A Comparative Analysis of Nutritional Composition in Acer truncatum Leaves and Seeds Over the Growing Stages

Acer truncatum is a valuable source of bioactive compounds, yet the dynamics of these components throughout its growth cycle remain poorly characterized, limiting the optimization of harvest timing for maximal yield. This study quantified key phytochemicals in leaves and seeds across growth stages. In leaves, total flavonoids, chlorogenic acid, and gallic acid reached their highest levels in May (5.62% ± 0.1%, 3.38 ± 0.31, and 6.87 ± 0.14 mg/g, respectively). Quercetin was highest in June (1.80 ± 0.17 mg/g), whereas vitamin C and free amino acids peaked in September (38.73 ± 1.40 and 85.76 ± 0.56 mg/g, respectively) and moisture content peaked in April (74.34% ± 0.17%). For seeds, total flavonoids and quercetin content were highest on September 30 and September 15, respectively, whereas total amino acids and moisture peaked on August 31. No significant temporal variation was detected in chlorogenic acid, gallic acid, or kaempferol. Regarding fatty acids (FA) in seeds, total FA, unsaturated FA (UFA), and monounsaturated FA (MUFA) increased through Sep 30 (reaching 85.36 ± 1.67, 76.63 ± 1.65, and 50.83 ± 1.24 g/100 g, respectively) and then declined slightly. In contrast, polyunsaturated FA (PUFA) decreased to a minimum on September 30 (25.80 ± 0.90 g/100 g) before rising markedly by October 15 (40.60 ± 2.13 g/100 g), whereas saturated FA (SFA) remained stable. These findings demonstrate that the accumulation of characteristic components in A. truncatum is markedly influenced by growth stage. Multivariate analyses and integrated nutritional quality evaluation confirmed that May was optimal for leaves, whereas September 30 was the optimal harvest time for seeds. In a word, the present study not only enhances the database of characteristic components during various growth stages of A. truncatum, but also establishes a theoretical foundation for the development of diverse harvesting and processing technologies for A. truncatum.