UK Met tephigrams used to have MINTRA lines on them, but I don't think they are plotted now. I have just called up a current Irish tephigram - no MINTRA. I think there used to be a DRYTRA line as well to mark the top of the contrail band.
I think, but memory is falible, that the old MINTRA related to piston engines, which had fairly consistent exhaust content and mixing, so contrails could be forecast with some accuracy. I do not recall ever using the MINTRA forecast when in a jet.
Dick W