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

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Abstract
Samples from evaporated milk stored at 32[degree]F were subjected to physicochemical analyses after 4 yrs. The average changes in Sn and Fe content were not significant in comparison with the fresh control. There was a considerable can-to-can variation. The Pb content was not significantly changed in storage. The visual color was not significantly darker, although reflectance at 400 m[mu] did indicate formation of browing compounds. The flavor was significantly changed in storage (when tested as a beverage but not in coffee). Milkfat separation, protein sedimentation and lime grain (mineral deposit) were not problems under these storage conditions. The pH dropped slightly (0.1 pH). 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 evidence of an increase in nonprotein N (NPN) and a substantial increase in free fatty-acids during storage. Electrophoretic patterns were essentially the same for both samples.