Unveiling the Floral Scent Dynamics of Calamondin (Citrus × microcarpa) Across Developmental Stages

The calamondin (Citrus × microcarpa) is highly valued for its ornamental appeal and rich aromatic compounds, making it suitable for therapeutic gardens and widely applicable in the cosmetics, food, pharmaceutical, and perfume industries. Despite its importance, there is a lack of research on its floral volatiles. This study utilized headspace solid-phase microextraction gas chromatography–mass spectrometry (HS–SPME–GC–MS) to detect the volatile organic compounds (VOCs) of calamondin at different floral developmental stages: bud (BS), half-open (HS), full bloom (FS), and senescence (SS). Multivariate statistical analysis was employed to elucidate the aromatic characteristics. The results identified 67 VOCs across the four stages, including forty-eight terpenoids, six esters, five aromatics, four aldehydes, one olefin, one alcohol, and two others. Thirty-three VOCs were common across all stages, while BS, HS, FS, and SS had three, three, four, and nine unique VOCs, respectively. The total VOC content increased initially and then decreased as the flowers developed, with terpenoids being the predominant compounds, accounting for over 90% of the total emissions at all stages. Principal component analysis and hierarchical cluster analysis confirmed significant differences in VOC profiles at different stages. Partial least squares discriminant analysis identified five VOCs with variable importance in projection (VIP) values greater than one, including limonene, linalool, β-pinene, germacrene D, and β-ocimene, indicating their varying emission levels across stages. These findings enhance our understanding of the VOC characteristics of calamondin flowers and provide a scientific basis for further ornamental and industrial applications.