Target temperature for infused cooking oil

A little context: I make craft chili oils for friends and family. I use a two-step infusion process. First, I infuse the oil for flavor by simmering spices in the oil held around 250 degrees Fahrenheit. Second, I add dried chili flakes into the flavored oil around 250 degrees Fahrenheit. I have used canola and grapeseed oil.


Questions: -Is there an ideal temperature to best extract flavors/fragrances from spices (for ex, from cumin seeds or star anise) into the oil?


-Do the flavor compounds deteriorate with prolonged cook times even if oil temp is kept below smoke point? For example, how does the oil change when kept at 250 degrees Fahrenheit for 1 hour vs 2 hours?


