Identification of key quality indicators for Zigui navel orange varieties through multivariate analyses

This study comprehensively characterized five representative Zigui navel orange cultivars regarding physicochemical properties, bioactive compounds, and volatiles. Quality indicators varied among navel orange cultivars (p < 0.05, η² > 0.78) for all parameters. Newhall Orange (NO) exhibited superiority in content of protein, vitamin C, total soluble solids, soluble sugars, total phenolics, and total flavonoids, and antioxidant activity. 14 characteristic quality indicators for Zigui navel oranges were identified through multivariate analyses (correlation analysis, HCA and OPLS-DA) and market-relevant parameters. These indicators were grouped into three principal components through PCA (KMO > 0.6 and Bartlett's test p < 0.05) with eigenvalues >1, accounting for 93.125% of the cumulative variance. A comprehensive quality score was calculated for each cultivar by weighted summation of the standardized values of these 14 indicators, with NO demonstrating the highest score. These findings provide theoretical guidance for nutritional evaluation and processing applications of Zigui navel oranges.