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Featured Application: The findings from this research may have a specific and so far unique application in creating new packaged food products that are not traditionally distributed as such. The results show that the selection of proper packaging material with good thickness, transparency and permeability characteristics along with favorable storage conditions can help to preserve the antioxidant compounds of fresh-cut nettle leaves for 14 days. Green leafy vegetables are very challenging in terms of storage and preservation, while packaging in controlled conditions with the selection of appropriate polymer material is crucial for maintaining their nutritional value and quality. Various packaging materials have different gas and water vapor permeability as well as physicochemical properties that can create a specific environment inside the package, therefore affecting the chemical composition, sensory characteristics, and overall quality of packed leafy vegetables. Stinging nettle is an edible plant with a high antioxidant content, making it a valuable leafy vegetable. Therefore, this study aimed to evaluate the influence of four packaging materials (biaxially oriented polypropylene (BOPP), low-density polyethylene (LDPE), polyamide/polyethylene (PA/PE), and polylactic acid (PLA)) on the antioxidant content of packed fresh nettle leaves during 14-day storage. Ascorbic acid content was the highest after 6 days of storage, equally well preserved in all tested films, with an average of 86.74 mg/100 g fm (fresh mass). After 14 days of storage, the total phenolic content was best preserved when packed in LDPE. The content of caffeoylmalic and chlorogenic acids was the highest in LDPE after 6 days. In addition, leaves packed in LDPE after 6 days of storage had the highest content of all photosynthetic pigments. According to FRAP analysis, the antioxidant capacity was best maintained in LDPE (at the 14th day, the measured capacity was 43.61 µmol TE/g). This study shows that the type of packaging material (BOPP, LDPE, PA/PE, and PLA) and storage duration (6 and 14 days) have a great impact on the level of antioxidant compounds in the nettle leaves, where LDPE and BOPP can be highlighted as the most favorable for the preservation of total and individual phenolic compounds, photosynthetic pigments, and antioxidant capacity. [ABSTRACT FROM AUTHOR]

Introduction: More than ever, traditional agricultural practices need a shift towards more resilient, sustainable, modern and adaptable practices that benefit the health of the planet and people. Today's consumers are constantly on the lookout for novel, highly nutritious foods that have a positive impact on their overall health and well-being. Nettle (Urtica dioica L.) is gaining recognition not only as a popular medicinal plant, but also as a desirable green leafy vegetable rich in phytonutrients. As it is difficult and even expensive to control the quality standards of wild-collected plants, the implementation of sustainable cultivation methods, especially hydroponics, with effective greenhouse management could be a possible solution to obtain a standardized product with high nutritional value. Therefore, the aim of this study was to investigate the effects of four nutrient solutions differing in the content of macro- and micronutrients (especially nitrogen, potassium, calcium, magnesium and iron) and two consecutive cuts on the number of leaves, yield, nitrate and mineral content and the content of specialized metabolites of stinging nettle from a floating hydroponic system. Methods: Nettle plants were cultivated in a hydroponic system using the floating hydroponics technique. The two-factorial experiment was performed with nutrient solution and consecutive cuts as factors. Results: The highest yield (2.49 kg/m2) was achieved after the 1st cut with plants cultivated in the nutrient solution with higher nutrient concentration. All tested nutrient solutions resulted in high levels of minerals and bioactive compounds in the plant material (ascorbic acid content of 102.30 mg/100 g fw and total phenolics content of 465.92 mg GAE/100 g fw), confirming floating hydroponics as a sustainable approach for cultivating nettle with enhanced nutritional value and antioxidant potential. Conclusion: It is important to highlight that the nutrient solution with the lowest nutrient composition yielded the highest concentrations of calcium (5.54%) and iron (180.67 mg/kg dw). Furthermore, it exhibited elevated levels of specific phenolic compounds, including caffeoylmaleic acid, ellagic acid, ferulic acid, naringin, and rutin trihydrate. Notably, this solution demonstrated the lowest nitrate content (4225.33 mg/kg fw) in the plant material. Therefore, it can be recommended as a preferable formulation for hydroponic nettle cultivation. [ABSTRACT FROM AUTHOR]

