Objective Eucommia ulmoides leaves are of wide uses in medical treatment, health care, food industry and antimicrobial-free breeding. To give a reference for the efficient utilization of E. ulmoides leaves, the high grade leaf-used resources were screened after comparing differences and dynamic changes of main nutrients in leaves of different improved varieties.
Method The contents of nine important active compounds and 15 amino acid components were determined in different leaf growth periods of 13 E. ulmoides improved varieties by HPLC method and automatic amino acid analyzer, respectively. Then the nutritional evaluation of E. ulmoides leaves was performed by principal component analysis and membership function.
Result Compared to quercetin, aucubin and geniposidic acid, the content differences of protocatechuic acid, rutin, chlorogenic acid, astragalin, kaempferol and abietin pinoresinol diglucoside in E. ulmoides leaves were more significant in the 13 varieties. To content of the same active compound, similar growth dynamic changes were found in different varieties. Among the 13 improved varieties, the ratio of essential amino acids to total amino acids (EAA/TAA) was 0.40−0.45, while the ratio of essential amino acids to non-essential amino acids (EAA/NEAA) was 0.66−0.82. Similar dynamic changes were found in contents of five amino acids including aspartic acid, threonine and serine. The contents of nine components, including total amino acids, essential amino acids and leucine, were selected as indexes for evaluating the nutritional value of the leaves.
Conclusion The amino acid composition and proportion in leaves of all 13 improved varieties reach the standard of the ideal protein pattern. Varieties of ‘Huazhong 10’ ‘Huazhong 24’ ‘Huazhong 13’ ‘Huazhong 30’ ‘Huazhong 12’ are of high grade improved varieties for E. ulmoides leaf use. ‘Huazhong 12’ and ‘Huazhong 24’ can be preferentially selected while extracting and utilizing leaf flavonoids in large scale.
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