Protein structural development of threadfin bream (Nemipterus spp.) surimi gels induced by glucose oxidase

Abstract

This study investigated the effect of glucose oxidase on the gel properties of threadfin bream surimi. The gel strength of surimi increased with the addition of 0.5‰ glucose oxidase after two-step heating. Based on the results of the chemical interactions, the hydrophobic interaction and disulfide bond of glucose oxidase-treated surimi samples increased compared with the control samples at the gelation temperature and gel modori temperature. The surface hydrophobicity of samples with glucose oxidase and glucose increased significantly ( p < 0.05) and total sulfhydryl groups decreased significantly ( p < 0.05). The analysis of Raman spectroscopy shows that the addition of glucose oxidase induced more α-helixes to turn into a more elongated random and flocculent structure. Glucose oxidase changes the secondary structure of the surimi protein, making more proteins depolarize and stretch and causing actomyosin to accumulate to each other, resulting in the formation of surimi gel.

Textural and physicochemical properties of threadfin bream surimi gels prepared with salted duck egg white as substitute for hen egg white

“…There are four major interactive forces involved in the protein interactions associated with gel strength: hydrogen bonds, ionic bonds, hydrophobic interactions and disulphide bonds (Wang et al ., 2018). A disulphide bond, a covalent bond associated with the gel strength of surimi (Liu et al ., 2014), was the main bond detected in the surimi gels prepared with either egg white protein (SDEW and HEP), as given in Table 1.…”

“…During the heating process, the hydrophobic regions of the denatured proteins can become exposed to the protein surface and the aggregation of protein molecules is generated to facilitate the formation of subsequent chemical bonds (such as disulphide bonds) (Li et al ., 2022). Therefore, the hydrophobic interactions played the most important role in the formation of the surimi gels (Hayakawa & Nakai, 1985; Wang et al ., 2018). However, the disulphide bonds are associated with the increase in breaking force of the surimi gels, and therefore, they exerted the most interactive forces at the cooling step (taking place within a 4–10 °C range after the heating process) (Lanier et al ., 2004; Wu et al ., 2019).…”

“…A small number of ionic bonds (the weakest bonds) were also identified in all surimi gels. The ionic bonds, involving protein dispersion during the mixing process of the surimi paste prepared with salt ions, were frequently abolished by the heating process (Wang et al ., 2018). Therefore, the addition of SDEW improved the gel structure and resulted in an improvement of the gel properties by enhancing the formation of disulphide bonds and hydrophobic interactions.…”

“…The chemical interactions or bonds were determined using the slightly modified methods of Wang et al . (2018) and Jiang et al . (2022).…”

“…The chemical interactions or bonds were determined using the slightly modified methods of Wang et al (2018) and Jiang et al (2022). Surimi gels were treated with chemical reagents selected for their capacity to cleave a certain type of bonds: 0.05 M NaCl (S1), 0.6 M NaCl (S2), 0.6 M NaCl + 1.5 M urea (S3), 0.6 M NaCl + 8 M urea (S4) and 0.6 M NaCl + 8 M urea + 0.5 M β-mercaptoethanol (S5).…”