Abstract：[Objective] The purpose of this study is to provide a scientific theoretical basis for the breeding and industrial development of superior large-fruit jujube (Ziziphus jujuba) varieties in Xinjiang and to explore a suitable method for evaluating the fruit quality of large-fruit jujube. [Methods] Six new large-fruit jujube varieties were used as experimental materials to measure 30 fruit quality indicators (individual fruit weight, edible rate, moisture content, soluble solids content, total acid, total sugar, reducing sugar, glucose, fructose, starch, polysaccharides, total amino acids, vitamin C, protein, fat, crude fiber, tannin, total flavonoids, total phenols, proanthocyanidins, total alkaloids, ash content, Na, K, Ca, Mg, Fe, Mn, Zn, Cu). Subordinate function method, factor analysis, and principal component analysis were used for comprehensive evaluation. [Results] The coefficient of variation for the 30 fruit quality traits of six new Xinjiang large-fruit jujube varieties ranged from 2.656% to 97.165%. The highest variability was in proanthocyanidins (97.165%), followed by calcium (67.785%), indicating significant differences among varieties in these two components. The variation was less than 10% for moisture content, soluble solids, total sugar, reducing sugar, fructose, starch, polysaccharides, total alkaloids, and copper, indicating low dispersion and more consistent distribution among varieties, with the smallest coefficient of variation for edible rate (2.656%). Correlation analysis was performed on 30 different fruit quality traits, and the indicators showed varying degrees of positive and negative correlations. Among them, reducing sugar and total sugar had a very significant positive correlation; starch and individual fruit weight had a significant negative correlation; polysaccharides and total acid had a significant positive correlation; total amino acids had a significant negative correlation with moisture content and significant positive correlations with total acid, total sugar, and reducing sugar; protein had a significant positive correlation with total acid, a very significant positive correlation with total amino acids, and a very significant negative correlation with moisture content; fat had a very significant negative correlation with polysaccharides; crude fiber had significant positive correlations with total acid and protein, a very significant positive correlation with total amino acids, and a significant negative correlation with moisture content; tannin had significant negative correlations with reducing sugar, total amino acids, and protein, and a very significant negative correlation with soluble solids; total flavonoids had a significant positive correlation with tannin; total phenols had significant negative correlations with soluble solids, total amino acids, and protein, a significant positive correlation with total flavonoids, and a very significant positive correlation with tannin; proanthocyanidins had a significant positive correlation with total flavonoids, a very significant positive correlation with tannin and total phenols, and a significant negative correlation; potassium had significant positive correlations with soluble solids, total amino acids, and protein, a very significant positive correlation with crude fiber, and a very significant negative correlation with moisture content; magnesium had significant positive correlations with total acid, total amino acids, protein, and total phosphorus; manganese had a significant positive correlation with calcium; zinc had a very significant positive correlation with starch; copper had a very significant positive correlation with fat and a significant negative correlation with polysaccharides. In the comprehensive evaluation of jujube fruit quality, considering the inconsistency of the dimensions of the quality indicators, external sensory indicators (individual fruit weight, edible rate, moisture content), and nutritional indicators (total sugar, reducing sugar, glucose, fructose, starch, polysaccharides, total amino acids, vitamin C, protein, fat, total flavonoids, proanthocyanidins, total alkaloids, ash, total phosphorus, potassium, calcium, magnesium, iron, manganese, zinc, copper) are all better with higher values; total acid, crude fiber, tannin, and total phenols are better with lower values. Therefore, before factor analysis, the subordinate function method was used to standardize the data. Principal component analysis was employed to simplify the plethora of raw information into a few synthetic variables for a comprehensive evaluation method, and five common factors with eigenvalues greater than 1 were extracted through factor analysis, accounting for 10% of the cumulative contribution rate, representing the 30 fruit quality indicators of the six types of large-fruit jujube, which can be used as indicators for the comprehensive evaluation of the fruit quality of large-fruit jujube. The first principal component (f1) synthesized information from 16 indicators: moisture content, soluble solids, total acid, total sugar, reducing sugar, polysaccharides, total amino acids, protein, fat, crude cellulose, tannin, total phenols, total phosphorus, potassium, magnesium, and copper. Of these, moisture content, fat, and copper had the greatest weight. The second principal component (f2) synthesized information from 7 indicators: individual fruit weight, edible rate, glucose, fructose, vitamin C, calcium, and iron, with individual fruit weight and edible rate having the greatest weight. The third principal component (f3) synthesized information from 4 indicators: starch, total flavonoids, proanthocyanidins, and zinc, with starch and proanthocyanidins having the greatest weight. with manganese having the greater weight.[Conclusion] The results of the study show that the quality of large-fruit jujube can be comprehensively evaluated by considering a set of factors, including external sensory indicators and nutritional indicators. The use of subordinate function method and principal component analysis provides a systematic approach to the evaluation of fruit quality traits, allowing for the identification of superior varieties and the improvement of breeding programs. The study also highlights the importance of considering a wide range of quality traits, as they are interrelated and can affect the overall quality of the fruit. The findings can guide the selection of large-fruit jujube varieties with high fruit quality for consumers and the industry, and support the development of new varieties with optimal quality traits.
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