Posidonia Natural Residues as Growing Substrate Component: An Ecofriendly Method to Improve Nutritional Profile of Brassica Microgreens

Soilless cultivation systems to produce tailored microgreens for specific nutritional needs

BACKGROUND

The awareness of the importance of following dietary recommendations that meet specific biological requirements related to an individual's health status has significantly increased interest in personalized nutrition. The aim of this research was to test agronomic protocols based on soilless cultivation for providing consumers with new dietary sources of iodine (I), as well as alternative vegetable products to limit dietary potassium (K) intake; proposed cultivation techniques were evaluated according to their suitability to obtain such products without compromising agronomic performance.

RESULTS

Two independent experiments, focused on I and K respectively, were conducted in a commercial greenhouse specializing in soilless production. Four different species were cultivated using three distinct concentrations of I (0, 1.5 and 3 mg L-1 ) and K (0, 60 and 120 mg L-1 ). Microgreens grown in I-rich nutrient solution accumulate more I, and the increase is dose-dependent. Compared to unbiofortified microgreens, the treatments with 1.5 and 3 mg L-1 of I resulted in 4.5 and 14 times higher I levels, respectively. Swiss chard has the highest levels of K (14 096 mg kg-1 of FW), followed by rocket, pea and radish. In radish, rocket and Swiss chard, a total reduction of K content in the nutrient solution (0 mg L-1 ) resulted in an average reduction of 45% in K content.

CONCLUSION

It is possible to produce I-biofortified microgreens to address I deficiency, and K-reduced microgreens for chronic kidney disease-affected people. Species selection is crucial to customize nutritional profiles according to specific dietary requirements due to substantial mineral content variations across different species. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Beach-cast seagrass wrack: A natural marine resource improving the establishment of dune plant communities under a changing climate

Seagrass wrack plays multiple ecological roles in coastal habitats but is often removed from beaches and used for economical processing, neglecting its potential role in sustaining dune plant establishment under changing climate scenarios. Rainwater shortage is a major stress for seedlings and reduced precipitations are expected in some coastal areas. We investigated in mesocosm how wrack influenced seedling performance of Cakile maritima, Thinopyrum junceum, and Calamagrostis arenaria under current and reduced precipitation. We also assessed wrack water holding capacity and leachate chemical/physical properties. Wrack stimulated seedling growth while reduced precipitation decreased root development. Wrack mitigated the effects of reduced precipitation on T. junceum and C. arenaria biomass. Wrack retained water up to five-fold its weight, increased water pH, conductivity, and nutrient content. Wrack promotes dune colonization by vegetation even under rainwater shortage. Thus, the maintenance of this natural resource on beaches is critical for improving dune resilience against climate changes.

Combined effect of an agro-industrial compost and light spectra composition on yield and phytochemical profile in mizuna and pak choi microgreens

This work aimed to evaluate the growth of two species of microgreens (mizuna and pak choi), using agro-industrial compost as growing media in two different mixes versus one hundred percent peat, under two different LED illumination spectra (LED 1 and LED 2) in a 14 h photoperiod. The experiment was carried-out for two times. Biomass yield, glucosinolates, and phenolic compounds, and nitrate (NO3-) content were analysed in leaf tissues. In both species, the highest fresh and dry biomass production was in compost:peat (50:50%) and LED 2 (Blue/Red/Far Red). In general, compost had a greater influence on nitrate content than light, but in the microgreen pak choi, the anthocyanin content was inhibited by the compost treatment. In the other hand both LED illumination had a positive effect on mizuna for glucosinolates and anthocyanins, and LED 2 also showed a positive effect on pak choi for anthocyanin. Therefore, the use of agri-food compost: peat (50:50%) with LED 2 (blue/red) lighting treatment to obtain microgreens in indoor crops is a plausible technology that provides nutritionally and phytochemically rich crops.

Valorization of Posidonia oceanica biomass: Role on germination of cucumber and tomato seeds

Biostimulants are organic compounds from plant sources such as botanical extracts and bioactive substances that promote plant growth, enhance photosynthesis and increase crop quality. The accumulation of detached Posidonia oceanica leaves on coasts of the Mediterranean Sea results in economic problems, due to the rejection of the tourists who frequent the beaches in the summer months. However, it is a plant with high content of secondary metabolites that can be used in sustainable agriculture. In this study we investigated the physicochemical characterization of Posidonia oceanica extracts with three different solutions and their application in tomato and cucumber seeds germination. The results showed that the aqueous extract of Posidonia oceanica had a high concentration of macro and micronutrients, as well as secondary metabolites with bioactive activity. The aqueous extract had a beneficial effect on both leaf and root growth on tomato seeds, specifically, an increase of 76% for the relative root growth and 73% for the germination index was obtained with respect to the control using the sample with the intermediate dilution (POe0.5). In addition, the extracts did not show toxicity to either germination or growth of the tomato plant. As for cucumber seed germination, the improvement was less significant and did result in a phytotoxic effect on both germination and plant growth. The most diluted extract had better results on seed germination. Therefore, the application of aqueous extracts of Posidonia oceanica were suitable to be appropriate for tomato germination and in turn contribute to eliminate the lots of Posidonia oceanica remains recovered in summer months in Mediterranean beaches.

Yield performance, mineral profile, and nitrate content in a selection of seventeen microgreen species

Introduction

Originally regarded as garnish greens, microgreens are increasingly valued for their nutritional profile, including their mineral content.

