Surface contact question

[Robert Mullen]

Thanks. I just began the journey and having been a sous vider I was expecting vacuum at that level. After reading around a bit I am starting to get the picture. Just for curiosity, what is different about a section of meat touching the bag vs. one that isn’t. Will the air exposed part rot? Will it simply not form bark?

Is there a technical explanation for how these bags work? Not sure if that is a secret.