Chromatographic and electrophoretic approaches for the analysis of protein quality of soy beverages

Furosine, generated by acid hydrolysis of fructosyllysine, an early Maillard reaction product, is a highly valuable indicator of food quality and, more specifically, of food protein quality. Ion pair RP-HPLC and CZE techniques were employed to determine furosine content in beverages based on soymilk (n = 15) and cow's milk supplemented with soy isoflavones (n = 1). The levels of furosine found in the samples ranged from 25.55 ± 0.18 to 170.72 ± 10.4 mg/100 g of protein by HPLC and from 28.67 ± 1.84 to 161.25 ± 5.78 mg/ 100 g of protein by CZE. Results obtained by both analytical techniques do not differ significantly (p >0.05), confirming their feasibility for furosine analysis in soymbased products.