Dextrin smoke bomb?!$@#&!

[Paradise]

I cook up dextrin in my kitchen oven as usual. 400° stir every 20 -25 min for 2 hours. It was 1 hour 55 min into

The cook. The color was looking a bit on the light side so I figured 15 mate minutes can't hurt. Bad figuring! 8 minutes later my kids said "dad your stuff is starting to stink" it was dark so the initial smoke cloud went undetected. I meandered upstairs and HOLY COW! UPON opening the oven thick smoke poured out and filled the whole house. The dextrin was bubbled up 7 inches off the cookie sheet burning. Whoa!

[Paradise]

Btw, I've made dextrin many times w out issue. I had no idea I was this close to a smoke show whenever I made dextrin in the past.

[carbonhalo]

The dextrin was bubbled up 7 inches off the cookie sheet ?

I'm finding it hard to picture this. How much dextrin were you making?

[Paradise]

The same amount that I always make. It is a 1 pound jar I believe although I'm not in front of it now. I divide it up between two cookie sheets both on the same oven rack. The plastic container it comes in is yellow with a blue wide mouth cap (screw on). The brand is Argo I believe. The reason I like is because I get a nice little plastic container to store my dextrin in out of the deal. It was the color of a perfectly golden brown marshmallow. It all happened REALLY fast and the pans where out the front door. The bubble created could not have been less than 5 inches if that is any easier to believe. I was not aware dextrin could behave like that

[OldMarine]

If the dextrin was damp, it's completely believable. Trapped moisture would dissolve the dextrin and form a glutinous type mass which the steam developed would inflate.The thickness of the mass was reduced after inflation which accounts for the smoke.

[Paradise]

The corn starch went directly from the sealed container into the pre-heated oven. In your opinion would it be better to start it at a much lower temp to ensure its dry then cook it up as usual? Or just use a lower temp for a longer period? Normally if the color looks tan and it's close to a couple hours I pull it out. Is there a simple way to KNOW when it's done instead of (in my case) basically guessing?

[CrossOut]

And that's how snakes are made lol

[Paradise]

I am realizing pretty quickly when and how to do a bit more research before asking a question. 😌

[TotalElectric]

If you mixed at regular intervals, the gelatinous mass would not have a chance to form. I suspect water was introduced without your knowledge. I also suspect your oven reaches peak temperatures that are too high, causing the "browning" of the dextrin.

Edited August 27, 2016 by TotalElectric

[OldMarine]

Did a little reading and like TotalElectric said, stirring is a must since until the starch is converted it can bubble up and form thin surfaces that scorch easily. Stirring breaks the steam bubbles before they can dry out and burn.

I learn something new every day and I LIKE IT!

[Paradise]

Every 20 minutes. I set the timer and stirred like clock work. Otherwise it gets real dark real quick I learned. The oven temp MUST be running higher than the 400° I set it at. Last time I made dextrin was October. That will be the first thing I check from now on.

[OldMarine]

In my better days i worked as a sous chef in several restaurants in Nashville and Wilmington NC. Part of my travel kit was an oven thermometer. Stock appliance stats have a notoriously wide swing in temps. Wally World has decent ones for under $10 and are accurate to within 10 deg F. These also keep one from drying roasts and other meats out during the holidays!

[Paradise]

If I did more cooking maybe I would have noticed something screwy. Your a man of many talents OM! 😉

[OldMarine]

Jack of all trades...master of none!

 

I made the mistake of trying to make dextrin in a convection oven. I forgot the fan forced air and blew a whole baking sheet of starch all over the oven!

Edited August 28, 2016 by OldMarine

[Fulmen]

AFAIK this process depends on the maillard reaction which is said to occur at 140 to 165 °C (284 to 329 °F). At higher temperatures pyrolysis begins to occur, and while it is net endothermic it can have an exothermic phase. You can speed up the reaction by increasing the temperature, but that requires mixing to ensure uniform heating. So my first advice would be to drop the temperature a bit and let it run for longer.

[OldMarine]

Heh, the exothermic phase is what gets your significant other throwing things at your head!

[Paradise]

Is the iodine test worthwhile in your opinion. I have read on this forum where people have gotten mixed results. I realize it may sound fishy but I do honestly stir religiously every 20 min. I did use a probe to check my oven temperature. When the oven is set at 400 the probe is reading 465. So I guess I will start by correcting that and maybe going a little lower to be on the safe side and not leave the oven during the last 40 minutes of cooking. Because if I have another smoke bomb....oh boy!!

