Spray food is a food brought back from the future with the Diffy's.

Spray food could produce enough food to feed at least a family of four (like the Diffy family), you need only aim and shoot.

On the show, cookies, brownies and brisket were shown being sprayed.
Tumblr lvvlnfGxyQ1qcu95w

Phil's dad is pictured spraying brownies directly into his mouth.