Trees in the kitchen

SELF-isolation under COVID-19 lockdown brings boredom and with it can come abnormal behaviour. In my case, sorting out the kitchen cupboards – and towards the back of the top shelf I unearthed a collection of dusty jars of assorted spices and arboreal additives, some dating back years. Dusting off the labels set me reflecting on just how many of those were from bits and pieces of trees, which set my salivary buds going and triggered this article.

WHAT’S ON THE MENU

Most bits or pieces of aromatic trees have some culinary or other use to people. Purists will have to forgive me for a taking a bit of poetic licence in this article and not fall into the quagmire of when is a bush a tree and vice versa. So, tea and coffee are off. Let’s also bin most whole edible tree fruits, nuts, and berries, and concentrate on the ingredients from trees that when added in small amounts can be the catalyst that turns an okay dish into a mouth-watering one. For starters, let’s savour a small selection of the more exotic spices and the like derived from trees and found commonly in UK cuisine, then concentrate on two of my favourites – cloves and cinnamon – and their turbulent history.

LEAVES

Lovers of stews, casseroles and meat sauces know to be on the lookout on their plate for a leaf or two of Laurus nobilis – the bay laurel – an aromatic evergreen tree or large shrub with green, glabrous, smooth leaves, in the flowering plant family Lauraceae.

Well known to cooks, this would-be tree is often kept pot-bound on the back patio in the UK but will grow to true tree size if allowed. This evergreen is native to the Mediterranean and is used for seasoning in cooking. Its common names include bay tree, bay laurel, sweet bay, true laurel, Grecian laurel or simply laurel.

Zooming eastwards, the curry tree or curry leaf tree (Murraya koenigii) is a tropical to sub-tropical tree in the family Rutaceae, and is native to India. Its foliage flavours many dishes in the Indian subcontinent. This is the true curry leaf plant used in South and West Coast Indian and also Sri Lankan cooking. Often referred to as sweet neem, the tree stands up to 6 metres tall.

NUTS

Myristica fragrans is an evergreen tree, indigenous to the Moluccas of Indonesia. It is valuable as the main source of not one but two spices – nutmeg grated from the nut itself and mace made from the husk. Nowadays, nutmeg is widely grown across the tropics including the Far East, the Indian subcontinent, the Caribbean and South America.

SAPS

Although not strictly a spice nor additive, more than 20 tree species can be tapped or bled for their edible sap as it rises in the spring and employed in cooking, as a syrup, or as the basis for beverages or alcoholic drinks.

The best-known trees are members of the Acer or maple family, harvested or tapped each spring in North America. Although much of today’s syrup on sale does originate from the sugar maple (Acer saccharum), all species of maple can be tapped. A good tree will yield 20–60 litres each season which is then refined and graded. Canada (Quebec Province) dominates the market which is worth roughly $400 million a year.

But birch (Betula sp.) sap is undergoing a renaissance in Scotland as a health food and is widely harvested in northern climes across the boreal forests of Northern Europe and Russia.

BUDS

Turning to one of my favourites, cloves are the aromatic flower buds of an evergreen tree in the myrtle family, Syzygium aromaticum, that reaches 8–10 metres tall. The common name in English derives from the French ‘clou’, meaning nail.

Harvested green just before buds open into red blooms, they are then dried and used either whole or ground. They are native to the Maluku Islands in modern-day Indonesia, and are commonly used as a spice. Cloves are available throughout the year due to different harvest seasons in diverse countries where they have been naturalised such as India, Madagascar, Mauritius and Zanzibar.

Cloves are the dried flower buds of this evergreen tree.

BARK

Cinnamon is obtained by shaving the stems of cinnamon trees (Cinnamomum sp.). The precious inner bark is then extracted and the woody parts discarded. When it dries, it forms strips that curl into rolls termed quills, also called cinnamon sticks, which can be ground to form a powder too.

