干燥方法对乳蛋白氧化及机体氧化还原状态的影响

Effects of drying methods on oxidation of dairy protein and redox state

目的:研究乳蛋白经过干燥后,乳蛋白氧化及对机体氧化还原状态的影响。方法:通过不同进风温度(160、170、180℃)对全脂乳和脱脂乳进行喷雾干燥及全脂乳的冷冻干燥处理,测定其羰基、巯基含量。小鼠分为6组,分别灌胃原奶、喷雾干燥不同温度乳粉、脱脂乳粉及冷冻干燥乳粉,测定0、30、60、90、120min血液中自由基水平,测定60、90min后小鼠肝脏、空肠、十二指肠、胃组织抗氧化能力指标(丙二醛MDA、总抗氧化能力T-AOC、GSH/GSSG)。结果:乳蛋白经过喷雾干燥及冷冻干燥处理后,羰基含量随温度的上升及脂肪含量的增多显著上升(p<0.05),巯基含量呈下降趋势。冷冻干燥组羰基含量比全脂喷雾干燥组低,巯基与之相比呈上升趋势。小鼠血液自由基的最高峰出现在灌胃90min时,灌胃喷雾干燥乳粉自由基含量显著高于其他组(p<0.05),并随温度的升高而增高。小鼠喷雾干燥组中组织总抗氧化能力T-AOC和谷胱甘肽比值GSH/GSSG均低于其他各组,丙二醛(MDA)含量高于别组。结论:喷雾干燥等加工方法会导致乳蛋白发生不同程度的氧化,导致乳蛋白理化性质的变化,短期灌胃氧化蛋白会引起机体的氧化应激,降低组织抗氧化的防御能力。

Objective=To investigate the effects of dairy protein modified by spray drying and freeze drying on physical and chemical properties as well as redox state in mice. Methods：Whole milk and skim milk were processed for different entering air temperature（160,170,180℃） by spray drying,the whole milk also was processed by freeze drying. The variation on carbonyl content,free thiol group of dairy protein was measured in vitro. The mice were divided into six groups,gavage different dairy protein separately. The production of free radical in mice blood was detected respectively at 0,30,60,90,120min after administration. The redox-related indicators （T-AOC, MDA, GSH/GSSG ） in liver, stomach, jejunum, duodenum were determined. Results ：The carbonyl content of dairy protein was increase along with the temperature increase and the fat increase（p〈 0.05）,while free thiol group content decreased. The free radical peak of blood appeared at 90min. The blood free radical was significantly higher in mice spry drying whole milk than that of skim milk and freeze drying whole milk. The T-AOC,GSH/GSSG content of tissues were significantly decrease that the whole milk by spry drying （170℃） compare to skim milk and the whole milk by freeze drying,while the MDA content was increase. Conclusion：The fat content and high temperature would promote dairy protein oxidation,the oxidation would lead to changes in physical and chemical properties of dairy protein. Short-term intake of oxidized dairy protein could cause a high oxidative stress in mice.