Contribution to the Varietal Delimitation of Irvingia gabonensis and Irvingia wombulu Chemical Composition Variability of Fats Extracted from Kernels

摘要

Irvingia gabonensis was long considered to comprise two varieties, one sweet and the other bitter. These have since been classified as distinct species, sweet I. gabonensis and the bitter I. wombulu, essentially on morphological and organoleptic criteria. Chemical analysis of the oil extracted from the nut and the processed results of multivariate statistical analysis, i.e., Principal Components Analysis (PCA) and Ascending Hierarchical Clustering (AHC) provides a more objective basis for this varietal delimitation. The first principal plane F1F2 in the PCA constructed with four variables (total oil and C14:0, C12:0 and C16:0 contents) gave a very clear-cut separation of the two species. Even within one species the oils obtained by different extraction processes presented a certain dispersion, reflecting some variability in their fatty acid composition. However, this variability was slight compared with the differences between the two species. AHC performed on the same variables gave two groups that coincided exactly with the two species. However, from a more practical standpoint, the simple criterion we recommend is the ratio (%C14:0)/(%C12:0). This value is about 1 for I. wombulu (0.8-0.9) and appreciably higher than 1 for I. gabonensis (1.4-2.8). The chemical composition of the unsaponifiable fraction allowed this varietal delimitation to be further refined.