Characterization of Characteristic Volatile Organic Compounds and Key Aroma Compounds in Peels of Variegated Calamondin at Different Maturity Stages Based on HS ‐ SPME ‐ GC ‐ MS and Multivariate Statistical Analysis

Variegated calamondin, a rare variant of four‐season orange, possesses a unique woody aroma and abundant sesquiterpenes in its peels, demonstrating tremendous value in the development of premium spices and functional products. This study employed headspace solid‐phase microextraction coupled with gas chromatography‐mass spectrometry (HS‐SPME‐GC‐MS) and electronic nose (E‐nose), combined with linear discriminant analysis (LDA), orthogonal partial least squares discriminant analysis (OPLS‐DA), and odour activity value (OAV) to systematically characterise the volatile organic compounds (VOCs) and key aroma compounds in variegated calamondin peels across three maturity stages. A total of 228 VOCs were identified, primarily consisting of heterocycles, terpenes, hydrocarbons, and alcohols. Notably, tetradecane concentration significantly increased from 3.42 ± 0.51 μg/g (green‐stem stage) to 8.76 ± 1.23 μg/g (mature stage) ( p < 0.01), while 2,6‐octadien‐1‐ol, 3,7‐dimethyl‐, (Z)‐ decreased from 15.83 ± 2.14 μg/g to 4.27 ± 0.89 μg/g ( p < 0.01). The LDA model achieved 100% classification accuracy across all maturity stages (sensitivity = 100%, specificity = 100%), and was further validated with an independent test set (accuracy = 97.2%). OPLS‐DA identified 112 characteristic VOCs through pairwise comparisons. Twenty‐nine key aroma compounds (OAV > 1) were identified: 1‐octen‐3‐one dominated the grassy odour in early development (OAV = 3191.30); (E,E)‐2,4‐decadienal (OAV = 821.09) and decanal (OAV = 298.94) characterised the colour‐change stage; butanoic acid, 3‐methyl‐, 2‐phenylethyl ester (OAV = 1674.89), decanal, β‐myrcene, and α‐pinene collectively contributed to the intense fruity, floral, and woody aroma at full maturity. This study elucidated the flavour evolution mechanisms during peel maturation and provided a theoretical foundation for standardised harvesting and high‐value utilisation of variegated calamondin.