Abstract: In order to optimize the indexes to evaluate the quality of Nostoc commune Vauch., 19 quality attributes including crude protein, total ash, phosphorus, total sugars, lipid classes, total lipids, water-soluble ash, water-insoluble ash, Ca, Na, K, Mg, Fe, Zn, Mn, Cu, Pb, Ni and Cd of N. commune Vauch. from 8 regions in Gansu province were analyzed by principal component analysis (PCA) and cluster analysis (CA). The results showed that the variation coefficients of total lipids, lipid classes, total sugars, Mn, Na and Zn were more than 30%, while those of other quality indexes were only about 3%. PCA showed that five principal components represented the 19 quality indicators N. commune Vauch., making 92.71% cumulative contribution to the total variance. According to the cluster analysis, six quality indexes including total sugar, water-soluble ash, lipids, Fe, Ca and P were sufficient to evaluate the quality of N. commune Vauch.. Among the 8 producing areas, N. commune Vauch. from Shandan had the best quality, followed by Tianzhu, and that from Ganzhou had the worst quality.

Key words: Nostoc commune Vauch., quality indexes, principal component analysis, cluster analysis