It was a white powder added to the Christmas tamales.
I found this, but it just says it is like a substitute for salt
A brief mention in soemone's personal recipe said it was like accent.
However, this stuff was bought at a street market and I find it hard to believe that street vendors in Central America are selling bags of msg. Please no 'witty' remarks about unidentified white Central American powder. No one got high and it was only about 25 cents for a bagful.
Any clues anyone?