פירוש על עבודה זרה 76:10

These date-husks were probably being cooked in order to make beer. The issue with the large cauldron is that we can assume that it had been used to cook unkosher food. The taste of the forbidden food that is in the walls of the cauldron will go into the brew. Therefore the date husks are prohibited. But the assumption with a small cauldron is that it is not used with unkosher food. Therefore, the date-husk beer is permitted.