Consumers associate the color of food with its freshness and quality. More and more attention is being paid to natural colorants that bring additional health benefits to humans. Such natural substances are the carotenoids (yellow to orange), the anthocyanins (red to blue), and the betalains (red and yellow), which are very sensitive to exposure to light, air, high temperatures, and chemicals. Stability and diversity in terms of color can be optimized by using environmentally friendly and selective extraction processes that provide a balance between efficacy, safety, and stability of the resulting extracts. Green solvents like water, supercritical fluids, natural deep eutectic solvents, and ionic liquids are the most proper green solvents when combined with different extraction techniques like maceration, supercritical extraction, and ultrasound-assisted or microwave-assisted extraction. The choice of the right extracting agent is crucial for the selectivity of the extraction method and the stability of the prepared colorant. The present work reviews the green solvents used for the extraction of natural food colorants from plants and focuses on the issues related to the selectivity and stability of the products extracted.

Recently, there has been a growing interest in protein-rich foods and functional foods, as well as plants characterized by high levels of drought resistance. Vigna unguiculata L. Walp. from the Fabaceae family, also known as cowpea, was chosen as the subject of the present study. The antioxidant potentials of 15 genotypes cultivated in Bulgaria, Southern Europe, were determined. The research focused on the green mass used as feed and on the seeds used as an “ancient” traditional crop. The total phenolic content (TPC), total flavonoid content (TFC), radical scavenging capacity, determined via the DPPH method, and crude protein content were measured. The seed coat extracts showed higher contents of phenolics (291.0 ± 4.6 mgGAE/g) and flavonoids (83.5 ± 1.1 mgCE/g) and a stronger radical scavenging capacity (50.4 ± 0.7 µmolTE/g) than those obtained from the leaves (22.0 ± 0.5 mgGAE/g, 13.7 ± 0.5 mgCE/g, and 19.7 ± 0.6 µmolTE/g, respectively). The protein content in the seeds ranged from 20.5% to 27.0%. According to the obtained results, the cowpea genotypes with dark-colored seed coats showed greater antioxidant potentials but lower protein contents. Due to its high antioxidant content, strong radical scavenging capacity, and high protein content, V. unguiculata L. shows great potential as a functional food for humans and animals.

In recent decades, species within the genus Amaranthus L. (amaranth) have garnered growing global interest due to their exceptional nutritional value, functional properties, and agricultural versatility. Traditionally consumed as leafy vegetables or pseudo-cereals, several Amaranthus species are now receiving renewed attention in the context of the development of modern functional foods. This review evaluates the data on nutritional composition, health-promoting properties, and potential applications of Amaranthus spp. in sustainable food systems in peer-reviewed publications from the last 25 years. Amaranth is rich in high-quality proteins, essential amino acids, dietary fibre, vitamins, and minerals, positioning it as a significant factor in addressing malnutrition and enhancing food security. Furthermore, its bioactive compounds, such as flavonoids, phenolic acids, and peptides, exhibit antioxidant, anti-inflammatory, and hypocholesterolemic activities, suggesting its potential as a part of healthy diets, alleviating the risk of non-communicable diseases. The presence of anti-nutritional factors, including saponins, phytates, and oxalates, has also been explored, with implications for nutrient bioavailability and overall health effects. In addition to its nutritional advantages, Amaranthus spp. demonstrate strong adaptability to diverse climatic conditions, thus performing as a crop resilient under climate stress. Their olfactory and sensory attributes are also considered important for consumers’ acceptance and market integration. By synthesising traditional knowledge and contemporary scientific research, this review underscores the potential of Amaranthus spp. as a multifunctional food source that could support health promotion, climate resilience, and agricultural sustainability.

