With the Ironworks now in Experimental, steel becomes available only in June 1855. Before that time, however, the Cannery still requires unobtainable steel -- should that be changed to Iron, or perhaps pottery (potted food predating canning)?
According to the brief history of canning in the UK on Wikipedia (https://en.wikipedia.org/wiki/Canning#In_the_United_Kingdom), iron cans were used as early as 1810.
maybe glass containers?
http://en.wikipedia.org/wiki/Early_modern_glass_in_England
We really need tin mines and tin smelting plants so that we can make tin cans (and other tin products while we're about it), albeit that would require an entirely new bulk cargo - tin ore (although the tin mine graphics would be rather splendid if they were based on the Cornish practice with the beam engines half protruding from the engine houses).
Until somebody feels like doing that, however, using iron seems reasonable.
There's a cannery? Is this just in experimental?
I put in a cannery a while ago - did it not make it to Standard...?