Keeping quality of evaporated milk depends primarily on the destruction of the contained organisms by heat. Normally, the heat treatment used is entirely satisfactory, but, occasionally, organisms survive. Some of these are species that do not cause changes ill evaporated milk in cans, while others are species that bring about conspicuous defects. Spoilage sometimes occurs when there has been no intentional or discernible modification of a heat treatment that has been employed successfully over extended periods. Outbreaks are frequently spasmodic but during their brief existence may cause extensive financial losses.