He doesn't say exactly what the food of the hell-beings is though.
''"And which, Master Gotama, are the possible places? Which are the impossible places?"
"There is the case, brahman, where a certain person takes life, takes what is not given, engages in sensual misconduct, engages in false speech, engages in divisive speech, engages in abusive speech, engages in idle chatter, is covetous, bears ill will, and has wrong views.
With the break-up of the body, after death, he reappears in hell. He lives there, he remains there, by means of whatever is the food of hell-beings. This is an impossible place for that gift to accrue to one staying there.http://www.accesstoinsight.org/tipitaka ... .than.html