Effect Of Gellan Gum Compounding System On Quality Characteristics Of Minced Pork And Its Application

Pork meatball is a kind of high fat emulsified minced meat product,which is prone to water loss,oil and loose texture after processing.Although meat proteins in pork meatballs,especially myofibrillar protein（MP）,have beneficial emulsifying properties to stabilize meat emulsion,they are highly sensitive to p H,salt content and temperature.Therefore,the addition of exogenous emulsifier can effectively inhibit the precipitation of water and fat to improve the product quality.High acyl-gellan gum（HA）is a linear,negatively charged extracellular polysaccharide,and low acyl-gellan gum(J₃₀₀)is the deacylated form of HA.Konjac gum（KG）is a kind of non-ionic water-soluble polymer polysaccharide,andτ-Carraneenan（τ-CG）is a linear anionic sulfate polymer.All of them can be used as emulsifiers in the food system.Although HA can bind with meat protein to stabilize the O/W interface,its property limitations will lead to many deficiencies to effectively stabilize emulsion-based meat products.Therefore,HA needs to be combined with the above colloids to obtain the synergistic emulsification effect.Here are the main research contents:（1）Using the emulsion-based meat products（pork meatballs）as the carrier,the optimal addition ratio of HA,J300,τ-CG and KG in pork meatballs was determined by single factor experiment.Then the gellan gum compounding system was obtained by combining HA with the optimal addition ratio respectively,and the influence of the compounding system on the emulsification characteristics of minced pork was explored.The results showed that the optimal proportions of HA,J300,τ-CG and KG were 0.4%,0.2%,0.3%and 0.3%,respectively.After the results of the compound experiment were normalized,the composite of 0.3%KG and 0.4%HA obtained the highest score of 6.1,which determined the combination of HA and KG as gellan gum compounding system.The compounding system significantly reduced the SAP loss rate of minced pork,protein surface hydrophobicity,protein solubility,minced meat viscosity and emulsifying ability（EC）were significantly increased.And the highest elastic modulus（G’）was obtained at the end of the rheological test,indicating that the gel structure of minced pork became more ordered.By confocal laser scanning microscopy,it was observed that the compound system promoted the decrease of fat droplets,uniform binding and entanglement of protein matrix.Raman analysis showed that the complex system promoted the secondary structure development of meat protein,theα-helix ratio decreased significantly,and theβ-sheet increased significantly.This is because the protein structure is ordered in the process of heat induction,forming a tight network structure.The use of complex colloid increases the hydrophobic contact between fat and protein side chains.The hydrophobic interaction is the main intermolecular force to maintain the functional properties of gellan gum compounding system,followed by the electrostatic interaction.（2）MP is an endogenous emulsifier that plays a major role in emulsified minced meat products.MP was extracted from minced pork and combined with colloid to form a coemulsifying system.The results showed that the emulsion activity（EAI）was significantly improved by the gellan gum compounding system,and the emulsion chromatography index（CI）value was 0,that is,no emulsion separation occurred during the 5-day storage period.In the kinetic stability analysis diagram,it was also observed that the emulsion phase separation speed was significantly reduced with the complex colloid and MP stable.Compared with blank group and positive control group,the value ofζ-potential was significantly increased（from 19.93 m V to 38.56 m V）.The smallest particle size（from 31.70μm to 17.83μm）was observed in both the emulsion particle size distribution and fluorescence microscope images.And the highest interfacial protein concentration was obtained（from 23.81 mg/m2 to 81.01 mg/m2）.In addition,the compounding colloid is more closely aligned with MP and more easily adsorbed at the interface,thus obtaining the highestπvalue.（3）In order to explore the mechanism of emulsifying properties of the co-emulsifying system,β-mercaptoethanol,sodium thiocyanate,1,2-pentanediol and urea were used to destroy disulfide bonds,electrostatic interactions,hydrophobic interactions and hydrogen bonds in the co-emulsifying system composed of HA/KG and myofibrillar protein.The results show that electrostatic interaction is the most important intermolecular interaction,followed by hydrophobic interaction and hydrogen bond.The anions in HA/KG are connected to MP by electrostatic interaction,which improves the flexibility of MP adsorption and arrangement at the interface,and the electrostatic repulsion can prevent droplet coalescence.In addition,HA/KG can inhibit the negative effects of disulfide bond on emulsification.（4）Gellan gum compounding system was used as a fat substitute to replace different proportions of fat in pork meatballs,so as to explore the possibility of overcoming the adverse effects of fat reduction.The results showed that with the increase of fat replacement ratio,the yield of pork meatballs increased significantly,reaching the maximum 94.32%at 50%replacement,and the oil yield decreased significantly to 0.1%.Once the substitution ratio is greater than 50%,the hardness,elasticity,cohesiveness and chewability of pork meatballs are significantly reduced,resulting in poor texture characteristics.The brightness of pork meatballs decreased with the increase of substitution ratio.Pork meatballs with a replacement ratio of less than 50%had deteriorated on the seventh day,while pork meatballs with a replacement ratio of more than 50%were still within the standard allowable range.Therefore,it is feasible to replace 50%fat with gellan gum compounding system to improve the final product quality of pork meatballs.