Phab (Traditional Fermentation Starters)

Phab (also romanised as pho) are traditional fermentation starters used throughout Bhutan to brew the country's indigenous alcoholic beverages, principally chang (beer) and ara (distilled spirit). Shaped as small, dry, round-to-flattened cakes or bagels, phab are handcrafted by women brewers — known as brewsters — from cooked grain mixed with powders derived from wild mountain plants including flowers, leaves, bark, and dried roots. The resulting cakes harbour complex microbial communities of amylolytic fungi and wild yeasts that perform the dual function of saccharification (converting starch to sugar) and fermentation (converting sugar to alcohol), making them the indispensable foundation of Bhutanese brewing.^[1]

Unlike modern brewing, which relies on industrially produced yeast and malted grain, the phab system represents an ancient biotechnology in which the brewer cultivates her own microbial culture from locally gathered ingredients. The practice is closely analogous to the marcha starters of Nepal and Sikkim and the qu starters of China, all of which belong to a broader Himalayan and East Asian tradition of amylolytic fermentation that predates written history. In Bhutan, the preparation and use of phab remains a living tradition, transmitted from mother to daughter across generations, and is inseparable from the social, ritual, and economic life of rural communities.^[2]

Composition and Microbiology

The microbial flora of phab is remarkably diverse. Scientific studies of analogous Himalayan starters have identified filamentous moulds such as Mucor circinelloides and Rhizopus chinensis, amylolytic yeasts including Saccharomycopsis fibuligera, and alcohol-producing yeasts such as Saccharomyces cerevisiae and Pichia anomala, alongside lactic acid bacteria like Pediococcus pentosaceus. The moulds and amylolytic yeasts are responsible for breaking down raw starch into fermentable sugars, while the alcohol-producing yeasts complete the conversion to ethanol. This simultaneous saccharification and fermentation — sometimes termed "parallel fermentation" — is a defining characteristic of Asian amylolytic brewing traditions and distinguishes them from the sequential malting-and-fermenting process of European beer.^[3]

The wild plant ingredients gathered by the brewster are not merely flavouring agents; they serve as carriers of the fungi and yeasts that colonise the cakes during preparation. Certain barks and roots may also contribute antimicrobial compounds that suppress unwanted bacteria, helping to select for the desirable organisms. The precise combination of plants varies by region and by family, representing closely guarded knowledge passed down through generations.^[4]

Preparation

To prepare phab, the brewster first cooks grain — typically wheat or maize — and allows it to cool to a temperature warm enough to support microbial growth but not so hot as to kill the organisms. She then grinds a portion of an older, proven phab cake into powder and meticulously works it into the cooked grain by hand, ensuring that the dried culture comes into contact with as many kernels as possible. The inoculated grain is shaped into small cakes or bagel-like rings and placed between two layers of pine needles, where it is left to incubate for fifteen to twenty days. During this period, the moulds and yeasts colonise the grain substrate, producing a network of mycelium that binds the cake together. The finished phab is dried thoroughly and can be stored for months.^[1]

A critical element of the process is the use of an older "mother" phab to inoculate each new batch — a form of back-slopping that maintains the microbial culture across brewing cycles. As one Scharchop woman from Radhi in eastern Bhutan has explained, newly baked cakes must be coated in an older mother bagel for the fresh ones to be truly effective. This practice ensures continuity of the microbial community and represents a form of domestication: over generations, the brewster selects for organisms that produce reliable, high-quality fermentation.^[5]

Use in Brewing

When the brewster is ready to make chang, she cooks her chosen cereal — barley, wheat, buckwheat, finger millet, rice, or maize — and allows it to cool. The phab is then crumbled or powdered and mixed into the cooked grain, which is packed into a fermentation vessel, often an earthenware pot or woven bamboo container. Fermentation proceeds over several days, during which the amylolytic fungi break down the grain starch and the yeasts convert the resulting sugars into alcohol. The first liquid drawn off is sin chang, a thick, nourishing, tangy beverage sometimes described as "liquid bread." This can be diluted and drunk as bang chang, or distilled over a wood fire to produce ara, a clear spirit with an alcohol content typically ranging from 15 to 25 per cent.^[1]

Cultural Significance

In Bhutan, brewing has traditionally been a woman's domain, and the ability to produce high-quality phab and brew excellent chang is a source of considerable prestige. The Bhutanese brewster uses no industrial yeast, malt, hops, food additives, or chemicals — only plants from her mountain and forest environment and home-grown cereals. This self-sufficiency reflects the broader values of Bhutanese rural life, in which households strive to produce as much as possible from their own land and surroundings. Chang and ara play central roles in Losar celebrations, religious offerings, community gatherings, and daily hospitality, making phab one of the most culturally significant biotechnologies in the country.^[5]

The tradition faces pressure from modernisation and the growing availability of commercially produced alcohol, but phab-based brewing persists in rural communities across Bhutan, particularly in the central and eastern districts. Ethnobotanists and food scientists have increasingly recognised the scientific and cultural value of these traditional starter cultures, and efforts to document and preserve the knowledge of Bhutanese brewsters are ongoing.^[2]

References

1. "Traditional Bhutanese beers." Beer Studies.
2. "Beer brewing in the Bhutanese style." Academia.edu.
3. "Identification of yeast strains isolated from marcha in Sikkim." PubMed.
4. "Amylolytic Fungi in the Ethnic Beer Starter." Frontiers in Sustainable Food Systems.
5. "Brewing in the Land of the Thunder Dragon." BeerAdvocate.
6. "Microbiological studies on amylolytic oriental fermentation starters." Mycopathologia, Springer.