Why molasses is black in colour?

The characteristic dark colour of molasses is primarily due to the presence of caramelized sugars and other compounds formed during the refining process of sugarcane or sugar beet. Specifically, when sugarcane juice or beet juice undergoes evaporation and boiling in the sugar production process, the natural sugars in the juice undergo a series of chemical reactions known as Maillard reactions or caramelization.

Maillard reactions: These reactions occur when reducing sugars, such as glucose and fructose present in the juice, react with amino acids, particularly asparagine, under the influence of heat. This interaction leads to the formation of various brown pigments, including melanoidins, which contribute to the dark colouring of molasses.

Caramelization: In addition to Maillard reactions, caramelization also plays a role in deepening the colour of molasses. Caramelization involves the heating of sugars to higher temperatures, leading to their breakdown and the formation of caramel compounds. These compounds impart a characteristic brown colour and a distinctive flavour.

The degree of darkness or colour intensity in molasses can vary depending on several factors, such as the duration and temperature of heating, the concentration of sugars in the original juice, and the processing methods employed. Darker molasses, such as blackstrap molasses, undergo a longer heating process, resulting in more pronounced colour and flavour development.

Therefore, the presence of caramelized sugars, Maillard reaction products, and caramel compounds, combined with the natural colour of the refined juice, contributes to the black colour of molasses.