What technique is used to avoid crystallization when boiling sugar syrup?

When boiling sugar syrup, washing down the sides of the pan with water is a key technique to prevent crystallization. This method helps to eliminate sugar crystals that may form on the sides of the pan during the cooking process. If sugar crystals remain lodged on the sides, they can fall back into the syrup and cause the entire mixture to crystallize, resulting in a grainy texture rather than a smooth syrup.

By using a brush or cloth dipped in water to wash the sides of the pan, you create a more uniform and stable syrup. This is particularly important when making candies or certain dessert sauces where a smooth texture is desired. The introduction of water helps to dissolve any sugar crystals that have already begun to form, maintaining the clarity and consistency of the syrup.

The other options, while they have roles in other cooking techniques, do not directly address the issue of crystallization in the context of boiling sugar syrup. For instance, adding salt may alter the boiling point but does not prevent crystallization, using a non-stick pan may affect cooking but does not specifically address sugar behavior, and stirring constantly can actually promote crystallization in certain scenarios.