釋氏要覽 1.405

1.405

以變壞為相。謂入腹變壞。能資益。諸根大種方成食相。

It takes transformation and decay as its characteristic. This means that entering the stomach, it transforms and decays, and can nourish and benefit; only when the faculties and primary elements [are nourished] does it constitute the characteristic of food.