Interesting fact: The smell of chocolate increases theta brain waves, which triggers relaxation.
Several types of chocolate can be distinguished. Pure, unsweetened chocolate, often called “baking chocolate”, contains primarily cocoa solids and cocoa butter in varying proportions. Much of the chocolate consumed today is in the form of sweet chocolate, which combines chocolate with sugar.
Milk chocolate is sweet chocolate that also contains milk powder or condensed milk. In the UK and Ireland, milk chocolate must contain a minimum of 20% total dry cocoa solids; in the rest of the European Union, the minimum is 25%. “White chocolate” contains cocoa butter, sugar, and milk, but no cocoa solids. Chocolate contains alkaloids such as theobromineand phenethylamine, which may have physiological effects in humans, but the presence of theobromine renders it toxic to some animals, such as dogs and cats. Chocolate contains “brain cannabinoids” such as anandamide, N-oleoylethanolamine and N-linoleoylethanolamine. Dark chocolate has been promoted for unproven health benefits.
White chocolate, although similar in texture to that of milk and dark chocolate, does not contain any cocoa solids. Because of this, many countries do not consider white chocolate as chocolate at all. Because it does not contain any cocoa solids, white chocolate does not contain any theobromine, so it can be consumed by animals.
Dark chocolate is produced by adding fat and sugar to the cacao mixture. The U.S. Food and Drug Administration calls this “sweet chocolate”, and requires a 15% concentration of chocolate liquor. European rules specify a minimum of 35% cocoa solids. Semisweet chocolate is a dark chocolate with a low sugar content. Bittersweet chocolate is chocolate liquor to which some sugar (typically a third), more cocoa butter, vanilla, and sometimes lecithin have been added. It has less sugar and more liquor than semisweet chocolate, but the two are interchangeable in baking.
Unsweetened chocolate is pure chocolate liquor, also known as bitter or baking chocolate. It is unadulterated chocolate: the pure, ground, roasted chocolate beans impart a strong, deep chocolate flavor. It is typically used in baking or other products to which sugar and other ingredients are added. Raw chocolate, often referred to as raw cacao, is always dark and a minimum of 75% cacao.
Poorly tempered chocolate may have whitish spots on the dark chocolate part, called chocolate bloom; it is an indication that sugar and/or fat has separated due to poor storage. It is not toxic and can be safely consumed.
The final process is called tempering. Uncontrolled crystallization of cocoa butter typically results in crystals of varying size, some or all large enough to be clearly seen with the naked eye. This causes the surface of the chocolate to appear mottled and matte, and causes the chocolate to crumble rather than snap when broken. The uniform sheen and crisp bite of properly processed chocolate are the result of consistently small cocoa butter crystals produced by the tempering process.
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.
|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|
As a solid piece of chocolate, the cocoa butter fat particles are in a crystalline rigid structure that gives the chocolate its solid appearance. Once heated, the crystals of the polymorphic cocoa butter are able to break apart from the rigid structure and allow the chocolate to obtain a more fluid consistency as the temperature increases – the melting process. When the heat is removed, the cocoa butter crystals become rigid again and come closer together, allowing the chocolate to solidify.
The temperature in which the crystals obtain enough energy to break apart from their rigid conformation would depend on the milk fat content in the chocolate and the shape of the fat molecules, as well as the form of the cocoa butter fat. Chocolate with a higher fat content will melt at a lower temperature.
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 45 °C (113 °F) to melt all six forms of crystals. Next, the chocolate is cooled to about 27 °C (81 °F), 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 31 °C (88 °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, other methods of chocolate tempering are 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 manually tempering chocolate are:
- Working 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.
- Stirring solid chocolate into molten chocolate to “inoculate” the liquid chocolate with crystals (this method uses the already formed crystals of the solid chocolate to “seed” the molten chocolate).
Chocolate tempering machines (or temperers) with computer controls can be used for producing consistently tempered chocolate. In particular continuous tempering machines are used in large volume applications. Various methods and apparatuses for continuous flow tempering have been described by Aasted, Sollich and Buhler, three manufacturers of commercial chocolate equipment, with a focus now on energy efficiency. In general, molten chocolate coming in at 40-50 °C is cooled in heat exchangers to crystallization temperates of about 26-30 °C, passed through a tempering column consisting of spinning plates to induce shear, then warmed slightly to re-melt undesirable crystal formations.
Chocolate is very sensitive to temperature and humidity. Ideal storage temperatures are between 15 and 17 °C (59 and 63 °F), with a relative humidity of less than 50%. Various types of “blooming” effects can occur if chocolate is stored or served improperly. Fat bloom is caused by storage temperature fluctuating or exceeding 24 °C (75 °F), while sugar bloom is caused by temperature below 15 °C (59 °F) or excess humidity. To distinguish between different types of bloom, one can rub the surface of the chocolate lightly, and if the bloom disappears, it is fat bloom. One can get rid of bloom by retempering the chocolate or using it for any use that requires melting the chocolate.
Chocolate is generally stored away from other foods, as it can absorb different aromas. Ideally, chocolates are packed or wrapped, and placed in proper storage with the correct humidity and temperature. Additionally, chocolate is frequently stored in a dark place or protected from light by wrapping paper.
If refrigerated or frozen without containment, chocolate can absorb enough moisture to cause a whitish discoloration, the result of fat or sugar crystals rising to the surface. Moving chocolate from one temperature extreme to another, such as from a refrigerator on a hot day, can result in an oily texture. Although visually unappealing, chocolate suffering from bloom is perfectly safe for consumption.
Come back regularly as I will be posting some delicious chocolate recipes!