Every 5% increase of milk fat content in chocolate formula will decrease the melting point of chocolate 1℃. Therefore, the melting temperature of different brands and varieties of chocolate is different, so it is best to consult the factory before using it. Generally speaking, the tempering temperature of chocolate is as shown in the following figure: the four temperatures respectively represent four stages: (1) heating and melting in water, (2) cooling, (3) heating, and (4) the end point of cooling and solidification packaging. Among them, bitter-sweet chocolate has the highest melting temperature because of the least amount of milk powder, so it needs to be heated to about 45℃ to melt, then cooled to 28℃, then heated to 32℃ for the convenience of molding, dipping and other operations, and finally placed to about 20℃ for solidification and packaging. The milk fat content in milk chocolate and white chocolate is higher than that in bitter-sweet chocolate, and the four temperatures are (40℃, 25℃, 30℃, 20℃) (40℃, 24℃, 28℃, 20℃). Ok, let's have a general concept first, and then why we need a process of Tempering, that is, the qualitative principle of tempering. After that, detailed steps will be provided on how to adjust the temperature, and what kind of chocolate needs to be adjusted and what is not.

Principle of temperature regulation: Why do you need temperature regulation? Chocolate is made from the seeds of the cocoa tree. Cocoa beans can be obtained by fermentation, drying and baking of cocoa pods, which contains about 5 1%~55% fat, that is, "cocoa butter". Cocoa butter, a kind of oil, is very magical. It is composed of various fatty acids, and its composition ratio is very different from other oils. Compared with butter, butter and other oils, its solid fat index curve is steep, and it begins to soften at 28 degrees Celsius, and the solid components quickly turn into liquid at 33 degrees Celsius. Why can chocolate remain hard and solid at room temperature, and it will be brittle when bitten, but it will melt in the mouth? It is cocoa butter, which has a narrow melting point and is close to human body temperature, that makes chocolate taste. The melting point of γ-type crystal is 16~ 18℃, which is very unstable and transforms into α-type in about 3 seconds. Negligible. The structures of the other three crystals are shown in the following figure: among them, α-type crystals (type I and type II): melting point 17~23℃, and transformed into β'-type crystals at room temperature for one hour. Soft, fragile and easy to melt. β'-type crystals (type III and IV): The melting point is 25~28℃, and it turns into β-type crystals at room temperature for one month. Hard texture, not brittle, easy to melt. The most stable β -type crystals (V-type and VI-type) have a melting point of 33~36℃, a hard and brittle texture and a melting temperature close to human body temperature. However, the most stable VI-type crystals with the highest melting point are coarse and have a bad taste, and Fat Bloom will appear on the surface (which is why a layer of "white frost" will form on the surface of chocolate after it is kept for a long time), so the metastable V-type crystals with a relatively stable and shiny appearance have become the most ideal oil structure. The purpose of temperature adjustment is to obtain the most ideal homogeneous polymorph by adjusting the temperature, so that the chocolate tastes better and looks better. Back to the four temperatures mentioned above, why is the second cooling point of bitter-sweet chocolate until 28℃? It is to prevent cocoa butter from forming other undesirable crystals, which will affect the quality of finished chocolate. In addition, cocoa paste and sugar in chocolate will also have an impact on the crystallization process, but relatively speaking, it is not as great as the impact of temperature regulation, so I will skip it here for the time being.