DEVELOPMENT OF AN ENZYME-LINKED-IMMUNOSORBENT-ASSAY FOR GEOSMIN

A direct competitive ELISA for geosmin (a musty/earthy off-flavor compound) was developed. Antibodies were produced in goats injected with a BSA-argosmin C (a dehydration product of geosmin) conjugate. The sensitivity and specificity of the antibody were respectively determined in a microtiter plate coated with the purified antibody which was subsequently detected with an alkaline phosphatase-argosmin C conjugate. The antibody had the most cross-reactivity with an argosmin C related compound, namely, 4,4a,5,6,7,8-hexahydro-4a-methyl-2(3H)-naphthalenone. It cross-reacted equally with geosmin, 2-ketogeosmin, and 2-decalone but had limited recognition for norbornane, indicating that the binding of the antibody was restricted mainly to the bicyclic structure (A and B rings) of geosmin. Because it had some cross-reactivity with 2-methylisoborneol (MIB), it was assumed that the methyl group in geosmin might also play a role in antibody recognition. In addition, the presence of two OH groups on the A and B rings of 1,5-decalindiol also had an effect on the antibody binding. The assay had a sensitivity of 1-mu-g/mL.