For sous-vide cooking, does the bag have to be completely immersed?

In the Ask our Chef section we have received the following question:

Hello Chef! I have placed the asparagus in the SmartVide and the bag floats. My question is, does the bag have to be totally immersed?

This was the response of Enrique Fleischmann.

Yes, it does. All low temperature cooking must be submerged, in order to ensure uniform and ideal cooking.

The reason you have air left in the bag is that the asparagus when cooked release the air inside them. Therefore, during cooking, the air inside the asparagus escapes into the bag. To avoid this problem, before cooking the asparagus you can submerge them in water inside the vacuum machine so that the air they have in their structure disappears and the water goes into them to prevent oxidation. Or, you can also generate a vacuum inside the chamber with only the asparagus inside the bag, but without sealing the bag, until the third round of vacuum. In this way, the air inside the asparagus is also emptied and the bag will not float.