Any lot of oranges, the juice content of which meets the following requirements, may be designated “U.S. Grade AA Juice (Double A)”:
    
    
        
        (a) 
         Each lot of fruit shall contain an average of not less than 5 gallons (18.9 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 10 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  § 51.1178.