Nutritional quality and health risk of pepper fruit as affected by magnesium fertilization

Global analysis of spatio-temporal variation in mineral nutritional quality of pepper (Capsicum spp.) fruit and its regulatory variables: A meta-analysis

Pepper (Capsicum spp.) is an important fruit vegetable worldwide, and it is a rich dietary source of minerals for human being. Yet, the spatio-temporal distribution of pepper fruit mineral composition and the factors influencing such variations at global scale remain unknown. A global meta-analysis of 140 publications providing 649, 562, 690, 811 datapoints was conducted to quantify and evaluate the nutritional quality, comprising potassium (K), magnesium (Mg), iron (Fe) and zinc (Zn), of pepper fruits and its influencing variables. The analysis showed that the global average of K, Mg, Fe and Zn content in pepper fruits was 20-25 g kg-1, 1-1.5 g kg-1, 80-100 mg kg-1, and 20-40 mg kg-1, respectively. There had been a downward trend in pepper fruit nutritional quality over the last decade, especially for Fe and Zn. And, the concentration of all these four nutrients were at lower levels in less developed regions, especially in Africa. Our results showed that the vegetable "green pepper" contains more K, Mg, Fe and Zn than the "hot pepper" used as spice. The concentration of K, Mg, Fe and Zn were increased with fruit yield but that of Fe and Zn were decreased with increase in single fruit weight. Nutritional quality was optimal at mean annual temperature of 10 ℃ - 20 ℃, and was adversely affected when mean annual precipitation was < 500 mm. Pepper fruits produced at pH 6.5-7.5 had higher fruit K concentration while acidic soils (pH<6.5) favored higher Fe and Zn concentrations. The higher soil organic matter (SOM) generally improved the nutritional quality of the pepper. Our results suggest that systematic selection of superior varieties and soil amelioration (adjusting pH and SOM) of the soil-crop system are needed to achieve higher nutritional quality of pepper fruit.

Novel Immunosensor Based on Metal Single-Atom Nanozymes with Enhanced Oxidase-Like Activity for Capsaicin Analysis in Spicy Food

Capsaicin (CAP) is a primary indicator for assessing the level of pungency. Herein, iron-based single-atom nanozymes (SAzymes) (Fe/NC) with exceptional oxidase-like activity were used to construct an immunosensor for CAP analysis. Fe/NC could imitate oxidase actions by transforming O2 to •O2- radicals in the absence of hydrogen peroxide (H2O2), which could avoid complex operations and unstable results. By regulating the Fe atom loads, an optimal Fe0.7/NC atom usage rate could improve the catalytic activity (Michaelis-Menten constant (Km) = 0.09 mM). Fe0.7/NC was integrated with goat antimouse IgG by facile mix incubation to develop a competitive enzyme-linked immunosorbent assay (ELISA). Our Fe0.7/NC immunosensing platform is anticipated to outperform the conventional ELISA in terms of stability and shelf life. The proposed immunosensor provided color responses across 0.01-1000 ng/mL CAP concentrations, with a detection limit of 0.046 ng/mL. Fe/NC may have potential as nanozymes for CAP detection in spicy foods, with promising applications in food biosensing.

Comparative metabolomics reveals complex metabolic shifts associated with nitrogen-induced color development in mature pepper fruit

Pigments derived from red pepper fruits are widely used in food and cosmetics as natural colorants. Nitrogen (N) is a key nutrient affecting plant growth and metabolism; however, its regulation of color-related metabolites in pepper fruit has not been fully elucidated. This study analyzed the effects of N supply (0, 250, and 400 kg N ha-1) on the growth, fruit skin color, and targeted and non-target secondary metabolites of field-grown pepper fruits at the mature red stage. Overall, 16 carotenoids were detected, of which capsanthin, zeaxanthin, and capsorubin were the dominant ones. N application at 250 kg ha-1 dramatically increased contents of red pigment capsanthin, yellow-orange zeaxanthin and β-carotene, with optimum fruit yield. A total of 290 secondary metabolites were detected and identified. The relative content of most flavonoids and phenolic acids was decreased with increasing N supply. Correlation analysis showed that color parameters were highly correlated with N application rates, carotenoids, flavonoids, phenolic acids, lignans, and coumarins. Collectively, N promoted carotenoid biosynthesis but downregulated phenylpropanoid and flavonoid biosynthesis, which together determined the spectrum of red color expression in pepper fruit. Our results provide a better understanding of the impact of N nutrition on pepper fruit color formation and related physiology, and identification of target metabolites for enhancement of nutritional quality and consumer appeal.

The power of magnesium: unlocking the potential for increased yield, quality, and stress tolerance of horticultural crops

Magnesium (Mg2+) is pivotal for the vitality, yield, and quality of horticultural crops. Central to plant physiology, Mg2+ powers photosynthesis as an integral component of chlorophyll, bolstering growth and biomass accumulation. Beyond basic growth, it critically affects crop quality factors, from chlorophyll synthesis to taste, texture, and shelf life. However, Mg2 + deficiency can cripple yields and impede plant development. Magnesium Transporters (MGTs) orchestrate Mg2+ dynamics, with notable variations observed in horticultural species such as Cucumis sativus, Citrullus lanatus, and Citrus sinensis. Furthermore, Mg2+ is key in fortifying plants against environmental stressors and diseases by reinforcing cell walls and spurring the synthesis of defense substances. A burgeoning area of research is the application of magnesium oxide nanoparticles (MgO-NPs), which, owing to their nanoscale size and high reactivity, optimize nutrient uptake, and enhance plant growth and stress resilience. Concurrently, modern breeding techniques provide insights into Mg2+ dynamics to develop crops with improved Mg2+ efficiency and resilience to deficiency. Effective Mg2+ management through soil tests, balanced fertilization, and pH adjustments holds promise for maximizing crop health, productivity, and sustainability. This review unravels the nuanced intricacies of Mg2+ in plant physiology and genetics, and its interplay with external factors, serving as a cornerstone for those keen on harnessing its potential for horticultural excellence.

