喷雾干燥工艺对胶束态酪蛋白结构及抗氧化性的影响

Effect of spray-drying conditions on the structure and antioxidant activities of micellar casein

以脱脂牛乳为原料,采用超滤技术获得胶束态酪蛋白,研究进口温度130℃和150℃、雾化压力0.05 MPa和0.1 MPa喷雾干燥工艺下胶束态酪蛋白粉末的水分含量、粒径、堆积密度、表面形貌、溶解性、内源荧光特性以及抗氧化活性(还原力、Fe 2+螯合力、DPPH和ABTS自由基清除活力),并以冷冻干燥样品为对照。结果显示,随着喷雾干燥温度和雾化压力的升高,胶束态酪蛋白粉末的水分含量显著降低(P<0.05),堆积密度显著增大(P<0.05),粒径在150℃-0.1 MPa条件下最大,为(2.16±0.29)μm;冻干胶束酪蛋白的粒径最小,为(1.31±0.02)μm,堆积密度最大,为(416.47±3.94)mg/mL,水分含量与130℃-0.1 MPa和150℃-0.05 MPa下喷干样品差异不显著(P>0.05)。随着喷干温度和压力的升高,胶束态酪蛋白的溶解性和内源荧光强度呈现下降趋势,但最大发射波长和表面形貌不变。冻干样品的溶解性在pH 7时为(87.63±0.35)%,与130℃-0.05 MPa下的喷干样品差异不显著(P>0.05)。就抗氧化活性而言,130℃喷干时胶束态酪蛋白具有较好的还原力和ABTS自由基清除活力,150℃喷干时胶束态酪蛋白的DPPH自由基清除能力较好。进口温度150℃和雾化压力0.05 MPa工艺下胶束态酪蛋白的Fe 2+螯合能力最强。研究结论可为胶束态酪蛋白产业化开发及干燥工艺选择提供参考依据。

In this study,cow skim milk was chosen as raw materials,and micellar casein was obtained by ultrafiltration and spray-dried under the temperature of 130℃and 150℃with a spray pressure of 0.05 MPa and 0.1 MPa,respectively.The following parameters,including moisture content,particle size,bulk density,topography,solubility,intrinsic fluorescence and antioxidant properties of micellar casein,were measured.Freeze-drying samples were used as the control group.The results showed that as spray-drying temperature and pressure increased,the moisture content decreased and bulk density increased significantly with the maximum particle size of(2.16±0.29)μm under the conditions of 150℃-0.1 MPa.The solubility of freeze-drying samples was(87.63±0.35)%at pH7,which was similar to the solubility of spray drying samples.The freeze-drying samples had a minimum particle size of(1.31±0.02)μm,and maximum bulk density of(416.47±3.94)mg/mL.And the moisture content was similar to those of samples under 130℃-0.1 MPa and 150℃-0.05 MPa spray-drying conditions.Moreover,the solubility and intrinsic fluorescence reduced when temperature and pressure increased.However,the maximum emission wavelength and micellar topography did not alter.The best reduce power was obtained with the spray-drying samples at 130℃had and ABTS free radical scavenging activities were also good,while samples obtained at 150℃had the best DPPH free radical scavenging activities.Furthermore,the spray-drying micellar casein at 150℃and 0.05 MPa had the best Fe 2+chelating capacity.This study could provide references for the industrial development of micellar casein and the optimization of spray-drying parameters.