This spell can only be cast upon food that heals 1200 or more life points. E.g. it will work fine on a monkfish, but will not work on a strawberry. The increase in time depends on the familiar's time rather than on the food used in general. The more time the familiar has, the more time is raised. This spell can also be cast on food from Herblore Habitat. Note that even if a player renews their pouch after they extend its timer they are still not allowed to recast Spiritualise food again as it would count as using the spell twice on the same familiar.