Initial Nitrate Concentration Research Articles

Treatment of nitrate-rich groundwater using electrocoagulation with aluminum anodes

In recent years, groundwater has been affected by anthropogenic pollutants such as nitrates. The latter has the potential to produce nitrosamines and can therefore cause blue baby syndrome as well as several types of cancer, including that of the digestive system. Moreover, nitrates lead to eutrophication in water bodies such as rivers and lakes. These adverse effects make it necessary to remove nitrates from water. This work consisted of the denitrification technique study by electrocoagulation (EC) of nitrate-rich groundwater for the production of drinking water. Tests were carried out on nitrate-based synthetic water prepared in the laboratory. The EC test was realized in a batch reactor, comprising two aluminum electrodes, powered by different DC voltages. The operating parameters were the applied voltage between the electrodes (5–30 V), a pH fixed at 7, an initial nitrate concentration of 100 mg/L. The results showed that the removal efficiency depended on the applied voltage and the immersed surface of the electrodes. This removal efficiency was 94.41% after 150 min under the following conditions: pH = 7, electrical voltage = 30 V, immersed surface = 33.75 cm2. In addition, this study concluded that the nitrate removal by electrocoagulation could be achieved by adsorption on Al(OH)3 and/or reduction to nitrites or to ammonium. A significant quantity of by-products, ammonium and nitrite, formed during the process. However the addition of Cl− allowed decrease in nitrite and ammonium formation. The current density monitoring determined the maximum current intensity that could be kept constant to improve removal efficiency and reduce treatment time.

Developing an artificial neural network model for predicting the growth of Chlorella sorokiniana in a photobioreactor

Microalgae have been long considered as a potential source of biofuel. Species such as Chlorella sorokiniana can store large amounts of carbohydrates and lipids which can be used to produce biofuels. This paper demonstrates a method for developing an artificial neural network model which can predict C. sorokiniana growth in a photobioreactor. The data used for training the model came from cultivation experiments conducted at the National Cheng Kung University in Taiwan. A feedforward backpropagation ANN model with three inputs (i.e. aeration rate, biomass concentration, and nitrate concentration) and two targets (i.e. biomass concentration and nitrate concentration after 24 hours) was used for this study. Using MATLAB, multiple configurations of this ANN model were created and tested by varying the number of neurons and hidden layers and the training algorithm. Models were initially assessed in terms of their mean square error (MSE) and training performance plots. The models were then further assessed based on their simulation capabilities. After setting the initial biomass and nitrate concentration and aeration profile, the model can already predict the daily biomass and nitrate concentration of C. sorokiniana for the whole cultivation period. The final model selected has one (1) hidden layer and four (4) hidden neurons and it was trained using the Bayesian regularization backpropagation algorithm. For the final selected model, the calculated mean absolute percentage error (MAPE) for the predicted daily biomass and nitrate concentration were all below 7.59% and 3.68% respectively. Thus, the simulation results showed that the final model can accurately predict C. sorokiniana growth at varying aeration profiles. For future studies, this model can be used to determine the aeration profile that can maximize C. sorokiniana growth in a photobioreactor while minimizing aeration costs.

Nitrate removal from drinking water using direct current or solar powered electrocoagulation

Nitrate levels are frequently high in ground and surface waters mainly because of anthropogenic activities. Electrocoagulation (EC) is a viable alternative to conventional coagulation in drinking water treatment and has been successfully applied to remove nitrate from drinking water. The objective of this study was to determine optimum operating conditions for maximizing nitrate removal from drinking water using electrocoagulation followed by settling and filtration. Batch experiments were carried out using iron electrodes (mild steel) and four types of water were tested (groundwater, tap water, untreated water from IIT Water Works and double distilled water). Experiments were conducted with direct current (DC) power or solar power. Operating parameters such as initial nitrate concentration, voltage, electrocoagulation time and settling time were varied to determine optimum conditions for achieving maximum removal efficiency. Nitrate removals after electrocoagulation and after settling were determined for all experiments. In 22 DC power experiments with all waters tested, maximum removal efficiencies were 37% (after EC) and 38.21% (after EC and settling). The highest removal efficiency was obtained in double distilled (DD) water at 10 V, initial nitrate concentration of 452 ppm, EC time of 4 h, settling time of 4 h and an initial pH of 9.89. Multiple linear regression analysis of DD water experiments was done. Model 1 based on removal efficiency after EC only was found to be a good fit and was statistically significant. Five solar experiments were carried out and the maximum removal efficiency obtained was 53% with 3 h of electrolysis time. The initial nitrate concentration was 95.53 mg/L, voltage was 14 V and initial pH was 10.8. Electrocoagulation coupled with solar energy can be used in rural areas in decentralized mode.

