Choosing sandwich panel for production - polyurethane or rock wool?

Dear all
We are planning to roasting and packaging of nuts(peanuts., pumpkin seeds, sunflower etc).
We are renting space in which we would like to separate one part with sandwich panels. Our problem is that fire safety regulations say that dividing wall between storage and production should be of inflammable material like brick wall or sandwich panel with rock wool on the other hand HACCP consultant says that rock wool could be the problem regarding food safety. Since we rent place we cannot make solid walls so we want to use sandwich panels either with rock wool or polyurethane filling does anybody have experience on this matter?
To clarify panels would be same on the outside (metal plate with white color) only core would be different ?
Thanks in advance

Any ideas on this question members?