In context:

> Elderly volunteers (or "mulchees") are provided with generous payments for their families before being rendered down and recombined with other chemicals into a range of substitutes for common foodstuffs, including hash browns (Grandmash™), bananas (Nanas™) and butter (Fauxghee™).

So one meaning is Faux Ghee (faux as in fake, Ghee as in a type of clarified butter, originating from South Asia) which follows the naming conventions of real substitute foods like Faux Turkey.

And the second meaning is "Fogey" as in an old person.