Thermo-reversible gelation and enhanced umami perception of myofibrillar proteins induced by protein-glutaminase-mediated deamidation

Abstract

In this study, the absolute electrostatic charge of myofibrillar protein (MP) was substantially increased by protein glutaminase (PG) treatment, which was a critical step for achieving the dissociation and solubility of MP under low salt condition. The PG-treated MP exhibited the capacity to form thermo-reversible gels that could be melted through heating and subsequently reformed into a stable gel structure upon refrigeration. The results of SDS-PAGE further revealed that the levels of soluble monomeric myosin and actin in the supernatant of deamidated MP (DMP) gels were markedly elevated, and confirmed the increased formation of intermolecular disulfide bond between myosin and actin. Additionally, moderate deamidation was beneficial for the improvements of MP gel properties, especially in terms of water-holding capacity and springiness. Electronic tongue and correlation analysis indicated that the umami perception of DMP was significantly enhanced because of the conversion of glutamine (Gln) to glutamate (Glu) residues that induced by PG deamidation.