Effect Of Chaotropic Ion And Rosemarinic Extract On The Functional Properties Of Pork Myofibrillar Protein

High-salt has become one of the major harmful factors affecting public health in the world,being as important targets of low-salt in food field,the existing ways of low-temperature emulsified meat products to reduce salt are still not perfect.Low-salt easily affects the emulsion stability and oil-holding capacity of meat emulsions.However,it is not clear that effect of salt and its analogues on the above change.Chaotropic ions(Cl-,K+,and L-histidine)play an important role in the function of muscle proteins at certain condition,which can solubilize muscle proteins and affect the emulsion stability and oil-holding capacity of meat batters,but its specific ways of effect are still not clear.This is the reason why firstly built a pork myofibrillar protein-olive oil emulsification system to explore effects of its concentration on oil-holding capacity and stability of emulsions,and analyze the effect of chaotropic ions on protein solubility and oil-holding capacity of emulsions and establish a correlation between them.Then,we further explored the causes of chaotropic ion-mediated protein aggregation or dissolution and indicated the reason for the change in oil-holding capacity at the aggregation state of the protein before adsorbed to the interface.The main conclusions of this research are as follows:1 Analysis of the stability of emulsions show differences in the protein concentration,when protein concentration were 5%and 10%,the stability of emulsion was significantly increased(P<0.05),the particle size was 1-10 μm,the amount of protein adsorption and oil-holding capacity were increased significantly(P<0.05).In addition,the oxidation of fresh emulsion(1%,5%,10%)was effectively inhibited by the interface protein membrane,which also being an important way for oil-holding capacity of the emulsion(1%).In contrast,when protein concentration was high(10%),the oil-holding capacity of emulsions were improved by interface adsorbed myofibrillar protein and gel matrix.2 The results showed that the solubility of pork myofibrillar protein increased significantly in the presence of L-histidine(80 mM)(P<0.05),which was compared to the control group(1 mM KCl)at low ionic strength,the particle size distribution of pork myofibrillar protein oil-in-water emulsions was mainly between 1-10μm when L-histidine was present at low ionic strength compared to the control group.The distribution was uniform and the emulsion microstructure was similar.It was confirmed that the particle size distribution of the emulsion formed was uniform and there was no obvious aggregation distribution.The emulsion stability was effectively improved,and the oil holding capacity was significantly increased(P<0.05),while the oil holding capacity of the conventional high salt(0.6 M)group was significantly greater than that of the low ion strength(P<0.05).The correlation analysis showed significant positive correlation between solubility and oil-holding capacity(P<0.01,R=0.954).The accumulation of pork myofibrillar proteins in bulk solution significantly affected oil-holding capacity,and the presence of L-histidine at low ionic strength can affect the oil-holding capacity of pork myofibrillar protein oil-in-water emulsions.3 The solubility of pork myofibrillar protein firstly increased significantly(P<0.05)with L-histidine concentration,the surface hydrophobicity and average particle size of the protein and protein particles were both significantly lower(P<0.05)than control group(1 mM KCl).Atomic force microscopy revealed that the aggregates of the protein aggregates in the L-histidine-treated group were less distributed than the control group at low ionic strength.The profile is highly prominent and there is no significant lateral aggregation between the samples.Thus,the presence of L-His at low ionic strength improves the aggregation behavior of myofibrillar proteins,which inhibits lateral aggregation between proteins and increases protein solubility,a process that may be associated with electrostatic interactions and changes in surface hydrophobicity.4 The results indicated that the addition of rosemarinic extracts go against the formation of stable gel network structure and the water holding capacity of pork myofibrillar protein became poorer under the NaCl concentration(0.45 mol/L).However,remarkably common role of rosemarinic extracts and NaCl(0.45 mol/L)on improving gel strength,storage modulus and the water holding capacity,decreasing the intrinsic fluorescence intensity.Owing to the advantageous change of MFP’s tertiary structure,the water holding capacity may has no obvious decline at the condition of section reducing NaCl dose.