Chocolate

Chocolate is perhaps one of the most popular ingredients used in baking. From chocolate chip cookies and brownies to chocolate cheesecake and gâteau au chocolat, these beloved chocolate treats all feature chocolate as the main ingredient. It is a complex mixture of various components that contribute to its unique flavour, texture and appearance. 

Components of Chocolate

• Cocoa butter

Cocoa butter is a type of fat derived from cocoa beans. It consists mainly of triglycerides, which are composed of one glycerol molecule bonded to 3 fatty acids. Glycerol is propane-1,2,3-triol which is bonded by ester bonds to the long chains of carbon atoms in fatty acids.

About 35% of all fatty acids found in cocoa butter are oleic acid, a mono-unsaturated fat containing a double bond. This introduces kinks in the fatty acid chains, preventing the acids from packing closely together. As a result, oleic acids have a lower melting point compared to saturated fatty acids, making cocoa butter partially liquid at room temperature. Hence, it is considered as a healthy fat given that it is less likely to clog arteries. Oleic acids are also found in hazelnuts.

• Sugar crystals

Sugar is a crucial ingredient found in chocolate, contributing to its sweetness and texture. The size and shape of the sugar crystals also affect the smoothness of the chocolate.

• Milk solids

Milk solids add creaminess and a subtle dairy flavour to milk chocolates. They interact with sugars and cocoa butter to create a smooth texture.

• Butyric acid

Found in American chocolate, butyric acid gives a distinctive dairy taste to chocolate. It can also help prolong the shelf life of chocolate.

• Maltol

Maltol is formed during the caramelisation process, such as roasting cocoa beans or when making caramel. When sucrose is heated, it breaks into glucose and fructose. These then decompose into various compounds, including maltol — has a roasty flavour and aroma, ethyl acetate — has a fruity flavour, furan — has a nutty flavour and diacetyl — has a buttery flavour.

• Vanillin

Vanillin is the major flavour component in vanilla. 1-2% of vanilla extract is consisted of natural vanillin extracted from vanilla beans. Whereas vanilla essence contains synthetic vanillin which often lacks the flavour complexity of natural vanillin.

• Phenylethylamine

• Theobromine

Theobromine is a stimulant found in chocolate which stimulate the release of nitric oxide in the body, reducing enzymes in our blood which constrict blood vessels. Hence, theobromine has the benefit of reducing blood pressure and aiding vasodilation.

• Caffeine

Differing by one methyl group from theobromine, caffein can bind to adenosine receptors, stopping us from feeling drowsy and making us more alert. However, if we consume a significant amount of caffein everyday, we might suffer from withdrawal symptoms once we stop consuming caffein.

Chocolate Tempering

Tempering is an important process in chocolate making to ensure a smooth, glossy finish to chocolate. Untempered chocolate is soft and dull, a white opaque layer — bloom — can form when water condenses on the surface, causing sugar crystals to be brought to the surface and to recrystallise. In comparison, tempered chocolate has a glossy shine, snaps crisply and melts smoothly in the mouth. The process of tempering involves carefully heating and cooling the chocolate to control the formation of different types of cocoa butter crystals.

Crystal Form	I	II	III	IV	V	VI
Melting Point/•C	17	23	25	27	34	36
Properties	soft and crumbly	soft and crumbly	firm but crumbly	firm but crumbly	nice gloss, melt in your mouth and has a nice snap	nice gloss but melt slowly in your mouth

Tempering Process

1. Heat to 50°C: melt all cocoa butter crystals.
2. Cool slowly to 27°C on a marble slab: type I to type III crystals cannot form because the temperature is above their melting points. This encourages type V crystals to grow.
3. Reheat to 30°C: melt type I to type IV crystals, allowing more type V crystals to grow.
4. Leave to set.

Reference

• Smalley, J. (2024) Chemistry in Chocolate. [lecture] University of Leicester. 13 March.