Tempering is a technique applied in chocolate production to create chocolate that is glossy, has a good snap and smoother texture and is more resistant to chocolate bloom. It involves cooling liquid chocolate while agitating it until a small amount of cocoa butter crystallizes. The liquid is then heated to maintain only the most stable crystal forms, which serve as nuclei for the rest of the cocoa butter to solidify around.
Crystallisation of chocolate was already a concern by the mid-19th century. A textbook of the time for chocolate making notes that good quality chocolate must have a shiny and smooth surface, a clean break, and an optimal mouthfeel. [1]
In 1902, chocolate makers believed the texture and appearance were improved when chocolate was cooled rapidly. By 1931, the tempering process was developed to control chocolate bloom, but it was not understood how it worked. The effects on the crystal structure were not understood until the 1970s. By the 1950s, the tempering process involved cooling chocolate to 86 °F (30 °C), until it was "mushy", then raised to 91.4 °F (33.0 °C) before it was molded. [2]
The invention of tempered chocolate has been attributed to Jean Tobler . [3]
By definition, most of the fat in chocolate is cocoa butter. Like all fats, cocoa butter is made up of several triglycerides, which solidify at different temperatures and rates. [4] [5] When these crystallize, they can form six different structures (traditionally named I through VI by the chocolate industry), and only one of these (V) produces the snap and gloss desired by consumers. [4] [6] [a] This ability of cocoa butter to crystallize in different forms is known as polymorphism. Of the forms the cocoa butter takes, ones that are more dense and have lower energy structures are harder to melt. [9] Chocolate will naturally crystallize into Form V when it is cooled to 93.2 °F (34.0 °C) and then mixed for several days. Tempering is a process to speed this up. [10]
The purpose of tempering is to create the most stable form of cocoa butter. [11] In tempering, a small amount of fat is crystallized (1–3%) to a specific structure, creating nuclei which help the rest of the fat crystallize in the correct form. [12] [13]
Tempering has four steps: [14]
The liquid is subject to high shear, which breaks down crystals and distributes them throughout the liquid. Broken down, more nuclei now exist for fat to crystallize onto. The shear also creates heat, which allows unstable crystals to melt, and later recrystallize, now in the ideal Form V. If there is too much heat however, all the crystals will melt. [10] Over-tempering increases hardness and stickiness, reducing gloss and lightness. [15] After the chocolate is tempered, it is ready for uses such as depositing in molds or being used in an enrober. For these uses, the chocolate is cooled, allowing the fats in the liquid chocolate to crystallize on the nuclei. [16] [17]
Chocolate bloom, a white powdery substance, can appear on the surface of chocolate if it is tempered incorrectly. [5] Untempered chocolate can have a gritty texture, as it can contain chocolate crystals with melting points greater than the temperature of the mouth. [18]
Tempering milk chocolate is more challenging than tempering dark chocolate, as the milk fat in milk chocolate affects how it sets and its final texture. The milk fat lowers the temperature needed for the crystal to seed, reducing it to 84.9 °F (29.4 °C), compared to 94.1 °F (34.5 °C) for dark chocolate. [19] Tempering milk chocolate is also made more difficult in some countries where different fats can be substituted for cocoa butter, as these fats, like milk fats, alter the texture and properties of the chocolate as a eutectic system is formed. [5]
Sugar lowers the melting point of crystal structures, as the sugar molecules are theorized to act as crystallization nuclei. The addition of lecithin to chocolate slows the rate at which fat crystallizes, as researchers theorize the lecithin coats the sugar molecules, creating a surface that the fat has more difficulty crystallizing onto. [20]
The conditions needed for tempering are difficult to control in large-scale productions. [13]
Chocolate, stored before tempering at around 113 °F (45 °C), must be cooled for the fat to crystallize. [21] They are cooled in tempering machines, where chocolate is stirred so it all touches the cool sides. [21] As it is stirred, the material is sheared. The faster it is sheared, the faster the rate of crystallization. As it is sheared in tempering machines, chocolate is worked upwards, through about three or four different temperature zones depending on the machine. In the first zone, the temperature is cooled to the point where crystals can form. In the second, the temperature is reduced further to create different types of crystals, and it is sheared at a higher rate. In the third and final, the temperature is raised, as any correctly formed crystals, which are heat resistant, will not melt in this stage. Some machines include a final stage, where the nuclei are allowed to stabilize by continuing to shear and slowly heat the chocolate. This is known as maturing the temper. [22]
In small-scale production, tempering is done by hand. This is done on a marble table, where chocolate can be moved across different areas which are heated to different temperatures. Initially poured on a cooler area, chocolate is mixed using a scraper, causing crystals to form. It is then moved to a warmer part of the table, where unusable crystals melt. Skilled chocolate makers assess if chocolate has tempered by putting some chocolate on their lip; they can tell it is tempered when they can feel a cooling sensation. Other chocolate makers use a machine known as a "temper meter". This machine observes whether chocolate sets very quickly when cooled, indicating it has been successfully tempered. It is desirable for enrobing and molding to have the chocolate begin to set at a higher temperature. [23] More sophisticated devices measuring whether chocolate is tempered use electric cooling to standardize the rate of cooling and analyze the results using computers. The form of crystals present can be measured using a differential scanning calorimeter. [24]
In a home setting, small amounts of set chocolate are grated into liquid chocolate that has been cooled to 86 °F (30 °C). This technique of tempering only works with chocolate containing cocoa butter, and requires the grated chocolate be distributed throughout the liquid. [10]
The fats in cocoa butter can crystallize in six different forms (polymorphous crystallization). [25] [26] The primary purpose of tempering is to assure that only the best form, Type V, is present. The six different crystal forms have different properties.
