Effect Of Flaxseed Gum On The Emulsified And Gelling Properties Of Minced Meat Products

With the improvement of living standard,the food industry in China has made rapid progress,and the food additives has also been developing in a healthier and more natural direction.Natural hydrocolloids and polysaccharides are widely applied in the meat products with low salt and low fat as fat substitutes.Flaxseed gum(FG),as a natural and healthy food additive,has attracted more and more attention due to its functional characteristics and safety.The addition of flaxseed gum in minced meat products can not only improve oil-and water-retaining property and edible quality,but also meet the consumers' requirements for health.Currently,the researches of flaxseed gum were mainly focused on the functional properties,composition and extraction technology.Few studies have reported the role of flaxseed gum on meat products.And the researches were mainly focused on the production and application.The mechanism of its emulsified and gelling properties was rarely reported.Therefore,the effects of flaxseed gum on the stability of lard emulsion,the emulsified and gelling properties of Myofibrillar protein(MP)and the quality of comminuted meat were investigated in this paper.From simple simulation system to complex comminuted meat system,the mechanism of emulsification and gel of flaxseed gum in meat products was identified.The research includes three parts:1.Effect of flaxseed gum and NaCl concentrations on the stability of oil-in-water emulsions.The effect of flaxseed gum and salt concentration on the stability of the emulsions were investigated by measuring the creaming index,particle size,microstructure,potential,rheological properties and NMR.In the study,the interaction of flaxseed gum and lard and the salt resistance of flaxseed gum with different concentrations would be confirmed.The increase of FG concentrations significantly decreased the creaming index(P<0.05)of emulsion and the more stable emulsions were made at lower NaCl concentrations.There was no creaming behavior in the emulsions with 0.4%and 0.5%(w/w)FG at low ionic strength.With the increase of FG concentrations and the decrease of NaCl concentrations,the droplet size decreased.Micrographs showed that aggregation/flocculation appeared in the emulsion with high FG content(0.4-0.5%,w/w).The potential value of FG stabilized emulsion remained negative under all ionic strength conditions.The value of potential decreased with the increase of ionic strength(P<0.05).And the FG concentrations had insignificant difference on the potential(P>0.05).Salt concentrations had no significant effect on the rheological properties of emulsion(P>0.05).The apparent viscosity and shear stress of the emulsion increased with the increase of FG concentration(P<0.05).The G'and G' of emulsion increased with the increase of FG concentration,and the G' was higher than that of G" on the whole.The emulsion containing 0.5%(w/v)FG appeared gel-like structure.It was found that-(CH2)n-group was far away from oil and water interface by nuclear magnetic scanning.With the increase of FG concentration and the decrease of salt content,the line width increased,which indicated the increase of interaction between oil molecules and FG.2.Effect of flaxseed gum on the emulsified and gelling properties of myofibrillar protein at different NaCl concentrations.The influence of FG on the emulsion stability of MP emulsion under different salt concentration was studied by creaming indx,potential value,particle size and microscopic observation.The effect of FG on the chemical force of MP gel was studied by force measurement.The addition of 0.4%flaxseed gum can significantly improve the emulsion stability of myofibrillar protein emulsion and its salt tolerance.There was no creaming behavior in the FG-MP emulsions at all given ionic strength.With the increase of salt concentration,the emulsion stability of MP emulsion increased significantly(P>0.05),but it would be affected by storage time under high salt condition.Both MP and FG-MP emulsions were kpet at negative charge state.The potential of FG-MP emulsion was bigger than that of MP emulsion.Moreover,with the increase of NaCl concentration,the potential value of MP emulsion gradually decreased(P<0.05).For the emulsion containing 0.4%FG,the potential value increased slightly with the increase of the salt concentration(P>0.05).By particle size measurement and microscopic observation,it was found that the particle size of MP emulsion decreased first and then increased with the addition of NaCl(P<0.05).The particle size reached the minimum at 0.4M NaCl.NaCl had insignificant effect on the particle size of FG-MP emulsions(P>0.05).And although the particle size of MP emulsion was smaller than FG-MP emulsion,there was a tendency to gather together in MP emulsion.The formation of MP gel and FG-MP gel system was contribution to disulfide bonds and non-disulfide covalent bonds,while ionic bonds and hydrogen bonds were not the main chemical forces to maintain the stable conformation of the gel.3.Effect of flaxseed gum on the emulsified and gelling properties of comminuted meat at different NaCl concentrations.The effect of flaxseed gum on the emulsified and gelling properties of comminuted meat under different NaCl concentrations was studied by measuring water-losing and oil-losing rate,texture,scanning electron microscope,surface particle protein and protein electrophoresis.With the increase of salt concentration,the oil-and water-losing rate of samples decreased significantly(P<0.05).The addition of FG could contribute to the water and oil retention.The hardness,elasticity,cohesiveness and chewiness of comminuted meat gels were significantly increased with the increase of NaCl concentrations(P<0.05).In addition,the texture indexes of samples without FG were greater than that with FG at 0.6M NaCl.Under other salt concentration conditions,the hardness and chewiness of the gel with FG were worse than that without FG,while the elasticity and cohesiveness of the FG gel were better.Scanning electron microscopy showed that the muscle protein was filamentous without adding salt,and had not formed the network structure.With the improvement of salt concentration,the three-dimensional structure of the gel began to form.Flaxseed gum could make meat gel network to present the sheet structure,and the structure became more compact.NaCl significantly improved surface protein adsorbed content(P<0.05).With the increase of NaCl concentration,the electrophoresis band of protein membrane increased and became clearer.The surface proteins are mainly composed of myosin heavy chain,myosin light chain 1,myosin light chain 2,C-protein,alpha myosin,actin,troponin T,myosin,troponin 1 and troponin C(calcium binding subunit).The addition of flaxseed gum can improve the kinds and contents of surface proteins and improve the stability of emulsion.