A thin piece of wet fruit puree of thickness L is placed on a plate. An antioxidant powder is kept in contact with the surface of this thin slab of puree such that its surface is saturated with respect to the antioxidant concentration, CA0. An irreversible zeroth-order reaction of the antioxidant takes place within the puree. Considering that the concentration of antioxidant will be dilute at all times during its diffusion, obtain a relation for the steady state antioxidant concentration profile within the puree if its diffusivity is D and the reaction rate constant is kA0. State your assumptions and show all the steps starting from a shell mass balance for the diffusing component on a representative shell volume element