Assessment of Potential Nitrite Safety Risk of Leafy Vegetables after Domestic Cooking

Improper cultivation can easily cause excessive nitrate accumulation in leafy vegetables, and the cooking processes used to prepare them can upset their nitrate/antioxidant balance, affecting their potential nitrite safety risk (PNSR). We investigated the impacts stir-frying, steaming, microwaving, and boiling on the nitrate, nitrite, and antioxidant capacity in water spinach and cabbage, and observed the impacts of storage duration on the PNSR. The antioxidant/in vivo nitrite ratio (A/N) was used to evaluate the nitrite risks in the cooked vegetables. Boiling achieved the highest A/N ratio (1.57) for water spinach, reducing the nitrate content by 25% without significantly affecting the antioxidant capacity. Stir-frying achieved the highest A/N ratio (6.55) for cabbage, increasing the antioxidant capacity by 140% without significantly affecting the nitrate content. Furthermore, it was found that the storage periods for boiled water spinach and stir-fried cabbage should not exceed 12 h and 24 h, respectively. Appropriate cooking methods and limited storage times are thus required for leafy vegetable to prevent adverse health effects.

Download Full-text

A Review of Environment Effects on Nitrate Accumulation in Leafy Vegetables Grown in Controlled Environments

Foods ◽

10.3390/foods9060732 ◽

2020 ◽

Vol 9 (6) ◽

pp. 732

Author(s):

Zhonghua Bian ◽

Yu Wang ◽

Xiaoyan Zhang ◽

Tao Li ◽

Steven Grundy ◽

...

Keyword(s):

Environmental Factors ◽

Molecular Mechanisms ◽

Management Strategies ◽

Leafy Vegetables ◽

Future Research ◽

Nitrate Content ◽

Vegetable Production ◽

Nitrate Accumulation ◽

Potential Threat ◽

Controlled Environments

Excessive accumulation of nitrates in vegetables is a common issue that poses a potential threat to human health. The absorption, translocation, and assimilation of nitrates in vegetables are tightly regulated by the interaction of internal cues (expression of related genes and enzyme activities) and external environmental factors. In addition to global food security, food nutritional quality is recognized as being of strategic importance by most governments and other agencies. Therefore, the identification and development of sustainable, innovative, and inexpensive approaches for increasing vegetable production and concomitantly reducing nitrate concentration are extremely important. Under controlled environmental conditions, optimal fertilizer/nutrient element management and environmental regulation play vital roles in producing vegetables with low nitrate content. In this review, we present some of the recent findings concerning the effects of environmental factors (e.g., light, temperature, and CO2) and fertilizer/nutrient solution management strategies on nitrate reduction in vegetables grown under controlled environments and discuss the possible molecular mechanisms. We also highlight several perspectives for future research to optimize the yield and nutrition quality of leafy vegetables grown in controlled environments.

Download Full-text

Successive Harvests Affect Yield, Quality and Metabolic Profile of Sweet Basil (Ocimum basilicum L.)

Agronomy ◽

10.3390/agronomy10060830 ◽

2020 ◽

Vol 10 (6) ◽

pp. 830 ◽

Cited By ~ 3

Author(s):

Giandomenico Corrado ◽

Pasquale Chiaiese ◽

Luigi Lucini ◽

Begoña Miras-Moreno ◽

Giuseppe Colla ◽

...

Keyword(s):

Antioxidant Capacity ◽

Nutrient Use Efficiency ◽

Quality Attributes ◽

Ocimum Basilicum ◽

Leafy Vegetables ◽

Nitrate Content ◽

Fresh Market ◽

Sweet Basil ◽

Use Efficiency ◽

The Impact

Sweet basil (Ocimum basilicum L.) is an aromatic, tender leafy green cultivated for the fresh market and industrial processing. Like many other leafy vegetables, this species can be harvested more than once to increase productivity. Although the cut-and-come-again (CC) harvest strategy is widespread in basil, not much is known about the effect of the cut. In this work, we examined differences in biomass, physiology, nutrient use efficiency and antioxidant capacity of basil leaves from two successive harvests. Moreover, we also performed an untargeted metabolomics analysis to reveal variations in the leaf metabolite profile. The data indicated that the cut affected many of the parameters under investigation, including a modest reduction of yield (−20%), of nitrogen use efficiency (−21%) and of some quality attributes such as the antioxidant capacity (−16%) and the nitrate content in leaves (+48%). Moreover, leaves of successive cuts displayed a significant variation of the profile of bioactive compounds, characterized by an overall decrease of phenylpropanoids and an increase in terpenoids. Our data revealed the impact of CC harvesting strategy in basil, and that this strategy offers the possibility to yield leaves with different metabolomics profiles and quality attributes.