The distinct smell and flavour of this spice are due to the oily part, which is rich in the compound cinnamaldehyde. Scientists believe that this chemical is responsible for most of cinnamon’s powerful effects on human health and metabolism.

Inner bark quills from at least four species of trees have been used as cinnamon but the two most important are C. verum (true cinnamon) from Sri Lanka and southern India, and C. aromaticum (cassia) from Myanmar/Burma and China.

C. verum is a small evergreen tree belonging to the family Lauraceae, native to Sri Lanka. Cinnamon from this species is considered of superior quality – the real stuff. 

Flavour differences among Cinnamomum barks are subtle but when used for commercial oil production, species differences are critical. The essential oil of true cinnamon bark is rich in cinnamaldehyde, while the leaf oil is eugenol-rich; in cassia, both bark and leaves are cinnamaldehyde-rich.

A pot-bound bay tree.

WORTH FIGHTING OVER

In the 21st century, spices from trees are on sale in every supermarket and found as an ingredient in various foods and recipes – but it was not always so.

Desire for spices is said to have initiated European expansion during the so-called Age of Discovery, from the early 15th century into the beginning of the 17th, during which European adventurers sailed the Seven Seas in search of new trading routes and partners; the beginning of globalisation.

SPICE ISLANDS, ROADS AND WARS

In the Far East, the Maluku Islands, or the Moluccas, are an archipelago in eastern Indonesia – once known as the Spice Islands – lie east of Sulawesi, west of New Guinea, and north and east of Timor.

Cloves and nutmeg from these islands were traded in Asia long before the Portuguese set up shop on the island chain from 1512, marking the beginning of many decades of deadly conflict over these precious commodities.

The maritime trade routes of the Portuguese navigators to and from the Moluccas across the Indian Ocean, round the Cape of Good Hope to Europe and back, were dubbed the Spice Roads and brought back pepper, ginger, cloves and nutmeg from the Moluccas, as well as a wide range of other prized merchandise picked up on the way.

Between the 15th and 17th centuries, the Spice Wars over these islands broke out amongst expanding European nations and continued on and off for about 200 years. Spain, Portugal, Britain and Holland all fought for control of the lucrative trade in what became known as the East Indies.

Indeed, so lucrative was the clove trade originating in the Moluccas that in 1667, following the Second Anglo-Dutch War, the British ceded the archipelago to the House of Orange in exchange for a faraway settlement then known as New Amsterdam – the bustling, 21st century Manhattan.

A pot-bound bay tree.

CEYLON AND CINNAMON

Since antiquity, this spice has been used for flavouring, incense, perfume, medicine and even aphrodisiacs. The funerary rites of wealthy Egyptians and Romans entailed vast amounts of the imported spice and gifts of cinnamon were so valuable they could be used to sway monarchs and pontiffs.

From the 16th century, the growing Sri Lankan or Sinhalese (then known as Ceylon) cinnamon trade was a constant battleground until the expanding European empires established networks of tropical botanic gardens elsewhere with similar climates to experiment with cultivating this product to satisfy their populations’ spicy desires.

CHEMICAL WARFARE

Many trees have the capacity to produce chemicals that are deterrents or toxic to insects and other pests, both great and small. Think, for instance, of tannins in UK oak bark.

Some trees and other plants can rapidly turn on that protective production or chemical warfare if attacked and release substances or scents into the air to warn neighbouring conspecifics to switch on their defences. 

A case of a potential tree toxin that is pleasant to the human taste buds at very low concentrations is in almonds or their derivatives. This bitter taste comes from amygdalin, a compound within the kernel that defends it from being eaten by pests in the wild. Amygdalin splits into two parts when exposed to moisture: the intense almond flavour that is actually edible, and hydrocyanic acid that can make the green nuts deadly.

So, next time you venture into the kitchen, run your eye over the spice rack and surprise yourself – and impress others – about the arboreal origins of many of the ingredients there.

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