Thks for the links.
As you noted, SS is clearly the usual material of choice although I deduce from the 3-A web-page that some alternatives to stainless steel may be acceptable, eg -
The benchmark for materials is the AISI 300, excluding 301, Series Stainless Steel or the Alloy Cast Institute (ACI) for cast equivalents. Metals that can be demonstrated to be at least as corrosion resistant as the AISI 300 Series Stainless Steel and are nontoxic and nonabsorbent are also acceptable. Exceptions to the AISI 300 Series Stainless Steel are usually permitted for specific materials reviewed by the 3-A Working Groups when the required function does not allow for the use of the AISI 300 Series Stainless Steel.
(Perhaps the current 3-A Standard expands on acceptable alternatives/functions)
The USDA link is dd 2001 and looks same as mentioned/commented in post 12. Still current ?.
Regardless, I think the advice in Posts 10,11 is the easiest way to go.
@ MDG - Comments ?