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.
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.
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.
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.
Chamomile (
L.) dried flowers contain a group of interesting biologically active compounds such as sesquiterpenes, flavonoids, coumarins, vitamins, phenolic acids and glucosides. Therefore, the aim ...of the present study was to characterize the composition in bioactive compounds (specialized metabolites) present in water and ethanol extracts of chamomile flowers, together with monitoring the impact of different extraction techniques (conventional vs. ultrasound-assisted extraction (UAE)) on the parameters under investigation. UAE treatment significantly decreased the extraction time of bioactive compounds from herbal material. Polyphenolic compounds content and antioxidant capacity were significantly higher in UAE extracts. Moreover, solvent type had a significant impact on the specialized metabolites content, while the highest vitamin C and polyphenols content were recorded in 50% ethanol (
/
) extracts. Optimization of basic extraction factors: solvent type, temperature and technique is crucial for obtaining the extracts with the highest content of specialized metabolites and antioxidant capacity.
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.
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.
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.
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.
Spices are a popular food of plant origin, rich in various phytochemicals and recognized for their numerous properties. The aim of the study was to evaluate the antioxidant and antimicrobial ...activity, as well as the content of specialized metabolites, of aqueous extracts of three spice species--garlic (
L.), ginger (
L.) and turmeric (
L.)--prepared by green extraction methods. Ultrasound treatment increased the chromaticity parameter b value of turmeric and ginger extracts, thus indicating a higher yellow color predominantly due to curcuminoids characteristic of these species. Ultrasound-assisted extraction significantly increased the content of total soluble solids, phenolic compounds, total carotenoids and vitamin C. The temperature of the system was also an important factor, with the highest (70 °C) conditions in ultrasound-assisted extraction having a positive effect on thermolabile compounds (vitamin C, phenolics, total carotenoids). For example, turmeric extract treated with ultrasound at 70 °C had up to a 67% higher vitamin C content and a 69.4% higher total carotenoid content compared to samples treated conventionally at the same temperature, while ginger extracts had up to 40% higher total phenols. All different concentrations of spice extracts were not sufficient for complete inhibition of pathogenic bacterial strains of
,
and
; however, only garlic extracts had an effect on slowing down the growth and number of
colonies. Spice extracts obtained by ultrasonic treatment contained a significantly higher level of bioactive compounds and antioxidant capacity, suggesting that the extracts obtained have significant nutritional potential and thus a significant possibility for phytotherapeutic uses.
In this study, the influence of stevia addition and sonication processing parameters on the phenolic content and profile as well as the steviol glycosides of strawberry juice-based samples was ...investigated. For this purpose, three matrices-control samples of strawberry juices without green stevia powder (CS), strawberry juices with green stevia powder (JGSP), and sonicated juices with green stevia powder (SJGSP)-were prepared. For sonication purposes, different conditions regarding probe diameters (7 mm and 22 mm), amplitudes (50%, 75%, and 100%), and time (15 min, 20 min, and 25 min) were tested. The results that were obtained upon the measurement of the total phenolic content, total flavonoids, steviol glycosides, and antioxidant capacity showed significant differences according to the matrices evaluated, obtaining overall higher values in the samples with stevia added. Moreover, when sonication was evaluated, it was found that a higher amplitude (100%), a larger probe diameter (22 mm), and a longer sonication period (25 min) led to higher values. Flavones such as luteolin and apigenin were identified and quantified in JGSP and SJGSP, while they were not found in CS. Besides these phenolic compounds, kaempferol, quercetin, pyrogallic acid, 4-methylcatechol, and 4-methoxybenzoic acid were also identified and quantified. Similarly to the total phenolic compounds, total flavonoids, and total antioxidant capacity, an increased amount of these compounds was found in SJGSP, especially after using the most intense sonication conditions. Therefore, the use of sonication together with stevia added could be a useful tool to preserve strawberry juices, increasing at the same time the sweetness and the antioxidant value of the beverages.