Galium verum (Yellow Bedstraw) is a rhizomatous perennial herb belonging to the Rubiaceae family. It is native to Eurasia and Africa but has also been introduced to southern Canada and the northern U.S. Widely used in traditional medicine, G. verum has been recognized for its diuretic, anti-inflammatory, antimicrobial, analgesic, and anticancer properties. Phytochemical studies have shown that the plant is rich in significant bioactive compounds, such as flavonoids, phenolic acids, iridoids, anthraquinones, phytosterols, coumarins, and tannins. Research suggests that G. verum exhibits strong antioxidant activity, protecting cells from oxidative stress and inflammation. Its antimicrobial potential has been demonstrated against various bacterial and fungal pathogens, supporting its traditional use in wound healing and infection treatment. Moreover, modern studies indicate its cytotoxic effects on cancer cells, suggesting potential applications in oncology. Additionally, its hepatoprotective and neuroprotective properties highlight its promise for treating metabolic and neurodegenerative disorders. Despite its well-known therapeutic potential, further studies are required to fully clarify its mechanisms of action and ensure its safety for medicinal use. Given the variety of bioactive compounds found in G. verum and their pharmacological benefits, this review emphasizes the importance of this species as a valuable medicinal plant, encouraging further scientific research for its application in pharmacology.

The aim of this study was to establish whether the type of the agricultural system has any influence on the essential oil production and antioxidant activity of industrial cultivated Rosa damascena Mill. in the Rose valley, Bulgaria. Six private farms from Kazanlak (Rose) Valley, Southern Bulgaria were included in the study conducted in the period 2019–2020. The first three selected farms are designated within the conventional farming and the other three are certificated as organic farms. GC/FID and GC/MS analyses were performed; the contents of total polyphenols and flavonoids in the methanol extracts from rose petals were determined. Additionally, the antioxidant activity of rose extracts was evaluated by four reliable methods: 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2´-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS), ferric reducing antioxidant power (FRAP), and cupric reducing antioxidant capacity (CUPRAC) assays. The impact of the agricultural system on the essential oil composition and antioxidant activity was evaluated by ANOVA statistical analysis. The results obtained showed that organic farming produced essential oil with a higher linalool and geraniol content and lower β-citronellol + nerol concentrations than conventional farming. It was found that organic farming production demonstrated a better antioxidant activity evaluated by the three DPPH, ABTS, and CUPRAC methods according to the averaged data for two years, 806.82, 797.66 and 1534.40 mM TE/g dw versus 510.34, 521.94 and 917.48 mM TE/g dw for CF, respectively, with high statistical significance for the DPPH and ABTS analyses. Consequentially, the rose extracts from the organic farming accumulated more phenolic compounds that corresponded to the higher antioxidant potential of the organic roses.

Malva sylvestris L. is a herbaceous plant, distributed worldwide, rich in biological active compounds, and known for its health benefits. In this study, extracts from different parts (leaves, flowers, and roots) of this plant were prepared using green classic (70% ethanol) and natural deep eutectic solvents (NADESs) based on choline chloride and acetic acid (NADES1) or glycerol (NADES2). Their antioxidant, antibacterial (against B. cereus, S, aureus, E. coli, and P. aeruginosa), and antifungal activity (against P. chrysogenum, F. oxysporum, A. parasiticus, A. flavus, A. niger A. carbonarius, and A. ochraceus) were compared. Ethanolic extracts were characterized with the highest total contents of phenols, flavonoids, and condensed tannins. Ethanolic and NADES flower extracts were the richest in the antioxidants tested. Alkaloids were extracted in low quantities. The experimentally determined antioxidant potential of the extracts proved the highest DPPH scavenging activity of ethanolic extracts and the lowest of NADES1 extracts. The ABTS scavenging capacity of NADES1 and ethanolic extracts displayed comparable results, while NADES2 extracts were characterized as having the highest FRAP activity. NADES1 extracts manifested pronounced antibacterial activity, partially due to the low pH of the pure solvent, as well as inconsistent antifungal activity—from moderate to a complete lack of activity. A strong positive correlation was reported between the DPPH radical scavenging capacity and phenolic compound content. Future detailed investigations on the mechanism of the antimicrobial activity of NADES1 extracts are necessary to clarify the observed phenomenon of the decreased antifungal potential of NADES1 extracts compared to the pure solvent NADES1.