Root beer is a carbonated beverage originally brewed using sassafras. It's one of America's most popular soft drinks. Mug was first produced by the Belfast Beverage Company in San Francisco, California during the early 1950s. It is made by PepsiCo. INGREDIENTS: Carbonated water, high fructose corn syrup and/or sugar, caramel color, sodium benzoate (preservative), natural and artificial flavors.