Abstract: To compare the amino acid composition of different Dendrobium,make nutritional assessment.Amino acid content of 6 different germplasm Dendrobium was determined by automatic amino acid analyzer,analyzing the components of essential amino acids.Nutrition evaluation was conducted by calculating non-biological indicators such as amino acid score (AAS),chemical score (CS) and amino acid ratio coefficient score (SRCAA).Results indicate that the variety of amino acids in Dendrobium is complete and nutritious,all Dendrobium contained 17 amino acids tested.The total amino acid content of Dendrobium varied from 3.58% to 8.09%.The total content of essential amino acids was between 42.62% and 47.23%,which was significantly higher than the WHO/FAO model value (35.00%).The chemical score indicated that the limited amino acids were cysteine and methionine.The amino acid content of different Dendrobium varied greatly (2.24%-5.37%),among them the content of SH4 was 2.40 times as high as that of SH3,however,the proportion of total amino acids is basically the same (60.96%-66.47%).The cluster analysis of 6 Dendrobium can be divided into 4 categories,D.moschatum,D.denneanum,D.hancockii can be regarded as high quality protein germplasm.To sum up,the amino acid of Dendrobium has important nutritional value,and the amino acid of different germplasm Dendrobium has significant differences.This result can provide theoretical guidance for the nutritional value,variety breeding and medicinal development of Dendrobium.

Key words: Dendrobium, amino acid composition, nutritional evaluation, cluster analysis