| Crystal | Melting temp. | Notes |
|---|---|---|
| I | 17 °C (63 °F) | Soft, crumbly, melts too easily |
| II | 21 °C (70 °F) | Soft, crumbly, melts too easily |
| III | 26 °C (79 °F) | Firm, poor snap, melts too easily |
| IV | 28 °C (82 °F) | Firm, good snap, melts too easily |
| V | 34 °C (93 °F) | Glossy, firm, best snap, melts near body temperature (37 °C) |
| VI | 36 °C (97 °F) | Hard, takes weeks to form |
Chocolate is a food made from roasted and ground cocoa beans that can be a liquid, solid, or paste, either on its own or as a flavoring in other foods. The cacao tree has been used as a source of food for at least 5,300 years, starting with the Mayo-Chinchipe culture in what is present-day Ecuador. Later, Mesoamerican civilizations consumed cacao beverages, of which one, chocolate, was introduced to Europe in the 16th century.
Magma is the molten or semi-molten natural material from which all igneous rocks are formed. Magma is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natural satellites. Besides molten rock, magma may also contain suspended crystals and gas bubbles.
A chocolate bar is a confection containing chocolate, which may also contain layerings or mixtures that include nuts, fruit, caramel, nougat, and wafers. A flat, easily breakable, chocolate bar is also called a tablet. In some varieties of English and food labeling standards, the term chocolate bar is reserved for bars of solid chocolate, with candy bar used for products with additional ingredients.
Frozen yogurt is a frozen dessert made with yogurt and sometimes other dairy and non-dairy products. Frozen yogurt is a frozen product containing the same basic ingredients as ice cream, but contains live bacterial cultures.
Milk chocolate is a form of solid chocolate containing cocoa, sugar and milk. It is the most consumed type of chocolate, and is used in a wide diversity of bars, tablets and other confectionery products. Milk chocolate contains smaller amounts of cocoa solids than dark chocolates do, and contains milk solids. While its taste has been key to its popularity, milk chocolate was historically promoted as a healthy food, particularly for children.
Fudge is a type of dessert bar that is made by mixing sugar, butter and milk. It has its origins in the 19th century United States, and was popular in the women's colleges of the time. Fudge can come in a variety of flavorings depending on the region or country it was made; popular flavors include fruit, nut, chocolate and caramel. Fudge is often bought as a gift from a gift shop in tourist areas and attractions.
Cocoa butter, also called theobroma oil, is a pale-yellow, edible fat extracted from the cocoa bean. It is used to make chocolate, as well as some ointments, toiletries, and pharmaceuticals. Cocoa butter has a cocoa flavor and aroma. Its melting point is slightly below human body temperature. It is an essential ingredient of chocolate and related confectionary products. Cocoa butter does not contain butter or other animal products; it is vegan.
Conching is a process used in the manufacture of chocolate whereby a surface scraping mixer and agitator, known as a conche, evenly distributes cocoa butter within chocolate and may act as a "polisher" of the particles. It also promotes flavor development through frictional heat, release of volatiles and acids, and oxidation. The name arises from the shape of the vessels initially used which resembled conch shells.
Crystallization is the process by which solids form, where the atoms or molecules are highly organized into a structure known as a crystal. Some ways by which crystals form are precipitating from a solution, freezing, or more rarely deposition directly from a gas. Attributes of the resulting crystal depend largely on factors such as temperature, air pressure, cooling rate, and in the case of liquid crystals, time of fluid evaporation.
