Why is black liquorice black?

Cut open a liquorice root and it is yellow inside. Yet the sweet made from it is black. The colour comes from the way the root is turned into an extract, helped along by a few dark ingredients.

From yellow root to black block

Liquorice is the root of a plant, Glycyrrhiza glabra. The root owes its yellow colour to natural compounds called flavonoids: see is liquorice a root?

To make liquorice for sweets, the roots are cut, dried and sold to a processor. They are stripped, made into a pulp with water, and the pulp is filtered and thickened into an extract, which is dried into blocks known as block liquorice. That concentrated extract is what gives traditional black liquorice both its flavour and its colour. Liquorice confectionery is usually defined as a sweet flavoured and coloured black with the extract of the roots.

The dark helpers

The extract is not the only dark ingredient. The basic recipe for black liquorice is liquorice extract, sugar and a binder, such as starch, flour, gum arabic or gelatine, and molasses is often added too. Cane molasses is used in traditional black liquorice because its robust flavour and dark colour strengthen both the colour and the taste, and it helps give the sweets a glossy shine. Some makers add caramel colour.

In the factory, the ingredients are dissolved in water, heated to about 135 degrees Celsius and poured into moulds pressed into trays of starch. Once set, the sweets are often sprayed with beeswax to make them shine.

Black, but not liquorice

Not every black sweet is liquorice. Many liquorice flavoured sweets get much of their taste from aniseed oil, which tastes very similar, so the actual liquorice content is low. Some black sweets are coloured black with added colour rather than extract. Barratt's Black Jack chews, for example, are labelled as an aniseed flavour chew, and in 2021 their ingredients included a colour, vegetable carbon: see is aniseed the same as liquorice?

The opposite is true of red liquorice. It is made in a similar way, as chewy ropes or tubes, but it usually contains no liquorice at all and is flavoured with strawberry, cherry, raspberry or other flavours instead.

A word of warning

Real liquorice root contains glycyrrhizin, a natural sweetener 30 to 50 times sweeter than sugar. In large amounts it can be harmful. Eating 50 g or more of liquorice sweets a day for as little as two weeks may raise blood pressure a little, and glycyrrhizin can make potassium levels fall, which can lead to abnormal heart rhythms in some people. In one extreme case in 2020, a man in Massachusetts who ate a bag and a half of black liquorice every day for several weeks died of a heart attack. Liquorice root extract should be avoided during pregnancy.

British liquorice

Black liquorice has deep roots in Britain, especially in Pontefract in Yorkshire, where the round black Pontefract cakes were first made, and where liquorice was called Spanish in parts of northern England: see why is liquorice called Spanish? Black liquorice also appears in liquorice allsorts and liquorice wheels. Many liquorice sweets use wheat flour as a base, so if you avoid gluten, check the label: see are sweets gluten free?

We sell liquorice allsorts and soft liquorice twists in our pick and mix.

Download as PDF