Kako povećati nutritivnu kakvoću koprive kontroliranom ishranom

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.Pozadina istraživanja. Budući da se proizvodnja hrane suočava s velikim izazovima, suvremene poljoprivredne prakse sve su više usmjerene na očuvanje resursa, smanjenje negativnog učinka na okoliš i održivu proizvodnju hrane s velikim udjelom fitokemikalija koje pozitivno utječu na ljudsko zdravlje. Tijekom uzgoja, brojni čimbenici mogu utjecati na kakvoću i kemijski sastav konačnog proizvoda. Pravilnim odabirom uvjeta uzgoja, posebice uravnoteženom ishranom (gnojidbom), može se znatno povećati nutritivna kakvoća sirovine te pozitivno utjecati na njezina biološka i funkcionalna svojstva. Kopriva je bogat izvor mineralnih tvari, vitamina, pigmenata, fenola i drugih bioaktivnih spojeva, a može se konzumirati kao zeleno lisnato povrće blagotvornog učinka na zdravlje ljudi. Stoga je svrha ovog istraživanja bila odrediti nutritivnu kakvoću i antioksidacijski kapacitet lista koprive tretirane različitim hranjivim otopinama tijekom tri ciklusa berbe. Eksperimentalni pristup. Pokus je proveden u plutajućem hidroponskom sustavu u kojem su biljke tretirane različitim hranjivim otopinama tijekom tri ciklusa berbe. Korišteni su sljedeći postupci: tretman 1 – iscrpljivanje hranjive otopine vodom, tretman 2 – prihrana standardnom hranjivom otopinom i tretman 3 – korekcija sastava hranjive otopine dodatkom nutrijenata. Od bioaktivnih spojeva ispitani su maseni udjeli mineralnih tvari, askorbinske kiseline, ukupnih fenola i fotosintetskih pigmenata, te je utvrđen antioksidacijski kapacitet pomoću spektrofotometrije, dok su udjeli pojedinih fenola određeni tekućinskom kromatografijom. Rezultati i zaključci. Različiti tretmani hranjivim otopinama i broj ciklusa berbe bitno su utjecali na udjele ispitanih bioaktivnih spojeva u listu koprive. Najveći udjel (u svježoj masi lista) ukupnih fenola izražen kao ekvivalent galne kiseline (377,04 mg/100 g), ukupnih flavonoida izražen kao ekvivalent katehola (279,54 mg/100 g), askorbinske kiseline (112,37 mg/100 g) i pigmenata (ukupni klorofili 1,84, ukupni karotenoidi 0,36 mg/g), te najveći antioksidacijski kapacitet izražen kao ekvivalent Troloxa (35,47 µmol/g) zabilježeni su u uzorcima prihranjenim standardnom hranjivom otopinom, ispitanim nakon treće berbe. Novina i znanstveni doprinos. Kopriva je prvi put uzgojena u plutajućem hidroponskom sustavu s kontroliranom ishranom biljaka. Ovaj način uzgoja uz višestruke cikluse berbe je postavljen kao inovativna tehnika proizvodnje nove hrane, poboljšane nutritivne vrijednosti, koja se može konzumirati kao zeleno lisnato povrće

Influence of the development stage on the content of phenolic compounds and antioxidant capacity of Chinese cabbage (Brassica rapa L. subsp. pekinensis (Lour.) Hanelt)

Sadržaj fenolnih spojeva, kao i njihov antioksidacijski kapacitet, ovise o razvojnom stadiju biljke. Do sada su u dostupnoj literaturi informacije o sadržaju fenolnih spojeva i antioksidacijskom kapacitetu pekinškog kupusa (Brassica rapa L. subsp. pekinensis (Lour.) Hanelt) zabilježene za odrasle biljke, no ne postoje usporedni podaci o kvalitativnom i kvantitativnom sadržaju fenolnih spojeva i antioksidacijskom kapacitetu različitih razvojnih stadija ove vrste. Stoga je u ovom radu ispitano pet različitih razvojnih stadija pekinškog kupusa; prvi stadij su činile mlade biljke s otvorenim kotiledonama, drugom stadiju pripadale su biljke s razvijenim dvjema kotiledonama i dva prava lista, trećem biljke s četiri lista, a biljke četvrtog i petog stadija imale su po šest, odnosno deset razvijenih listova. Spektrofotometrijski je određen sadržaj ukupnih fenola, flavonola i hidroksicimetnih kiselina, metodom tekućinske kromatografije visoke moći razlučivanja su identificirani i kvantificirani najzastupljeniji pojedinačni flavonoidi i fenolne kiseline, te je određen antioksidacijski kapacitet pet razvojnih stadija pekinškog kupusa metodama koje se temelje na redukciji radikala 2,2'-azinobis (3- etilbenzotiazolin-6-sulfonske kiseline) i 2,2-difenil-pikrilhidrazila, te metodom određivanja antioksidacijske jakosti redukcijom željeza. Rezultati su pokazali da se najraniji stadij (samo kotiledone) pekinškog kupusa na razini količine ukupnih fenola, flavonola, hidroksicimetnih kiselina i kvercetina, kao i antioksidacijskog kapaciteta statistički ne razlikuje (p≤0.05) od stadija sa šest ili deset listova. Ova tri stadija ujedno imaju i značajno veće vrijednosti spomenutih parametara u odnosu na stadij s kotiledonima i dva prava lista ili stadij s četiri lista.Phenolic compounds content so as their antioxidant capacity depend on plant development stage. In the present literature, informations on the phenolic compounds content and antioxidant capacity of Chinese cabbage have been reported for mature plants, but there are no comparative data on the qualitative and quantitative phenolic compounds content and antioxidant capacity of Chinese cabagge different development stages. Therefore, in this study, five different development stages of Chinese cabbage were investigated; the first stage consisted of plants with developed cotyledones, the second stage were plants with developed two cotyledones and two leaves, the third stage consisted of plants with four leaves, and the plants of the fourth and fifth stages had six or ten developed leaves. Content of total phenols, flavonols and hydroxycinnamic acids was measured spectrophotometrically, most abundant individual flavonoids and phenolic acids were identified and quantified using High-Performance Liquid Chromatography method, and antioxidant activity of five different stages of Chinese cabbage were determined using methods based on a reduction of radicals 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) and 2,2-diphenyl-1-picryl-hydrazyl, and Ferric reducing/Antioxidant power method. The results showed that the earliest stage (containing cotyledones only) of Chinese cabbage, at the level of total phenols, flavonols, hydroxycinnamic acids and quercetin as well as antioxidant capacity does not statistically differ (p≤0.05) from the stages with six or ten leaves. These three stages also have significantly higher values of the mentioned parameters compared to the stage with the cotyledons and two leaves or the stage with four leaves

