I love sugar, especially when it’s in the form of a caramel or a butterscotch-type “quick caramel” sauce, drizzled over cakes and ice cream, or baked apples. Unfortunately, sugar can be a bitch a pain to work with. I should know: half my PhD was spent struggling with sugars in the lab. Sadly, my sugar chemistry wasn’t the kind you could eat, and my relationship with sugar was so tumultuous that there were days when I would have happily set fire to my lab bench and just walked away. At conferences, when I’d talk about my work, other chemists would literally laugh at me because they could envision just how “messy” my sugar chemistry was and I think they were all-too-pleased to not be standing in my shoes, facing my daily battles with sugars.
In the kitchen, I think the number one problem with working with sugar is that it crystallizes, especially when you don’t want it to, like when you are making quick caramel sauces. Fortunately, there are tricks that you can do so that your caramels and sauces don’t turn gritty.
What is sugar?
In the kitchen, the most common form of sugar is granulated sugar. People often assume that granulated sugar is glucose, but it’s not. Glucose, along with fructose, are actually the building blocks that make up each molecule of sucrose that is granulated sugar. Brown sugar, like white sugar, is also mostly sucrose. It’s important to note that in sucrose, glucose and fructose are chemically bonded.
The other type of sugar you need to be aware of is “invert sugar”, such as corn syrup. Invert sugars are made when larger sugars, like sucrose, are broken down to their basic building blocks, glucose and fructose. What most people don’t realize is that corn syrup actually comes from corn starch. Starch is the storage form of glucose in plants, and it’s a long chain of glucose molecules bonded together. If you treat starch with either an enzyme (amylase) or an acid and a little heat, the starch chains break down into their building blocks: you obtain lots of glucose. Corn syrup is thus a mixture of glucose, fructose, and sucrose. Honey is also an invert sugar: bees drink flower nectar containing sucrose, and they secrete an enzyme (invertase) that breaks down the sucrose (digestive acids also help this process) to form glucose and fructose.
Why do we need to know about sucrose?
When sucrose is present in high concentrations, like when you are making butterscotch that’s loaded with brown sugar, the sucrose molecules tend to pile up and crystallize. The molecules just can’t help but crystallize because there is so much sucrose around. The caramels and quick caramels can become powdery, or even gritty (if larger crystals form) because the sucrose is essentially precipitating/crystallizing out of the sauce.
How do you stop sugar from crystallizing?
The proof is in the pudding