The Science of Spice

What Is a Spice? 11

Black pepper

Peppercorns are the

small dried berries

of one of around a

thousand different

flowering vine species

in the plant family

Piperaceae.

Clove

The nail-shaped,

dark brown clove

is neither a seed

nor a dried fruit,

but the dried

flower bud of an

evergreen tree

from Indonesia.

Star anise

The seeds of this

strikingly shaped spice

are contained within

a woody protective

covering, called a

carpel, where much

of the flavour is in

fact concentrated.

Fresh cloves

are picked when

the buds have

developed a

pinkish tint

Unpicked buds

open into flowers

with frothy heads

of stamens

Seed pods

(fruits) are

harvested when

still unripe and

allowed to dry

Fully ripe berries are

pink-red in colour; black

and green peppercorns are

picked when underripe

Berries are carried

in clusters on spikes

Insect repellence

The heat from pepper is produced

by a chemical called piperine

which, as well as irritating hot

pain nerves on the tongue, is

highly repellent to insects and has

been harnessed by the chemical

industry as an insecticide.

Health protection

Star anise’s dominant flavour comes

from anethole, a substance that

appears to have evolved to fight off

infections and repel insects, and

which incidentally has an appealing

taste – 13 times sweeter than sugar

• to the animal tongue.

Pollinator attraction

Clove contains a high concentration

of eugenol, a chemical with a warm,

eucalyptus-like fragrance and sweet

effect on the tongue. In the living

plant, eugenol serves to attract

pollinating insects and

also repel infections and pests.

SEEDS

The majority of spices are seeds; think of cumin,

cardamom, mustard, and fenugreek, or less

obviously nutmeg, which is a seed kernel. It is little

wonder that plants frequently concentrate their

strongest-tasting defensive chemicals in seeds,

since these are the precious packets of new life that

will sprout into the next generation of plants.

FLOWERS

Many flowers are known for their attractive aromas,

which have evolved to entice insects into paying a

visit and pollinating the flower as they do so. Only

a few have strong enough appealing flavours to be

considered a spice, most famously saffron, whose

red strands are pollen-receiving female sex parts

(stigmas) of a crocus flower. Another notable flower

spice, it may be surprising to discover, is clove.

FRUITS

The seeds of flowering plants are contained in fruits.

Many have evolved to be sugar-rich so that they

make an appealing meal for animals, who thereby

distribute the seeds over a wide area. Numerous

spices are derived from fruits, including allspice,

sumac, vanilla, and chillies. Several “seed” spices

are technically fruits, including dill and ajwain.

Cross section of a clove

Cloves are rich in highly flavoured

oils, stored in oil glands just beneath

the surface of both the rounded top

of the bud and the “stalk”.

Oil glands

are more concentrated

in the round head

of a clove

“Stalk” comprises

the outer sepals

of the flower bud,

and also contains

oil glands

Round head

is made up of the

dried, unopened

petals of the bud

Flavour stores

The vast majority of flavour

compounds in spices are oil- rather

than water-soluble and are stored

within bubbles of oil. Spices are

structured to keep these oils locked

away, to be released only if the

plant is damaged or attacked by

infection. Once the bubbles rupture

and the oil is exposed to air, the

flavour compounds quickly

evaporate into gases.

Glands rupture when the outer

surface is damaged. In the kitchen

this happens through bruising,

grinding, and application of heat.

Flavour compounds in the released

oils evaporate as a fragrant gas.

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