Manganese in pineapple juices

Levels of manganese (15-22 ppm) in commercial pineapple juices were found t o be consistently much higher than those of Cr, Fe, Ni or Cu and much highe r than in other common fruit juices. The manganese levels in juice extracte d from fresh Australian pineapples were variable, with some high and some l ow 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 resona nce spectroscopy shows that most of the manganese is present as the Mn(H2O) (6)(2+) species. The remainder is released in this form if the juice is aci dified to pH 1. (C) 1999 Elsevier Science Ltd. All rights reserved.