Sugar-coating the facts: crystallisation
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The sucrose molecule: C12H22O11
Try the activities below for more about physical and chemical changes in cooking
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How sweet it is: the science of sugar The most commonly used sugar in cooking is granulated sucrose, C12H22O11. Sucrose is made from two simpler sugars: fructose and glucose. Sucrose interacts with other ingredients in the following ways:
...I want candy: confectionery and the science of sugar* Whether you call it candy, sweets or lollies, making confectionery is a precise science: playing with sugar and heat allows you to transform matter from one state to another, and judging when and how to make changes can result in the difference between a pan full of scorched sugar or a delicious, gooey or glass-like treat. Sugar's ability to solidify into crystals is extremely important when making confectionery. Candies can be categorsied in two way:
Recipe ingredients and procedures for noncrystalline candies are designed to prevent the formation of sugar crystals, because they give the resulting candy a grainy texture. When making confectionery, a batch can be ruined if the heated sucrose returns to its crystallised state. One way to prevent crystallisation is to ensure that there are other types of sugar - usually, fructose and glucose -to get in the way. It's harder for sucrose crystals to reform when fructose and glucose molecules are in the mix, as different molecule sizes and shapes don’t fit together as readily. One way for glucose and sucrose to be part of a mix is to "invert" the existing sucrose in a recipe by addition of an acid. Weak acids (cream of tartar, citric acid or vinegar) invert (break the sucrose down) into fructose and glucose. Fats in candy work similarly: ingredients such as butter and cream interfere with crystallisation - again, by obstructing sucrose molecules from reforming crystals. Toffee's brittleness and smooth texture are due to butter in the recipe, prohibiting sugar crystals from reforming. * remember, all things in moderation... The Candy-o-Matic : see the effect of increasing sugar temperature and the types of confectionery created
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