Genetic and environmental variation in protein composition of Belgian soy determined with a novel size-exclusion chromatography method

To allow the determination of soy protein composition on protein subunit level in a quantitative manner, a novel method combining size-exclusion high-performance liquid chromatography (SE-HPLC) and peak deconvolution was developed. Peaks corresponding to the different soy protein (subunits) were identified based on the analysis of (i) marker proteins, (ii) 7S and 11S globulin-enriched fractions, and (iii) cross-validation with SDS-PAGE analysis. Given the recent introduction of soybean cultivation in Belgium, the optimized SE-HPLC method was here applied to study the impact of genotype, growing location, harvest year and inoculation strategy on the protein composition of Belgian soy. Especially genotype and harvest year were key to determining protein composition, while all factors influenced the chemical composition of soy flour. The developed SE-HPLC method can be used to further understand the impact of soybean cultivation practices in Belgium and elsewhere on protein composition, which is highly relevant for novel applications of soy. In addition, this SE-HPLC method can be used to determine how various soy processing methods may affect protein composition.