Scaling Down Caramelized Sweetened Condensed Milk

I make a caramel sauce using sweetened condensed milk as the base at work. I recently faced a common cooking "problem" of scaling a recipe. Besides using the caramelized milk for sauce, I also harden it so I can use it as a caramel ingredient in other recipes. The hardened caramelized milk has a similar flavor to Kraft caramels; you know - the ones you can use to make caramel apples. I decided to use the hardened caramel in an ice cream recipe that I tested at home. Since I needed only a small amount, I decided to purchase the 14 oz. cans available on the retail market. The question I faced was how to convert my procedure for cooking a #10 can, which is approximately 96 oz., into a procedure for cooking a 14 oz. can.

To get the sweetened condensed milk to the proper caramel color, I cook the #10 can in barely simmering water for five hours, monitoring it closely and adding more water if the level goes below the top of the can. Please keep in mind that the manufacturer specifically says not to boil the milk in the cans. However, as long as the water isn't boiling (it is barely even bubbling), I have never encountered a problem. Once the milk has spent the required time in the water, I pull it out of the water and allow it to cool at room temperature for at least an hour and a half before opening the can. This allows the inside pressure to stabilize so the contents won't come shooting out when you open the can. So if a #10 can takes 5 hours to get to the proper temperature, how long will a 14 oz. can take - 2 hours, 4 hours? I decided to cook two cans to get my answer. I pulled the first one out of the water after two hours and the second one out of the water after four hours. After allowing them to cool at room temperature for an hour, I opened them up to see the results. I expected the can that cooked four hours to be very dark and the two hour one to be just about right. I actually found that neither can was dark enough. My final conclusion - I should have cooked the 14 oz. can for five hours - the same amount of time as the #10 can.

Since neither can was cooked enough, I needed to continue the cooking process to achieve my desired end result of a darker color and richer flavor. Someone brought to my attention an article from the internet about caramelizing the condensed milk in the microwave. I decided to give it a try. The directions say to put the milk in a deep bowl or 2-quart glass measure as the mixture boils up. I used a 74 oz. glass bowl and discovered that it wasn't deep enough because indeed, the mixture did boil over as the cooking process progressed. I followed the directions carefully (50% power for 4 minutes, stirring after 2 minutes, and then 30% power in 2 minute intervals until done) and in the end I got the results I was after.

I came to the conclusion it was much more time effective to use the microwave to achieve the same end results. A distinct plus with the microwave method is that you can see your product turn into caramel before your eyes and you can stop the process when the color is right. Cooking in the can is complete guess work and several factors, such as the heat level, can change the results each time.