This is a letter written by a person who is deemed a “Process Authority”; someone with expert knowledge of thermal processing requirements of food products. Not all food products need a process authority letter. There are three types of recognized process authorities for food mentioned in the U.S. federal regulations; two for FDA-regulated products, and one for USDA regulated products. For FDA products, this includes 1. Low acid canned foods 2. Acidified foods (This includes foods with a pH of 4.6 or below) that have a water activity (aw) of greater than 0.85.) For USDA products, this includes food products containing meat, poultry, or eggs. If your product does not fall into any of these categories, you do not need a process authority letter.