I've been thinking about what would make a really good 200th blog post for the past couple of weeks when I came across my blog analytics and the things that you search for in Google that lead you to my humble corner of the internet. So, let's go, I'm going to answer all of your questions in detail. Let’s start with your most favourite question: Lemon crystals are a crystallized form of lemon juice , which is used in cooking and food preparation to give a citrusy, tart and sour taste to whatever you're making and can also be used to create lemon juice or lemonade.