Functional properties of Maillard reaction products of rice protein hydrolysates with mono-, oligo- and polysaccharides

The Maillard reaction was carried out under wet reaction conditions using rice protein product from limited hydrolysis to conjugate with various mono-, oligo- and polysaccharides. The Maillard reaction products (MRPs) prepared with rice protein hydrolysates at 5% degree (hydrolysed by Protease N) and dextran T20 (20 min at 100 °C) showed the greatest improvement in functionality. The solubility, emulsification activity (EA), and emulsification stability (ES) of the MRPs increased by factors of 3.5, 5.3 and 7.3 times, respectively as compared to MRPs formed with native rice proteins and dextran T20. Amino acid analysis indicated that lysine and arginine decreased significantly in the MRPs. Formation of MRPs reduced the surface hydrophobicity, which was in agreement with the change of solubility. However, further decreasing of the surface hydrophobicity resulted in lower EA and ES during the late stage of the reaction. Fluorescence analysis suggested that formation of late stage MRPs occurred after 20 min of the Maillard reaction. The molecular weight distributions showed that the functional properties of MRPs and the mechanisms of formation were affected by the peptide chain length.

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