Nettle is a highly valued medicinal plant that is still largely neglected, both in terms of nutrition and use for pharmacological purposes. Tinctures, i.e., alcoholic extracts, are becoming ...increasingly popular nettle products, mainly because they allow better availability of phytochemicals and their stability over a longer period of time. The production of alcoholic extracts is a chemically demanding process that is still usually carried out using conventional techniques, which have numerous drawbacks. The use of green technologies such as ultrasound-assisted extraction (UAE), which is characterized by high efficiency of phytochemical extraction, shorter treatment time, and a much lower environmental footprint, is a suitable and sustainable solution. Therefore, the aim of this study is to determine the influence of the extraction method, conventional and ultrasound (by varying two ultrasound equipment systems), time and ethanol concentration on the extraction of specialized metabolites from nettle powder. Ultrasonic extraction using a probe system significantly contributed to increase the ascorbic acid yield, polyphenolic compounds, and antioxidant capacity of nettle extracts compared to conventional extraction. In addition, when a probe system was used during UAE, significantly less time was required for isolation of individual specialized metabolites compared to ultrasonic extraction in the bath. Ethanol concentration (50 and 80% v/v) also proved to be an important factor in the efficiency of extraction of specialized metabolites, with 80% ethanol being more effective for the isolation of ascorbic acid and pigment compounds (chlorophyll and carotenoids), while 50% v/v for the extraction of polyphenolic compounds. It can be concluded that extraction with the ultrasonic probe system is much more efficient in obtaining higher yields of specialized metabolites from nettle powder in a shorter time (average process duration 5-10 min) both compared to UAE in the bath and classical extraction. However, optimization of the key factors of time, solvent type, and ultrasonic power is necessary to maintain the nutritional quality of the nettle extract in order to obtain a final product with a high specialized metabolites content, antioxidant capacity, and functional value. The future application of alcoholic nettle extracts is based on the fact that these products have significant potential as functional foods and pharmacological preparations for the treatment of a number of but also to strengthen the immune system, mainly due to the rich nutritional composition and high content of various specialized metabolites. The prepared extracts can be safely taken orally by diluting the tinctures with water immediately before ingestion.
Cryoprotective freezing methods are increasingly being developed and used as an effective means of protecting valuable bioactive compounds in processed berry fruits. The quick-freezing method allows ...the bioactive compounds in the plant material to be preserved over a longer period of time, thus providing a high-quality product with significant antioxidant capacity. The aim of this study was to determine the effects of the quick-freezing method on physico-chemical properties and bioactive compounds content of fruits in three soft fruit species: tayberry, raspberry, and blackberry, and to evaluate the stability of specific phytochemicals during the three-month storage period. The freezing method had a significant effect on the physicochemical properties with a significantly less drip loss observed after thawing in fruit frozen by quick-freezing (at −34 °C for 25 min) compared to fruit frozen classically (−18 °C to 24 h). The color of quick-frozen fruits also changed significantly less compared to fresh fruits. Of the bioactive compounds analyzed, it should be noted that there was a significantly lower loss of ascorbic acid recorded during quick-freezing. On average, the quick-frozen fruits contained 28% more ascorbic acid than the classical frozen fruits. In general, the quick-freezing procedure contributed to a better preservation of total polyphenolic compounds and anthocyanins, and thus berry fruits also showed higher values of antioxidant capacity during quick freezing than during the classical procedure. During the storage period of three months, a decrease in the content of all the bioactive compounds studied was observed, although it should be emphasized that this loss during storage was not as pronounced in fruits frozen by the quick-freezing method as in classically frozen fruits. It can be concluded that the quick-freezing contributes significantly to the preservation of valuable bioactive compounds of berries and that this processing method can be considered important for maintaining the nutritional properties of berry fruits.
