Carnation evaporated milk is not a good substitute for fresh milk in the 1:1 ratio recommended on the can. But how about watering it down first?
Evaporated milk has been heated to remove half of its water. When we tested a straight 1:1 substitution for fresh milk as recommended on a can of Carnation (the most widely available brand), we found that the concentrated sugars, fats, and proteins in the milk caused recipes to fail: Cakes were denser and puddings were overly thick.
To see if a dilution would work better, we tested three different ratios of evaporated milk and water in vanilla pudding, sponge cake, and béchamel sauce. A mixture of 75 percent evaporated milk to 25 percent water was still too concentrated—pudding was gluey, sponge cake was dense, and béchamel was thick and cloying. Dialing the ratios down to 67 percent evaporated milk and 33 percent water helped only a little. But a 50-50 mix produced results that were close to the all-regular-milk versions in all three cases. It’s good to know that we can keep a ready substitute for fresh milk in the cupboard.