Discriminant compounds and a predictive S-score for the manual grading standard of Jasminum sambac

Jasmine (Jasminum sambac) is a highly valued aromatic plant, widely used for scenting tea and extracting essential oils. Flower quality directly influences the market value of these products. However, the classification of jasmine flowers currently relies on empirical visual inspection and mechanical sieving, lacking objective chemical markers. In this study, freshly picked commercial jasmine buds (grade A and grade B) and fully bloomed flowers (grade I and grade II) were analyzed to examine differences in their volatile compound profiles using headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS). According to the general commercial grading standards used by growers and tea companies, 25 compounds differed significantly between grade A and grade B buds, while 134 compounds differed significantly between grade I and grade II opened flowers (P < 0.05). Intersection analysis identified six compounds common across grade comparisons. By comprehensively evaluating their fold changes and relative abundances, three compounds-(E)-3-Hexen-1-ol, Caryophyllene, and (E,E)-3,5-Octadien-2-one-were selected as potential markers. Based on the current dataset, the S-score provides an objective, data-driven approach to distinguish jasmine flower grades. However, as a preliminary model, its proposed threshold (S > 9.5) requires independent validation using samples from different seasons, regions, or production batches before any practical application.