The lower boiling point of water found at high altitudes not only affects foods cooked in water but also foods cooked in deep fat. To prevent deep fat-fried foods from over-browning on the outside while being under-cooked in the inside, the temperature of the fat must be lowered at high altitudes. Temperature decrease varies according to the food you are frying. A rough guide to follow is lowering the frying temperature about 3oF, for each 1,000 feet increase in elevation. For example, at 5,000 feet, a sea-level recipe calling for frying doughnuts at 370F, would be lowered to 355F.