Download Full-text

Effect of Different Cooking Methods on Polyphenols, Carotenoids and Antioxidant Activities of Selected Edible Leaves

Antioxidants ◽

10.3390/antiox7090117 ◽

2018 ◽

Vol 7 (9) ◽

pp. 117 ◽

Cited By ~ 17

Author(s):

K. Gunathilake ◽

K. Ranaweera ◽

H. Rupasinghe

Keyword(s):

Antioxidant Activity ◽

Antioxidant Capacity ◽

Antioxidant Activities ◽

Radical Scavenging ◽

Leafy Vegetables ◽

Cooking Methods ◽

Oxygen Scavenging ◽

Total Antioxidant ◽

The Impact ◽

Dpph Radical Scavenging

This study aimed to evaluate the effect of cooking (boiling, steaming, and frying) on polyphenols, flavonoids, carotenoids and antioxidant activity of six edible leaves. The total antioxidant capacity of the fresh and cooked leaves was determined using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and singlet oxygen scavenging assays. The results revealed that frying caused a reduction in major bioactives and antioxidant activities in all leafy vegetables tested. However, steamed and boiled leaves of C. auriculata and C. asiatica have shown greater levels of polyphenols, flavonoids, and antioxidant capacity compared with fresh leaves. Polyphenol and flavonoid contents of boiled S. grandiflora and G. lactiferum were higher than that of their fresh form. Boiled and steamed O. zeylanica and S. grandiflora have shown higher carotenoids. Boiled and steamed leaves of P. edulis have shown higher antioxidant activity. The impact of cooking on the changes in bioactive concentrations and antioxidant capacities are dependent on the species and the method of cooking.

Download Full-text

NITRATE ACCUMULATION IN LETTUCE AND ROCKET IN RESPONSE TO NITROGEN FERTILIZATION IN INTERCROPPING

Revista Caatinga ◽

10.1590/1983-21252020v33n128rc ◽

2020 ◽

Vol 33 (1) ◽

pp. 260-265

Author(s):

AURÉLIO PAES BARROS JÚNIOR ◽

ARTHUR BERNARDES CECÍLIO FILHO ◽

BRÁULIO LUCIANO ALVES REZENDE ◽

HAMURÁBI ANIZIO LINS

Keyword(s):

Block Design ◽

Strong Association ◽

Leafy Vegetables ◽

Nitrate Content ◽

Nitrate Accumulation ◽

Lack Of Information ◽

Randomized Block Design ◽

Nitrogen Concentrations ◽

N Dose

ABSTRACT In the cultivation of leafy vegetables, it is common to apply high amounts of nitrogen fertilizer. The imbalance between the absorption and the use of nitrogen (N) by the plant increases the nitrate content and decreases the quality of the vegetables because nitrate has a strong association with compounds harmful to human health. On the other hand, there is a lack of information on how N dose in intercropping, in order to improve yield, affects the quality (nitrate content) of vegetables. Thus, the objective of this study was to evaluate the nitrate content of intercropped lettuce and rocket, with nitrate content acting as a function of the nitrogen dose applied to these crops. The experiment was carried out at UNESP, Jaboticabal, SP, from September to December 2006. The experimental design was a complete randomized block design with four replications. The treatments were arranged in a 4 × 4 + 2 factorial scheme, with four varying concentrations of N each for lettuce and rocket (0, 65, 130 and 195 kg ha-1 of N), plus two treatments corresponding to lettuce and rocket monocrops. Nitrate content in lettuce under intercropping is 42% less compared to that in the monocrop. Increasing nitrogen concentrations increased nitrate levels for lettuce and rocket under intercropping; however, these levels are below those found for their respective monocrops.

Download Full-text

(224) In Situ N Monitoring for Safe Leafy Vegetables using Quick and Advanced Tools

HortScience ◽

10.21273/hortsci.40.4.1074d ◽

2005 ◽

Vol 40 (4) ◽

pp. 1074D-1074

Author(s):

Chin H. Ma ◽

Manuel C. Palada

Keyword(s):

