Estimation of food-grade galactomannans by enzyme-linked lectin assay

A highly sensitive (lower detection limit of approximately 10 ng/ml) enzyme-linked lectin assay (ELLA), using the Bandeiraea simplicifolia lectin, has been developed for the rapid detection/quantification of guar and locust bean gum (LBG). Although guar and LBG could not be differentiated, the ELLA specifically detected the galactomannans but not other common 'food' polysaccharides (e.g. xanthan, carrageenan, pectin and alginate). Mono- and disaccharides inhibited the ELLA for guar to varying extents depending on the nature and concentration of the sugars. The ELLA successfully detected and, possibly, quantified guar in commercial food products containing it (minestrone soup and horseradish sauce) and correctly classified the food (seafood soup) as negative when guar was not present. Finally, the ELLA is compared with electrophoresis and sugar hydrolysis-GC methods of polysaccharide analysis reported in the literature.