Are you the same AM that wrote the root node? If so, then what are you trying to say? That the problem appears not to be a spurious "\n"? Well, in any case the form of my reply should have implied that IMNSHO you didn't give us enough elements.

So I suggest you should give us more info, possibly preparing a minimal example still exhibiting the problem. Chances are that while doing so you will find an answer yourself. Otherwise you will help us to help you, which is fine, isn't it?

Incidentally, re

$value = $glycan_type{"$_"};
[download]

no need to put $_ in quotes.