I made tonkotsu broth. I've made it before about a year ago, in the high setting of slow cook, lid on venting. I remembered it kept bubbling throughout, so much so that sometimes I'd turn it to low because it was too much.

This time, there was no bubbling at all. It was still quite hot (I wish I had a thermometer -_-), but a skin formed on top because it was so still. Could that top layer be in the temperature danger zone? It looked like a creme brulee.

I strained the bones and quick cooled in an ice bath and have it in containers in the fridge, my plan after work was to add the aromatics and simmer for about an hour to add flavor. But I don't know if I'm being paranoid about what could've happened overnight.