Normal pasteurization temps start at 140F and go up from there. Generally speaking, the higher the temperature, the shorter the amount of time the product is held at that temperature, and the more completely resident organisms (and delicat flavor compounds) are destroyed. Milk that is held at 140F for 30 min is considered pasteurized, if it's held at 160F for 5 minutes its ultra-pasteurized. (You can go higher but then you start to hit Parmalet territory

). 150F was probably a good compromise. (And I'm not suggesting cooking raspberries for half an hour either.)