Description

DMS Bai Yai Sen Oolong Tee

DMS Bai Yai Sen Oolong Tea is a Northern Thai Oolong speciality made from native large-leaf Assam varieties. Unlike many Oolong teas produced in Doi Mae Salong today, it does not come from a cultivar introduced from Taiwan. Instead, it comes from a type of tea plant that has long been native to Northern Thailand. Our local producer partner, the Banphotsikorn family, cultivates the Assamica plants used for this tea in their own tea gardens.

The tea owes its name to two characteristic features. “Bai Yai” means “large leaf” in Thai. The name refers to the characteristically large leaves of the Assam-type tea plants used for this tea. “Sen”, on the other hand, describes the elongated, strand-like shape of the processed leaves.

In taste, Bai Yai Sen Oolong is bold and spicy. Its clear, amber-coloured liquor combines mineral and earthy depth with notes of dry, well-seasoned wood and pronounced roasted aromas. Subtle nuances of dried fruit add complexity and contribute to the distinctive character of this Oolong.

The Tea Plant – Northern Thailand’s native („Assam“) Varieties

The large-leaf tea plants used for DMS Bai Yai Sen Oolong Tea belong to the group commonly known as the Assam varieties of Camellia sinensis. Their name, however, owes less to an origin confined to Assam than to a historical coincidence. In the early 19th century, Western botanists and colonial officials first became aware of this large-leaf type of tea plant in Assam.

Its natural range actually extends far beyond the region in northeastern India from which it takes its name. It stretches from the eastern Himalayas through Myanmar and Northern Thailand to Laos, Vietnam and Southwest China. Northern Thailand is therefore itself part of the natural range of these large-leaf forms of the tea plant

In evolutionary terms, these native Northern Thai tea plants are closely related to the large-leaf tea forms of neighbouring Yunnan. Many tea drinkers know these primarily as the raw material for traditional Pu-erh and Dian Hong teas. Yunnan, however, does not represent an isolated point of origin. The province forms part of a much larger region encompassing Southwest China and mainland Southeast Asia. This wider region played an important role in the evolution and domestication of large-leaf forms of Camellia sinensis.

Origin and Terroir – Doi Mae Salong, Northern Thailand

The tea gardens producing the leaves for DMS Bai Yai Sen Oolong Tea lie in the mountains of Doi Mae Salong. This region is located in Thailand’s far north, not far from the border with Myanmar. At elevations of around 1,200 metres, comparatively cool nights combine with high humidity, regular rainfall and lush subtropical vegetation. These conditions encourage slower growth. They also create an environment in which tea has long ranked among the region’s characteristic cultivated plants.

For the native large-leaf tea plants in particular, Doi Mae Salong is more than simply a suitable place for cultivation. As described above, Northern Thailand lies within their natural range. Bai Yai Sen thus combines the distinctive conditions of the Northern Thai highlands with a tea plant native to this wider region.

A Brief Look at the Hitory of Doi Mae Salong

The tea culture of present-day Doi Mae Salong is closely linked to the history of the region. In the 1940s, parts of the Chinese Kuomintang army settled here after fleeing China following the Chinese Civil War. Their families came with them. They also brought agricultural knowledge and cultural influences from southern China and Taiwan.

IDuring the 1960s and 1970s, the region gained unfortunate notoriety as part of the so-called “Golden Triangle”. At the time, this was one of Southeast Asia’s most important opium-growing areas. Social and economic conditions were correspondingly unstable.

A fundamental transformation began in the 1980s. Initiatives supported by the Thai Royal Family promoted legal highland agriculture, with tea becoming one of the central pillars of this transformation.

For more information about the history of Doi Mae Salong and tea cultivation in the region, please follow the link below:

Doi Mae Salong – Center of Tea Cultivation in North Thailand

Tea Plants & Cultivare in Doi Mae Salong

Alongside the Taiwanese cultivars for which Doi Mae Salong is known today, native large-leaf Assamica-type tea plants continue to play an important role. These tea forms have long been native to Northern Thailand and provide the botanical basis for Bai Yai teas. “Bai Yai” means “large leaf” in Thai and refers to the characteristic leaf size of these tea plants.

Taiwanese tea cultivars arrived in Northern Thailand only later, as part of the Royal Thai Development Project. Tea experts from Taiwan selected several cultivars particularly well suited to the regional terroir. Local growers subsequently established these cultivars through asexual propagation from cuttings.

