Master Burger is a fast food chain, possibly a rival to Kool Kow, that prides itself on the use of real, rather than synthetic, meat. It has recently been a target by the Bovine Liberation Organization because it gets its meat from genetic factories. Master Burger has over 40,000 branches, including one in the Newport Metro.
Master Burger also has a similar menu to Kool Kow, including Triple Whammy Cow Patties, Greaseonions and Bingo! Cola. Therefore, it's possible Ragnar chose to change the name, and Master Burger and Kool Kow are in fact one and the same.