Nitrate Content Of Vegetables Research Articles

Nitrate contamination of different organic and non-organic vegetable varieties: A case study in Morocco

Nitrates are chemical substances naturally present in the environment (plants, soil, water) and are involved in the natural nitrogen cycle. They represent the most stable oxidation state and are essential nutrients for plant growth. The exposure and ingestion of nitrates by the population are mainly through the consumption of vegetables and occasionally through water intake. The objective of this study is to determine the nitrate content of various varieties of vegetables from industrial agriculture consumed by the population in three cities in northern Morocco's Rabat-Salé-Kenitra region, as well as to demonstrate the health risk of consuming a high concentration of nitrate. The results determine the nitrate content of 77 vegetable samples harvested in Morocco’s Rabat-Salé-Kenitra region. The results showed that nitrate concentrations in vegetables varied depending on different areas in the city and whether the sample was organic or non-organic. The results of our study vary from 31.4 mg/kg (red onion) to 7860 mg/kg (beetroot) in the different vegetable varieties studied. It is recommended that this level be monitored on a regular basis and that the population be made aware of the recommended daily consumption of nitrates (0.84 mg-N/kg/d or 3.7 mg NO3-/kg/d) in the region to prevent excessive exposure to these potentially toxic compounds. In addition, it is advised to promote sustainable agriculture techniques aimed at lowering overall nitrate levels in the food supply and boosting the health and sustainability of the area's food system

Nitrate containing vegetables and dietary nitrate and nonalcoholic fatty liver disease: a case control study

BackgroundVegetables is the main sources of dietary nitrate. Studies suggested the potential link between nitrate content of vegetables and reduce the risk of chronic diseases. We aimed to assess the association between nitrate-containing vegetables (NCVs) with odds of nonalcoholic fatty liver diseases (NAFLD) in Iranian adults.MethodThis case-control study was performed on a total of 225 newly diagnosed NAFLD cases and 450 controls aged 20–60 years. Individuals’ dietary intakes were determined using a valid and reliable food frequency questionnaire.ResultsThe mean ± SD age and BMI of participants were 38.1 ± 8.8 years and 26.8 ± 4.3 kg/m2, respectively. In the fully adjusted model, the odds of NAFLD were decreased across tertiles of total NCVs [(adjusted OR: 0.20, 95%CI: 0.10–0.40), (Ptrend < 0.001)] and low-nitrate vegetables [(adjusted OR: 0.22, 95%CI: 0.11–0.48), (Ptrend < 0.001)]. Our results showed that each one SD increments in nitrate content of vegetables (adjusted OR: 0.73, 95%CI: 0.55–0.97) and nitrate content of fruits (adjusted OR: 0.59, 95%CI: 0.36–0.97) was associated with reduced odds of NAFLD (P < 0.05). However, there was a positive association between each one SD increments in nitrate content of dairy products and meats and processed meats with odds of NAFLD (adjusted OR: 1.34, 95%CI: 1.03–1.74), (P < 0.05).ConclusionOur finding suggested that a higher intake of vegetable nitrate may be related to a decrease the odds of NAFLD.

