Green Botanica · Tea Guide
Morus alba
Bai mon · ใบหม่อน · sang ye · kuwacha
White mulberry is the tree that feeds the silkworm. It has been grown across Asia for silk for thousands of years, and its leaves have long been brewed as well: as sang ye in China, kuwacha in Japan and cha bai mon in Thailand. Cut and dried, the leaf makes a mild, softly sweet, caffeine-free tea.
Meet the plant
White mulberry is a deciduous tree of the mulberry family, Moraceae, native to central China. Left alone it grows into a spreading tree; on silk farms it is pruned low, into bushes of fresh shoots that are easy to pick.
Its leaves vary remarkably, from deeply lobed on young shoots to almost entire on older wood, often on the same tree. They are smooth to the touch, unlike the rough leaves of black and red mulberries. And despite the name, the fruit is not always white: many trees ripen it through shades of red and purple.
The silkworm’s food, and the reason the tree spread around the world.
Cut and dried for cha bai mon in Thailand, kuwacha in Japan and sang ye tea in China.
Tender young leaves cook in kaeng kai bai mon, a chicken curry with mulberry leaves.
Bai mon chup paeng thot: young leaves dipped in batter, fried and served with a sweet-sour sauce.
In the Thai northeast, young shoots and leaves also go into soups such as hot and sour duck.
Eaten fresh or made into jam, jelly, juice and wine.
The story
The history of mulberry is the history of silk. But wherever the tree went, someone also put its leaves in a cup.
White mulberry has been cultivated in China for at least 4,700 years, to feed the silkworms whose cocoons give silk.
The Shennong Bencao Jing, China’s oldest surviving herbal, records the mulberry tree, its bark and its leaves. Later Chinese herbals continued to describe the leaf, preferring leaves picked after the first frost.
In Japan, the monk Eisai wrote Kissa yōjōki, the book that made green tea famous there. Next to tea he recommended mulberry in nine forms — among them mulberry leaf tea, mulberry porridge and even a pillow of mulberry wood.
White mulberry reached Italy for silk around 1410 and spread to France and Spain. In 1607 King James I urged his subjects to plant it, and tens of thousands of young trees were brought to England from Languedoc. English silk never took off.
King Chulalongkorn founded Thailand’s first silk department to spread knowledge of mulberry and silk. Today the Queen Sirikit Department of Sericulture breeds mulberry varieties and teaches farmers how to make mulberry leaf tea.
In China, sang ye is both a food and a traditional medicinal herb, on the official list of “food and medicine” plants since 2002. In Japan, kuwacha is simmered in a kettle or brewed in a teapot; in Korea, ppongip-cha is one of the traditional leaf teas.
In Thailand, cha bai mon is one of the everyday herbal teas, and the leaf also goes into the kitchen, especially in the northeast, where mulberry fields and silk weaving go together.
From tree to pouch
On mulberry farms the trees are kept low and cut back regularly, so they push out fresh shoots and tender leaves — the same leaves silkworms are raised on. The tea comes from these leaves, picked, cleaned of stems and dried.
Leaf age shapes the cup. In a Chinese study, tea from young leaves tasted more savoury and slightly more bitter; tea from mature leaves was less astringent and a little more tart.
Thailand’s Department of Sericulture describes three ways to make mulberry tea: steamed, then pan-dried, for a light green cup; pan-roasted, for a yellow-brown cup; and roasted longer and ground, for a golden-brown cup.
Fresh leaves are mostly water. It takes about 5.3–6.3 kg of fresh leaves to make 1 kg of dry mulberry tea.
Chinese tradition prizes mulberry leaves picked after the first frost of autumn. Research has found that the leaves’ flavonoids peak at about that time. In tropical Thailand there is no frost, and leaves are picked all year.
The science of flavour
Mulberry leaf is not a tea plant: it contains no caffeine and little of the bitterness of Camellia tea. Its gentle aroma comes from a mix of volatile compounds, and how the leaf is processed changes that mix a great deal. In ten commercial mulberry teas, researchers found up to twenty times more aroma compounds in some teas than in others.
