Compositional and Bioactive Differentiation of Opuntia spp. Fruit Varieties by PCA and LDA

The nutritional, mineral, and bioactive profiles of four Opuntia fruit varieties-Opuntia robusta red variety (OR-RV) and three Opuntia ficus-indica varieties (red, yellow, and green: OFI-RV, OFI-YV, and OFI-GV, respectively)-were characterized to assess their compositional diversity and potential discriminant markers. Standard analytical procedures were applied to determine proximate composition, individual sugars, fibre content, mineral concentration, and bioactive compounds, followed by antioxidant activity assays. Principal Component Analysis (PCA) and Linear Discriminant Analysis (LDA) were used to explore multivariate patterns and identify variables with the greatest discriminatory power. Results revealed significant inter-varietal differences across all measured parameters (p < 0.05). OR-RV displayed the highest non-fibre carbohydrate, protein, copper, and ascorbic acid contents, as well as superior antioxidant activity. OFI-GV stood out for its high soluble and insoluble fibre, magnesium, and strontium levels, while OFI-YV was characterized by elevated sodium and calcium, and OFI-RV by increased protein and glucose contents. LDA identified ascorbic acid, protein, and five mineral elements (Sr, Zn, Cu, Mn, B) as key discriminant variables, achieving 100% classification accuracy. These findings highlight compositional diversity among Opuntia varieties and support their differentiated use in food and health applications.