Research background. As food production faces major challenges, modern agricultural practices are increasingly focused on conserving resources, reducing negative environmental impacts and sustainably producing food with a high content of health-promoting phytochemicals. During production, many factors can affect the quality and chemical composition of a final food product. Proper selection of cultivating conditions, especially a balanced nutrition, can significantly increase nutritional value and result in foods with strong biological and functional properties. Stinging nettle is a rich source of minerals, vitamins, pigments, phenols and other bioactive compounds and can be consumed as a green leafy vegetable with beneficial effects on human health. Therefore, the aim of this study is to determine the nutritional quality and antioxidant capacity of stinging nettle leaves under the influence of different nutrient solution (NS) treatments and three harvest cycles. Experimental approach. The experiment was conducted in a floating hydroponic system in which treatments with different nutrient solutions were applied and three harvest cycles were carried out. After each harvest, the following treatments were applied: treatment 1 - depletion of nutrient solution by adding water, treatment 2 - supplementation of nutrient solution by adding initial nutrient solution and treatment 3 - correction of nutrient solution by adding nutrients. Among the bioactive compounds, minerals, ascorbic acid, phenols and photosynthetic pigments content, as well as antioxidant capacity were analysed spectrophotometrically, while individual phenols were determined by liquid chromatography. Results and conclusions. Different nutrition solution treatments and the number of harvest cycles had a significant effect on the content of the analysed bioactive compounds. The highest mass fraction (on fresh mass basis) of total phenols expressed as gallic acid equivalents (377.04 mg/100 g), total flavonoids expressed as catechol equivalents (279.54 mg/100 g), ascorbic acid (112.37 mg/100 g) and pigments (total chlorophylls 1.84, and total carotenoids 0.36 mg/g) as well as the highest antioxidant capacity expressed as Trolox equivalents (35.47 μmol/g) were recorded in the samples supplemented with nutrient solution (treatment NS2) and analysed after the third harvest. Novelty and scientific contribution. This is the first time that stinging nettle leaves have been produced in a floating hydroponic system by controlled plant nutrition. We have set this type of nutritional manipulation with multiple harvest cycles as an innovative technique for the production of novel food with improved nutritional value that can be consumed as green leafy vegetables. [ABSTRACT FROM AUTHOR]

As the impact of global warming intensifies drought effects, plants need to adapt to drought and other climate change-induced stresses through various defense mechanisms. One of them is the increased synthesis of bioactive compounds (BCs), which helps plants overcome adverse environmental conditions. This effect can be used in sustainable controlled cultivation as a tool for the nutritional improvement of crops, so this study focused on growing stinging nettle (Urtica dioica L.) for human consumption in a controlled environment. Since nettle can be consumed as a green leafy vegetable due to its nutritional value, the aim of this study was to determine the content of BCs (ascorbic acid, phenolic compounds, and pigments) and antioxidant capacity of nettle leaves grown under different drought stress conditions in an ebb and flow hydroponic system. During the experiment, plants were treated with a nutrient solution adjusted for nettle cultivation for 1 hour and then exposed to three different drought intervals: 24, 48, and 96 h. During the 48 h drought interval, the plants accumulated the highest amounts of total phenolic content and total non-flavonoid content (400.21 and 237.33 mg GAE/100 g, respectively), and during the 96 h drought interval, the nettle accumulated the highest amount of ascorbic acid (96.80 mg/100 g fw). The highest antioxidant capacity was recorded during the 24 and 48 h treatments (2435.07 and 2444.83 µmol/TE, respectively) according to the ABTS and during the 48 h treatment (3773.49 µmol/TE) according to the FRAP assay. The obtained results show that different drought stress durations caused by the absence of nutrient solutions can have a positive effect on the accumulation of nettle BCs. [ABSTRACT FROM AUTHOR]

Microgreens are young plants of various vegetables, medicinal and aromatic plants, cereals and edible wild plants that were first associated with nouvelle cuisine as decoration in dishes due to their attractive appearance and strong flavor. Recently, they have become more sought after in the market due to their high nutritional value. This is due to the growing interest of consumers in a healthy lifestyle that includes a varied diet with emphasis on fresh, functional foods. Nowadays, commercial production of microgreens is shifting to modern hydroponic systems due to their numerous advantages, such as accelerated plant growth and biomass production, earlier harvesting, and more production cycles that positively affect yield and chemical composition. Therefore, the aim of this study was to determine the content of specialized metabolites and antioxidant capacity of hydroponically grown alfalfa (Medicago sativa) cv. 'Kangaroo', yellow beet (Beta vulgaris var. conditiva) cv. 'Yellow Lady', red cabbage (Brassica oleracea L. var. rubra) cv. 'Red Carpet', and fennel (Foeniculum vulgare) cv. 'Aganarpo' microgreens. The highest content of total phenols (408.03 mg GAE/100 g fw), flavonoids (214.47 mg GAE/100 g fw), non-flavonoids (193.56 mg GAE/100 g fw) and ascorbic acid (74.94 mg/100 g fw) was found in fennel microgreens. The highest content of all analyzed chlorophyll pigments (Chl_a 0.536 mg/g fw, Chl_b 0.248 mg/g fw, and TCh 0.785 mg/g fw) was found in alfalfa microgreens. However, in addition to alfalfa, high levels of chlorophyll a (0.528 mg/g fw), total chlorophyll (0.713 mg/g fw) and the highest level of total carotenoids (0.196 mg/g fw) were also detected in fennel microgreens. The results suggest that microgreens grown on perlite in floating hydroponics have high nutritional potential as a functional food important for human health and therefore could be recommended for daily diet. [ABSTRACT FROM AUTHOR]

