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:
- 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)?
- 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?