The aim of the research was to evaluate the influence of the ripening stage on the accumulation of polyphenols and antioxidant activity in fruits of Solanum species. The experiment included two factors: I—four different Solanum species (S. melanocerasum, S. nigrum, S. villosum, and S. retroflexum) and II—three ripening stages. High-performance liquid chromatography (HPLC) was used to analyze the individual phenolic compounds (flavonoids and phenolic acids), and the spectrophotometric method was applied to determine antioxidant activity. The results revealed that the accumulation of polyphenols and antioxidant activity in fruits of Solanum species depends on the stage of ripening and species. All studied Solanum species fruits had the highest content of total phenolic acid at ripening stage III and the greatest antioxidant activity at ripening stage I. Fully ripe fruits of S. melanocerasum contained significantly more total flavonoids, whereas S. nigrum contained significantly more total phenolic acids than other investigated Solanum species fruits. The significantly highest antioxidant activity was found in S. melanocerasum fruits at ripening stage I.

Studies on the mineral and vitamin C contents of different species and ripening stages of Solanum fruits are very limited. The aim of the research was to evaluate the content of the mineral elements and vitamin C of four different Solanum species (S. melanocerasum—SM, S. nigrum—SN, S. villosum—SV and S. retroflexum—SR), and three ripening stages. The mineral composition of Solanum fruits was detected using a CEM MARS 6^® (Matthews, NC, USA) digestion system outfitted with a 100 mL Teflon vessel, by microwave-assisted extraction (MAE). In total, eleven mineral elements were detected (K, Ca, Mg, P, Fe, Na, Cu, B, Mn, Al, and Zn). Vitamin C content was assessed by a spectrophotometric method. Depending on the ripening stage/species, content of microelements ranged from 756.48 mg kg⁻¹ DW in SV fruits at ripening stage III, to 211.12 mg kg⁻¹ DW in SM fruits at ripening stage III. The dominant microelement was Fe. The total content of macroelements in Solanum fruits ranged from 26,104.95 mg kg⁻¹ DW in SV fruits at ripening stage II to 67,035.23 mg kg⁻¹ DW in SR fruits at ripening stage I. The dominant macroelement was K. The data from two experimental years showed that the significantly highest content of vitamin C was in SM fruits and ranged from 48.15 mg 100 g⁻¹ at ripening stage I to 45.10 mg 100 g⁻¹ at ripening stage III.

The goal of this study is to assess the impacts of ripening stage of four Solanum fruit species: (Solanum melanocerasum, Solanum nigrum, Solanum villosum, and Solanum retroflexum) on the content of amino acids and protein. Our objective is to enhance comprehension of the maturity process, with a particular focus on Solanum fruits, in order to determine the most advantageous time for harvesting. Amino acids play a crucial role in human nutrition by serving as building blocks for various primary and secondary metabolites. They are either a source of nutraceutical substances or important dietary components. The studied Solanum fruit’s amino acid profiles were found essential and nonessential amino acids. Our findings showed that dominant amino acids were nonessential amino acids. Depending on the ripening stage, the nonessential amino acid content of the Solanum melanocerasum fruits varied from 8.22 to 9.25 g 100 g⁻¹, Solanum villosum from 5.34 to 6.60 g 100 g⁻¹, Solanum nigrum from 6.12 to 8.73 g 100 g⁻¹, and Solanum retroflexum from 8.27 to 9.75 g 100 g⁻¹. A differentiated level of total protein is found in Solanum fruits at different ripening stages. The interval was from 10.62 to 28.06 g 100 g⁻¹ depending on species or ripening stages.

This four-year study assessed the nutritional profiles of fermented Chamerion angustifolium leaves from natural, organic, and biodynamic cultivation systems. Vitamins, pigments, and sugars were analyzed under standardized aerobic solid-state fermentation (SSF) for 24 and 48 h. Biodynamically grown leaves showed 42.7% and 49.7% higher β-carotene levels than organically and naturally grown leaves, while naturally grown leaves accumulated the most chlorophylls and total sugars. Organic cultivation promoted the highest vitamin C and L-ascorbic acid concentrations. Prolonged fermentation (48 h) significantly enhanced vitamin C (18.48%) and L-ascorbic acid (16.50%) only in naturally grown leaves. These findings demonstrate consistent cultivation-dependent nutritional trends and highlight the functional potential of fireweed leaves as bioactive ingredient carriers for functional foods, with applications in dairy products, beverages, and dietary supplements.

Potatoes are a valuable source of diverse bioactive compounds, including phenolics. In recent years, red- and purple-fleshed cultivars have garnered increasing scientific interest due to their higher content of phenolic compounds. The aim of this study was to evaluate the impact of 60%, 80%, and 100% methanol concentrations on the extraction of bioactive phenolic compounds from three red- and purple-fleshed potato cultivars. The qualitative and quantitative composition of phenolic compounds, the total anthocyanin content, as well as antioxidant activity in the prepared potato extracts were investigated. The results showed that the contents of the tested compounds and antioxidant activity in potato tuber methanolic extracts varied depending on the cultivar and methanol concentration. The potato extract obtained by 60% and 80% methanol showed the significantly highest contents of total phenolics (TPs) and total phenolic acids (TPAs). ‘Violet Queen’ extracts with 60% and 80% methanol had the significantly highest contents of TP, TPA, and caffeic acid. The significantly highest contents of p-coumaric acid were observed in ‘Mulberry Beauty’ extracts using 60% and 80% methanol. The significantly highest contents of epicatechin and quercetin were found in ‘Violet Queen’ extracts with 80% methanol, while the highest contents of myricetin, m-coumaric, and o-coumaric acids as well as the highest antioxidant activity were recorded in ‘Violet Queen’ extracts with 60% methanol.