Analysis of the relationship between Daqu´s physical and chemical parameters and its quality using rough sets

Daqu is important for Chinese liquor production, and it determine the yield as well as quality of Chinese liquor. Daqu can be evaluated through the physical and chemical indicators such as liquor force (LF), esterifying power (EP), aroma force (which is divided into ammoniacal nitrogen (AN) and transforming ability of starch (TAS)), volume weight of caky starter (VWCS), moisture (M) and acidity (A). These indicators have different effect in liquor production. According the role in liquor production, Daqu´s quailty is divided into three levels. Due to Daqu´s different storage time and production month, the relationship between Daqu´s indicators and its quality are different. Duqu´s significant physical and chemical indicators, as well as the relationship between these sigmificant indicators and Daqu´s quality, are studied using rough set theory. The information table has been built, with all seven physical and chemical indicators of two kinds of Daqu produced in July, the latest Daqu and that after a month´s storage, as conditional attributes, with the Daqu quality level as decision attribute. The table is quantized and reduced. For the latest Daqu the liquor force, the transforming ability of starch and the acidity are selected as the significant indicators deciding the quality of Daqu according to the result of reduction, while the liquor force, the esterifying power and the acidity are selected for the Daqu after a month´s storage. The realtionship between significant indicators and Duqu´s quality are represented through the corresponding simplified rules of the table.