Bag losing suction during the cook

I’ve noticed that at some point during the cook the bags lose suction. It isn’t a ton, but definitely noticeable and often times enough that the fat/seasoning/herbs lose direct contact with the food. Is this something that just happens or can someone please suggest a fix? Thank you.

Depends on what you’re cooking. I once had a bag of carrots inflate like a balloon during cooking, I figure this was because I didn’t scrub or peel them first and bacteria on the surface decomposed and emitted gas during heating. Since then I’ve made sure to scrub them under running hot water first and it’s never happened again since. Are you using a vacuum sealer or the immersion method? I’ve got to say, other than that one occasion with carrots, nothing like that has ever happened to me. 

Most things we cook contain some air or gasses that are slowly released during longer cooks. Vegetables actually have quite a bit and the volume of the gasses expands exponentially as the temperature goes up.  Also, clamp type vacuum sealers do not pull any where near a full vacuum so there is always some residual air although small in a bag.