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.