Kyouko's seemingly offhand statement about the foodchain brought something to my attention. Mami sips a cup of tea after defeating Gertrude. Charlotte devours Mami. The sight of a yellow egg reminds Madoka of Mami's last moments, and she weeps after putting it to her mouth. Homura warns Madoka with a cup of coffee. Kyouko is shown eating in all of her appearances so far (crepes, waffles, taiyaki).

I'm currently pretending that this somehow represents their appetite for power or their degree of corruption, with Madoka being the most reluctant, Homura and Mami sipping in moderation, and Kyouko being the most voracious so far.