Abstract: 【Objective】Sweetpotato (Ipomoea batatas (l.) Lam) is one of the most important starchy root crops, also a kind of raw material for staple food, animal feed and industrial products in China. Nutritional quality analysis and evaluation is a significant procedure of sweetpotato variety breeding and comprehensive utilization. This study was conducted to analyse nutrient quality of different color-fleshed sweetpotato storage root, establish a suitable and cost-effective evaluation method for sweetpotato nutrient quality, discuss the key factors influencing the comprehensive evaluation of sweetpotato nutrient quality, and provide a basis for sweetpotato breeding and its utilization. 【Method】Thirty sweetpotato materials with different flesh colors were chosen to measure their starch, protein, glucose, sucrose, fructose, polyphenols, flavonoids, anthocyanin, carotene, iron (Fe), calcium (Ca), magnesium (Mg), zinc (Zn), phosphorus (P) and potassium (K) contents by using conventional chemical method and near infrared spectroscopy analysis (NIRS). A comprehensive evaluation on nutritional quality of sweetpotato root was obtained with subordinate function and factor analysis.【Result】The results showed that some differences of nutrient quality existed in thirty sweetpotato storage root materials with different fresh colors. High CV values (coefficient of variation) appeared in carotene, anthocyanin, flavonoids, polyphenols and fructose content, yet little in protein and carbohydrate content. Purple flesh sweetpotato had much Fe, Zn, Mg, flavonoids and polyphenols, more than white flesh and yellow flesh, but its starch rates were lower than the other two kinds. There was a certain correlation among most nutrient quality indexes. From sixteen nutrition quality indexes converted data matrix and factor analysis, the cumulative variance contribution of eight principal factors extracted was 92.36% approximately. The primary nutrition quality indexes can be classified as functional material factor, carbohydrate factor and fundamental nutritional quality factors, and the variance contribution rate and weight index of three common factors were 33.34%, 38.7%, 20.32% and 0.36, 0.42, 0.17, respectively. The results showed that factor analysis is a good statistical method for describing nutritional quality variability among similar, correlated variables. According to weight index and subordinate function value of eight principal factors, the comprehensive evaluation of nutritional quality showed a significant difference in different color-fleshed sweetpotato varieties (or lines) (P＜0.05). Purple flesh type had highest value, which was attributed mainly to much flavonoids, polyphenols, anthocyanin and other functional materials in storage root. The white was the lowest. Hence, functional materials can be used as an important index to assess the comprehensive evaluation on sweetpotato nutritional quality. Nevertheless, some fundamental nutritional quality factors including carbohydrate and protein had no obvious impacts on comprehensive evaluation. 【Conclusion】There were some differences of nutrient quality characteristics among different color-fleshed sweetpotato storage roots. Meantime, evident difference existed in comprehensive evaluation on different nutrient qualities using factor analysis. The comprehensive evaluation value of purple flesh sweetpotato varieties was more than white and yellow ones. The key factors affecting nutrient quality evaluation were successively functional substances factor, carbohydrate factor and fundamental nutrient quality. This study has enriched and perfected the evaluation system of sweetpotato storage root nutrient quality.

Key words: sweetpotato , storage root , nutrient quality , factor analysis , comprehensive evaluation