Improvement of the rheological properties and freeze-thawing stability of Pickering emulsions filled emulsified surimi gels:Effects of the interfaces of surimi particles and konjac glucomannan

Abstract

The emulsified surimi gels (ESGs) with soft texture and smooth taste are extremely susceptible to deterioration during freeze-thawing (FT) processes, which often brings about poor appearance and acceptability. However, how to improve the FT stability of ESGs remains an unmet challenge. In this work, the ESGs with single soybean oil , or surimi particles (SPs) and konjac glucomannan (KGM) based Pickering emulsions via one-step or layer-by-layer approaches were first prepared and the rheological characteristics of these ESGs were investigated. Then, the gel properties, lipid oxidation, protein degradation and protein-lipid interactions of ESGs subjected to various FT cycles were further explored. Results showed that the SPs and KGM based Pickering emulsions acting as active fillers improved the viscoelastic modulus of ESGs, rather than simply “dispersing in the pores of gel networks”, in contrast to samples with single soybean oil. Although successive FT cycles destroyed the thawing drip loss , water holding capacity and network skeletons, as well as increased lipid oxidation of ESGs, the SPs and KGM based Pickering emulsions filled ESGs exhibited greater gel properties than the groups without addition of Pickering emulsions after FT treatments, indicating both Pickering emulsions were beneficial to maintain the initial quality of ESGs during these FT processes. Additionally, both Pickering emulsions changed the crystallization behaviors of water and oil in the ESGs. From a molecular view, we also observed that these existed protein aggregates with low or high molecular weight, and strong protein-lipid interactions in the Pickering emulsions filled ESGs whether FT treatments or not, which were closely related to the high FT stability of samples. Generally, the SPs and KGM stabilized Pickering emulsions with various interface structures had certain potential to regulate the formation and FT stability of the ESGs. • SPs and KGM based Pickering emulsions improved the rheological feature of ESGs. • The thawing drip loss of all ESGs gradually increased with increasing FT cycles. • FT treatments destroyed the network skeletons and protein aggregates of ESGs. • Pickering emulsions changed the crystallization behaviours of water and oil of ESGs. • Pickering emulsions filled ESGs exhibited better gel properties after FT treatments.