White chocolate is a form of chocolate made of cocoa butter, sugar and milk. Unlike milk and dark chocolate, it does not contain cocoa solids, which darken the chocolate. White chocolate has an ivory color, and can smell of biscuit, vanilla or caramel, although it can also easily pick up smells from the environment and become rancid with its relatively short shelf life. Like milk and dark chocolate, white chocolate is used to make chocolate bars and as a coating in confectionery.
Sugar candy is any candy whose primary ingredient is sugar. The main types of sugar candies are hard candies, fondants, caramels, jellies, and nougats. In British English, this broad category of sugar candies is called sweets, and the name candy or sugar-candy is used only for hard candies that are nearly solid sugar.
Mango oil, mango kernel fat, or mango butter, is an oil fraction obtained during the processing of mango butter. Mango oil is a seed oil extracted from the stone of the mango, the fruit of the Mangifera indica tree. The oil is semi-solid at room temperatures, but melts on contact with warm skin, making it appealing for baby creams, suncare balms, hair products, and other moisturizing products. The oil is a soft yellow color with a melting point of 32–42 °C (90–108 °F).
In geology, texture or rock microstructure refers to the relationship between the materials of which a rock is composed. The broadest textural classes are crystalline, fragmental, aphanitic, and glassy. The geometric aspects and relations amongst the component particles or crystals are referred to as the crystallographic texture or preferred orientation. Textures can be quantified in many ways. A common parameter is the crystal size distribution. This creates the physical appearance or character of a rock, such as grain size, shape, arrangement, and other properties, at both the visible and microscopic scale.
Chocolate is a food made from roasted and ground cocoa beans mixed with fat and powdered sugar to produce a solid confectionery. There are several types of chocolate, classified primarily according to the proportion of cocoa and fat content used in a particular formulation.
The history of chocolate dates back more than 5,000 years, when the cacao tree was first domesticated in present-day southeast Ecuador. Soon after domestication, the tree was introduced to Mesoamerica, where cacao drinks gained significance as an elite beverage among different cultures including the Maya and the Aztecs. Cacao was extremely important: considered a gift from the gods, it was used as a currency, medicinally and ceremonially. Multiple cacao beverages were consumed, including an alcoholic beverage made by fermenting the pulp around cacao seeds, and it is unclear when a drink that can be strictly understood as chocolate originated. Early evidence of chocolate consumption dates to 600 BC; this product was often associated with the heart and was believed to be psychedelic.
Chocolate bloom is either of two types of whitish coating that can appear on the surface of chocolate: fat bloom, caused by changes in the fat crystals in the chocolate; and sugar bloom, due to crystals formed by the action of moisture on the sugar. Fat and sugar bloom damage the appearance of chocolate but do not limit its shelf life. Chocolate that has "bloomed" is still safe to eat, but may have an unappetizing appearance and surface texture. Chocolate bloom can be repaired by melting the chocolate down, stirring it, then pouring it into a mould and allowing it to cool and re-solidify, bringing the sugar or fat back into the solution.
Ganache is a glaze, icing, sauce, or filling for pastries, made from chocolate and cream.
A chocolate temper meter is used to measure the presence of various types of the crystal forms IV, V in semi-molten cocoa butter in the preparation of well tempered chocolate. It works by measuring "the temperature of a standard weight of chocolate as it crystallizes when cooled in a controlled way." A modern, digital version, the Greer temper meter, can measure the degree of temper at any required time.
Aerated chocolate, also known as air chocolate, is a type of chocolate that intentionally contains gas, forming bubbles.
Dark chocolate is a form of chocolate made of cocoa solids, cocoa butter and sugar. Without added sweetener, dark chocolate is known as bitter chocolate or unsweetened chocolate. Dark chocolate, above white and milk chocolate, is valued for claimed, albeit unsupported health benefits and for being a sophisticated choice of chocolate. Like milk and white chocolate, dark chocolate is used to make chocolate bars and as a coating for confectionery.
Pour reconnaître si la préparation du chocolat a été bien faite, les tablettes doivent être d'un brun clair tirant plutôt sur le rouge que sur le noir; leur surface doit être lisse, brillante; et si, au toucher avec les doigts, la lucidité disparaît; si elle devient terne, on peut déjà avoir de fortes préventions contre sa bonté; sa cassure doit être unie, sans aspérités; il doit fondre doucement sur la langue, sans donner aucune odeur âcre ou piquante; il ne doit développer aucune aigreur, aucune rancidité.[To recognize if the preparation of the chocolate has been well done, the tablets must be of a light brown tending more towards red than black; their surface must be smooth, shiny; and if, when touched with the fingers, the lucidity disappears; if it becomes dull, one can already have strong prejudices against its goodness; its breakage must be uniform, without asperities; it must melt gently on the tongue, without giving any acrid or pungent odor; it must not develop any sourness, any rancidity.]
