How do I deduct food loss after a power outage?

You cannot deduct that.  Sorry.

Question: what if, due to the los angeles county & palisades fire recently, is declared a disaster.  However, I was not in the affected area but live in the county and suffered loss of food from power outages?

It will depend on the zip code you live in and what areas are declared a disaster versus a major disaster.  If your area is declared a disaster area or major disaster area, then yes, food loss from the power outages would likely be deductible. If your zip code is not declared a federal disaster area, then no, you would not be able to deduct food loss.