I recently helped a friend with his raspberry wheat. He had purchased fresh raspberries, so we had to pasteurize them. Here's the method I used:
1.5 # fresh raspberries per gallon of beer
Working in batches, mash raspberries to release some juice and break down the structure of the berry. Transfer to a stock pot. Bring stock pot to a very gentle simmer over medium low heat. When raspberry pulp reaches 160F, cover and remove from heat. Allow to stand for 20 minutes. Check to make sure that after 20 minutes, the temperature is 140F or above. Pasteurization is complete. Keep pot covered and allow to cool (using an ice bath is ok, but not necessary). Using a sanitized funnel and spoon, transfer raspberry pulp to a sanitized secondary fermenter. Rack beer on top of raspberries and secure with a sanitized airlock.