Validation of a Method for Quantitation of Soybean Lectin in Commercial Varieties

Quantification of lectin in soybeans and soy products by liquid chromatography-tandem mass spectrometry

Lectin is one of the major anti-nutritional factors in soybeans and inhibits digestion of dietary protein. Here, an absolute quantification method was developed to detect lectin using synthetic peptide 183TTSWDLANNK192 as reference standard and corresponding isotope labeled peptide TTSWDLANNK (Alanine-13C3,15N) as internal standard to normalize results. After the ground soybeans and soy products were defatted with n-hexane and extracted with extraction buffer, the crude protein extract was digested on filter membrane by trypsin. Further, the enzymatic hydrolysis peptides were quantified using liquid chromatography-tandem mass spectrometry. The synthetic reference peptide showed a detection limit of 0.27 ng/mL and a linear relationship in the range of 3.2-1000 ng/mL (r2 > 0.997). Correspondingly, the detect limit of lectin in soybean samples was 35.5 μg/g. The results showed that the recoveries of the lectin in spiked samples ranged from 80.9% to 108.7% with intra-day precisions (% CV) less than 9%. The method was successfully used to evaluate lectin levels in hundreds of soybean seeds from different varieties and soy products from different soybean processing techniques. Furthermore, the method may provide a potential application as a general method for the ultrasensitive detection of various protein anti-nutritional factors in food.

Variability of Crops' Compositional Characteristics: What Do Experimental Data Show?

Common pillar across the risk assessment strategies implemented worldwide for genetically modified plants is the comparison of their compositional profile to that of conventional counterparts deemed safe. If differences are observed, those that cannot be attributed to natural variation are further evaluated for their safety relevance. This principle is clear, but its implementation is challenging. Here we first discuss the difficulties of estimating natural variation of crop-specific compositional end-points and the various attempts made, together with their advantages and limitations. Second we present the empirical distribution curves of compositional end-points for two crops bearing a large commercial interest worldwide, maize and soybean. These curves provide novel information on end-point specific variability relevant for further progressing in the risk assessment process.

Stacked Genetically Engineered Trait Products Produced by Conventional Breeding Reflect the Compositional Profiles of Their Component Single Trait Products

An expanding trend for genetically engineered (GE) crops is to cultivate varieties in which two or more single trait products have been combined using conventional breeding to produce a stacked trait product that provides a useful grouping of traits. Here, we report results from compositional analysis of several GE stacked trait products from maize and soybean. The results demonstrate that these products are each compositionally equivalent to a relevant non-GE comparator variety, except for predictable shifts in the fatty acid profile in the case of stacked trait products that contain a trait, MON 87705, that confers a high-oleic-acid phenotype in soybean. In each case, the conclusion on compositional equivalence for the stacked trait product reflects the conclusions obtained for the single trait products. These results provide strong support for conducting a reassessment of those regulatory guidelines that mandate explicit characterization of stacked trait products produced through conventional breeding.