Why put flour in Oven Bag?
This question is about the plastic "Oven Bags" used to roast various kinds of meat or poultry in. I have some of these made by Reynolds Co., and in the Cooking Guide that came along in the package, it says: "Add 1 TBSP flour to bag. Shake! This helps prevent bag from bursting." This was before you put the rest of the food into the bag. Well, it didn't burst, so I guess that means it worked, but they also had me cut six slits into the bag to let steam escape.
My question is how would the 1 TBSP flour prevent the bag from bursting, and why would it burst anyway, with six slits in it?
Best Answer
See this 1972 NYT article from back when these bags were a recent invention and the explosion problem was still current news. https://www.nytimes.com/1972/04/08/archives/why-cooking-bags-explode.html
In recent years, news was made of the dangers of boiling water in the microwave in something like a Pyrex measuring cup, because water heated in that manner could potentially become superheated (hotter than the normal boiling point, but not bubbling, steaming, or visibly boiling) if the surface of the container is so smooth that "nucleation sites" don't form. It then sits there, hotter than boiling but looking still (as if it weren't boiling yet) -- until something disturbs the surface (like the next ingredient, or your hand jostling the cup), at which point it can violently and simultaneously boil, seeming to explode.
Apparently the same thing was thought to be happening in these cooking bags due to water getting trapped under a layer of grease from the meat, and the flour would help those nucleation sites to form (called "boiling chips" in the NYT article) and also bind with some of the fat and water to form a gravy instead of letting the water remain separated. I am not a scientist but I don't think I've said anything egregiously wrong.
Justin Wilson mentioned the explosion risk and the need to use flour in one of his cooking shows back in the day while demonstrating the bag, but didn't go into the science of it, just mentioned that the flour was needed and went on with the show. It's in an episode called "Cajun Meat and Potatoes".
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Quick Answer about "Why put flour in Oven Bag?"
Always shake one tablespoon of flour in an oven bag before cooking. It protects the bag against bursting and thickens juices so sauces and gravies cook right with the meat— no extra pots or pans!What happens if you forget to put flour in an oven bag?
\u2191 What happens if you don't put flour in an oven bag? Without the flour, a layer of water may form under the layer of melted fat. The water under the fat will boil. The trapped steam can create enough pressure to cause a boil-up through the fat layer.Do you have to put flour in the oven?
Flour is considered a raw ingredient and it should never be consumed without being cooked or baked first. It is rare for consumers to get sick from flour, however it can happen, and again, it is highly advised that one should always cook or bake their flour.What do you put in a roasting bag?
When risen and ready to bake, you poke or cut a few holes in the bag. Fans say the steam in the bag helps the crust, particularly for French breads. You can also use oven bags in a microwave, if that is your preference.How To Make Chicken In A Bag
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Answer 2
My hypothesis is that they believe (correct or not) that the flour will absorb excess moisture. Absorbing this moisture could prevent a build up of steam and the bag "blowing up", and perhaps they also think it could lead to crisper skin. I don't know how true this is, but it seems like a plausible hypothesis!
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