Peterfile:
“How do you stop primary fermentation, by cold crashing once gravity hits a few points above where you expect it to finish up?”
Yes, although cold crashing is not instant. You stop say at 1011, cool then see what it actually stabilizes at. Then adjust.
“Then do you bottle and let it warm back up so that….”
No. Ferment as normal, although you tend to stop it slightly earlier – therefore slightly weaker (alc), slightly more sugar. These are very slights. Cool down to drop out all of the yeast (not using finings). Bottle the clear beer, re-add a drop of yeast, seal. Note this is for bottle-conditioned beers. For the others, just filter/bottle/carbonate.
Note that we have very effective cooling/heating and sterile enviroment controls. It’s probably the biggest differences between home and commercial.
If you have oxidation, there is not much you can do. Beer is decomposing anyway and oxygen lets the bacteria go out and play 🙁 The ‘peak’is subjective anyway, hence ourselves and lots of other people researching it.
Hope that’s clear, ask away anything else. If you have specific questions, feel free to email me, I should be able to find out, the two owners have been doing this for 25+ years.