Analysis of Nutritional Quality of Tonggu Polygonatum cyrtonema Hua from Different Planting Ways and Growing Years and Construction of Its Evaluation System

To comprehensively explore the nutritional quality and construct evaluation system, this paper studied the effects of different planting ways and growing years on the 23 nutritional qualities of Tonggu Polygonatum cyrtonema Hua, and constructs of its evaluation system by correlation, factors, and clustering analysis. The results showed that the content of ethanol-soluble extractives, protein, essential amino acids (EAA), medicinal amino acids (MAA), ash and 5 constant mineral elements in Polygonatum cyrtonema Hua from greenhouse planting (GP) was the highest, and the nutritional score of EAA was also the optimal. Also, the content of polysaccharide and saponins in Polygonatum cyrtonema Hua from open planting (OP) was the most, and the four trace elements (Fe, Mn, Zn and Se) were the highest in underwood planting (UP). The Polygonatum cyrtonema Hua from wild (W) had the highest content of flavonoids and total phenols. In addition, as the extension of growing years, the content of ethanol-soluble extractives, lipid, and polysaccharides in Tonggu Polygonatum cyrtonema Hua increased gradually, while there was no significant difference in the saponins, flavonoids and total phenols (P>0.05). However, the content of starch, crude fiber, protein, ash, nutritional score of EAA and mineral elements in Polygonatum cyrtonema Hua was negatively correlated with the growing years. In particular, the decline of nutritional quality in GP was the most significant. Through the analysis of correlation, factor, and cluster, the 22 indicators of nutritional quality were simplified into 13 indicators, and then a comprehensive evaluation model was established by principal component analysis (PCA). It was found that the comprehensive score (−1.331~1.161) of nutritional quality of 8 types was GP-3>UP-3>W-4>GP-5>GP-4>OP-3>UP-4>OP-4, that is, the nutritional quality of GP-3 was optimal. And on this basis, a 6-level standard for the nutritional quality comprehensive evaluation of Polygonatum cyrtonema Hua was established. These results will provide a theoretical basis for the screening of raw materials for development of high-value products and variety improvement of Polygonatum cyrtonema Hua.