Why are my bags floating?
The answer may seem simple - trapped air - but it can often be more complex. You have used the immersion method and squeezed out every visible air pocket, or even vacuum sealed your bag, yet it still floats. What gives? Sometimes the food itself is buoyant, as with most vegetables, liquids with a lower specific gravity than water (think infused alcohols), and frozen meat and seafood. Other times, the gas forms during the cooking process. This happens most notably with Brussels sprouts and other cruciferous vegetables, though it can also occur with meat when particular bacteria are present* on the surface. *For the latter situation, this is typically an issue with longer cooks and the development of harmless lactobacillus bacteria. This can usually be countered with a quick sear or 30-second dip into boiling water pre-packaging for sous vide!
What can I do about it?
Get as much air out as you possibly can.The most popular method to do this is the immersion method because it requires no special equipment and is very effective. One tip we have learned from our community is to execute this method in cool water as opposed to directly in the cooking bath; Anova-warmed water may not be boiling, but it sure can get HOT! Save your fingers by either using the immersion method in a separate container of cool water, or do it in the cooking bath before it heats up. If you have or can use a vacuum sealer, by all means do so!
Do what you can to hold the bags in place.We achieve this with bulldog or binder clips in the majority of our cooking experiments, but racks in vessels that can accommodate them are a great help. Racks, whether specially designed for sous vide or repurposed dish racks, file organizers, or lid-holders, provide a bit of stability to hold those cooking bags. The friction alone will discourage floating while the water is still able to circulate freely.
You can also make a bit of a “net” by tying a strand of cooking twine across the top to hold the floating bags down. I don’t personally recommend trying to tie the bag itself to the rack for the simple reason that it’s not that easy to securely tie a slippery plastic bag to anything, let alone in moving water.
Weigh your sous vide bag downWhen getting all the air out and preventing the bags from moving is not enough, we look to the next level of options to get those floating bags in check. Weigh the bags down. We can achieve this using both internal and external weighting systems.
Internal WeightingInternally (inside the bag), the most commonly used method is to add a (dull) butter knife or two to the inside of your cooking bags. The food-grade stainless steel will not contaminate your meal, and most people have a spare butter knife or two laying around.
External WeightingAlternately, you can use these same weights externally, instead clipping their sealed pouches to the bottom of your cooking bag with a small bulldog or alligator clip! This is especially helpful when you are batch cooking and plan to transfer your packages directly from the water bath to the refrigerator or freezer (with appropriate chilling in between, of course!).
Another convenient external weighting tool is the simple stainless vegetable steamer basket placed upside-down on top of the bags. Because these expand from 5 ½ - 9 ½”/~14 - 24cm, they will fit most saucepans and stockpots. Steamer baskets are also ideal because they hold your floating bags down while still allowing water circulation through their built-in perforations. For more buoyant bags, they also provide a foundation upon which to place additional weights, like heavier ceramic bowls, plates or even just coffee mugs, water glasses, or Mason jars you place water into.
We have also seen other creative external weighting options in our community, like artfully arranged cooking tongs, small sauce pans, and even bricks! Please feel free to tell us what works for you in the comments, with pictures if possible. The more we share, the more we learn.
When all else failsThere will be cases when despite getting as much air out as possible and weighing your bag down will still not work. For these rare situations, we are going to give you a most counterintuitive piece of advice: Don’t seal your bag.
Leaving bags unsealedThis works well for times when there's either so much gas created in the bag, or you're working with a super persnickety product. The solution is to create a valve-like situation for the gas to be released. Leaving your bag partially unsealed will allow this to happen. In order to do this, you must also meet certain other conditions to ensure those typically perfect Anova results that you have become accustomed to! When employing this fix to floating bags, you MUST:
- Ensure that the bag is large or deep enough for whatever you’re cooking to be completely submerged by water while the top remains clipped to the side of the container. This is effectively a constant application of the immersion method, so air will not be making its way in from the top given pressure of the outside water.
- Keep the unsealed opening OUT of the water AT ALL TIMES.
- Periodically assist any gathered gases towards that opening using a silicon spatula or wooden spoon. Use something that will not compromise the integrity of the bag with sharp edges.