Контроль вмісту нітратів у харчових продуктах – актуальні питання

Abstract. Nitrates are natural metabolic products of all plants. They are vital to plants – without them their normal growth and development is impossible. However, the uncontrolled use of nitrogen fertilizers has led to their uncontrolled accumulation in food products. When eating vegetables with high amounts of nitrates, they are partially restored to nitrites in the intestinal tract, and the latter, entering the bloodstream cause diseases – methemoglobinemia. Therefore, quantitative and qualitative determination of nitrates and nitrites in plant and animal products, water and soils are relevant today. Based on the analysis of scientific literature, the essence of the problem of excessive accumulation of nitrates in agricultural products and their negative impact on human health is highlighted. Aim. The aim of the research was to determine experimentally the concentration of nitrates and nitrites in plant and animal products, water and soils, to compare it with the maximum allowable concentration as required by Commission Regulation (EU) No 1258/2011 on maximum nitrate content in vegetables and by State sanitary rules and regulations on Maximum Permissible Levels of Certain Contaminants in Food, approved by the Order of the Ministry of Health of Ukraine of May 13, 2013 No 368 (as amended by the order of the Ministry of Health of Ukraine of May 22, 2020 No 1238). Materials and Methods. Sources of information retrieval in printed and electronic publications, databases search engines, methods of analysis, comparison and generalization of data. Photometric method. Results. The analysis of the value of nitrates in nature, sources of this substance in food was conducted; normalization of the content of nitrate components, the problem of plant products quality decline due to the uncontrolled use of fertilizers was studied; the content of nitrates in plant and animal products; the harmful effects of products with high nitrate content were considered; a comprehensive assessment of nitrate content in plant products was carried out; comparative characteristics of methods for determination of nitrate compounds were given; the consequences of consumption of products with high nitrate content were analyzed. Conclusions. The problem of nitrate pollution is becoming increasingly significant, because the amount and speed of the nitrate nitrogen cycle in the environment is constantly increasing, which increases its impact on natural systems and the possibility of nitrate accumulation in crop products, humans and animals. Therefore, the implementation of analytical control of food and environmental objects is important to obtain objective information about the content of man-made pollutants, which are nitrates and nitrites. Key Words: nitrates, maximum permissible level, nitrate compounds, nitrate pollution.

The impact of short-term nitrogen starvation and replenishment on the nitrate metabolism of hydroponically grown spinach

Nitrate is used as a source of supplemental nitrogen for plants, but it can also contribute to nitrate accumulation in green vegetables, which is unhealthy for humans. This study involves short nitrogen starvation and nitrogen replenishment treatments to minimize the nitrate content in spinach (Spinacea oleracea L.) in order to maximize nitrogen consumption and reduce the nitrate content. For this purpose, five different nitrogen application levels (N0 = 0 mmol·L−1, N4 = 4 mmol·L−1, N8 = 8 mmol·L−1, N12 = 12 mmol·L−1, N16 = 16 mmol·L−1) were used in hydroponic culture, in order to screen out the appropriate nitrogen application level of spinach and carry out short-term nitrogen starvation and replenishment treatment, the nitrate and nitrite contents, nitrate reductase and nitrite reductase activities, nitrate reductase gene and nitrite reductase gene were measured every 5 days, and plant growth was monitored during the experiment together with morphological adaptations at the root level. Our results showed that N8 level of the five nitrogen levels was the most effective for the growth of hydroponic spinach. In contrast to the N8 level, spinach roots and leaves thrive healthier after subsequent short-term nitrogen starvation and replenishment (N8*), optimum nitrate metabolism and key enzymes, and decreased expression levels of NR and NiR genes after nitrogen deprivation, however, their expression increased after nitrogen replenishment. It indicated that NR and NiR genes can be used as a reference gene to reduce the nitrate content in vegetables. In conclusion, our results provided a practical approach for optimum nitrate fertilization that will not only improve spinach growth but also reduce nitrate content harmful for human intake.

Assessment of the accumulation of nitrate in cultivated vegetables in Thu Dau Mot, Binh Duong

Vegetables are the major source of dietary Nitrate that have a range of variations in Nitrate. The presence of Nitrate in vegetables is often associated with harmful effects on human health. The study investigated Nitrate intake of vegetables in Phu My ward, Hiep An ward, and Tuong Binh Hiep ward in Thu Dau Mot city by UV-VIS Molecular Absorption Spectrometer to determine of Nitrate concentration with measurement wavelength of 410 nm. The vegetable samples were collected in the field-trip based on TCVN 9016:2011 and the Nitrate concentration was determined according to TCVN 8742:2011 (Vietnam Ministry of Sciences and Technology, 2011). The results showed that there were 3 fresh spinach samples, 3 bok choy samples, containing the Nitrate concentration that exceeded the WHO standard of Nitrate contents in vegetables. These results warn the farmers and policy administrators of Thu Dau Mot city to recommend some solutions to control Nitrate concentration in vegetables produced in Binh Duong province.

