Subsequently widely made in haciendas dotted across the central highlands, pulque became the staple tipple of Mexico's working class until, amid false rumors that it was made with excrement, it was gradually eclipsed with the advent of beer. A decade or so ago pulque slipped into what producers and pulquería owners feared could be a terminal decline — until it was rediscovered by a new generation of drinkers.

The 19-year-old restaurant worker is among thousands of young Mexicans rediscovering the so-called “nectar of the gods” first made more than 1,000 years ago by the Aztec civilization of the country’s central highlands and drunk by priests in rituals, including human sacrifice.

“It's got a great taste … and it's a natural product that doesn't have chemicals in it,” Ivan Alejandro Camarillo said, explaining pulque's appeal as he sipped it from a brightly colored plastic beaker. “It's also really mellow and doesn't make you crazy” like other drinks, he added.

But on one recent afternoon, patrons packed into the tiny hole-in-the-wall bar is a mixed crowd of under-30 patrons who have developed a thirst for this historic Mexican drink brewed from unadulterated maguey juice.

MEXICO CITY — For decades, the clientele at the historic Los Paseos de Santa Anita pulquería was a dwindling group of working-class men with a taste for the tangy, viscous drink made from the fermented sap of the maguey plant that was fast losing market share.

“It's a complete lie … pulque has a 100 percent natural fermentation,” said Franquiz, standing beside softly fizzing tanks of fermenting juice in the cool interior of the tinacal, or brew house, at the hacienda. “When people come here, we show them that the myth isn't true. We give them the honey water to take to Mexico City, and then they see that it starts to ferment without adding anything at all.”

At the historic Hacienda Xochuca , in Tlaxcala, manager Vicente Franquiz takes a growing number of visitors around the fields of hulking magueys, relatives of the blue agaves used to make tequila. Visitors to the estate founded in the 1800s are shown them the traditional techniques to gather the sap known as aguamiel (honey water) that is used to make pulque. He one day hopes to bring output back from the current 130 gallons a day to the 26-32,000 gallons that the estate produced in its heyday, although he finds himself battling a rumor that is endlessly repeated in Mexico that a cloth-wrapped bundle of excrement — dubbed a muneca (doll) — is added to the sap to kickstart fermentation.

The revival is also giving a boost to rural areas where pulque is produced, like the nearby state of Tlaxcala where emigration to find work is common.

The drink's popularity peaked in the late 1800s when there were some 1,100 pulquerías across the capital, according to some estimates, of which perhaps 80 to 100 have survived. Renewed demand in the past five or six years has reinvigorated some of the older bars, and led to a rash of start-ups in Mexico City's trendy Condesa and Roma neighborhoods, where the ancient drink is now served to a dance music beat.

“Now it's all young people that come in,” said Noe Hernandez, Los Paseos' proprietor for the past 45 years, as he cast his eye over his youthful clientele sipping several varieties of pulque, some “cured” or mixed with fruit including guava and passion fruit that make the pungent drink more palatable. About half of the customers are “new faces,” he added.

'We thought it was going to die off, because there was no demand and no one was interested in planting maguey ... But now it's quite the opposite.'

In the small agricultural town of Nanacamilpa less than an hour's drive away in western Tlaxcala, local pulque producer Senobio Garcia is also ramping up maguey production to meet demand for the milky and highly perishable drink that he estimates has grown threefold in the past five to six years, following a long period of decline that left him fearful for its future.

“We thought it was going to die off, because there was no demand and no one was interested in planting maguey” anymore, said Senobio Becerra, representative for Grupo Pulmex, an association of small local producers around the highland town. “But now it's quite the opposite. We're concerned that sales are growing and we don't have enough maguey in production to meet demand.”

Scores of workers have joined Pulmex full time in recent years to plant and harvest several varieties of maguey used to make pulque, which take 10 to 12 years to reach maturity. In a sign of buoyant demand for the drink, Becerra fielded a call from a restaurant in the city of Tlaxcala, the state's capital, with an order for 15 containers of pulque in six different flavors for delivery before the weekend.

“They have a large group in, and they were worried that they were going to run out,” said Becerra, who also markets a range of pulque-related products, including a syrup made from the sugary sap and a fiery maguey distillate that tastes a little like tequila.

In a bid to cater to growing interest in pulque from visitors from the capital city and beyond, another historic hacienda in central Tlaxcala is getting back into production after a break of a decade. The owners of the historic Hacienda Tepetzala, a 715-acre estate founded in the 1500s complete with its own chapel, recently planted 26,000 magueys and are overhauling its ancient tinacal to brew pulque and receive tourists in coming weeks.

“We are taking the hacienda back to its origins. It's something that gives us a great deal of satisfaction,” said Emilio Sanchez over lunch at the estate which is owned by his family. “We have all the work force, all the tools and utensils that we need and, the most important, the maguey itself,” he added.

It remains to be seen whether pulque is enjoying a brief revival or is set to reclaim its place as one of the country's most popular drinks. Many believe much will depend on efforts to can or otherwise preserve the drink — which is as perishable as milk — so as to tap lucrative export markets where Mexican beers, tequilas and mezcals are already well established.

At least one firm, Hacienda 1881, exports canned pulque in a range of flavors to countries including the United States, France and Germany. The reviews are mixed. Some drinkers find it flat and muted compared to the real product, while others like the fact that is not so sharp or sticky. But enthusiasts are hopeful that the ancient drink can nevertheless make inroads abroad.

“They need to find a way to preserve it so that it can be taken to other places,” said transport engineer Emilio Garcia over a glass of nut-flavored pulque at the recently established Expendio de Pulques Finos "Los Insurgentes," one of the newer pulquerias in Mexico City. “To have pulque wherever you are … for example in China or Germany, would be great.”

Correction: A previous version of this story incorrectly referred to the maguey plant as a cactus.