Mooncake syrup can be used for other Chinese and Western snacks in addition to making mooncakes, and it can also be used as a substitute for sugar. Mooncake syrup is granulated sugar boiled with water and acid for a certain period of time and at the right temperature, then cooled. This syrup can be kept for a long time without crystallization, and is mostly used in Chinese mooncake crusts, sauces and various products that replace granulated sugar. It is rich in sugar and is an essential ingredient for cakes.

When sugar and water are mixed and boiled, the water will slowly evaporate and the sugar water will become more and more concentrated. When the concentration of sugar water reaches a certain level, after cooling, the sugar will crystallize and precipitate. In order to prevent this phenomenon from happening, we add some acidic substances (citric acid, tartaric acid, etc.) when boiling sugar water. Sometimes lemon juice is used instead), some of the sugar will be broken down by the acid into monosaccharides that are less likely to crystallize. This process is called sugar conversion.