Characterization of soybean beta-conglycinin and glycinin proteins from selected genotypes

Soy protein fractions β-conglycinin and glycinin were isolated from K1430, Hutcheson, K93-90-29, and KS4997 genotypes grown in 1998 and KS4997 grown in 1999. Spectroscopy, chemical, and physical (functional) tests were used to differentiate among the isolated fractions grown in the same and different crop years.; Using spectroscopic tryptophan emission and synchronous fluorescence techniques, isolated protein fractions from different genotypes and crop years were discriminated. The β-conglycinin and glycinin emission fluorescence intensities ranged from 1.08–1.53 and 1.00–1.31, respectively, whereas the β-conglycinin and glycinin synchronous fluorescence intensities ranged from 1.00–2.41 and 1.01–1.52, respectively.; The amino acid residues of each respective soy fraction exhibited the same NMR spectra but with different peak intensities. NMR spectra of fractions revealed that soy proteins from different genotypes have unique signatures. In the KS4997 evaluated, soy proteins from crop years 1998 and 1999 exhibited distinctive NMR signatures.; The individual fractions and a 50:50 mix were evaluated and compared for their chemical characteristics and functional properties. Protein contents of β-conglycinin and glycinin fractions ranged from 85.1–90.1% and 89.9–93.3%, respectively. There were significant differences in functional properties among genotypes grown in 1998. K93-90-29 β-conglycinin significantly had best mean values for all functional properties, while KS4997 the lowest. Hutcheson glycinin significantly exhibited the highest functional properties mean values, while KS4997 the lowest and the different genotypes exhibited significantly different thermal stabilities. Significant differences in functional properties mean values were reported for 50:50 mix. The 50:50 mix showed that glycinin has better functional properties than β-conglycinin. Significant differences were found between crop year 1998 and 1999 of KS4997 for all chemical and functional properties evaluated.; The research showed that spectroscopic methods are rapid, reliable, and effective techniques to differentiate among different soybean genotypes from different crop years. Spectroscopic methods can determine unique soy protein signatures of individual genotypes and fractions and can be used to assess protein quality of different crop years. Soy genotypes and crop years play an important role in influencing functional properties of soy foods.