It’s recently come to my attention that there seems to be some debate about if you should put oil or butter or a fat in your bag before you throw it in the bath.
Sous Vide Everything (on youtube) did an experiment back in 2017 and found steak only salted was more beefy and flavorful than the one cooked with butter.
I myself have always put either a pat of butter or a little extra virgin olive oil in the bag before the cook. Before my grocer stopped stocking it, my go-to was a pack of tri-tip steaks, which really lends itself to experimentation (they are always cut into small 2" strip steaks so you can portion them to experiment on).
Recently I had the inclination to buy some duck fat and use that in the bag instead of butter or oil. We did some steaks with and some without, and the duck fat did something…
The plain steaks had a “sharper” flavor, for lack of a better term–the duck fat rounded out the flavors in a really nice way and kind of melded everything together. My SO literally said (about the plain steaks) “I can’t believe we thought THAT was good this whole time.”
But in reality, I think the flavor impact might be minimal, just like in SVE’s YT video: “Both steaks were amazing but if I get to pick I’d rather have no butter.”
I’ve seen elsewhere online that butter (and duck fat) in particular absorb a lot of the seasoning and flavors and “suck them out” into the juice, which is usually discarded (I know some people make a sauce from it but I never do unless it’s a roast).
So, in general, what’s your policy? Butter/oil/fat or nothing at all? I don’t think I’ve ever tried “nothing at all.”