Physical Stability and Tinplate Deterioration in Cans of Evaporated Milk Held Under Refrigeration

Average changes after 4 yr in tin and iron content were not significant in comparison with the fresh control. However, there was a considerable can-to-can variation. The lead content was not significantly changed in storage. The visual color was not significantly darker, although reflectance at 400 mµ did indicate formation of browning compounds. The flavor (hedonic scale) was significantly changed in storage, when consumed as a beverage, but not in coffee. Milk fat separation, protein sedimentation, and lime grain (mineral deposit) were found not to be problems under these storage conditions. The pH dropped slightly (0.1 pH), whereas viscosity and whippability were normal and appeared unchanged relative to fresh controls. Vitamins B1 and B6 did not change, but B2 was reduced 25% and B12 reduced 33% of the original values. Rat feeding tests did not indicate a significant difference in protein quality between storage and control samples. There was some evidence of an increase in NPN and a substantial increase in free fatty acids during storage. Electrophoretic patterns were essentially the same for both the storage samples and controls.