Is there a technical reason for cooking a tomato sauce until the oil separates?
I've encountered that in recipes--not sure if there is a technical reason or not. When I make pizza sauce, since I use a decent amount of olive oil, it separates rather fast. Not sure if there is a firm fast rule why it happens..
Could be a simple rule of thumb to ensure a long enough cook time, especially when dealing with canned tomatoes.
On the other hand, a sauce made from fresh summer tomatoes, say, peeled and run through a food mill, can be perfect with a very brief cook time (just until thickened) to keep that fresh brightness of fresh tomatoes.
Thanks for the input I think you were right. I was looking though my cookbooks and found a note from Marcella Hazan. She notes that the oil will separate and run clear when the tomatoes have been cooked down and have evaporated their water content. This may increase the concentration of naturally occurring glutamate, major flavor enhancer, my thought.