Invasive plant species (IAS), with their numerous negative ecological, health, and economic impacts, represent one of the greatest conservation challenges in the world. Reducing the negative impacts ...and potentially exploiting the biomass of these plant species can significantly contribute to sustainable management, protect biodiversity, and create a healthy environment. Therefore, the main objective of this study was to evaluate the nutritional potential, phytochemical status, and antioxidant capacity of nine alien invasive plant species: Abutilon theophrasti, Amaranthus retroflexus, Ambrosia artemisiifolia, Datura stramonium, Erigeron annuus, Galinsoga ciliata, Reynoutria japonica, Solidago gigantea, and Sorghum halepense. Multivariate statistical methods such as cluster and PCA were performed to determine possible connections and correlations among selected IAS depending on the phytochemical content. According to the obtained results, R. japonica was notable with the highest content of vitamin C (38.46 mg/100 g FW); while E. annuus (1365.92 mg GAE/100 g FW) showed the highest values of total polyphenolic compounds. A. retroflexus was characterized by the highest content of total chlorophylls (0.26 mg/g) and antioxidant capacity (2221.97 µmol TE/kg). Therefore, it can be concluded that the selected IAS represent nutrient-rich plant material with significant potential for the recovering of bioactive compounds.
The aim was to determine the differences in nutritional quality between chokeberry juices sweetened with sucrose and green stevia powder. The quality of chokeberry juices during refrigerated storage ...was studied. Chokeberry juices with added green stevia powder had the higher content of analyzed bioactive compounds in comparison with juice samples sweetened with sucrose; vitamin C content increased up to two times, total phenol content up to 6% and antioxidant capacity for 3%. The content of studied bioactive compounds and antioxidant capacity during storage in period of 30 and 60 days was significantly reduced with the exception of steviol glycosides which content was not significantly reduced during the storage period.
Practical applications
Chokeberry juice is a popular, widespread product of chokeberry fruit characteristic for the dark intense red color, slightly unpleasant, bitter taste and extremely rich bioactive compounds content. Because of high nutritional quality, chokeberry juice is often consumed but with the biggest barrier of characteristic astringent taste which can be diminished by addition of sweetener. Producers often combine a low‐cost sweeteners like sucrose which shows numerous negative effects on human health. A good alternative to the sucrose and artificial sweeteners are natural sweeteners extracted from the plant material like steviol glycosides. Except sweetness, stevia products like green powder shows beneficial effect on the bioactive compounds content in the juices sweetened with it. Juices sweetened with stevia shows increased content of bioactive compounds, so such product may represent quality product from category of functional food.
The strawberry tree fruit and leaf are a rich source of minerals, easily digestible sugars, dietary fibers, vitamins (especially vitamin C) and many bioactive compounds of significant functional ...value. Due to their favorable chemical composition, fruits have recently become increasingly popular in consumption. The aim of this study was to determine the physical-chemical composition, content of bioactive compounds, and also the antioxidant capacity of the fruit and leaves of wild strawberry tree populations among the Adriatic coast in Croatia, as well as to investigate the influence of location on the content of specific bioactive compounds. According to the obtained results, both fruit and leaves are pronouncedly high in vitamin C content, the average value for fruits amounted to 224.21 mg/100 g FW, while that for leaves amounted to 138.08 mg/100 g FW. Additionally, significantly high values of total polyphenolic compounds were recorded both in fruits (average value of 637.94 mg GAE/100 g FW) and especially in leaves (average value of 2157.01 mg GAE/100 g FW). Several pigments from different categories were determined in the fruit depending on fruit maturity, including: total anthocyanins, β-carotene and lycopene; while in leaves chlorophylls and carotenoids. Given the high content of different bioactive compounds high values of antioxidant capacity were determined (the average value for fruits was 2269.96 µmol TE/kg and for leaves, 2237.16 µmol TE/kg). Location strongly influenced the physical-chemical composition and also the content of specialized metabolites; populations collected from southern areas (central and south Dalmatia) of the Adriatic coast tended to have higher amounts of vitamin C, total phenols, total anthocyanins and β-carotene.
PDF
