Study On Ultra High Hydrostatic Pressure Sterilization Technology And Storage Period Of Liquid Whole Eggs

This project uses fresh eggs as raw materials to prepare liquid whole eggs.Liquid whole eggs were treated with Ultra High Hydrostatic Pressure(UHHP)with and without table salt.Effect of UHHP on total bacterial count,liquid whole eggs quality and shelflife was evaluated and compared with effect of pasterurization.Possibility of using UHHP to replace traditional pasterurization was investigated from those three aspect.The results are as follows:No Salmonella was detected after UHHP processing and UHHP processing with table salt treated.All E.coli detected met the standard requirment.The total number of colonies is1.95×10~2~6.03×10~2 CFU/mL(reduced by 4.40~4.39 logarithmic values)which is lower than the count 7.50×10~2 CFU/mL(reduced by 4.38 logarithmic values)from pasterurization,confirming UHHP processing is more effective than pasteurization.After Ultra High Hydrostatic Pressure processing,Liquid Whole Egg particle size,surface potential,protein denaturation rate,whiteness,and apparent viscosity increase with increasing pressure and dwell time.Foaming properties,foam stability,and sensory scores decrease with increasing pressure and dwell time.Decrease;For UHHP with table salt treated,the salt suppresses the increase in particle size,surface potential,whiteness and viscosity caused by stress,promotes foaming and foam stability first and then inhibits it,increasing protein denaturation rate and reducing senses score.The processing conditions with the least impact on the physical properties and sensory quality of Liquid Whole Egg were obtained:holding pressure at 300 MPa for 5 min and adding 3%common salt,holding pressure at 250 MPa for7.5 min.Compared with pasteurization,the particle size of Liquid Whole Egg after UHHP processing was 2242.63 and 1676.23 nm,the surface potential was-6.18 and-6.80 mV,the protein denaturation rate was 24.84 and 24.18%,and the whiteness was 62.00 and 50.70.The foamability was 58.86 and 66.20%,the foam stability was 61.50 and 70.07%,the apparent viscosity was 0.0602 and 0.0400 Pa.s,respectively,and the sensory scores were 85 and 87points.Compared with pasteurization,its physical properties are closer to fresh liquid whole eggs,which has less effect on sensory quality.Ultra High Hydrostatic Pressure processing(300 MPa holding pressure for 5 min)and UHHP with table salt(adding 3%table salt,250 MPa holding pressure for 7.5 min)liquid whole eggs can be stored at 4?for 22 and 26 d,respectively,at 25?Stored at 12 and 14 d respectively,the shelflife is longer than that of pasteurized Liquid Whole Egg(12 d at 4?,6d at 25?).No Salmonella was detected during storage time,the number of E.coli and the total number of colonies continued to increase,and the physical properties and sensory quality decreased.Compared with pasteurization,UHHP and UHHP with table salt have a better inhibitory on Salmonella and E.coli..The physical properties change less or are closer to fresh eggs,and the sensory scores are higher than pasteurization.UHHP can not only greatly extend storage time,but also has less impact on physical properties and sensory quality.It is fully confirmed that Ultra High Hydrostatic Pressure treatment can be used as a new method to replace traditional pasteurization in processing liquid whole eggs.