Any lot of oranges, the juice content of which meets the following requirements, may be designated ``U.S. Grade A Juice'':
(a) Each lot of fruit shall contain an average of not less than 4\1/2\ gallons (17.0 liters) of juice per standard packed box of 1\3/5\ bushels.
(b) The average juice content for any lot of fruit shall have not less than 9 percent total soluble solids, and not less than one-half of 1 percent anhydrous citric acid, or more than the permissible maximum acid specified in Table II of Sec. 51.1178.