[The making method of Shen Qu in Qi Min Yao Shu]

Shen Qu was distiller's yeast in Qi Min Yao Shu, the most completely preserved of the ancient Chinese agricultural texts in the North Dynasty. The making process of Shen Qu (medicated leaven) in this book had far-reaching influence on the processing of Liu Shen Qu. In terms of pharmaceutical composition, Flour-qu in Shen Qu, which developed into Whole-bran-wheat-qu and then Bran-qu, is still used up to this day. The use of polygonum, as a supplementary material from the buckwheat and knotweed family polygonaceae, was gradually narrowed to polygonum hydropiper and polygonum orientale. In terms of production and processing, fresh herbs were developed from boiling or boiling and juicing in parallel. Wheat processing was simplified from the method of raw wheat, steaming and frying together into the method of using raw wheat only. Psychrometrics of Qu-cake "Sou Yu Gang" is still taken as the measurement of production and processing today. The method of shaping Qu-cake evolved to hand kneading and moulding. The covering material of Qu-cake was developed from wheat straw and Artemisia annua to Vitex negundo. The wrapping material of Qu-cake were Ramie leaves, broussonetia papyrifera leaves and paper. Some techniques in the processing, such as Fan-qu, Ju-qu and Wengsheng, were lost in the historical development of the making method of Shen Qu. The drying method was developed from hanging clusters of Qu-cakes to hanging single paper wraped cakes alone. As a mainstream processing method, Yan-qu was then developed into the methods of Fengqu and Zao Jiang Huang. The making method Bao-qu, which outdated Qu was added, and is still the method of Yan-qu. In this sense, current production and processing technology of Yan-qu and Zao Jiang Huang came from Qi Min Yao Shu.The issues for further studies are: the use of Artemisia annua, Polygonum hydropiper and Xanthium sibiricum, Qu-cake moulding, single strain fermentation or dominant population fermentation, the Feng-qu method, the materials for covering and wrapping Qu-cake, and comparison between Flour-qu, Whole bran wheat- qu and Bran-qu.