Pomelo Green Production on Acidic Soil: Reduce Traditional Fertilizers, but Do Not Ignore Magnesium

Orchards in acid soils are at risk of magnesium (Mg) deficiency which negatively affects the plant growth, yield, and quality. However, the impacts of Mg supplementation on fruit yield, quality, and environmental and economic benefits have only been rarely addressed. We conducted 15 pomelo (Citrus grandis L.) orchard trials in South China to assess more efficient integrated nutrient management (INM) practices, including local farmer fertilization practices (FP; average application rate of nitrogen, phosphorus, and potassium were 1,075 kg N ha−1, 826 kg P2O5 ha−1, and 948 kg K2O ha−1, respectively), optimum fertilization practice (OPT; average application rate of nitrogen, phosphorus, and potassium were 550 kg N ha−1, 295 kg P2O5 ha−1, and 498 kg K2O ha−1, respectively) and optimum fertilization supplemented with Mg (OPT+Mg; average application rate of Mg was 196 kg MgO ha−1). The results showed that the yield, total soluble solid-to-titratable acidity ratio, and economic benefits under OPT practice were not significantly different from those of FP, while those of OPT+Mg were significantly higher than those of FP, by 8.76, 8.79, and 15.00%, respectively, while titratable acidity contents were significantly lower by 7.35%. In addition, compared with those from FP, the energy inputs and greenhouse gas (GHG) emissions from OPT were 31.00 and 26.48% lower, and those from OPT+Mg were 26.71 and 23.40% lower, respectively. Compared with those of OPT, the marginal efficiency of energy, GHG emissions, and capital of Mg under OPT+Mg were reduced by 62.30, 44.19, and 21.07%, respectively. Overall, adopting OPT+Mg for pomelo production could further enhance yield, fruit quality, and economic benefits while reducing the environmental burdens.

Multidimensional Scaling of the Mineral Nutrient Status and Health Risk Assessment of Commonly Consumed Fruity Vegetables Marketed in Kyrgyzstan

Intensive production of fruits and vegetables causes heavy metal accumulation. Consumption of this kind of foodstuff is a growing concern of the modern world with the additional distress of the supply of enough foodstuffs. To contribute to this global purpose, this research aimed to find out the mineral nutrient and heavy metal concentrations of commonly consumed fruity vegetables in Kyrgyzstan. Totally, ten different fruity type vegetables were collected from five different large bazaars of Kyrgyzstan. From these, 20 samples, including washed/unwashed rinds of vegetables, were quantified in terms of their B, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, and Zn contents by using inductively coupled plasma-optical emission spectrometry (ICP-OES). The concentrations of the fruity vegetables were found in the following range: B (1.392-25.816), Ca (92.814-4095.466), Cd (0.007-0.086), Cr (0.009-0.919), Cu (0.351-8.351), Fe (4.429-126.873), K (920.124-10,135.995), Mg (61.973-879.085), Mn (1.113-78.938), Na (36.132-266.475), Ni (0.039-1.215), Pb (0.081-2.906), and Zn (1.653-87.107) (mg kg^-1). It was determined that red capia pepper was the vegetable having the highest daily nutritional value according to evaluation done in our study. Taking into account of the HI values, all of the vegetables analyzed were determined to be lower than the limit value of 1 that falls into acceptable limits in terms of being safe. Peppers demonstrated the highest variation in terms of the elemental content. The high Cr content rendered hot pepper risky for consumption by both genders regarding with CR, and in terms of CR, it has been observed that nickel contents being found in vegetables including tomatoes pose a moderate risk for consumption. Quite lower risk was detected in red/Brandy-wine tomatoes, eggplants, and cucumber for both genders. As most striking result in our study, the Brandy-wine type tomato was found to be healthiest (as well as safest) and nutritious vegetable looking from the viewpoint of consumption in Kyrgyzstan.

Graphene oxide exhibited positive effects on the growth of Aloe vera L

There is increasing evidence for graphene associated plant growth promotion, however, the chronic effects of soil-applied graphene remain largely unexplored. The present study investigated the morphological, physiological and biochemical responses of graphene oxide (GO) on Aloe vera L. over the concentration range of 0-100 mg/L for four months. Our results demonstrated that GO, with the best efficiency at 50 mg/L, could enhance the photosynthetic capacity of leaves, increase the yield and morphological characters of root and leaf, improve the nutrient (protein and amino acid) contents of leaf, without reducing the content of the main bioactive compound aloin. Compared with leaves, the effect of GO on root growth was more obvious. Although the electrolyte leakage and MDA content were raised at high concentrations, GO treatment did not increase the root antioxidant enzymes activity or decrease the root vigor, which excluding typical stress response. Furthermore, injection experiments showed that the GO in vivo did not change the plant growth state obviously. Taken together, our study revealed the role of GO in promoting Aloe vera growth by stimulating root growth and photosynthesis, which would provide theory basis for GO application in agriculture and forestry.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s12298-021-00979-3.