青霉素-牛乳蛋白复合物及其热稳定性的研究

Study on the Penicillin-Milk Protein Complex and Its Thermal Stability

目的:采用超滤法联合高效液相色谱研究青霉素与牛乳蛋白结合形成的复合物及其热稳定性。方法:模拟牛乳环境,在pH 6.6、37℃水浴条件下,将青霉素分别与脱脂乳、酪蛋白和乳清蛋白混合,水浴培育10、30、60、90、120 min,经超滤离心后使用高效液相色谱仪测定其结合率。通过结合率的变化得出结合达到平衡的时间。经巴氏杀菌和超高温灭菌处理后的脱脂乳与青霉素的结合率的测定方法同上。结果:青霉素与脱脂乳、α-酪蛋白、β-酪蛋白、κ-酪蛋白、牛血清白蛋白达到结合平衡分别需要10、30、30、30、60 min,结合率分别为28.80%、20.36%、16.13%、5.61%、10.07%。青霉素未与β-乳球蛋白、α-乳白蛋白结合。经过巴氏和超高温杀菌后青霉素与脱脂乳的结合率分别为28.83%和44.62%。结论:牛乳中,酪蛋白是与青霉素结合的主要成分,乳清蛋白中的牛血清白蛋白与青霉素也有结合。巴氏杀菌过程对青霉素与脱脂乳的结合没有影响,而超高温灭菌过程会使结合率升高。

Objective：The penicillin-milk protein complex and its thermal stability were studied by ultrafiltration and HPLC.Method：In order to determine the binding rate by HPLC after centrifugal ultrafiltration,penicillin was mixed with skim milk,casein and whey protein respectively,and incubated in pH6.6,37 ℃ water bath for 10、30、60、90 and 120 min.The time to reach equilibrium was obtained by the change of binding rat.The method of determining skim milk after pasteurization and UHT was same as above.Result：The time for penicillin binding skim milk,α-casein,β-casein,κ-casein and bovine serum albumin to reach equilibrium were 10 min,30 min,30 min,30min and 60 min respectively,and the binding rate were 28.80%,20.36%,16.13%,5.61% and 10.07% respectively.However,penicillin could not bind to β-lactoglobulin and α-lactalbumin.After pasteurization and UHT,the rate of penicillin binding skim milk were 28.83% and 44.62% respectively.Conclusion：Casein is the main penicillin binding component in milk,and bovine serum albumin could also bind to penicillin.Penicillin binding rate with skim milk was not affected by pasteurization,but would rise after UHT.