Burnt taste, phosphates?

[guyd]

Hi

I have done a fair bit of searching on here (and ahem, other sites) and I cant seem to find an answer to my question - how do I know/tell if my molasses have phosphates in?

My first run of rum, with a 90%/10% molasses sugar ratio (or so) from a tried&tested recipie, tastes 'burnt' like cigarette ash. My pot still is basic, and entirely stainless. I did lots of cuts - I have 20 mason jars - and lo and behold the first cut was nail varnish-y and got chucked away.

The molasses is a feed grade, from a reputable supplier, but has no information about content, as in the uK animal feed does not require labelling.

any ideas?

thanks