Cloves are the dried buds of a large flowering tree, which are grown in the Zanzibar islands in the Indian Ocean off the east coast of Tanzania.
Zanzibar has some of the oldest clove trees in the world, and Zanzibar cloves have a significantly higher percentage of essential oils (15-18%) than other clove producers.
Their essential oil content is so high that they are used locally as a natural substitute for anesthesia.
Zanzibar was at one point the largest producer of cloves in the world, but the rise of plantation-style cultivation and exploitative labor practices in other countries have made it difficult for smallholder farmers in Zanzibar to compete despite producing a much higher quality product.
Our cloves are grown by a cooperative of smallholder artisan farmers, many of whose families have been growing cloves and other spices (including our cinnamon, black pepper and nutmeg) for generations.
Burlap and Barrel is the exclusive importer of Zanzibar cloves into the United States.
The clove tree is a small evergreen tree that grows to a height of 12-20 metres. It thrives in coastal regions with temperatures between 15 and 30°C, average rainfall and a distinctive dry season (the optimum level of rainfall is 1750 to 2500mm a year).
It is a low altitude plant that grows best at altitudes lower than 300m above sea level although it will also grow at altitudes above 900m.
The young leaves of the clove tree are bright pink and change to a greenish yellow as they mature.
The flowers develop in clusters of three to ten groups, each with three flowers per group.
Harvesting Clove trees are first harvested when the tree is 6-8 years old.
The timing of harvest of the clove buds is critical.
The buds should be harvested before the purple or crimson flowers start to develop. The correct time of harvest is when the outer green leaves (the calyx) of the flower bud change from olive green to yellow pink and before the petals fall to expose the stamens.
Clusters of flower buds are hand-picked from the branches. It is important that the branches are not removed or damaged as this will reduce the yield of future crops.
Pre-treatment After harvest the buds are detached from the stalks by holding a cluster in one hand, pressing it against the palm of the other hand and slowly twisting so that the buds fall off.
The hands of the processor and the room in which the buds are separated must be very clean to prevent contamination of the cloves.
The stems and buds are separated and dried separately.
The stems can be used for oil distillation.
Neil Noble / Practical Action Clove processing Practical Action 2 Drying The buds have to be dried quickly or they will start to ferment.
They are usually dried in the sun, spread on clean mats.
The cloves should be raked and turned frequently to ensure they develop an even brown colour.
The colour of buds changes from pale russet to a darker brown as the clove dries.
The drying process takes about four to five days.
It cannot be speeded up or the cloves will become dry, brittle and withered rather than plump.
The final moisture content of the dried cloves should be 8-10%. Experienced clove driers will know when the cloves are fully dry as the buds will snap easily.
During the rainy season, cloves should be dried using a mechanical drier such as a tray drier.
Badly dried cloves are pale brown and classified as khuker.
Winnowing The dried buds are winnowed using a traditional winnowing basket to remove dust and other foreign matter.
Small cleaning machines are available that use a blower to remove the dirt and dust.
Benefits of Cloves
May protect against cancer, some research shows that the compounds found in cloves can help protect against cancer.
One test-tube study found that clove extract helped stop the growth of tumors and promoted cell death in cancer cells.
Another test-tube study had similar results, showing that concentrated amounts of clove oil caused cell death in 80% of esophageal cancer cells.
The eugenol found in cloves has also been shown to have anti-cancer properties.
A test-tube study found that eugenol effectively promoted cell death in cervical cancer cells.
However, keep in mind that these test-tube studies used very concentrated amounts of clove extract, clove oil and eugenol.
Can Kill off Bacteria
Cloves have been shown to have antimicrobial properties, meaning they can help stop the growth of microorganisms like bacteria One test-tube study showed that clove essential oil was effective at killing off three common types of bacteria, including E. coli, a strain of bacteria that can cause cramps, diarrhea, fatigue and even death.
What’s more, the antibacterial properties of cloves could even help promote oral health. In one test-tube study, the compounds extracted from cloves were found to stop the growth of two types of bacteria that contribute to gum disease.
May Improve Liver Health
Studies show that the beneficial compounds in cloves could help promote liver health.
The compound eugenol may be especially beneficial for the liver.
One animal study fed rats with fatty liver disease mixtures containing either clove oil or eugenol.
Both mixtures improved liver function reduced inflammation and decreased oxidative stress.
Another animal study showed that the eugenol found in cloves helped reverse signs of liver cirrhosis, or scarring of the liver. Unfortunately, research on the liver-protecting effects of cloves and eugenol in humans is limited.
May Help Regulate Blood Sugar
Research shows that the compounds found in cloves may help keeps blood sugar under control.
An animal study found that clove extract helped moderate blood sugar increases in diabetic mice.
Another test-tube and animal study looked at the effects of clove extract and nigericin, a compound found in cloves, both on human muscle cells and in diabetic mice.
Cloves and nigericin were found to increase the uptake of sugar from the blood into cells, increase the secretion of insulin and improve the function of cells that produce insulin.
May Promote Bone Health
Low bone mass is a condition that affects an estimated 43 million older adults in the US alone. It can lead to the development of osteoporosis, which may increase the risk of breaks and fractures.
Some of the compounds in cloves have been shown to help preserve bone mass in animal studies.
For example, an animal study found that clove extract high in eugenol improved several markers of osteoporosis and increased bone density and strength.
Cloves are also rich in manganese, providing an impressive 30% of the daily recommended amount in just 1 teaspoon (2 grams) of ground cloves.
May Reduce Stomach Ulcers
Some research indicates that the compounds found in cloves could help treat stomach ulcers.
Also known as peptic ulcers, stomach ulcers are painful sores that form in the lining of the stomach, duodenum or esophagus.
They are most commonly caused by reductions in the protective lining of the stomach that are due to factors like stress, infection and genetics. In one animal study, the essential oil from cloves was shown to increase the production of gastric mucus.