Candy Science - Boiling Sugar

I'm Randy and I make candy, but tonight I'm talking science. Stick around. Greetings my confectionary compadres, and welcome to Randy Makes Candy, where I help you make tasty treats that people love to eat. A few weeks ago, in the Starburst episode, I asked if you'd like me to talk about the science behind boiling sugar to make candy. Your positive response is what prompted this video. A lot of candy making deals with changing the structure of crystals, whether it's the cocoa butter in chocolate or the sucrose in sugar. Simply put, we want to separate those crystals from each other, usually by applying heat, then put them back together in a formation of our choosing. When we do that with chocolate, it's called tempering, and I'm going to refer you to the tempering video I did a while back. Tonight, though, we're going to talk about boiling sugar. Boiling sugar is one of the first steps in making candy like fudge, caramels, or hard candy. Raising the temperature of the liquid allows us to add enough sugar to supersaturate it, so that when it cools, it'll recrystallize into a solid mass. You may have heard terms like softball or hard crack. Those are ways to describe the results of bringing your sugar solution to a certain temperature. Here's a chart that correlates temperature with these results, also known as stages. I'll put a link to it in the description below. As you can see, the higher the temperature, the harder the candy. If you want to go old school, instead of using a thermometer, periodically take a bit of the boiled solution, drop it into a glass of cold water, and see if it's as firm as you want. If so, you take it off the heat. If not, you keep boiling it. If it's too firm, you start over. I'll stick with a thermometer. Thank you very much. What we're doing by increasing the temperature is changing the ratio of water to sugar. The longer we boil it, and the higher the temperature, the less water available to soften the mixture. One thing that I don't see often enough in these charts is the fact that they're only accurate at about sea level. Atmospheric pressure lowers as you gain altitude. This leads to a corresponding decrease in the boiling point of water. A good rule of thumb is that the boiling point decreases 2 degrees Fahrenheit for every increase of 1,000 feet above sea level, or 1 degree centigrade for every 300 meters of elevation. We're at about 2,000 feet here in the candy kitchen, so that means that the boiling point of water here is 208 degrees Fahrenheit, as opposed to the 212 degrees we were taught in science class. As a result, if a recipe calls for the temperature of a mixture to be brought up to 248 degrees Fahrenheit, I would only bring it to 244. Think of it this way. If you're at altitude and your water starts boiling below the temperature you expect, then by the time you reach the temperature in the recipe, your mixture has been boiling longer than it should have, you'll have boiled out more water than expected, and you're not going to get the results you want. Of course, this all assumes you have an accurate thermometer. The best way to check this is to boil some water, and as it's boiling, put your thermometer in and check the results. If the thermometer reads 212 degrees Fahrenheit, you're good. Just follow the temperatures in your recipes. If it's lower than 212, or higher, for those of you compadres who live in Death Valley, adjust accordingly. Now that we've dissolved the crystals and gotten the ratio of sugar to water exactly where we want it, what next? Next is controlling the reformation of crystals. If you've been a compadre for a while, you've seen me put a lid on my saucepan for a bit right after the mixture comes to a boil. That's because the process of adding and mixing ingredients may leave some sugar crystals stuck to the side of the pan. If those join the party at the wrong time, they could start a chain reaction and create crystal formations that we don't want. Putting the lid on a pan of boiling liquid traps the steam inside, washing any stray crystals down so they can be melted before they do any harm. You can also use a wet pastry brush to wash down the sides of the pan. I just find the lid method to be a little easier. Once your sugar solution has reached the proper temperature, it needs to cool. As it cools, the sugar starts to recrystallize.