Why does sweetened condensed milk turn dark and become lumpy?
Rating: 97 If sweetened condensed milk is stored for a long period of time, it might become lumpy and darken in color. The lumpiness comes from protein thickening. The color change is from the Maillard reaction. It is safe to use if the can is still in good condition. You may not want to use it in a product where lightness in color is desired. PREPARED BY: Angela M. Fraser, Ph.D., Associate Professor/Food Safety Specialist, and Carolyn J. Lackey, Ph.D., R.D., L.D.N.