The potential of lectins for analysis of food-grade galactomannans: double-diffusion lectin assay

The potential of D-galaetose-speeific Bandeiraea simplicifolia lectin (BS-lectin) and Artocarpus integrifolia lectin (Jacalin lectin) for specific detection of the galactomannans of guar and locust bean gum (LBG), from polysaccharide mixtures and foods, has been investigated. In a double-diffusion assay (in agarose gel) using the BS-lectin the lower limit of detection of guar and LBG was 100 and 1000 mu g/ml respectively. In a similar assay the Jacalin lectin specifically detected guar, but not LBG, at a concentration; >= 50 mu g/ml. In addition. the Jacalin lectin specifically detected guar down to similar to 50-100 mu g/ml in blends of polysaccharides containing either guar/LBG/xanthan or guar/LBG. The double-diffusion Jacalin lectin assay successfully detected guar in commercial food products containing guar (minestrone soup and horeseradish sauce) and correctly classified the food (seafood soup) as negative when guar was not present.