Rapid methods for lipoxygenase assay in sweet corn

Potential methods for rapid assay of sweet corn lipoxygenase (LPO) were evaluated and compared by visual inspection. Both model system (partially purified) and vegetable (LPO extract) system studies were carried out. Model system studies indicated that LPO had maximum activity at pH 6.0 and 2.0 mM linoleic acid. Methylene blue bleaching (MBB), carotene bleaching (CB), and potassium iodide-starch (KI-S) methods were evaluated both spectrophotometrically and visually. Both MBB and KI-S methods were effective for the model system. For the vegetable LPO extract systems (sweet corn and green beans), the MBB method indicated positive results for both, the CB method was not effective for either, and the KI-S method was very effective for green beans but not for sweet corn.