Methods

A study was conducted under controlled environmental conditions utilizing a selection of seventeen microgreen species belonging to seven different botanical families to investigate the genetic variation of macro- and micro-minerals and nitrate (NO3 -) content. Plants were grown in a soilless system using a natural fiber mat as the substrate. After germination, microgreens were fertigated with a modified half-strength Hoagland solution prepared using deionized water and without adding microelements. At harvest (10 to 19 days after sowing, based on the species), yield components were measured and dry tissue samples were analyzed for the concentration of total nitrogen (N), NO3 -, P, K, Ca, Mg, S, Na, Fe, Zn, Mn, Cu, and B.

Results and discussion

Genotypic variations were observed for all of the examined parameters. Nitrogen and K were the principal macronutrients accounting for 38.4% and 33.8% of the total macro-minerals concentration, respectively, followed in order by Ca, P, S, and Mg. Except for sunflower (Helianthus annuus L.), all the tested species accumulated high (1,000-2,500 mg kg-1 FW) or very high (>2,500 mg kg-1 FW) NO3 - levels. Eight of the studied species had a K concentration above 300 mg 100 g-1 FW and could be considered as a good dietary source of K. On the other hand, scallion (Allium fistulosum L.), red cabbage (Brassica oleracea L. var. capitata), amaranth (Amaranthus tricolor L.), and Genovese basil (Ocinum basilicum L.) microgreens were a good source of Ca. Among micro-minerals, the most abundant was Fe followed by Zn, Mn, B, and Cu. Sunflower, scallion, and shiso (Perilla frutescens (L.) Britton) were a good source of Cu. Moreover, sunflower was a good source of Zn, whereas none of the other species examined could be considered a good source of Fe and Zn, suggesting that supplementary fertilization may be required to biofortify microgreens with essential microminerals. In conclusion, the tested microgreens can be a good source of minerals showing a high potential to address different dietary needs; however, their yield potential and mineral profile are largely determined by the genotype.

Sustainable Exploitation of Posidonia oceanica Sea Balls (Egagropili): A Review

Posidonia oceanica (L.) Delile is the main seagrass plant in the Mediterranean basin that forms huge underwater meadows. Its leaves, when decomposed, are transported to the coasts, where they create huge banquettes that protect the beaches from sea erosion. Its roots and rhizome fragments, instead, aggregate into fibrous sea balls, called egagropili, that are shaped and accumulated by the waves along the shoreline. Their presence on the beach is generally disliked by tourists, and, thus, local communities commonly treat them as waste to remove and discard. Posidonia oceanica egagropili might represent a vegetable lignocellulose biomass to be valorized as a renewable substrate to produce added value molecules in biotechnological processes, as bio-absorbents in environmental decontamination, to prepare new bioplastics and biocomposites, or as insulating and reinforcement materials for construction and building. In this review, the structural characteristics, and the biological role of Posidonia oceanica egagropili are described, as well as their applications in different fields as reported in scientific papers published in recent years.

Nitrate, nitrite and nitrosamines in the global food supply

Inorganic nitrate provided by either nitrate salts or food supplements may improve cardiometabolic health. However, current methods to assess dietary nitrate, nitrite and nitrosamine consumption are inadequate. The purpose of this study was to develop a reference database to estimate the levels of nitrate, nitrite and nitrosamines in the global food supply. A systematic literature search was undertaken; of the 5,747 articles screened, 448 met the inclusion criteria. The final database included data for 1,980 food and beverages from 65 different countries. There were 5,105 unique records for nitrate, 2,707 for nitrite, and 954 for nitrosamine. For ease of use, data were sorted into 12 categories; regarding nitrate and nitrite concentrations in food and beverages, 'vegetables and herbs' were most reported in the literature (n = 3,268 and n = 1,200, respectively). For nitrosamines, 'protein foods of animal origin' were most reported (n = 398 records). This database will allow researchers and practitioners to confidently estimate dietary intake of nitrate, nitrite and nitrosamines. When paired with health data, our database can be used to investigate associations between nitrate intake and health outcomes, and/or exercise performance and could support the development of key dietary nitrate intake guidelines.

Mineral Composition and Bioaccessibility in Rocket and Purslane after Zn Biofortification Process

Zinc (Zn) is an essential key nutrient in different biochemical and physiological processes. The nutritional deficit of this mineral element is estimated to affect the health of over 3 billion people worldwide. Several strategies are available to reduce the negative impact of mineral malnutrition; among them, biofortification is the practice of deliberately increasing the nutrients and healthy compounds in the edible parts of vegetables. This study aims to evaluate Zn bioaccessibility in biofortified and non-biofortified rocket and purslane using an in vitro gastrointestinal digestion process and measure the concentration of other mineral elements (Al, B, Ca, Fe, K, Mg, Mn, and Sr) released during the digestion process from rocket and purslane biofortified with Zn. The bioaccessible Zn in biofortified rocket and purslane ranged from 7.43 to 16.91 mg/kg, respectively. In addition, the daily intake, the RDA coverage (%), and the hazard quotient (HQ) for the intake of Zn (resulting from the consumption of 100 g of rocket and purslane) were calculated. The calculated HQ highlights the safety of these baby leaf vegetables. The study confirms that it is possible to obtain Zn-biofortified rocket and purslane with high Zn bioaccessibility by adopting an appropriate mineral plant nutrition solution enriched in Zn.