form in the fluid chocolate mass which is necessary to ensure a long shelf life. Incorrectly tempered chocolate has a short shelf life, poor gloss and low stability. A fault known as bloom can develop. This appears in two forms 1. Development of crystals of unstable fat on the surface of the chocolate. 2. Sugar crystallization on the surface of the chocolate. The fats in cocoa butter can crystallize in six different forms (polymorphous crystallization). The primary purpose of tempering is to assure that only the best form is present. The six different crystal forms have different properties. Crystal Melting temp. Notes I 17o C (63o F) Soft, crumbly, melts too easily. II 21o C (70o F) Soft, crumbly, melts too easily. III 26o C (78o F) Firm, poor snap, melts too easily. IV 28o C (82o F) Firm, good snap, melts too easily. V 34o C (94o F) Glossy, firm, best snap, melts near body temperature (37°C). VI 36o C (97o F) Hard, takes weeks to form. Making chocolate considered "good" is about forming as many type V crystals as possible. This provides the best appearance and texture and creates the most stable crystals so the texture and appearance will not degrade over time. To accomplish this, the temperature is carefully manipulated during the crystallization. Generally, the chocolate is first heated to 45o C (115o F) to melt all six forms of crystals. Next, the chocolate is cooled to about 27o C (80o F) (the chocolate thickens at this temperature), which will allow crystal types IV and V to form. At this temperature, the chocolate is agitated to create many small crystal "seeds" which will serve as nuclei to create small crystals in the chocolate. The chocolate is then heated to about 31o C (88o F) to eliminate any type IV crystals, leaving just type V. After this point, any excessive heating of the chocolate will destroy the temper and this process will have to be repeated. However, there are other methods of chocolate tempering used. The most common variant is introducing already tempered, solid "seed" chocolate. The temper of chocolate can be measured with a chocolate temper meter to ensure accuracy and consistency. A sample cup is filled with the chocolate and placed in the unit which then displays or prints the results. Two classic ways of tempering chocolate are Manual working of the molten chocolate on a heat-absorbing surface, such as a stone slab, until thickening indicates the presence of sufficient crystal "seeds"; the chocolate is then gently warmed to working temperature. 09
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