An international study on residue from pottery shards from the Neolithic era has revealed how people made alcoholic beverages in China during that time.

The study was conducted by a team of researchers from Stanford University in the United States, China's Zhengzhou University, the Chinese Academy of Social Sciences and Shaanxi Provincial Institute of Archaeology.

According to the researchers, making alcoholic beverages can be dated back to approximately 13,000 years ago, and people did it in different ways depending on what ingredients they could get.

In the early Neolithic era, people living in what is now the Wei River Valley, in northwestern China, had rice, millet and several other ingredients that allowed them to make fermented beverages.

They reported in the U.S. journal Proceedings of the National Academy of Sciences that traces of starch, fungi and some plant tissue, ingredients used to make fermented beverages, are found in pottery shards that can be dated back to approximately 7,000 to 8,000 years ago.

The researchers said people at that time could have been making alcoholic beverages in at least two ways. One is to make grains to sprout (cereal malts), which will free sugar in the plant. The other is to use moldy grains and herbs as starters which allows saccharification and fermentation at the same time.

They also found that special pottery vessels were also made to promote fermentation. For instance, some vessels were small-mouthed with wide sides but thin necks. The design better seals the vessel, keeping fresh air out, which can boost the anaerobic brewing process for low-alcohol beverages.

They said making alcoholic beverage might be linked with social and religious activities. People who could provide alcoholic beverages to others could have been bestowed some social status. (Xinhua)