Effect of Ultrasound Pretreatment on Glycation Characteristics of Parvalbumin with Galactose

Glycation is the initial stage of the Maillard reaction and plays an important role in food processing and storage. This study aimed to explore the effect of ultrasound pretreatment on the glycation characteristics of parvalbumin with galactose. The multilevel structure, glycation degree, glycated peptides and sites of glycated parvalbumin were characterized by high performance liquid chromatography (HPLC) combined with size exclusion chromatography (SEC), intrinsic fluorescence, ultraviolet absorption, synchronous fluorescence spectroscopy and high-resolution mass spectrometry (HR-MS). The results showed that glycation significantly increased the molecular mass, reduced the free amino content, intrinsic fluorescence and ultraviolet absorption intensity, and changed the tertiary structure of parvalbumin. This effect was further promoted by ultrasound pretreatment. The glycated parvalbumin without ultrasound pretreatment contained four glycation sites (K46, K55, K65 and K88), while the number of glycation sites increased to six (K46, K55, K65, K88, K97 and K108) after ultrasonic pretreatment combined with glycation. Therefore, ultrasound pretreatment can result in protein unfolding, increase the degree of glycation, and thereby improve the characteristics of protein glycation.