Comparative Assessment of Nitrate Concentrations in Vegetables Grown on Commercial and Subsistence Farms in the Saratov Region

Background: Food safety is one of the prerequisites for a healthy diet of the population of the Russian Federation. At the same time, successful functioning of modern agricultural complexes is almost impossible without a widespread use of various agrochemicals, including nitrogen-containing fertilizers. The objective of our study was to conduct a comparative assessment of the nitrate content of vegetables grown on commercial and subsistence farms located in industrially contaminated areas of the region and used as local food. Materials and methods: The research was carried out in the summer and autumn periods of 2017–2019 in a number of polluted areas of the Saratov Region. Nitrate concentrations in local vegetables were measured by a potentiometric method. Results: We established that the nitrate content of vegetables grown in most environmentally disadvantaged areas varied greatly. Concentrations of this contaminant depended on the type of vegetables, growing conditions and region; yet, they did not exceed the maximum permissible level in any vegetable sample tested. At the same time, the level of nitrates in crops grown on commercial farms was significantly higher than that in vegetables grown in private gardens (p &lt; 0.05) due to a more extensive application of nitrate fertilizers in the form of commercially produced ammonium nitrate. Private gardeners, on the opposite, use biomass species, usually legumes, contributing to a better conversion of nitrates into proteins and preventing their excessive accumulation in the produce.

A Comparative Study on Nitrate Contents in Vegetables between Northern Part of China and the Watershed of Lake Tega in Japan

Humankind is continuously exposed to nitrate through water and food. Excessive intake of nitrate could lead to health problems. Among the food products consumed by human beings, both fresh and processed vegetables are the major source of dietary nitrate intake. In this study, investigations on nitrate contents in vegetables are conducted in the northern part of China and the watershed of Lake Tega in Japan. Four groups of vegetables, leafy, brassica, root and tuber, and fruiting, were sampled for testing. The study focuses on the differences of the nitrate distributions in various crops. As a developed country, Japan has a much stricter regulation on the utilization of nitrogen in fertilizers, with a recommended yield goal N rate of 250 kg/ha/year. Whereas in China, the recommended N rate is 450 kg/ha/year. Meanwhile, the watershed of Lake Tega in Japan has an average annual precipitation of 1348 mm, which is much higher than the Northern part of China. High concentration of nitrate was found in vegetables grown in both Northern China and the watershed of Lake Tega, although the social and environmental conditions are drastically different in these two regions.

Reducing the Nitrate Content in Vegetables Through Joint Regulation of Short-Distance Distribution and Long-Distance Transport.

As an important nitrogen source, nitrate (NO3−) absorbed by plants is carried throughout the plant via short-distance distribution (cytoplasm to vacuole) and long-distance transportation (root to shoot), the two pathways that jointly regulate the content of NO3− in plants. NO3− accumulation within the vacuole depends on the activities of both tonoplast proton pumps and chloride channel (CLC) proteins, and less NO3− is stored in vacuoles when the activities of these proteins are reduced. The ratio of the distribution of NO3− in the cytoplasm and vacuole affects the long-distance transport of NO3−, which is regulated by the proteins NPF7.3 and NPF7.2 that play opposite but complementary roles. NPF7.3 is responsible for loading NO3− from the root cytoplasm into the xylem, whereas NPF7.2 regulates the unloading of NO3− from the xylem, thereby facilitating the long-distance transport of NO3− through the roots to the shoots. Vegetables, valued for their nutrient content, are consumed in large quantities; however, a high content of NO3− can detrimentally affect the quality of these plants. NO3− that is not assimilated and utilized in plant tissues is converted via enzyme-catalyzed reactions to nitrite (NO2−), which is toxic to plants and harmful to human health. In this review, we describe the mechanisms underlying NO3− distribution and transport in plants, a knowledge of which will contribute to breeding leafy vegetables with lower NO3− contents and thus be of considerable significance from the perspectives of environmental protection and food safety.

Nitrate content in vegetables and fruits in Russia and Mongolia

This article deals with the actual problem of high nitrate content in vegetables and fruits. The literature review describes the consequences of increased nitrate concentration in the human body and the diseases associated with it. Different countries have different standards for the content of nitrates in agricultural products and the maximum permissible daily doses. The increased content of nitrates negatively affects human health, so it is necessary to maintain strict control over compliance with the concentration standards to the maximum permissible concentrations. Research was carried out on the content of nitrates in vegetables and fruits purchased in the trade networks of the two countries in Russia and Mongolia. The measurements were performed using a portable nitrate - tester SOEKS. As a result of the study, it was found that agricultural products purchased in the trade network of Ulan Bator (Mongolia) meet the established standards, in fruits purchased in St. Petersburg (Russia) in excess of tangerines 1.5 times and 1.6 times. The products that were found to contain excess nitrates were imported from China.

