Abstract: Multivariate analysis was conducted to evaluate the amino acid composition and nutritional values of 7 types of Chlorella including Chlorella vulgaris, Chlorella autotrophica, Chlorella minutissim, Chlorella spp., Chlorella pyrenoidosa, Chlorella protothecoides and Chlorella ellipsoidea. The results showed all kinds of amino acids were detected in the 7 types of Chlorella. The ratios between essential amino acids and total amino acids were 35.86%, 39.75%, 37.58%, 36.35%, 38.05%, 37.98% and 40.28%, and the essential amino acid indexes were 66.63, 79.41, 67.96, 71.17, 57.69, 70.02 and 65.39 in Chlorella vulgaris, Chlorella autotrophica, Chlorella minutissim, Chlorella spp., Chlorella pyrenoidosa, Chlorella protothecoides and Chlorella ellipsoidea, respectively. Cluster analysis and principal component analysis indicated that Chlorella cultured in seawater-based medium and freshwater-based medium could be classified as two different types according to the contents of amino acids. Three principal components were analyzed to reveal a contribution rate of 73.727% for the first principal component, 10.021% for the second principal component and 7.052% for the third principal component, respectively. The cumulative contribution rate of three principal components was 90.80%.

Key words: Chlorella, amino acid, multivariate analysis