Characterization of yuanbaofeng (Acer truncatum Bunge) samaras: Oil, fatty acid, and phytosterol content

Abstract

Acer truncatum is an important oil-bearing woody tree and its kernel oil is rich in nervonic acid. Samaras of 20 Acer truncatum grafted accessions were collected to evaluate the variations of their morphological characteristics, oil content, and fatty acid and phytosterol composition. Significant differences were found in the measurements of the samaras of all Acer truncatum accessions. The average samara dry biomass, nutlet dry biomass, kernel dry biomass, and kernel percentage were 0.43 ± 0.06 g, 0.29 ± 0.05 g, 19 ± 0.03 g, and 44.39%, respectively. The average oil content of the kernels was 47.60%, ranging between 37.77% and 54.63%. The 11 fatty acid compounds were determined, of which linoleic acid was the major constituent, accounting for 33.80 ± 1.80%, whereas nervonic acid and erucic acid accounted for 6.10 ± 0.63% and 16.87 ± 0.73%, respectively. The average total phytosterol content was 327.41 ± 42.66 mg/100 g, which mainly consisted of seven types of phytosterol. β-Sitosterol (106.59 ± 16.69 mg/100 g) and Δ7-stigmastenol (103.41 ± 15.33 mg/100 g) were the dominant phytosterols. In addition, this is the first time Δ7-stigmastenol, 24-methyl-colest-7-en-3β-ol, and Δ7-avenasterol have been identified in Acer truncatum oil. The results of correlation analysis indicated that samara base width had significant positive correlations with wing length (r = 0.549, P <0.05), samara dry biomass (r = 0.582, P <0.01), nutlet dry biomass (r = 0.574, P <0.01), and kernel dry biomass (r = 0.625, P <0.01). The oil content had negative correlations with saturated fatty acids (r = −0.595, P <0.01) and total phytosterol content (r = −0.448, P < 0.05). Principal component analysis revealed that the first two principal components explained 55.12% and 67.60% of the total variance of fatty acids and phytosterol composition, respectively. Furthermore, the germplasm resources with high oil yield, high nervonic acid content, and high phytosterol content were selected.