Eating habits are changing over time and new innovative nutrient-rich foods will play a great role in the future. Awareness of the importance of a healthy diet is growing, so consumers are looking for new creative food products rich in phytochemicals, i.e., specialized metabolites (SM). The consumption of fruits, vegetables and aromatic species occupies an important place in the daily diet, but different edible flower species are still neglected and unexplored. Flowers are rich in SM, have strong antioxidant capacities and also possess significant functional and biological values with favorable impacts on human health. The main aim of this study was to evaluate the content of SM and the antioxidant capacities of the edible flower species: Calendula officinalis L. (common marigold), Tagetes erecta L. (African marigold), Tropaeolum majus L. (nasturtium), Cucurbita pepo L. convar. giromontiina (zucchini) and Centaurea cyanus L. (cornflower). The obtained results showed the highest content of ascorbic acid (129.70 mg/100 g fw) and anthocyanins (1012.09 mg/kg) recorded for cornflower, phenolic compounds (898.19 mg GAE/100 g fw) and carotenoids (0.58 mg/g) for African marigold and total chlorophylls (0.75 mg/g) for common marigold. In addition to the esthetic impression of the food, they represent an important source of SM and thus can have a significant impact if incorporated in the daily diet. [ABSTRACT FROM AUTHOR]

Wild garlic (Allium ursinum L.) is one of the species widely distributed in Europe and Asia and is often nutritionally neglected, characterized by a high content of various phytochemicals with high therapeutic potential and a range of biological activities. The aim of this study was to determine the content of bioactive compounds in the leaves of wild garlic populations collected from different micro-locations, and to determine the differences in the content of phytochemicals in the vegetative and generative phases. A significant content of different specialized metabolites was detected in all analyzed leaves of wild garlic populations regardless of the different factors (location and phenophase): vitamin C content with the highest determined value of 63.31 mg/100 g fw; total phenolic content with the highest determined value of 186.18 mg GAE/100 g fw (according to gallic acid in fresh sample); and antioxidant capacity with the highest determined value of 2230.66 µmol TE/L (according to Trolox). Significant differences in all the phytochemicals analyzed were observed depending on both the location and phenophase of the plants, with the most pronounced differences depending on the phenophase. Thus, lower levels of polyphenolic compounds and vitamin C were generally observed before the flowering phase, while the trend toward higher levels of pigment compounds was observed during the flowering phase of the plants. The results suggest that the leaves of wild garlic can be considered a valuable source of a variety of specialized metabolites with high antioxidant capacity, and thus have high production potential for various functional products and food supplements of natural origin, which are important for the promotion of human health. [ABSTRACT FROM AUTHOR]

Plants have evolved various adaptive mechanisms to environmental stresses, such as sensory mechanisms to detect mechanical stimuli. This plant adaptation has been successfully used in the production practice of leafy vegetables, called mechanical conditioning, for many years, but there is still a lack of research on the effects of mechanically-induced stress on the content of specialized metabolites, or phytochemicals with significant antioxidant activity. Therefore, the aim of this study was to determine the content of specialized metabolites and antioxidant capacity of lettuce and green chicory under the influence of mechanical stimulation by brushing. Mechanically-induced stress had a positive effect on the content of major antioxidants in plant cells, specifically vitamin C, total phenols, and flavonoids. In contrast, no effect of mechanical stimulation was found on the content of pigments, total chlorophylls, and carotenoids. Based on the obtained results, it can be concluded that induced mechanical stress is a good practice in the cultivation of leafy vegetables, the application of which provides high quality plant material with high nutritional potential and significantly higher content of antioxidants and phytochemicals important for human health. [ABSTRACT FROM AUTHOR]