Review Paper: Nitrate Content in a Human Daily Intake

There is no doubt that the quality of food closely related to the human health. That is why on that field are applying much efforts to educate young, inform people, produce and sell high quality food. The most usual contaminant of food is the high nitrate content in vegetables, water or cured meat. Nitrates and nitrites enter in the food chain through the polluted environment from intensive agriculture or from food industry where are used as food additives. Despite of all measures to produce and sell high quality food, human daily intake still can contain high number of nitrates or nitrites that can cause undesirable healthy problems.

Nitrate content in fruits and vegetables from commercial chains in Bulgaria

The aim of this monitoring is to evaluate the nitrate content in vegetables and fruits from the commercial chain in Bulgaria. The vegetables were purchased from the food chains in June and July. The measurements of NO3- ions were carried out with a Greentest appliance, Model ECO 5. Four samples from the conducted monitoring were with higher NO3- amount that is allowed for trade and accepted as healthy (potato, radish, and strawberries). The content of NO3- in fresh potato were 645 mg/kg at the accepted safety level 250 mg/kg. The level of nitrates also was higher in the both samples of radish 3700 mg/kg and 2934 mg/kg at accepted level as safety for consumption 1500 mg/kg. This small survey suggests that on the market in the country are still in the trade food products with not enough good quality.

Modeling of nitrate leaching kinetics during Spinach Leaf Midribs blanching

Background: Although nitrates, are sometimes favorable to health, they can however convert to nitrosamines inside the body thanks to the acidic medium of gastrointestinal tract. So, the investigation of the nitrate content in food products becomes an imperative since it allows consumers to choose their food deliberately. Aims: The leaching kinetics of nitrates during water blanching of spinach leaf midribs (SLM) was investigated at different conditions of time and temperature. Material and Methods: The nitrate leaching kinetics, during the water blanching of SLM samples, was studied at 60, 70 and 80 °C; for 3 and 15 minutes. Presently, six models, namely Henderson and Pabis, logarithmic, zero order, Lewis, Page, Wang, and Singh were tested to analyze experimental data. Moreover, to elucidate the effect of the temperature on the nitrate diffusion rate, the equation of Arrhenius was applied. Results: Results showed that after 15 min of blanching, the removal rate (RR) of nitrates was of: 23.851 ± 3.477c, 64.809 ± 0.474b and 75.949 ± 5.366a % at 60, 70 and 80 °C, respectively; with a significant difference between values at (p ≤ 0.05). Furthermore, among the six tested models, the logarithmic model seemed to be the most appropriate (R2 &gt; 0.993) to describe the diffusion kinetics of nitrates from food matrix into the blanching water, whatever the processing temperature. Finally, the activation energy (35.76 kJ. Mol-1), characterizing the nitrate leaching, was assessed based on the rate constant appearing in the most appropriate model. Conclusions: Blanching in water constitutes an effective tool for controlling the nitrate content in vegetables, by varying the time and temperature of treatment. Keywords: Nitrate, quantification, spinach leaf midribs, blanching, modeling.

Quantitative Nutrient Management Reduces Nitrate Accumulation in Hydroponic Butterhead Lettuces Grown under Artificial Lighting

To reduce nitrate concentrations in vegetables grown under artificial lighting, we determined nitrate accumulation under various conditions of nitrate availability. Butterhead lettuce plants were grown with nutrient solutions of various concentrations, which were maintained according to electrical conductivity (EC) throughout the cultivation period. Under these conditions, growth in nutrient solutions with lower EC led to slight decreases in nitrate concentrations in leaves, but also decreased fresh and dry weights of shoots, leading to the risk of a yield loss under EC control management (ECM). By contrast, when total nitrate requirement was supplied only at the start of cultivation, nitrate concentrations in leaves were decreased significantly with only slightly reduced plant growth. Hence, marketable-sized butterhead lettuces with lower nitrate concentrations can be produced by supplying total nitrate requirements in the nutrient solution at the start of cultivation.

