Even if you managed to find an inexpensive solution for cooking sous vide at home , it used to be the case that you were
Even if you managed to find an inexpensive solution for cooking sous vide at home, it used to be the case that you were still on the hook for a vacuum sealer, and the $150 FoodSaver was the de facto appliance for the job. Sure, for short cooking times, you can immerse a zip-top bag in water and force out most of the air, but that strategy doesn't let you safely cook-then-chill foods for reheating later. Furthermore, as the small amount of remaining air expands in non-vacuumed bags, they tend to float to the surface and cook unevenly. However, Ziploc recently introduced a line of vacuum seal bags that use an inexpensive hand pump and achieve nearly the same results as that pricey FoodSaver. Read on for my head-to-head test and conclusions:
The Ziploc vacuum bags work via a special flat, plastic valve built into one corner. To seal foods, you zip the top of the bag closed, then place the hand pump over the valve and pump until all the air is removed. This process only takes a few seconds, but achieves a similar compression strength to that of the FoodSaver (I attempted to measure the strength of the vacuum, but neither the FoodSaver nor the Ziploc registered a vacuum pressure high enough to register on my vacuum pressure gauge). And, unlike the FoodSaver, there's no heat sealing required. If you've ever had the unpleasant experience of trying to get a FoodSaver to seal moist foods, you'll know that heat sealing and liquids are nearly incompatible. I can't count the number times I've had to reseal a vacuum bag of meat because the heat seal failed. The Ziploc bags don't solve the liquids problem completely (for that, you want a chamber vacuum sealer) but it does seal just as well for wet foods as dry ones.
To compare the seal and permeability of each bag, I placed a folded paper towel in a Ziploc vacuum bag and an equivalently sized FoodSaver bag. I measured the mass of each paper towel before sealing, then placed both bags in a 60C water bath for 8 hours. I dried the bags and measured the mass of the paper towels from each; if there were any increase in mass, I could attribute it to a leak in the bag's seal, or the water permeability of the bag itself. For both the Ziploc and FoodSaver bags, there was no detectable increase in mass, implying that when sealed properly, both bags offer the same leak resistance.
Since pricing varies among retailers, I'm running the numbers based on Amazon's prices.
Although the Ziploc bags are just slightly cheaper than their FoodSaver equivalents, the FoodSaver system offers continuous rolls of bag material, which I find to be extremely convenient for sealing odd-size foods like a rack or ribs. In addition, the FoodSaver offers accessories such as rigid vacuum canisters. In my experience, these canisters are the best part of the FoodSaver system. Whereas vacuum bags don't create negative atmospheric pressure (since the atmosphere keeps pressing the bag against the food), the canisters allow you to actually create a vacuum environment. This is highly useful for making vacuum-set foams, vacuum brining, or vacuum-infusing foods.
Since the Ziploc bags don't rely on a heat seal, the bag is not permanently altered when you use it. That means that you could theoretically reuse your Ziploc bags over and over again. Ziploc (wisely) recommends against reuse in general because the bags are difficult to clean and the risk of contamination between uses is significant. However, if you're using the bags to store dry goods like rice or grain, you can open the top, take what you need, then reseal. If you were using a FoodSaver, the bag would get about three inches shorter every time you wanted to open and close it.
Both FoodSaver and Ziploc bags are BPA-free and have been tested for to meet food safety standards. The Ziploc bags are advertised as microwave-safe, but are not intended for use in boiling water. After eight hours at 60C in the sous vide bath, the Ziploc bag showed no signs of deterioration. That's great news if you want to cook red meat. However, I did not test higher-temperature cooking conditions. The Ziploc bags are not marketed for sous vide cooking, though ironically the words "sous vide" appear on the bag because they are printed in both French and English ("sous vide" is French for vacuum).
Given my experience so far, I highly recommend the Ziploc system. For the ability to vacuum-seal foods for less than five dollars, there's no reason not to give it a try. In my opinion, this is a great step toward reducing the total cost of cooking sous vide at home and reducing the barriers to entry for people who aren't obsessively geeky in the kitchen. And, of course, if you're still looking for a good way to heat your water bath, may I recommend another cheap solution?
[If you noticed that the picture at the top of this post looks just like the picture comparing sous vide bags from Modernist Cuisine, +10 points! Instead of sealing colored water, though, I opted for a heartier payload.]