Ceramic vats filled with soy beans and yeast are sunbathed in a soy sauce workshop in Rugao. [Photo provided to nantong.gov.cn]

The soy sauce brewing technique in Rugao, Nantong, East China's Jiangsu province, enjoys a history of more than 1,000 years, and in 2017 the technique was listed as an intangible cultural heritage item in Nantong.

Rugao locals used to make soybean paste themselves, and soybean paste and soy sauce were popular homemade seasonings usually presented as gifts.

A person stirs a mixture in a vat to help them ferment. [Photo provided to nantong.gov.cn]

In the late Qing Dynasty (1644-1911), Rugao was home to more than 10 soy sauce stores, all of which preserved the ancient brewing technique and tools.

Rugao-made soy sauce uses unique fermentation containers and requires extended exposure to the sun.

Semi-finished soy sauce in a vat. [Photo provided to nantong.gov.cn]

The ceramic vats used to brew soy sauce in Rugao, made 1,000 years ago, are air permeable and have no water seepage, allowing yeast to have full contact with the air.

Soy sauce is made using an ancient Rugao technique. [Photo provided to nantong.gov.cn]

These vats are usually sunbathed for more than one year, during which time the soy bean in the vat is stirred each day to become fully fermented and allow the protein of the soy beans transform into various amino acids necessary to human beings.

The soy sauce made using the ancient technique in Rugao features a bright color, rich aroma, and mellow taste.