Block Design ◽

Application Rate ◽

Leafy Vegetables ◽

Nitrate Content ◽

Vegetable Production ◽

Nitrate Accumulation ◽

N Accumulation ◽

Chlorophyll Meter ◽

Leaf Chlorophyll ◽

Nitrate N

High levels of N fertilizers are generally applied in intensive leafy vegetable production in the peri-urban agriculture of Southeast Asia. This study was conducted to develop a simple and rapid method of determining nitrate-N accumulation in selected leafy vegetables. Five leafy vegetables, including amaranth (Amaranthus tricolor), kangkong (Ipomoea aquatica), Ethiopian kale (Brassica carinata), choysum (Brassica campestris sp. parachinensis), and leafy lettuce (Lactuca sativa) were grown on raised beds in 32-mesh nethouse in randomized complete-block design with four replications. The crops were fertilized with eight N levels: 0, 50, 100, 150, 200, 250, 300, and 350 kg·ha-1 in three splits. At harvest, nitrate contents were determined in tissue sap of fully expanded leaf blades, petioles and whole plant using a Cardy nitrate meter. Chlorophyll content readings were also measured on the same leaf using a chlorophyll meter. Nitrate accumulations varied with vegetable species. Significant correlations (P< 0.001) existed between N fertilizer rate and nitrate content as well as leaf chlorophyll and yield. Using N application rate of 200 kg·ha-1, nitrate accumulation in Ethiopian kale was highest (7000 ppm), followed by kangkong (4000 ppm), amaranth (3500 ppm), and leafy lettuce (1200 ppm). The correlation between leaf chlorophyll meter reading (LCMR) and nitrate content was also significant (P< 0.001), suggesting the feasibility of using Cardy nitrate meter test and LCMR for monitoring production of low-nitrate and safe vegetables. The Cardy meter was also sensitive in detecting soil nitrate-N below 20 ppm and is a rapid and reliable alternative to conventional distillation method.

Download Full-text

The Role of Polyphenols in the Modulation of Plasma Non-Enzymatic Antioxidant Capacity (NEAC)

International Journal for Vitamin and Nutrition Research ◽

10.1024/0300-9831/a000116 ◽

2012 ◽

Vol 82 (3) ◽

pp. 228-232 ◽

Cited By ~ 7

Author(s):

Mauro Serafini ◽

Giuseppa Morabito

Keyword(s):

Antioxidant Capacity ◽

Dietary Intervention ◽

Ex Vivo ◽

The Body ◽

Dietary Polyphenols ◽

Enzymatic Antioxidant ◽

Endogenous Antioxidant

Dietary polyphenols have been shown to scavenge free radicals, modulating cellular redox transcription factors in different in vitro and ex vivo models. Dietary intervention studies have shown that consumption of plant foods modulates plasma Non-Enzymatic Antioxidant Capacity (NEAC), a biomarker of the endogenous antioxidant network, in human subjects. However, the identification of the molecules responsible for this effect are yet to be obtained and evidences of an antioxidant in vivo action of polyphenols are conflicting. There is a clear discrepancy between polyphenols (PP) concentration in body fluids and the extent of increase of plasma NEAC. The low degree of absorption and the extensive metabolism of PP within the body have raised questions about their contribution to the endogenous antioxidant network. This work will discuss the role of polyphenols from galenic preparation, food extracts, and selected dietary sources as modulators of plasma NEAC in humans.

Download Full-text

Potential Risk of Consuming Vegetables Planted in Soil with Lead and Cadmium and the Influence on Vegetable Antioxidant Activity

Applied Sciences ◽

10.3390/app11093761 ◽

2021 ◽

Vol 11 (9) ◽

pp. 3761

Author(s):

Wen-Lii Huang ◽

Wei-Hsiang Chang ◽

Shu-Fen Cheng ◽

Huai-Yuan Li ◽

Hsiu-Ling Chen

Keyword(s):

Sweet Potato ◽

Contaminated Soils ◽

Vegetable Consumption ◽

Accumulation Rate ◽

Leafy Vegetables ◽

Water Spinach ◽

Potato Leaf ◽

Cd Accumulation ◽

Lead And Cadmium ◽

Cd Exposure

Once in soil and water, metals can enter the food chain, and the consumption of contaminated crops can pose a serious risk to human health. This study used pot experiments to evaluate the accumulation of metal elements and their influence on levels of antioxidants in vegetables. The current study clearly demonstrates that metals accumulated in the five vegetables that were planted in the contaminated soils, especially so for water spinach. Cd accumulation of all of the vegetables planted in the contaminated soils was greater Cu. The low accumulation rate that was seen in sweet potato leaf, potato, and tomato indicated their suitability for planting in suspected contaminated soil, such as at farms nearby metal industries, in replacement of high accumulators, such as leafy vegetables. The non-carcinogenic HI of Cd exposure from water spinach and sweet potato were >1, whereas those for Cu were <1. This study suggests that residents may experience health risks due to vegetable consumption, and that children are vulnerable to the adverse effects of heavy metal ingestion.

Download Full-text

Comparative assessment of bioactive compounds, antioxidant capacity and nutritional quality of red seaweeds and water spinach

Regional Studies in Marine Science ◽

10.1016/j.rsma.2021.101878 ◽

2021 ◽

pp. 101878

Author(s):

Md. Solaiman Hossain ◽

Saad Al-din Sifat ◽

M. Afzal Hossain ◽

Sazlina Salleh ◽

Mofazzal Hossain ◽

...

