###### Abstract  
The integration of HS-SPME-GC/MS and UPLC-MS/MS techniques enabled the profiling of volatile organic compounds (VOCs) and amino acids (AAs) in 18 crabapple flower cultivars, facilitating the development of a novel VOC-AA model. Among the 51 identified VOCs, benzyl alcohol, benzaldehyde, and ethyl benzoate were predominant, categorizing cultivars into fruit-almond, fruit-sweet, and mixed types. The amino acids, namely glutamic acid (Glu), asparagine (Asn), aspartic acid (Asp), serine (Ser), and alanine (Ala) constituted 83.6% of the total AAs identified. Notably, specific amino acids showed positive correlations with key VOCs, suggesting a metabolic regulatory mechanism. The Orthogonal Partial Least Squares Discriminant Analysis (OPLS-DA) model, when combined with volatile organic compounds (VOCs) and amino acid profiles, enabled more effective aroma type classification, providing a robust foundation for further studies on aroma mechanisms and targeted breeding. Crabapple (_Malus_ spp. ); volatiles; amino acids; VOC-AA integrated model  
the breeding of ornamental plants, the manufacture of high-end perfumes, the enhancement of food flavors, and the development of natural medicines [8; 9; 10]. Regarding their biosynthetic pathways, floral VOCs are categorized into three major classes: terpenoids, benzenoids/phenylpropanoids, and fatty acid derivatives [11]. Terpenoids, as the most abundant volatile component, play a critical role in plant-environment interactions, particularly in attracting pollinators [12]. Benzenoid/phenylpropanoid compounds, representing the second largest class of volatiles, are vital secondary metabolites [4]. Meanwhile, volatile fatty acid derivatives contribute distinct scent characteristics and perform multiple roles in plant-environment interactions, often in response to biotic stress [13]. Thus, floral VOCs demonstrate complex ecological interactions, providing both adaptive functions, such as stress resistance and defense, and a wide range of applications in fragrances, food products, and pharmaceuticals. Nonetheless, the metabolic regulatory networks and coordinated functions that underpin these volatiles require further elucidation. The crabapple is celebrated for its splendid blossoms, and numerous fragrant varieties have been cultivated successfully through both natural selection and artificial breeding [14]. Breeding programs have largely concentrated on ornamental characteristics, including flower shape, color, and fragrance [15]. In response to the increasing demand for fragrant ornamentals, breeders have given priority to cultivars with pronounced aromas during the selection process [16; 17]. Current research suggests that the diversity of VOCs in crabapple flowers forms the basis of their unique scent profiles, predominantly comprising alcohols, aldehydes, esters, and terpenoids [18]. Significant variances in VOC composition are evident among different cultivars. For instance, in the ornamental crabapple cultivar _Malus_ 'Lollipop', esters, benzenoids, and alkanes are the primary components [17], while in _Malusiensis_ 'Prairie Rose', benzyl alcohol, lilac aldehyde, and benzaldehyde contribute distinct fragrances to different crabapple varieties [14]. Although these studies have elucidated the chemical foundations of the crabapple scent, they have generally focused on individual VOC components and lacked comprehensive multi-metabolite comparative analyses, such as those integrating AAs or anthocyanins with VOCs, across different cultivars. This gap has resulted in a partial understanding of the aroma germplasm diversity in crabapple, thus limiting the targeted enhancement of fragrance traits and the development of innovative cultivars. Previous studies have documented associations between AA levels and the intensity of floral scent.