Analysis of Volatile Components in Pittosporum brevicalyx under Different Flowering Periods and Storage Temperatures

Using Pittosporum brevicalyx as materials , volatile components at different flowering stages (bud, half-open, full bloom and late bloom) and under various storage temperatures (−20 °C, 0 °C, 4 °Cand 20 °C) were determined by GC-MS, the similarities and differences in these components were compared, which provided a theoretical basis for the preservation of fresh flowers and essential oil extraction of P．brevicalyx. The results indicated that a total of 45 volatile compounds were detected during four flowering stages,predominantly consisting of terpenes and esters．Among these compounds, the relative contents of ( + )-camphene (26.66%), benzyl acetate (34.18%), and geranyl acetate (20.85%) were relatively high. The content of terpenes decreased initially and then rised slowly as flowers bloom, while esters increased first and then declined. At different storage temperatures, 44 volatile compounds were detected in the petals of blooming P．brevicalyx flowers, predominantly terpenes and esters. At −20 ℃, 4 ℃, and 20 ℃, the relative contents of benzyl acetate were 32.05%, 49.68%, and 25.55%, respectively, the volatile components in each treatment group were quite similar to each other. At 0 ℃, the relative amount of ocimene was at its highest, reaching 26.99%. Compared to the fresh flowers of P. brevicalyx, the variation in volatile components of petals under −20 ℃treatment was relatively minor.In contrast, at 0 ℃ and 4 ℃ treatments, there was a significant reduction in terpenes, esters, and alcohols. Therefore, storage at −20 ℃ was considered the optimal choice. Clustering analysis, PCA, and OPLS-DA results indicated significant differences in volatile components among samples from different flowering periods and storage temperatures, with 13 and 10 differential components identified respectively. Common differential components include ocimene, myrcene, 3-carene, pinene, geranyl acetate, and β-pinene. These findings provide valuable insights for the development and utilization of P. brevicalyx.