A staff member checks fermentation process of brewing mature vinegar at Donghu Vinegar Garden in Taiyuan, capital of north China's Shanxi Province, Aug. 15, 2013. Donghu Vinegar Garden is a theme museum displaying a unique technology of making Shanxi mature vinegar. With over 3,000 years of history, Shanxi mature vinegar, one of the four famous vinegar in China, is made from sorghum, barley and other raw materials. The whole making process of such vinegar is of purely natural fermentation without any chemical catalysts.(Xinhua/Zhan Yan)