Can LED Lighting Be a Sustainable Solution for Producing Nutritionally Valuable Microgreens?

With its quality, intensity, and photoperiod, light is a decisive abiotic factor that directly influences plant biomass and the accumulation of specialized metabolites (SMs). Photosynthetically active radiation (PAR) has significant effects on primary and secondary plant metabolism and thus influences the morphological characteristics of plants and their antioxidant systems. The aim of this study was to investigate the effects of blue, red, and a 50:50 combination of blue and red LED lighting on the SM content in broccoli, mustard, and garden cress microgreens grown in an indoor farm using the zero-acreage farming technique (ZFarming). This research aims to provide valuable insights into the optimization of light spectra to improve the nutritional quality of microgreens, with a focus on sustainable and space-saving cultivation methods. After eight days, the samples were cut in the cotyledon phenophase and analyzed in a fresh state. The microgreens grown under the blue spectrum LED lighting had the highest content of ascorbic acid (112.70 mg·100 g fw−1), total phenolics (412.39 mg GAE·100 g fw−1), and the highest antioxidant capacity (2443.62 µmol TE·L−1). The results show that the highest content of SMs in all the studied microgreens species was accumulated under the blue spectrum LED lighting. This study underlines the favorable influence of the blue spectrum (400–500 nm) on the nutrient content, especially the enhancement of SMs, in the microgreens investigated. Furthermore, the use of supplemental LED lighting proves to be a sustainable and effective means of producing microgreens with superior nutritional properties through the innovative practice of the zero-acreage farming technique

Edible Flower Species as a Promising Source of Specialized Metabolites

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

Energy vs. Nutritional Potential of Virginia Mallow (Sida hermaphrodita L.) and Cup Plant (Silphium perfoliatum L.)

The world today faces several pressing challenges: energy from non-renewable sources is becoming increasingly expensive, while at the same time the use of agricultural land for food production is decreasing at the expense of biofuel production. Energy crops offer a potential solution to maximizing the use of land. In order to provide new value to the by-product, it is necessary to investigate its possible nutritional and functional potential. Therefore, the main objective of this study was to determine the energetic, nutritional, and functional potential of the species Sida hermaphrodita L. and Silphium perfoliatum L. in different phenophases. The analyzed energy potential of the mentioned species is not negligible due to the high determined calorific value (17.36 MJ/kg for Virginia mallow and 15.46 MJ/kg for the cup plant), high coke content (15.49% for the cup plant and 10.45% for Virginia mallow), and desirably high carbon content, almost 45%, in both species. The phenophase of the plant had a significant influence on the content of the analyzed specialized metabolites (SM) in the leaves, with a high content of ascorbic acid at the full-flowering stage in Virginia mallow (229.79 mg/100 g fw) and in cup plants at the end of flowering (122.57 mg/100 g fw). In addition, both species have high content of polyphenols: as much as 1079.59 mg GAE/100 g were determined in the leaves of Virginia mallow at the pre-flowering stage and 1115.21 mg GAE/100 g fw in the cup plants at the full-flowering stage. An HPLC analysis showed high levels of ellagic acid and naringin in both species. In addition, both species have high total chlorophyll and carotenoid concentrations. Due to their high content of SM, both species are characterized by a high antioxidant capacity. It can be concluded that, in addition to their energetic importance, these two plants are also an important source of bioactive compounds; thus, their nutritional and functional potential for further use as value-added by-products should not be neglected