Active soybean lectin in foods: quantitative determination by ELISA using immobilised asialofetuin

A recently described immunoenzymatic method for the quantitative determination of biologically active lectins in unknown samples has been adapted to measure the concentration of active soybean lectin (SBA) in foodstuffs. The method was developed by using purified SBA to build up reference standard curves and to determine the specificity and the sensitivity of the assay. Detectable amounts of soybean lectin were found in soy-based edible products such as hamburger, milk and sprouts and they have been compared to those determined in standard hemagglutination tests. Particular attention has been given to SBA quantitation in soy sprouts as a function of germination time. SBA was not degraded during germination although the hamagglutination activity of sprout extracts rapidly decreased. SBA expression was modulated during the first 10 days of germination, a time period spanning that used to produce soy-sprouts for alimentary purposes.