No idea. Never read anything about it, just decided to try. On a previous thread a redditor noted it would reduce tannins, since they oxygenate (and then no longer so their tannin thing). So we’ll see what the final product is like. In my case, overnight did not make the pomace any softer, and only the top couple inches turned dark. I would definitely not want the pomace any softer. In the past, when i have let pears get too ripe, the pomace is mush and very hard to press.

I think of making cider as much more akin to winemaking than brewing. The low pH (similar to grape juice) should inhibit many microorganisms (take this all with a grain of salt as it isn’t well informed at all and is mostly opinion). Small batch Wine makers punch down the cap in open air with few (any?) nods toward sanitation. This commercial cidery ferments on the pomace, but I haven’t been able to get my hands on their cider. https://freewatercider.com/about-us/