Although modern mechanical production can save much human labor, the use of aged cellars at the Wuliangye plant keeps the company rooted in the most traditional procedures, mainly to protect the aged cellars and guarantee the liquor quality, old workers said.

An old worker demonstrated the difference by digging out a piece of cellar mud with a grayish sheen, which was clearly unlike the yellow mud in the newly built cellars.

He told reporters that the gray color with luster is the character of aged cellars. The mud absorbed the essence of fermentation through generations and forms several microbial communities, thus developed their own aroma - strong and peculiar at the first smell, but gradually turns into sophisticated fragrance.

The latest studies done by the company found that there are more than 600 varieties of microorganisms in the aged cellars. These microbial communities form the foundation for liquor making. They help form Wuliangye's special aroma system, workers said.

The mud in the aged cellars is well preserved by strict rules. Even waste mud is tested before disposal to make sure that few microbial communities are left inside, according to the company.

"We are not only making spirits but also helping the microbes to maintain their own ecosystem," workers at Wuliangye said.