Extension of Aquaponic Water Use for NFT Baby-Leaf Production: Mizuna and Rocket Salad

Aquaponics is a recirculating technology that combines aquaculture with hydroponics. It allows nutrients from fish waste to feed plants and thus saves water and nutrients. However, there is a mismatch between the nutrients provided by the fish waste and plant needs. Because of this, some nutrients, notably N, tend to accumulate in the aquaponic water (APW or AP water). The aim of this study was to investigate how APW, which is depleted of P and K but still rich in N, could be further utilized. APW was used in a mesocosm and compared with APW from the same source that had been supplemented with macro-nutrients (complemented AP water or CAPW) and a hydroponic control (HC). Mizuna (M) and rocket salad (R) were used as short-cycle vegetable crops in a NFT system. The results revealed that the low production potential of APW was mainly caused by the lack of P and K. If these were supplemented, the yields were comparable to those in the HC. M yield in CAPW was significantly higher than that of HC, probably due to biostimulant effects connected to the organic components in the water as a result of fish farming. Water type, cultivation density, and intercropping significantly influenced the qualitative characteristics of the crop in terms of antioxidant compounds and minerals. Nitrate content in vegetables was lower than European regulation limits. The extended use of APW is viable if the missing nutrients are supplemented; this could be a strategy to increase the efficiency of water and nitrogen use, while further reducing environmental impact.

Nitrate in fruits and vegetables

Abstract The current article provides an updated review of scientific advances regarding nitrate accumulation in plant tissues and a critical examination of the genetic, agroenvironmental and postharvest factors that can modulate nitrate levels in a wide range of horticultural crops, including herbs, roots and tubers, inflorescences, buds, seeds, stems, and leafy vegetables, fungi as well as fruits. A refined classification of horticultural crops is presented according to the nitrate content of their edible product. The role of plant cultivar/morphotype and tissue age in nitrate accumulation is discussed along with the physiological role of nitrate as osmoticum in maintaining turgor and driving leaf expansion under conditions of variable photosynthetic capacity. Nitrate accumulation is examined in respect to key cultural practices, such as the timing-rate-form of N application and the use of plant biostimulants (natural substances and microbial inoculants), as well as the potential interaction with other nutrients (e.g., P, Ca, Mo and Cl). The influence of environmental conditions during plant growth (light intensity, spectral quality, photoperiod, air and root-zone temperature and atmospheric CO2 concentration), harvest stage and diurnal timing of harvest is assessed. Postharvest storage conditions (temperature, light, and duration) are discussed in respect to their effects on the putative endogenous conversion of nitrate residues to nitrites. Several approaches that may be adopted to reduce nitrate content in vegetables, fruits and herbs are analysed and warranted future research subjects are identified.

Glucose and Sucrose Supply Regulates the Uptake, Transport, and Metabolism of Nitrate in Pak Choi

Core Ideas The optimal levels of glucose and sucrose for pak choi growth were 25 and 15 μM with 18 and 25% increase in pak choi biomass.The optimal glucose level reduced the uptake and N contribution of nitrate.The optimal glucose level decreased the nitrate transportation to shoots by reducing the NRT1.1 expression, while enhancing the nitrate assimilation ability. High nitrate content in vegetables is regarded as a serious threat to human health. The effects of exogenous sugars on the uptake, transportation, and assimilation of nitrate were studied with vitro grown pak choi. The optimal levels of glucose and sucrose for pak choi growth were 25 and 15 μM, respectively, which led to an increase in pak choi biomass by 18 and 25%, respectively. The uptake and N contribution of nitrate in pak choi grown under optimal glucose levels were significantly lower than those in pak choi grown without glucose. The optimal levels of both glucose and sucrose decreased the active nitrate uptake in roots. However, the optimal glucose level decreased the nitrate transportation to shoots by reducing the NRT1.1 expression, while enhancing the nitrate assimilation ability by increasing the activities of nitrate reductase (NR) and glutamine synthetase (GS) and the gene expression of Gln1 and Gln2 as compared to the pak choi grown under optimal sucrose level. Under optimal glucose levels, the nitrate content of pak choi decreased by 37%, improving its edible quality in the mixed nitrogen. We recommend supplying pak choi with optimal levels of exogenous glucose to reduce its nitrate content, and thus improve its edible quality.

