Effect of Na-gluconate on the physical properties of preheated and two-step heated gel prepared from walleye pollack surimi

Abstract

Effect of Na‐gluconate on physical properties of preheated and two‐step heated gel prepared from walleye pollack surimi was investigated in connection with the progress of the cross‐linking reaction of myosin heavy chain (HC). The salt‐ground surimi to which either 8% sorbitol or Na‐gluconate was added, was preheated at 25°C or 40°C. Increases in the breaking strength and the breaking strain, together with the cross‐linking reaction of HC, of the salt‐ground surimi with Na‐gluconate proceeded more slowly than in that with sorbitol during the preheating period. The subsequent heating at 90°C for 30 min enhanced the breaking strength of the preheated gel but slightly decreased the breaking strain irrespective of the type of additive used. Gel stiffness of the two‐step heated gels formed with Na‐gluconate was higher than that formed with sorbitol at the same breaking strength, suggesting that the two‐step heated gels with Na‐gluconate were harder but not elastic. This characteristic of the two‐step heated gels formed with Na‐gluconate was mainly developed due to the subsequent heating. The cross‐linking reaction of HC largely proceeded during the preheating period but hardly took place during the subsequent heating period. These results strongly suggest that Na‐gluconate contributed to the production of the two‐step heated gel with higher gel stiffness by affecting the formation of non‐covalent bonds, such as the hydrophobic interaction between myofibrillar proteins.

Changes in physical properties of heat-induced gel on addition of gluconate associated with suppression of myosin denaturation in walleye pollack salt-ground surimi during preheating

“…For example, microbial transglutaminase enhanced breaking strength through cross‐linking of myosin by ε‐(γ‐glutamyl)lysin and resulted in the formation of harder two‐step heated gels 20 . On the contrary, salt‐ground surimi with Na‐gluconate formed less elastic gel despite the suppression of cross‐linking of myosin with covalent bonding, suggesting the involvement of modification in network formation by intermolecular bonding and/or tangling of myosin molecules by non‐covalent interactions 8 . Further, Kitakami et al.…”

“…Our previous papers 7,8 demonstrated that salt‐ground surimis with Na‐gluconate formed two‐step heated gels with higher gel stiffness than those without Na‐gluconate at identical breaking strength. Thus, two‐step heated gels with Na‐gluconate were characterized as harder but less elastic.…”

“…20 On the contrary, salt-ground surimi with Na-gluconate formed less elastic gel despite the suppression of cross-linking of myosin with covalent bonding, suggesting the involvement of modification in network formation by intermolecular bonding and/or tangling of myosin molecules by noncovalent interactions. 8 Further, Kitakami et al 21 indicated that the grade of walleye pollack surimi and the way of heating (either two-step heating or direct heating) also affected the quality of kamaboko gel detected as an increase in SBS0. Thus, there are various factors involved in the increase in SBS0.…”

“…Thus, we studied the effect of Na-gluconate on the quality of two-step heated gels and revealed that the two-step heated gel from walleye pollack surimi with Na-gluconate is characterized as harder but less elastic. 7 Further, our subsequent paper 8 suggested that the change in physical properties of two-step heated gels on addition of Na-gluconate is caused by the modification of non-covalent type interactions between myosin molecules, which are the main proteins responsible for gel formation, during subsequent heating process at 90°C. In general, the formation of non-covalent bonding, especially intermolecular hydrophobic interaction, is postulated to depend on the denaturation process of protein.…”

Permeation of carboxylates as ionic compounds into fish meats by soaking and its osmotic dehydrating effect

“…For example, Na‐gluconate is known to have a cryoprotective effect as well as a solubilizing effect of myofibrillar protein 8,9 . Because of these characteristics, together with the weak salty taste and the healthy function to improve intestinal bacterial flora, 10,11 several studies 12–16 have been carried out on the application of Na‐gluconate to seafood processing as a substitution of NaCl and/or sugars. Na‐malate has been already applied for reduction of NaCl content in fish egg products 17 .…”