Plantas alimentícias não convencionais: perfil de nutrientes, antinutrientes e compostos bioativos

Abstract

Unconventional food plants (UFP) represent a promising alternative to combat food insecurity, especially in low-income countries. However, there is still a significant gap in knowledge regarding their nutritional composition. This study analyzed the centesimal composition, mineral content, vitamins A, C, and E, carotenoids, antioxidant activity, total phenolic compounds, and antinutrients (phytates and oxalates) in the leaves of Bidens pilosa, Turnera subulata, Costus spicatus, and the leaves and stems of Talinum fruticosum, collected in the Vale do Middle Rio Doce, MG, Brazil. The centesimal composition was determined using standard methods, while minerals were analyzed by atomic absorption and emission spectrometry. Phenolic compounds and antioxidant capacity were quantified using the DPPH and ABTS methods, while vitamins, carotenoids, phytates, and oxalates were analyzed by high-performance liquid chromatography (HPLC). Analysis of variance (ANOVA) was used for species comparisons. The results indicated significant nutritional variation among the UFP, with high levels of proteins, minerals, and vitamins A, C, and E, surpassing the levels found in conventional vegetables such as lettuce, broccoli, kale, and spinach. Additionally, these plants exhibited notable antioxidant capacity, reinforcing their potential for dietary diversification and nutritional enrichment. The stems of T. fruticosum and the leaves of B. pilosa and C. spicatus showed high moisture content (>90%). Regarding protein content, T. subulata and the leaves of T. fruticosum stood out, with values of 6.72 mg/100g and 3.24 mg/100g, respectively. In terms of total energy density, T. subulata had the highest value among the studied UFP (97 Kcal/100g), making it an excellent plant-based energy source. The stems and leaves of T. fruticosum and T. subulata proved to be good sources of vitamin C (11.21 mg/100g, 12.41 mg/100g, and 10.60 mg/100g) and vitamin E (4122 µg/100g, 3685 µg/100g, and 1170 µg/100g), respectively. Furthermore, B. pilosa and T. subulata exhibited high levels of β-carotene, with 26.57 mg/100g and 10.42 mg/100g. Regarding minerals, B. pilosa proved to be a significant source of calcium (16.8 mg/100g), iron (1.97 mg/100g), magnesium (3.24 mg/100g), and zinc (0.467 mg/100g). Among bioactive compounds, T. subulata and C. spicatus had the highest levels of total phenolic compounds, with 12.16 mg GAE/g and 11.72 mg GAE/g. Antioxidant capacity, assessed by the DPPH method, was highest in C. spicatus (18.83 µmol Trolox/g) and T. subulata (17.13 µmol Trolox/g). The antinutrient analysis revealed that oxalate was present in all samples, with T. subulata and B. pilosa showing the highest levels, at 26.57 mg and 12.05 mg, respectively. Phytates were detected only in B. pilosa and C. spicatus. In conclusion, the analyzed UFP were rich sources of nutrients, reinforcing their potential as a nutritional supplement.