Infrared spectroscopy as applied to glycinin film and gel formation kinetics

Secondary structural changes of glycinin during film and gel formation were studied by infrared spectroscopy. Two complementary data treatments-i.e., principal component analysis and two-dimensional correlation spectroscopy-w ere applied to the infrared spectra in order to determine the time evolutio n of conformational changes. Kinetic curves, assessed by taking scores of t he first principal components into account, revealed more pronounced change s in the case of film formation. The development of aggregates in film and gel, through intermolecular beta -sheets, was identified by an increase of the absorbance band at around 1620 cm(-1). Two-dimensional infrared correla tion spectroscopy made it possible to observe a decrease in both alpha -hel ices and disordered structures prior to the appearance of aggregates. Chang es in intramolecular beta -sheets took place in a second step. The more dra stic changes observed in the case of film formation were believed to result from dehydration and aggregation coupled phenomena.