Effects Of Processing Conditions And Frozen On Emulsifying Properties Of Pork Myofibrillar Proteins

During the processing of emulsion-type meat products, the meat proteins give them unique flavor,taste and nutrition, in addition, some of its features, such as emulsifying, plays an important role on the final quality of the products. The role of emulsifying determines the final quality and taste of the products. However, the lax controls of productions,improper operation, especially the bad meat emulsion or bad meat emulsion stability, result in the products out of oil,loose structure and so on,they may bring the manufacturers economic loses. In this study, turbidimetry was used to measure emulsifying properties of myofibrillar proteins in different speed,pH and concentration, also the impaction of freeze-thaw times and freezing time.they provide a theoretical basis for the development of the emulsion-type products. The specific content and results are as follows:1 The effects of pH(5.0,5.5,6.0,6.5,7.0) and protein concentration (1,2.5,5,7.5,10,12.5,15mg/mL) on the emulsifying properties were investigated, the emulsion was formed by the myofibrillar proteins((0.6mol/L KCl, pH6.5,20 mmol/L phosphate buffer solution(PBS)). The emulsifying properties included the emulsifying activity index(EAI) and emulsifying stability index(ESI). Determined the emulsion viscosity with a viscosimeter and observed the emulsion microstructure under a Phase-contrast microscope. The results showed that when pH was closed to the isoelectric point, the EAI was higher but the ESI was poorer, the EAI and ESI had no significant difference when pH changed from 6.0 to 7.0; The EAI decreased when the emulsion concentration changed from lmg/mL to 15mg/mL, while the ESI increased. the oil in water emulsion structure was formed when concentration arrived at 5mg/mL.2 The effects of shear speeds,which expressed with speeds of the homogenization machine(4000,6000,8000,10000,12000,14000rpm) and oil quantity(6,8,10, 12,14,16mL) on the emulsifying properties were investigated. The results showed that the EAI and ESI increased with increasing speed from 4000rpm to 14000rpm, the particals became smaller when the speeds increased, the EV had the same trend with the ESI. The EA and ESI increased when the oil quantity increased from 6mL to 14mL, but the ESI suddenly decreased when the oil quantity increased from 14mL to 16mL, the EV suddenly increased but the ESI suddenly decreased, the aggregation of the oil droplets can be observed under a Phase-contrast microscope.3 The effects of freeze-thaw times(0,1,3,5,7 times)and frozen time(0,10, 20,30,40,50days)of the meat on the emulsifying properties of myofibrillar proteins were investigated. The results showed that it formed oil in water emulsions when the freeze-thaw times increased, the emulsifying activity index(EAI) didn't change significantly, but the emulsifying stability index(ESI) was lowerer. The viscosity, solubility and surface tension of the proteins were decreased, they have the same trends with the ESI; When the frozen days became longer, the EAI decreased, the ESI decreased within 30 days, while then increased, the solubility and surface tension of the proteins are decreased, but the viscosity of the emulsions have the same trend with ESI.In conclusion, protein concentration, pH, speeds, oil quantity, freeze-thaw times and frozen time are all the important factors witch affect the emulsifying properties of myofibrillar proteins, the emulsions have different characteristics under different conditions.