What is a supersaturated solution

When a solvent is filled with the substance in solution so that it cannot dissolve any more it is said to have formed a 'saturated' solution of that substance.

Sugar is soluble in water. Water is therefore the solvent and sugar is the solute. To illustrate the principle of super-saturation, start by dissolving as much sugar as possible into some water. After adding sugar and constantly stirring the mixture for some time you will find it impossible to dissolve any more sugar. If you do add more it will remain undissolved and sink to the bottom of the beaker. If the contents of the beaker are now gently heated, the sugar at the bottom will dissolve and if more sugar is added it can also be dissolved. This process can be continued until once again the water can dissolve no more sugar. Again the water is saturated with sugar. It is obvious that the same amount of hot water has more sugar in solution than it could hold when cold. If the solution is then allowed to cool without stirring to the same temperature as the cold solution, the previously warm solution will contain more sucrose: it will be a cold supersaturated solution.

If a quantity of water at boiling point in which is dissolved as much sugar as it can hold is continued to be heated then, as the solution boils, water is driven off but the amount of sugar remains the same. This results in a hot super-saturated solution. The longer the solution is heated, the less water remains and the greater the degree of super-saturation. This causes a rise in temperature, which continues to increase until not only is all the water driven off but the sugar decomposes. At any stage between the production of super-saturation until caramelisation occurs the solution is in a very unstable condition. It would be easy to understand how simple it would be to cause the sugar to form again as crystals, and very little agitation, or merely the addition of a single crystal of sugar will cause the whole of the sugar to crystallise out again. This must be guarded against in the boiling of sugar and is also seen in some icings as surface eruptions.

To prevent the mass from graining through the ebullition of boiling liquid an acid (usually cream of tartar) is added or an amorphous sugar, such as corn syrup, which effectively does the work of preventing graining taking place until it is required to happen.

Continue reading here: What was the Aquazyme process

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