液态配方乳储藏过程中物理性质变化的研究

为研究液态配方乳在储藏期内物理性状的变化及温度对其变化的影响,将液态配方乳在25、30、40 ℃下储藏6个月,通过测定pH、黏度、粒径、Zeta-电位、颜色、上下层脂肪和蛋白质以及底层矿物质含量来进行对比分析。结果表明,储藏期间液态配方乳pH、黏度降低,色差和粒径逐渐增大,并且随温度升高,变化速度加快。25 ℃时,脂肪上浮和蛋白质沉淀略有变化,但40 ℃时变化情况较为严重。通过相关性分析发现,矿物质与蛋白质沉淀形成关系密切。回归分析表明,不同指标在同样的加速条件下对常温下货架期的预测关系是不同的,实际操作时需根据产品的配方特性筛选出适用的指标进行货架期预测。本研究有助于液态配方乳储藏期内品质保持、储运条件的选择及货架期的预测。

Study on Physical Properties Change of Liquid Formula Milk during Storage

The physical properties of liquid formula milk and effect of temperature on the properties were studied under different storage temperatures(25,30 and 40 ℃)for 6 months. pH,viscosity,particle size,Zeta-potential,color,fat(upper and bottom)and protein,bottom minerals were analyzed. The results indicated that pH and viscosity of liquid formula milk decreased while color change and particle size increased gradually during the storage,and the rate of change accelerated with the increase of temperature. Fat separation and protein precipitation increased slightly at 25 ℃,but became more serious at 40 ℃. Correlation analysis showed that bottom mineral contents were significantly related to protein precipitation. Uni-variate regression analysis indicated that different indexes had different prediction relationship for shelf life at room temperature under the same accelerated condition,and the applicable indexes of shelf life prediction should be selected according to the formula characteristics of products in practical analysis. This research could provide some guidelines for the quality maintenance of liquid formula milk during transportation and storage,also for its shelf-life prediction.