Impact of Gellan Incorporation on Properties of Fish Gelatin and Surimi Gels

Abstract

Effect of gellan (GL) on properties of fish gelatin (FG) gel was investigated GL at different levels (5-20% of FG substitution) was incorporated into FG. Gel strength and hardness of FG/GL mixed gel increased, while springiness and cohesiveness decreased as the levels of GL were increased (p < 0.05). Gelling and melting temperatures also increased with increasing levels of GL incorporated (p < 0.05). L*- and b*-values of FG/GL mixed gel decreased, whereas E*-value increased with increasing GL levels. The denser structure with very small voids in gel network was observed with GL addition. GL at a low level (5%) had no adverse effect on acceptance, and no effect on syneresis of FG/GL mixed gels. When calcium chloride (CaClz) at various concentrations (3-9 mM) was used in combination with GL (2.5-7.5% FG substitution) in FG gel, gel strength and hardness of FG/GL mixed gel increased as the levels of GL and CaCh increased (P < 0.05). Conversely, the increasing GL and CaCk levels caused a decrease in springiness but an increase in syneresis of mixed gels. Gelling and melting temperatures were increased as levels of both GL and CaCk increased. L*- and b*. values of mixed gels decreased, whereas 4E*-value increased with increasing GL and CaCh levels. Mixed gel in the presence of CaCk at higher levels had denser structure with smaller voids in gel network. Therefore, either 5% alone GL or 2.5% GL in conjunction with 6 mM CaCi could be used to improve gelling property of FG via increasing gel strength and gelling point without affecting acceptance of the resulting gels. Influence of GL with two different forms, powder (GLP) and suspension (GLS), on gel properties of bigeye snapper surimi was studied. Surimi gels added with GLP or GLS had the increases in breaking force and hardness as the levels (2-8% based on surimi solid content) were increased (p < 0.05). The highest breaking force and hardness were observed in surimi gel containing 8% GLS (p < 0.05). Water holding capacity and whiteness of resulting gels were increased as levels of GLP and GLS increased. GL at all levels had no effect on polymerization of myosin heavy chain (MHC). Addition of GLP and GLS could enhance the interconnection between protein chains during heating as indicated by the higher G'. Both GLP and GLS increased acceptability of surimi gel as the level of gellan increased up to 6%. Finer and denser network was observed in surimi gel containing 6% GLS in comparison with that of the control. GL at varying levels (2-6% based on surimi solid content) and CaCle at various concentrations (25-75 mmol/kg) were used to improve gel property of surimi from bigeye snapper. Breaking force, hardness and whiteness of surimi gel increased but expressible moisture content decreased as the levels of GL and CaCk increased (p < 0.05). GL and CaCk at all levels had no effect on polymerization of MHC. The highest overall likeness score was found in gel containing 4% GL and 75 mmol CaCk/kg. Both GL and CaCk also increased breaking force, water holding capacity and whiteness of translutaminase (TGase) free surimi gels. Based on rheological study, GL and CaCi could enhance the interconnection between protein chains during heating as indicated by the higher G'. Different G' curves were obtained between surimi in the presence and absence of Gase. Finer and denser network was observed in surimi gel containing 4% GL and 75 mmol CaCl/kg in the presence of TGase. Therefore, gellan, prepared as suspension, at an appropriate level (6%) could increase gel strength of bigeye snapper surimi with an increased acceptability. In addition, 4% GL in combination with 75 mmol CaClz/kg could improve gel properties of surimi having low and high setting phenomenon mediated by endogenous TGase. Overall, GL was shown as a promising hydrocolloid, which was able to improve properties of both FG and surimi gels.