Several Taiwanese cultivars grow in Doi Mae Salong today. These include Ruan Zhi (TRES #17), Jin Xuan (TRES #12), Chin-Shin / Qingxin and Si Ji Chun (Four Seasons). Together with the native large-leaf tea plants, they form the botanical basis for Doi Mae Salong’s diverse tea production.

Ou Local Producdr Partner

The Chinese-descended Banphotsikorn family has cultivated tea gardens in Doi Mae Salong since the mid-1980s. Mrs Sumalee Banphotsikorn oversees the tea gardens and production.

Tea Production in Doi Mae Salong

Tea production in Doi Mae Salong today brings together two distinct botanical foundations and processing traditions. Producers work both with native large-leaf Assamica-type tea plants and with cultivars introduced from Taiwan several decades ago.

The resulting spectrum of teas is correspondingly diverse. Producers use both groups of tea plants to make Oolong, green and black teas. They adapt picking and processing to the particular leaf material and intended style. Production remains predominantly small-scale. It combines the distinctive conditions of the Northern Thai highlands with a variety of tea-making methods.

Natural Cultivation & Biodiversity

The Banphotsikorn family cultivates its tea gardens naturally and without pesticides. Areas of biodiverse vegetation separate the small individual garden plots and help maintain a stable ecological balance.

Picking & Processing

For DMS Bai Yai Sen Oolong Tea, the producers pick only developed leaves, including some slightly older ones. This somewhat more mature leaf material provides ideal conditions for subsequent Oolong processing.

After picking, the fresh tea leaves first undergo withering. During this stage, they lose some of their moisture and become more pliable for further processing. The producers repeatedly move and mechanically work the leaves during this phase. This treatment breaks cellular structures, particularly along the leaf surfaces and edges, and deliberately promotes enzymatic oxidation.

Further mechanical processing and rolling continue to promote this process. Damage to the leaf structures releases compounds that come into greater contact with oxygen. This allows the partial oxidation characteristic of Oolong tea to develop. Unlike green tea processing, Oolong production does not stop oxidation at an early stage. Instead, the process actively encourages oxidation before heat stops it at the desired level.

Rolling also gives the leaves their characteristic elongated, strand-like Sen shape. Further thermal processing and final drying stabilise the tea and develop its pronounced roasted profile. The finished leaves remain open and elongated. Their appearance therefore still clearly reveals the size of the Bai Yai leaves.

Taste, Aroma and Visual Appearance

The dry leaves of DMS Bai Yai Sen Oolong Tea display the characteristic elongated Sen shape. Processing gives them a dark colour that transitions into shades of brown. During infusion, the rolled leaves largely unfold to their original form. The wet leaves reveal a distinctly olive-green appearance with brown areas and edges resulting from oxidation.

The clear liquor initially shows a dark amber colour and develops reddish hues with longer steeping. Its taste is bold and spicy, with pronounced mineral and earthy depth. Notes reminiscent of dry, well-seasoned wood combine with distinct roasted aromas and pronounced natural sweetness. Subtle hints of dried fruit add further complexity. Together, these elements create a deep and multi-layered flavour profile with full-bodied richness and aromatic complexit.

Spicy, mineral and roasted notes remain particularly persistent in the finish. Natural sweetness and subtle fruitiness accompany these darker aromas, giving the finish a pleasantly smooth character.

Preparation

Western-style preparation: We recommend approximately 3–4 grams of tea leaves per 200 ml of water at a temperature of 90–95°C. A steeping time of around 3–5 minutes develops the full spicy-mineral character and pronounced natural sweetness of Bai Yai Sen Oolong. You can prepare 1–2 further infusions by gradually increasing the steeping time.

Gong Fu preparation: This tea is particularly interesting when prepared with more leaves and a succession of short infusions. We recommend approximately 5–6 grams of tea per 100 ml of water at 95°C. Start with a brief first infusion to awaken the tea leaves. The first drinking infusion can then be poured after approximately 15–20 seconds. Gradually increase the steeping time for each subsequent infusion. This method reveals the development of the tea’s mineral, earthy, roasted, woody and fruity-sweet facets over multiple infusions.

For more information about this tea, please also see the following blog article:

Bai Yai – Northern Thailand’s Ancient Tea Tree

For our selection of teas from Northern Thailand, please follow the link below:

Tea from Northern Thailand @ Siam Tea Shop