I will use the flat top and ring as you did in your video. For those who were concerned about microwaves and metal, the book explained about the ratio between metal and non-metal objects. Also, if round metal tops are used the microwaves do not arch -- so reports the author. There was good info about canning certain foods especially vegetables. For this method, I'm sticking to fruits for the long term storage. She is from Australia by the way. Thanks, again. I'm off to the store to buy new lids for my jelly jars!
kmn53 years ago
I'm surprised there wasn't any arcing between the jar lids...
I would only do this if I was planning on throwing out the microwave.. any metal in the microwave can cause damage
http://answers.yahoo.com/question/index?qid=20090705052859AAftUAB
rhinostas (author)  kmn53 years ago
Nope. No arching. I also use staples in a brown paper bag when I make my own Microwave Popcorn.

Crazy I tell ya!
rhinostas (author)  kmn53 years ago
Metal is safe in the microwave - if done properly. The video is not a hoax.
bettyroug543 years ago
I have been canning for over 35 years, and I would never risk using this type of process to put up put any kind of food for long term storage. Most veggies nowadays are hybrids and do not contain enough acid to process by any means short of pressure canning. I don't want to sound mean, but this seems to be a very unsafe way to put up food.
rhinostas (author)  bettyroug543 years ago
I understand your fears Betty. And not all foods are safe with this method. But a lot are.
bws20103 years ago
Not reccomended method for food preservation, here's a link to the USDA food safety and the use of microwave for canning: http://www.fsis.usda.gov/factsheets/microwave_ovens_and_food_safety/index.asp
rhinostas (author)  bws20103 years ago
This is safe if done properly. I admit a lot of people may not do it properly, and the recommendations are generalized for masses of people who don't / won't follow directions precisely.

This method has been done in Australia - SUCCESSFULLY since the microwave oven was invented.
cwerlein3 years ago
What gave you the idea to do this? I mean, metal in the microwave has always been an issue however, I have to agree with some of those above... Canning and preserving food is a serious business and just because you have a seal doesn't mean you will have healthy safe foods when you open it again!
Interesting. My only real concern would be sterility. For it to be genuinely sterile, it needs to be between 121–134 °C. At least 15 minutes at 121 °C or 3 minutes at 134 °C. I am not sure I would trust a microwave over a pressure canner.
bahi3 years ago
Be careful you could damage the microwave oven and cause your food to be heated unevenly. Metal could cause to arcing between the metal lid and the walls of the oven, at least try to avoud sharp metal edges lids.
N4CRLucky3 years ago
Oh my. I still don't think I'm going to try it.. o.O
rhinostas (author)  N4CRLucky3 years ago
Oh come on! ;)