Why China's craft breweries are tapping into ancient beer recipes

(CNN)China is home to one of the oldest civilizations, so it's only fitting that it's home to ancient beer as well.

But no one knew how its ancient beer was made -- until in 2015 a team of archaeologists from Stanford University conducted studies on a primitive brewery discovered on a Neolithic site in China.
The 5,000-year-old brewery is the earliest evidence of barley- and millet-based beer-making in the country.
Inspired by the scientists' findings, two breweries -- Jing-A Brewing Co in Beijing and Moonzen Brewery in Hong Kong -- set out to give the modern world a taste of an ancient experience by recreating the original beer recipe.

    Tapping into history

    An ancient brewing pot, repaired with plaster.
    It all started in 2006. While excavating Mijiaya, an ancient site near Xi'an in central China, researchers from the Shaanxi Provincial Institute of Archaeology found subterranean pits dating back 5,000 years.
    Two of these pits contained sets of pottery vessels, including open-mouthed pots, funnels and small-mouthed jars.
    The instruments and setup seemed to resemble a primitive microbrewery, where the pottery vessels would have been used for mashing, filtration and fermentation.
    "People use the same equipment today for beer-making," says Li Liu, a professor in Chinese archaeology at Stanford University.
    Liu has studied residues of ancient alcohol on pottery since 2012, and found connections between funnels and alcohol making at other sites.
    "The funnel is functional and has been in the same shape for thousands of years."
    Upon learning about the Mijiaya site, Liu and her team began conducting analysis on the pottery, hoping to shed more light on their earlier research.

    A barley breakthrough

    Those pottery vessels had a layer of yellowish residue on the inside surface -- possibly a sign of beer ingredients, but scientists were unable to prove the theory without closer analysis under a microscope.
    The team narrowed it down to microscopic plant remains from barley, millet, yam, snake gourd root and Job's tears.
    Barley, while common today, was one of the most surprising ingredients to be identified.
    "This finding added a new dimension that was really unexpected to us, because we understood that barley was introduced to China about 4,000 years ago," says Liu.
    "When we found the barley, we realized why this exotic food was introduced to a new land and used for special purposes.
    "It wasn't just in the ordinary diet in the food and not for everyday consumption, as there are very few barley remains from the Neolithic times in central China."

    Developing new brews

    China's rural landscape.
    In March, the two brewers -- Jing-A brewery from Beijing and Moonzen Brewery from Hong Kong -- visited the ancient Mijiaya site to learn more about the beer-making process.
    "We were really fascinated by the idea of recreating the Mijiaya beer and seeing what people were drinking 5,000 years ago," says Alex Acker, co-founder of Jing-A Brewing Co.
    As it turns out, the actual fermentation process hasn't changed much. But modern beer uses a slightly different set of core ingredients -- malted barley, hops, yeast and water.
    In the Neolithic era, there were no hops, and people would have used a different set of cereals, grains and starches.
    The yeast was also quite different. Whereas today, yeast is controlled for consistency, back then beer would have seen as a more spontaneous fermentation process.
    "One of the most interesting things we did on this trip was go back to find an indigenous wild yeast that they're still using with hunjiu (hazy wine) today, which is also a millet-based beer," says Acker.
    Yeast plays a huge role in the flavor of the beer, so the brewers felt it was crucial to bring back samples of the yeast to use in their brews.
    "The reason why German wheat beer tastes very different from an American wheat beer is because of the yeast used. German beers can sometimes have banana-like flavors in them even if there's no banana in the beer -- it's the yeast that makes the difference."

    What does it taste like?

    The finished beer is light, fruity, and slightly sour.
    Acker describes the beer as "sour barnyard" ... but in a good way.
    "It's an un-hopped beer and a unique recipe that we wanted to stay true to," says Acker.
    "Without the hops in there and with these other unusual ingredients, you get a starchy, grainy flavor and aroma with a bit of sourness, almost like an ancient berliner weisse."
    He says it's light and fruity, slightly sour with a touch of honey and hawthorn berry -- both of which would have been available at the time.
    "In addition to local wild yeast, we used broomcorn millet, Job's tears, snake gourd root and lily bulb sourced during our trip -- just as Mijiaya brewers would have done 5,000 years ago."
    Jing-A has brewed 350 liters of the beer, which will be available at the brewery's various Beijing outlets by the end of April.
    Meanwhile, in Hong Kong, Moonzen is brewing 100 liters and distributing the beer at its brewery. Both brewers say proceeds will benefit the Shaanxi Institute's research.
    "I really love the aroma and flavor," says Acker.
    "There is definitely a cross over to the hunjiu that we brewed with the farmer. This is a beer that I'd enjoy drinking myself, and I think beer fans are really going to have fun tasting a bit of ancient history."

    Ancient social circles

    Discovering an ancient beer recipe is just one takeaway from Liu's research.
    The Neolithic period in China, about 4,000 to 6,000 years ago, is often associated with farming communities.
    Knowing that they brewed beer for pleasure and possibly celebrations, paints a more complete picture.
    "Some individuals in some households began to deviate from others and we also saw some social standings in our research. We need to study more to understand how alcohol played an important role in the development of a complex society," says Liu.
    It also speaks to the root of socio-economic evolution, where different strata experienced varying qualities of life.
    "We need to study how alcohol-making was linked with power development in ancient times," says Liu. "We want to see how feasting behavior helped individuals to get power and how alcohol was used."