Substituting a sweetener that is mostly sucrose (table sugar, maple syrup) or fructose (agave nectar, 90% fructose) will not work. If you do not use the proper substitute, the fat will separate out of your caramel and the caramel will either end up brittle, or too greasy to stick to your apples. Sucrose is a disaccharide of fructose and glucose; in other words, sucrose is fructose linked to glucose. With caramel apples, the glucose essentially keeps everything in solution. Sucrose has a completely different structure. If there is not enough glucose, the sucrose recrystallizes and the fat gets pushed out of the caramel, and you do not have that chewy creamy goodness. So what is the magical mother nature substitute for corn syrup? HONEY! Honey has about the same glucose and fructose content as corn syrup. It took me 59 caramel apples worth of experimentation, but at the end of it all, I came up with a repeatable recipe for caramel apples that does not include any corn syrup or high-fructose corn syrup.
This video shows a condensed version of the process. The footage is from one of my experimental batches using corn syrup in order to observe the properties of that kind of caramel. Just pretend that I'm adding half a cup of honey instead of Karo syrup:
Step 1: Ingredients and equipment
8 apples (7 if you are a pessimist)
1 cup Heavy Cream
1 cup Brown Sugar (Brown sugar is nice because it already has a caramelly flavor)
1/2 cup Honey
4 tbsp Butter (half of one stick)
That's it. I know. crazy.
1 medium sized pot (one with thick sides works better than a plain old steel one)
1 stirring implement, most likely a spoon
1 greasy little square of aluminum foil big enough to set your caramel apples on
1 cup or small bowl, full of cold water
8 sticks or forks or somethings you will use to jab your apples and hang on to when you eat them
***You will NOT be needing a thermometer of any kind***
Most of the time, the thermometers you buy on a whim at the grocery store can't be trusted. I will teach you how to determine when your caramel is done using the cold water test. Then when you're on a deserted island without your candy thermometer, you can still delight the natives with tasty treats.