## 3 Results and Discussion
### Overall Determination of Volatile Compounds
Alcohols had the highest content in the total volatile components in the order of FD-S (277.970 \(\pm\) 17.246 \(\upmu\)g/L) > SH-S (222.436 \(\pm\) 20.121 \(\upmu\)g/L) > FD-A (218.201 \(\pm\) 11.173 \(\upmu\)g/L) > SH-A (186.700 \(\pm\) 4.954 \(\upmu\)g/L). Moreover, among the content of alcohols, linalool was the highest (76.755-102.197 \(\upmu\)g/L), followed by geraniol (52.084-108.070 \(\upmu\)g/L), and the above substances all showed floral aroma (Table S1). The content of ketones varied greatly in the four groups of samples, followed by FD-S (76.789 \(\pm\) 6.59 \(\upmu\)g/L) > SH-S (52.613 \(\pm\) 0.653 \(\upmu\)g/L) > SH-A (17.539 \(\pm\) 1.507 \(\upmu\)g/L), FD-A (17.591 \(\pm\) 2.182 \(\upmu\)g/L). There were significant differences in contents of hydrocarbons between each other (\(p\) < 0.05). Meanwhile, there were no significant differences in contents of aldehyde, esters, and sulfur for each group (\(p\) < 0.05). To 'Sanhua1951' white teas, the contents of acids, alcohol, hydrocarbons, ketone, naphthalene, and sulfur in SH-S were significantly higher (\(p\) < 0.05) than in SH-A. To 'Fudingdabai' white teas, the contents of acids, hydrocarbons, ketone, naphthalene, and others in FD-S were significantly higher (\(p\) < 0.05) than in FD-A (Figure 3). In conclusion, autumn teas had lower contents of aldehyde, alcohol, ketone, and total volatile components. Autumn-harvested teas exhibited higher ester content than spring-harvested ones. This is attributed to esters mainly originating from the lipoxygenase pathway and amino acid metabolism, processes that typically intensify at maturity [34]. It was noteworthy that acids were not detected in autumn teas (Figure 3). This also explained why the flavor score of autumn teas was lower than that of spring teas in the sensory evaluation results (Table 1). The results of this study were consistent with previous studies, where the tea's volatile components were greatly affected by harvest seasons and tea cultivars [35,36]. The comparative analysis of white teas produced from two cultivars revealed that 'Sanhua1951' teas consistently exhibited a higher content of volatile compounds than 'Fudingdabai' across both spring and autumn seasons. In this study, the volatile components of white teas were mainly due to seasonal factors rather than the two tea cultivars. Figure 2: Venn diagrams of four tea samples. (**A**) The number distribution of volatile compounds in ‘Sanhua1951’ between spring and autumn; (**B**) The number distribution of volatile compounds in ‘Fudingdabai’ between spring and autumn. As shown in Figure 4, alcohols (51.971%, 54.137%, 57.859%, 61.533%), aldehydes (12.644%, 10.750%, 14.559%, 13.110%), ketones (12.293%, 14.955%, 5.435%, 4.961%), and esters (12.896%, 9.868%, 16.496%, 13.79%) were identified as the predominant volatile compounds across the four groups (SH-S, FD-S, SH-A, FD-A). This composition is consistent with findings from prior white tea studies. In particular, similar to Dianhong tea, the proportion of alcohol in the four groups was the highest among the categories, which may be related to the genetic basis of tea cultivars and the growing environment [37]. It is worth noting that, as shown in Figure 4, the proportions of alcohols were higher in the autumn teas (SH-A, FD-A) than in the spring teas (SH-S, FD-S), while the total contents of these volatile compounds were lower in the autumn teas than in the spring teas (Figure 3). This differences between quantitative and qualitative value of alcohols correspond with different value of ketone but in opposite directions. The proportions of ketones were higher in the spring teas then in the autumn teas. Obviously, significant differences were observed in the proportions of volatile compounds between the spring and autumn harvests of white teas from the two cultivars.