Manganese in pineapple juices

Levels of manganese (15–22 ppm) in commercial pineapple juices were found to be consistently much higher than those of Cr, Fe, Ni or Cu and much higher than in other common fruit juices. The manganese levels in juice extracted from fresh Australian pineapples were variable, with some high and some low levels. Most of the manganese was found in the filtered juice and little in the pulp retained on an 0.4 micron filter. Electron paramagnetic resonance spectroscopy shows that most of the manganese is present as the Mn(H2O)62+ species. The remainder is released in this form if the juice is acidified to pH 1.