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What happens if I just use a zip lock bag, and closed it on the food, without sucking out the extra air, and then used a heavy spoon at the bottom of a pot, with boiling water ?

What i am trying to do is just get zip lock bags, without any other special equipment.

@Jefromi , looking for easy & economic way of cooking, with minimal effort to clean the pot afterwards.

sharp12345
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  • What's the goal here? It sort of sounds like you're talking about an approximation to sous vide, except 100C is really hot for that. – Cascabel Nov 07 '16 at 00:50
  • @Jefromi , looking for easy & economic way of cooking, with minimal effort to clean the pot afterwards. – sharp12345 Nov 07 '16 at 01:32
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    I don't understand why you want to leave the air in the bags. Without the air, it will cook more evenly and it won't float, so you don't have to weigh it down. – Catija Nov 07 '16 at 02:26
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    You'll get lots of yummy hot carcinogens from the plastic in a ziplock bag at 100C. – GdD Nov 07 '16 at 12:59

2 Answers2

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During sous vide cooking, it is not uncommon to place food in a zip lock bag and leave the top unsealed and hanging over the edge (so water does not get in) of the vessel you are cooking in. It can easily be weighed down with some flatware, as you suggest. There is no need to suck a vacuum and seal, in most cases. Alternately, you can use the displacement method to remove air and seal the zip lock. However, your temperature is a concern. Many vegetables can be cooked sous vide at or near 90C, but I don't think it is wise to go much beyond that, as zip lock bags can fail...and there really is nothing you want to cook that high anyway. If you want to boil something, just place it in a pot of water and boil it.

moscafj
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You will wind up with a melted plastic bag and ruined food.

When you're boiling a pot of water, keep in mind that only the water is necessarily at 100 C (because above that temperature it changes state and boils off as vapor). The pot itself can get hotter, especially the bottom if you're using a conventional stovetop that applies heat from the bottom of the cooking vessel.

The plastic on a standard zip-lock bag isn't designed to take high heat; it could soften and warp even when exposed to 100 C. If you use something to weight down the bag such that it's in contact with the much hotter bottom of the pot, the bag will melt all over your food, and probably rupture so that you'll have to clean the pot anyway. (That is, if the expansion of the remaining air as it heats doesn't overwhelm the seal and pop the bag open before then.)

Don't do this. There's no benefit of convenience to be gained, just a lot of frustration and ruined meals. If you want to boil something, just boil it in the pot.

logophobe
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  • isn't sous-vide plastic bags supposed to handle that amount of heat ? – sharp12345 Nov 07 '16 at 23:46
  • @sharp12345 Sous-vide is typically done at a lower, consistent temperature, and the heating elements are guarded so that there's no contact with the bag. There's no hot spot like the bottom of a boiling pot for the bags to contact, so there isn't the same risk of melting. Having to hold the bag down to keep it submerged is the main problem in this scenario. – logophobe Nov 07 '16 at 23:59