Thermo/cooking question

[xela]

The canonical advice for sous vide on the cheap is to put the food in A ziplock, submerge it to the lip of the bag to force the air out, seal the bag, et voila!

I've never been able to make this work properly: I invariably end up with enough air in the bag for it to float, leaving a portion of the food at or above the waterline, where it would presumably risks coming out partly under-cooked if I didn't find a way to force it back under. Which is a pain in the ass.

This is the main reason I've only used my Anova Precision Cooker — which I've had longer than most, since I was a Kickstarter backer — less than a dozen times for anything other than eggs. (Man, I wish more food came in its own sous vide-ready packaging.) The price of vacuum- sealers has gotten less outrageous, but — I don't know. Maybe at this point I've just got my back up about it.

One thought I've had is to find something foodsafe that I could put in the ziplock with the food (and easily find and seperate out later) that would be dense enough to hold the bag down even if there were a small pocket of air. My question is, what should I use? Marbles are one possibility — assuming marbles are still made of glass, and that, as children's toys, aren't made of glass that will leech anything very toxic into the food. Stainless steel ball bearings are another. I know Borosilicate beads are available as a lab supply, but being transparent seems like it would be a strike against being easy to find and separate out after cooking.

Before I go any further down this road, I want to ask two questions of the hive mind:

1. Do I need to give any serious thought to the thermal conductivity characteristics of the material I use? Or can I rely on my intuition — which, for both glass and stainless, is that the material will be uniformly the same temperature as the water bath within a few minutes, and will transfer that heat to the food as well as the LUPE of the ziplocks)?
2. Is this a well-trodden road among foodies? If so, what materials do people like? Is there some better technique I haven't thought of? Or am I the only one who has this problem? Or am I borrowing trouble, and let a corner of my ziplocks float in the water bath?

Comments

[chenoameg.livejournal.com]

I have no sous vide experience, but when I am freezing food I use a straw to suck the extra air out of the ziploc bag.

(except not chopped peppers. Ow.)

[pekmez.livejournal.com]

I have used a straw while I seal the ziploc, gradually submerging as i seal and then using the straw to finish it off. I have used it that way for sous vide, though I've used mine even less than yours despite also being a kickstarter backer... _and_ i now have a food saver vacuum sealer that I haven't actually gotten around to trying with sous vide.

[jered]

Have you considered an inexpensive vacuum sealer? Many zip-top bags are not rated for the temperature that you sous vide at anyway.

[cfox.livejournal.com]

Pie weights are an item, albeit a possibly overpriced one. Sometimes they come threaded on a string (which you don't remove).

[nuclearpolymer.livejournal.com]

I think you are more likely to leach plasticizer out of the bag than anything you put into the bag?

[nacht_musik]

How about a stainless spoon, at least for non-acidic foods?

[nakor.livejournal.com]

Air doesn't just make it float. It insulates. Archimedes' trick works if the food will express enough liquid to conform to the bag; otherwise you will have raw spots.

S/edge/corner in those instructions and see if that helps? I can usually get under an oz of air, and it's okay if a bit of water seeps in with vegetables.

[fredrickegerman.livejournal.com]

I came here to say basically the same thing. Air pockets are a food safety issue even if it's submerged. I seem to recall putting a bit of oil or liquid or something in (not enough to fill the bag limply by any stretch) before sealing the time I tried this, but it's been a while I'll admit.