[Mumbles]

Technically a maillard reaction requires proteins or amino acids. I don't know what exactly this would be, probably just pyrolysis.

 

I typically cooked at a slightly lower temperature, around 350F, and ramped up toward the end of needed for a nice tan color. This worked fine for me, never burned, and never made much of a smell that some people encounter. I wonder if the odor is a genetic thing, where some people can smell it or are overly sensitive to it, and some are not. There seems to be a strong divide between making dextrin is basically odorless, and making dextrin stinks up the whole house. Anyway, I cooked at 350 stirring every 20-30 min and never had any issues.

 

One way to test is with iodine. Make up a small solution/suspension of your dextrin and add a drop of iodine solution. It turns black or purple in the presence of starch, and tend to be more red with dextrin. Cooking at home it's almost impossible to convert 100% of the starch, but it will be less purple toward the end. It sounds kind of weird, but I sometimes went by taste. It's chalky and starchy at the beginning, but gets sticky and slippery as it converts. It even takes on a somewhat sweet taste toward the end in some instances.

 

I say all of this, but have to point out that commercial dextrin is superior to homemade dextrin in basically every way. It's stickier, more soluble, and a better binder. If you consider your time to be worth anything, it's probably cheaper too. The yellow dextrin that Phil (http://www.ihaveadotcom.com/cart/index.php?main_page=product_info&cPath=72_119&products_id=283) supplies is wonderful for what it's worth.

[otto]

When the oven is set at 400 the probe is reading 465. So I guess I will start by correcting that and maybe going a little lower to be on the safe side and not leave the oven during the last 40 minutes of cooking.

 

Most older electric ovens I know of have a "calibration" adjustment on the back of the temp setting knob. If you know your actual oven temp you can adjust the knob to reflect that temperature (or nearly so). I don't know if digital ovens have that feature but they should. 65 degrees is a big difference no matter what you are cooking / baking and a stand alone thermometer that will read actual temp is a must for any reliable oven use.

[Paradise]

That seemed the simplest idea to me was to leave the probe in the oven where I could see it it may not be the most accurate but it should keep me out of trouble. I would also aim closer tp 350° as mumbles stated. I like the taste idea. Just one more thing to get me in the ballpark next time I place an order I will plan on dextrin since I did not know that commercial stuff was so much more Superior and cost next to nothing. Thanks for the info 👍

[OldMarine]

I've not used my homemade dextrin for pyro but for paper mache we were using on wire frames for temporary decorations for Halloween. I had no idea you could buy it almost as cheap as wheat flour or I'd gone that route! The cause of the convection oven debacle was my impatience with the process.

I can hear my old Gunny Sgt now "Getting in a hurry just means you'll F°<k up faster"

[Paradise]

True words. I know from personal experience uuugh! Btw THANK you fulman for your technical input it is much appreciated.

[FlaMtnBkr]

If you left the oven door open while you stirred the starch, it's quite possible much of the hot air escaped which caused the thermostat to kick on the heating element. With a traditional element it is either on or off and the power is not adjusted based on the temperature differential. So the element kicks on red hot until the thermostat has time to respond which can take a while. And since the element is red hot there is significant radiant heat which heats almost instantly compared to conductive heating thru hot air. This is why broiling will brown something so quickly.

 

Anyways, if you were towards the end of the cook and the starch/dextrin had plenty of time to get close to the set oven temp, the glowing element could have quickly heated the dextrin over it's scorching point resulting in it quickly starting to smoke and burn. I personally think this is more likely than water being present after almost 2 hours of cooking. Unless corn starch has attached waters of hydration that require a certain temp to break the molecular bonds? I'm not a chemist and that is all purely speculation.

 

This is also why recipes specify to pre heat the oven. So what you are cooking is not exposed to the glowing red elements/radiant heat for 20 minutes while the oven comes up to heat. As it can burn, dry out, and/or over cook the outside of what you are cooking.

 

Though a pretty darn good steak can be cooked under the broiler if you don't have a (charcoal) grill or are in a hurry. You can get a nice crispy 'crust' and still have a rare to medium rare center. Or if you like a ruined steak you can turn the heat down and place on center rack until desired 'doneness' is reached.