全蛋液微波巴氏杀菌动力学及蛋白质变化研究

Study on microwave inactivation kinetics and protein variation of liquid whole egg

热传导式的传统巴氏杀菌方法由于传热方式的限制,会导致全蛋液的过度热加工,造成蛋白质变性、产品品质劣变。微波体积式加热效率高,有利于降低巴氏杀菌过程对热敏蛋白质的影响。该文研究了全蛋液的微波巴氏杀菌,探究了微波巴氏杀菌对全蛋液中3种典型微生物(大肠杆菌、沙门氏菌和金黄色葡萄球菌)的杀菌效率、微波巴氏杀菌动力学及对全蛋液蛋白质的影响。结果表明,微波巴氏杀菌升温迅速(<50 s)且杀菌效果显著(致死对数>5 log10)。Log-Logistic模型拟合精度和稳定性最佳(R2:0.998~0.999,均方根误差:0.002~0.072),Log-linear+Tail模型拟合效果好且变量少(R2:0.982~0.999,均方根误差:0.026~0.298)。模型拟合结果与存活曲线趋势一致,进一步证明了模型的有效性和准确性。微波巴氏杀菌使蛋白质溶解度增加0.021~0.030。微波诱导蛋白质适度展开,极性基团暴露,游离巯基含量增加,有利于产品品质的改善。

Due to the heat transfer limitation of conductive heating,traditional pasteurization method may lead to overheating of liquid whole egg(LWE),denaturing the proteins and thus damaging the LWE products.Microwave volumetric heating,with merit of high ther-mal efficiency,could mitigate the influence of pasteurization on thermal-sensitive proteins.This study investigated the microwave pasteur-ization process for LWE.The sterilization efficiency on three typical microorganisms(Escherichia coli,Salmonella Enteritidis,and Staphy-lococcus aureus),the inactivation kinetics of microwave pasteurization,and the protein variation of LWE were studied.The results showed that microwave pasteurization had short processing time(<50 s)and high sterilization efficiency(lethality>5 log10).The Log-Logistic model had the best fitting accuracy and stability[R2:0.998-0.999,root mean square error(RMSE):0.002-0.072],while the Log-linear+Tail model had fairly good fitting accuracy and less variables(R2:0.982-0.999,RMSE:0.026-0.298).These results were consistent with the trend of survival curves,further proving the effectiveness and accuracy of the models.Furthermore,microwave pasteur-ization dramatically increased the protein solubility by 0.021-0.030.The ordered structure of proteins was unfolded under microwave fields,leading to the exposure of polar groups and the increase of free sulfhydryl groups,thus improving the quality of products.