High-Resolution and Non-destructive Evaluation of the Spatial Distribution of Nitrate and Its Dynamics in Spinach (Spinacia oleracea L.) Leaves by Near-Infrared Hyperspectral Imaging.

Nitrate is an important component of the nitrogen cycle and is therefore present in all plants. However, excessive nitrogen fertilization results in a high nitrate content in vegetables, which is unhealthy for humans. Understanding the spatial distribution of nitrate in leaves is beneficial for improving nitrogen assimilation efficiency and reducing its content in vegetables. In this study, near-infrared (NIR) hyperspectral imaging was used for the non-destructive and effective evaluation of nitrate content in spinach (Spinacia oleracea L.) leaves. Leaf samples with different nitrate contents were collected under various fertilization conditions, and reference data were obtained using reflectometer apparatus RQflex 10. Partial least squares regression analysis revealed that there was a high correlation between the reference data and NIR spectra (r2 = 0.74, root mean squared error of cross-validation = 710.16 mg/kg). Furthermore, the nitrate content in spinach leaves was successfully mapped at a high spatial resolution, clearly displaying its distribution in the petiole, vein, and blade. Finally, the mapping results demonstrated dynamic changes in the nitrate content in intact leaf samples under different storage conditions, showing the value of this non-destructive tool for future analyses of the nitrate content in vegetables.

The risk of cancer as a result of elevated levels of nitrate in drinking water and vegetables in Central India

The objective of the present study was to determine the effect of nitrates on the incidence of gastrointestinal (GI) cancer development. Nitrate converted to nitrite under reducing conditions of gut results in the formation of N-nitrosamines which are linked to an increased gastric cancer risk. A population of 234 individuals with 78 cases of GI cancer and 156 controls residing at urban and rural settings in Nagpur and Bhandara districts of India were studied for 2 years using a case-control study. A detailed survey of 16 predictor variables using Formhub software was carried out. Nitrate concentrations in vegetables and primary drinking water supplies were measured. The logistic regression model showed that nitrate was statistically significant in predicting increasing risk of cancer when potential confounders were kept at base level (P value of 0.001 nitrate in drinking water; 0.003 for nitrate in vegetable) at P < 0.01. Exposure to nitrate in drinking water at >45 mg/L level of nitrate was associated with a higher risk of GI cancers. Analysis suggests that nitrate concentration in drinking water was found statistically significant in predicting cancer risk with an odds ratio of 1.20.

Nitrate contents in some vegetables in Tunisia

This study reports the nitrate level of 22 vegetables species collected from 40 farms in several locations of an intensive agricultural area in two regions of Tunisia (Sousse and Monastir). Nitrate levels ranged between 57 and 2970 mg kg‒1. The highest and the lowest levels were found in turnip and tomato, respectively. Only five species (potato, field bean, cauliflower, pea and artichoke) had exceeded the norms established by the World Health Organization. Factors influencing nitrate accumulation in some vegetables were analyzed and discussed. It was observed that nitrate contents in vegetables varied depending on the type of vegetables, genetic factor, level of nitrogen fertilization and soil nitrogen content.

Effect of some processing methods on nitrate changes in different vegetables

This study reports the levels of nitrate of four commonly consumed fresh vegetable samples, (onion, potato, carrot and tomato), from markets in Isfahan, center of Iran. Nitrate levels ranged between 34.67 and 198.09 mg kg−1. The maximum residue levels established for nitrate in carrot followed by, onion, potato and tomato. The effects of various cooking (traditional boiling, boiling in microwave system and frying) methods on nitrate-N contents in vegetables have also been studied. The study showed that the nitrate content of traditional boiling reduces nitrate content by 38.79–74.03 %. Lower reduction of the nitrate level, compared to traditional boiling vegetables, resulted from boiling in microwave system. The frying in soya bean oil elevated nitrate contents from 81.33 to 159.10 %. A comparison of the nitrate obtained by standardized method and the nitrate contents in vegetables of other countries are also presented.