A 5,000-year-old brewery in China used what was then an unusual ingredient — barley.

Credit: Proc. Natl Acad. Sci. USA

A team led by Jiajing Wang at Stanford University in California analysed starch grains from pottery resembling brewing vessels (reconstructions pictured), which were discovered at the Mijiaya site in northern China about a decade ago. The vessels contained a mixture of millet, tubers, a tropical grass known as Job's tears, and barley. Some grains were swollen and deformed as though they had been mashed, a process that uses hot water to extract sugars. Chemical analysis of residues on the pottery revealed calcium oxalate, a common by-product of beer making.

Barley was domesticated in Western Eurasia around 10,000 years ago, but it did not become a major crop in China until around 2,200 years ago. The Mijiaya brewers may have seen barley as an exotic treat, the authors suggest.

Proc. Natl Acad. Sci. USA http://doi.org/bhwm (2016)