Keyword(s):

Antioxidant Capacity ◽

Bioactive Compounds ◽

Nutritional Quality ◽

Comparative Assessment ◽

Water Spinach ◽

Red Seaweeds

Download Full-text

EC Sensitivity of Hydroponically-Grown Lettuce (Lactuca sativa L.) Types in Terms of Nitrate Accumulation

Agriculture ◽

10.3390/agriculture11040315 ◽

2021 ◽

Vol 11 (4) ◽

pp. 315

Author(s):

Noémi Kappel ◽

Ildikó Fruzsina Boros ◽

Francia Seconde Ravelombola ◽

László Sipos

Keyword(s):

Lactuca Sativa ◽

Nitrate Content ◽

Saline Condition ◽

Fresh Weight ◽

Nitrate Level ◽

Nitrate Accumulation ◽

Strong Negative Correlation ◽

Lactuca Sativa L ◽

Hydroponically Grown ◽

European Markets

The goal of this research was to investigate the effect of electrical conductivity (EC) levels of the nutrient solution on the fresh weight, chlorophyll, and nitrate content of hydroponic-system-grown lettuce. The selected cultivars are the most representative commercial varieties grown for European markets. Seven cultivars (‘Sintia,’ ‘Limeira,’ ‘Corentine,’ ‘Cencibel,’ ‘Kiber,’ ‘Attiraï,’ and ‘Rouxaï’) of three Lactuca sativa L. types’ (butterhead, loose leaf, and oak leaf) were grown in a phytotron in rockwool, meanwhile the EC level of the nutrient solutions were different: normal (<1.3 dS/m) and high (10 dS/m). The plants in the saline condition had a lower yield but elevated chlorophyll content and nitrate level, although the ‘Limeira’ and ‘Cencibel’ cultivars had reduced nitrate levels. The results and the special characteristic of the lollo-type cultivars showed that the nitrate level could be very different due to salinity (‘Limeira’ had the lowest (684 µg/g fresh weight (FW)) and ‘Cencibel’ had the highest (4396 µg/g FW)). There was a moderately strong negative correlation (−0.542) in the reverse ratio among the chlorophyll and nitrate contents in plants treated with a normal EC value, while this relationship was not shown in the saline condition. Under the saline condition, cultivars acted differently, and all examined cultivars stayed under the permitted total nitrate level (5000 µg/g FW).

Download Full-text

Nutrient Solution Deprivation as a Tool to Improve Hydroponics Sustainability: Yield, Physiological, and Qualitative Response of Lettuce

Agronomy ◽

10.3390/agronomy11081469 ◽

2021 ◽

Vol 11 (8) ◽

pp. 1469

Author(s):

Michele Ciriello ◽

Luigi Formisano ◽

Antonio Pannico ◽

Christophe El-Nakhel ◽

Giancarlo Fascella ◽

...

Keyword(s):

Nutrient Solution ◽

Potential Effect ◽

Quality Parameters ◽

Leafy Vegetables ◽

Nitrate Content ◽

Yield Reduction ◽

Quality Performance ◽

Floating Raft ◽

Amino Acids Profile ◽

Excessive Nutrients

Hydroponics growing systems often contain excessive nutrients (especially nitrates), which could lead to a quality loss in ready-to-eat leafy vegetables and posing a health risk to consumers, if managed inadequately. A floating raft system was adopted to assay the production and quality performance of lettuce (Lactuca sativa L. cv ‘Maravilla De Verano Canasta’) deprived of the nutrient solution by replacement with only water, three and six days before harvest. Yield and quality parameters, mineral composition, pigments, organic acids, amino acids profile, soluble proteins, and carbohydrate content were determined. Nutrient solution deprivation six days before harvest resulted in a significant reduction in leaf nitrate (−53.3%) concomitant with 13.8% of yield loss, while plants deprived of nutrient solution three days before harvest increased total phenols content (32.5%) and total ascorbic acid (102.1%), antioxidant activity (82.7%), anthocyanins (7.9%), sucrose (38.9%), starch (19.5%), and γ-aminobutyric acid (GABA; 28.2%), with a yield reduction of 4.7%, compared to the control. Our results suggest that nutrient solution deprivation three days before harvest is a successful strategy to reduce nitrate content and increase the nutritional quality of lettuce grown in floating raft systems with negligible impact on yield. These promising results warrant further investigation of the potential effect of nutrient solution deprivation on the quality attributes of other leafy vegetables cultivated in floating raft systems and in a “cascade” growing system.

Download Full-text