Woody, floral and berry-like. One of the strongest contributors to the aroma of mulberry tea.
Rose-like and fruity, adding a soft floral depth.
Fresh and floral, the same note found in many flowers and herbs.
Citrus-like and bright.
Fresh and herbal, a cool, clean note.
Green and slightly citrus, part of the fresh-leaf impression.
Leaf dried without roasting keeps its green colour and a soft, hay-like, green-tea character.
Roasting turns the cup yellow-brown and adds a toasted note, with a mild astringency.
In a Chinese study, longer processing faded the grassy notes, softened the bitterness and brought a rich, baked fragrance.
Young leaves carry more amino acids, which give a savoury, umami taste. As leaves mature, flavonoids such as rutin build up and the cup becomes softer and less astringent. Both are good tea; they are simply different.
Tea & kitchen
| Tea | Plant | Caffeine | Character |
|---|---|---|---|
| Mulberry leaf | Morus alba leaf | None | Mild and green, softly sweet, little bitterness |
| Green tea | Camellia sinensis leaf | Yes | Grassy and fresh; turns bitter with a long steep |
| Hojicha | Camellia sinensis, roasted | Yes, less | Toasty and smooth |
| Pandan | Pandanus amaryllifolius leaf | None | Jasmine rice and popcorn, vanilla-like sweetness |
Recipes
A Japanese kettle brew and a fragrant blend to start with, then notes from our own kitchen.
The Japanese way with kuwacha
Bring the water to the boil, add the leaf in its bag and turn the heat to low. Simmer gently for about 5 minutes, then lift out the bag. Drink warm through the day, or cool it and keep it in the fridge for a mild iced tea.
A soft, fragrant cup
Put the leaf and blossoms in a warmed teapot, pour over the water and cover. Steep for 5 minutes and strain. The jasmine adds a sweet floral top note to the green, hay-like mulberry. For a fresher cup, swap the jasmine for a few peppermint leaves.
Mulberry leaf’s mild, green character in new pairings — not Thai tradition:
Chill the kettle brew, add a slice of lemon and a little honey, and serve over ice.
Brew 1.5 g mulberry leaf with a pinch of dried lemongrass for a brighter, citrus cup.
Add a few pieces of dried pandan leaf for a softer, rice-like sweetness.
In the spirit of Japanese ochazuke, pour hot mulberry tea over a bowl of rice with salted fish or pickles.
Beyond flavour
Mulberry leaf is first of all a mild tea, but it also has a long place in traditional medicine and a growing one in research.
Mulberry leaf has been part of Chinese herbal medicine for some two thousand years. In 1211 the Japanese monk Eisai recommended mulberry, beside tea, against five illnesses he believed were caused by demons. In Thai folk tradition, the leaf has been used in many household remedies. These are traditional uses, not proven treatments.
Mulberry leaf contains 1-deoxynojirimycin (DNJ), a sugar-like compound that, in laboratory tests, slows the enzymes that break down starch in the gut. Its amount varies with leaf age, variety, season and drying. Most studies use extracts or powders with a measured DNJ content, not a cup of tea.
Two small studies in Thailand have tested mulberry leaf in people:
Complementary Therapies in Medicine · 2020
Human study · randomisedMulberry leaf powder with a measured DNJ content, taken three times a day for 12 weeks. Fasting blood glucose fell by about 4 mg/dL and HbA1c by 0.1 %; glucose tolerance did not improve. The most common side effects were bloating, wind and loose stools.
J Pharmacy and Nutrition Sciences · 2016
Human study · crossover14 adults without diabetes drank mulberry leaf tea or a placebo with a meal, in random order. Blood glucose and insulin tended to be lower with the tea, but the difference was clear only at 30 minutes; insulin sensitivity did not change.
Educational product information. Not medical advice. If you are pregnant, breastfeeding or taking medication, consult your doctor before using a new botanical product.
