What is the process technique for boiling syrup?

Conversion and crystallization of sugar
Sugar is readily soluble in water to form a sugar solution. At room temperature, 2 parts of sugar can be dissolved in 1 part of water, forming a saturated solution.

Under heating conditions, the amount of sugar in the sugar solution can even reach more than 3 times the amount of water, i.e. a supersaturated solution. When it is stirred or placed, the sugar will crystallize from the solution, a phenomenon known as sugar recrystallization, commonly known as sugar back to the sand. Because sucrose has coarse crystalline particles, it is sometimes necessary to inhibit this crystallization.

When a sugar solution is heated to boiling, the sucrose molecules are hydrolyzed to 1 molecule of fructose and 1 molecule of glucose. This action is known as sugar conversion, the two products are called converted sugar. The sugar solution becomes syrup, or converted syrup, when it is heated to boiling. The degree of conversion of sugar has an important effect on the recrystallization properties of sugar. Because converted sugar is not easy to crystallize, so the higher the degree of conversion, the less sucrose can be crystallized, the lower the role of sugar crystallization.
Controlling the rate of the conversion reaction can control the crystallization of sugar to some extent. Acid (such as organic acids) can catalyze the conversion reaction of sugar, glucose has fine grains, both can inhibit the crystallization of sugar back to the sand, or get fine crystals (microcrystalline), so that the products are fine and bright.

In the production of paste decorations such as cream paste and egg white paste, usually to boil the syrup to 116 to 118 ℃, to achieve this degree of conversion of the syrup, when added to the whipped cream or egg whites, not only can form a smooth sugar paste, but also due to the high viscosity of the syrup, so that the egg whites or cream in the foam more stable. Syrup boiling process and characteristics
Sugar syrup in the boiling process, water evaporation, sugar concentration gradually increased, becoming more and more viscous, the boiling temperature (boiling point) is also a progressive increase. The boiling temperature (boiling point) also rises progressively. There is a certain correspondence between the syrup concentration and the boiling point. In addition to the use of sugar meter measurement, but also by the physical characteristics of the syrup to determine the temperature and concentration of the syrup, so as to grasp the syrup boiling whether the required temperature has been reached.

The following is an introduction to the “hand method” to identify the syrup boiling a number of stages and the corresponding temperature. The beginning of the boiling stage 104.5 ℃, sugar bubbling. Line stage 107 ℃, with the index finger contact the surface of the syrup, and then together with the thumb, and then separate the two fingers, you can pull the syrup into a thin line of sugar with stretch. Pearl stage 110°C, in the same way as above; when the thread breaks, a liquid bead can be formed at the end. Blowing stage 113 ℃, with a wire loop into the syrup and then take out, the loop can form a film, and the film can be gently blown. Feather stage 115 ℃, the syrup film can be blown into a feather. Soft ball stage 118 ℃, dipped in a little syrup, drops into cold water, that is, with two fingers pinch the sugar drops, when the two fingers gently rubbed, you can feel the syrup between the fingers to form a soft ball with plasticity. Hard ball stage 121 ℃, the same method as above, the syrup to form a solid hard ball. Soft shell stage 132 ~ 138 ℃, the surface of the sugar ball has a thin shell, and will be slightly broken. Hard shell stage 138 ~ 154 ℃, the surface of the sugar ball into a thick shell, it requires a greater force to make it broken. Caramel stage 154 ~ 180 ℃, the sugar becomes amber color, and with the increase in temperature from light to dark. Syrup boiling method
1, the sugar and water (about half of the sugar) into a clean pot, placed on a small fire heating, while constantly stirring until the sugar is completely dissolved.
2, turn up the heat, continue to heat until the sugar solution boils. If you need to add organic acids (such as citric acid) or glucose, can be added at this time.
3, once boiling, stop stirring. If sugar crystals appear on the edge of the pot, use a small amount of water to rinse them into the sugar solution. In the boiling process, skim off the surface foam at any time.
4, quickly boil the syrup to the desired temperature while it lasts.