Impact of dextran conjugation on physicochemical and gelling properties of sweet potato protein through Maillard reaction

Covalently linked sweet potato protein (SPP)–dextran conjugates were produced through Maillard reaction, and the effects of this conjugation on physicochemical and gelling properties of SPP were studied. Formation of SPP–dextran-conjugated product was confirmed with increase in browning intensity and molecular weight, with concomitant reduction in free amino group content of the protein. Dry-heating period of 0, 1, 3, 5 and 7 days gave rise to 0%, 12.8%, 19.0%, 25.2% and 22.8% degree of conjugation (DC), respectively. High molecular weight protein polymer with polydispersed band above 50 kDa was formed. FTIR spectroscopic analysis showed that the C-O (amide I) and C-N (amide II) stretching bands were modified by the Maillard reaction. Conjugation of SPP with dextran reduced its denaturation temperature. SPP–dextran conjugate gels’ network structures were sustained by both physical interactions and covalent bonds. SPP–dextran conjugates’ gels had significantly improved hardness and resilience in comparison with the unmodified SPP (P < 0.05).