Misflavour

The flavour thresholds of the 239 compounds examined varied over a range of 2 x 10¹², and on occasion, compounds of high chemical purity (99% +) were organoleptically impure or even misflavoured.

Source: wiktionary

This means that impurities present at the ppu level can easily misflavour the compound under study.

Source: wiktionary

'Chemically pure' compounds may be strongly misflavoured by contaminants, and in some cases the threshold measured may inadvertently be that of an impurity.

Source: wiktionary

Powders produced in those days were, compared with today's standards, of poor flowability and solubility, difficult to handle, dusty, and prone to misflavour as a result of degradation in the drying process.

Source: wiktionary