Nutritional composition and multivariate characterization of five Amaranthus species grown under uniform conditions in southeastern Nigeria

This study evaluated the proximate composition, mineral content, vitamin profile, phenolic and flavonoid compounds of five Amaranthus species ( A. cruentus, A. spinosus, A. dubius, A. hypochondriacus, and A. tricolor ) to assess their nutritional variability and potential for dietary applications. Significant differences (p < 0.05) were observed across all measured parameters. Moisture content ranged from 87.98-90.24%, while protein (2.83-4.65%) and dietary fiber (2.50-4.25%) varied notably among species. A. dubius exhibited the highest iron (0.419 mg/g FW) and calcium (3.19 mg/g FW) contents, whereas A. hypochondriacus showed the highest zinc concentration (0.292 mg/g FW). A. tricolor was richer in β-carotene (1.06 mg/g FW) and folate (2.80 mg/g FW). Total phenolic content (2.44-4.67 mg GAE/g FW) and flavonoids (2.05-3.99 mg QE/g FW) were highest in A. dubius . Principal component analysis (PCA) revealed distinct nutrient clustering, with A. dubius associated with mineral and bioactive compounds and A. tricolor with vitamin-related components. Strong positive correlations were observed between phenolics and flavonoids (r ˃ 0.85), as well as β-carotene and folate. The results demonstrate significant nutritional diversity among Amaranthus species and highlight their potential for targeted dietary use, functional food development, and food composition database enrichment. Future research incorporating ICP-OES or similar high-resolution analytical tools is recommended to further validate and refine the mineral composition data reported in this study.