Optimizing the removal of nitrate by adsorption onto activated carbon using response surface methodology based on the central composite design

This study sheds light on the adsorption process for the removal of nitrate ions from synthetic aqueous solutions. This contaminant pose a potential risk to the environment and can cause health effects including cancers and methemoglobinemia in infants. When the adsorption process is carried out, the effect by the several operating parameters such as initial nitrate concentration, pH, mass of activated carbon, and contact time becomes apparent. The essential process variables are optimized using response surface methodology (RSM) based on the central composite design (CCD) experiments. For this purpose 31 experimental results are required to determine the optimum conditions. The optimum conditions for the removal of nitrates is found to be: initial nitrate concentration = 15 mg/L; initial pH 4.0; mass of activated carbon = 25 mg, and contact time = 70 min. At these optimized conditions, the maximum removal of nitrates is found to be 96.59%.

The effect of conventional water disinfection methods on nitrate level.

Some common ways to increase the microbial quality of drinking water may compromise another aspect of the quality of water due to making side products or concentrating pollutants. In this research, three common methods of chlorination, iodination and boiling used as popular and very practical ways to improve the quality of drinking water were investigated to examine their effects on increasing or decreasing concentration of nitrate as a chemical contaminant. The experiments were designed using the software R version 3.5.1 for chlorine and iodine. The variables of chlorine and iodine concentration, the initial concentration of nitrate, and time were determined as independent variables and the final concentration of nitrate as the dependent variable. In the boiling test, water containing a certain concentration of nitrate was boiled for half an hour and the effect of each boiling minute on changing nitrate concentration was investigated. In this study, it was found that all three factors of chlorination, iodination, and boiling increase the concentration of nitrate in water.

The effect of conventional water disinfection methods on nitrate level

Some common ways to increase the microbial quality of drinking water may compromise another aspect of the quality of water due to making side products or concentrating pollutants. In this research, three common methods of chlorination, iodination and boiling used as popular and very practical ways to improve the quality of drinking water were investigated to examine their effects on increasing or decreasing concentration of nitrate as a chemical contaminant. The experiments were designed using the software R version 3.5.1 for chlorine and iodine. The variables of chlorine and iodine concentration, the initial concentration of nitrate, and time were determined as independent variables and the final concentration of nitrate as the dependent variable. In the boiling test, water containing a certain concentration of nitrate was boiled for half an hour and the effect of each boiling minute on changing nitrate concentration was investigated. In this study, it was found that all three factors of chlorination, iodination, and boiling increase the concentration of nitrate in water.

A natural polymer based bioadhesive with self-healing behavior and improved antibacterial properties.

Bioadhesives are of great interest for tissue/wound closure to reduce surgical time, minimize treatment invasiveness, and prevent body fluid leakage. However, bacterial infections remain a major concern during wound healing and tissue bonding. Hence, the development of bioadhesives with antibacterial properties is necessary. In this study, a hydrogel bioadhesive based on silk fibroin (SF) and tannic acid (TA) was combined with silver nanoparticles (AgNPs) generated in situ during hydrogel formation to improve its antibacterial abilities. In this system, TA can be regarded as a phenolic glue molecule to spontaneously co-assemble with SF to fabricate the adhesive matrix network and also as a reductant to induce silver nitrate to form AgNPs evenly within the adhesive network. Furthermore, the influence of the amount of silver nitrate was considered. The produced hybrid hydrogel bioadhesives with different amounts of AgNPs exhibited self-healing capabilities, considerable wet tissue adhesion strengths (14.32 ± 1.85 kPa-28.80 ± 2.29 kPa) and good cytocompatibility. When the initial concentration of silver nitrate was more than 0.05 wt%, the produced STA bioadhesive showed effective antibacterial properties in vitro. These results demonstrate that these STA bioadhesives have the potential to be used in tissue/wound closure, especially when bacterial infections are a main problem.

EFFECTS OF NATURAL ANTIOXIDANTS IN PROCESSING AND STABILITY OF ITALIAN TYPE SALAMI DURING STORAGE

The aim of the study was to elaborate formulations of Italian type salami by adding natural antioxidant of green tea (Camellia sinensis) and to evaluate the stability during the shelf life. Formulations (F1, F2 and F3) were elaborated varying the concentrations of green tea (0.008 to 0.016%), sodium erythorbate (0.048 to 0.097%), sodium nitrite (0 to 0.012%), sodium nitrate (0 to 0.016%), curing salt (0 to 0.189%) and dehydrated glucose (0.589 to 0.959%), keeping fixed the concentrations of swine meat, bacon, water, refined salt, pepper and starter culture. To verify oxidative stability, the moisture, water activity, sodium nitrate and nitrite, pH, acidity, TBARS and product acceptance were evaluated during 120 days of storage. F1 stood out in terms of acceptance, with a higher initial and residual concentration of nitrates and nitrites up to the 80 th day of storage and less lipid oxidation, that has 0.016% green tea, 0.012% sodium nitrite, 0.013% sodium nitrate, 0.081% sodium erythorbate and 0.806% dehydrated glucose in its formulation. The results indicated that the addition of green tea, associated with sodium nitrate/nitrite and sodium erythorbate reduced the formation of TBARS and did not affect the sensory quality of the product. Thus, this natural antioxidant can be easily used in Salami to improve quality and provide safer products.

Impact of organic fertilisation on lettuce biomass production according to the cultivation duration in tropical soils

ABSTRACTThe productivity levels of two arenosol (Ar40) and fluvisol (FL40) fields that had been cultivated for over 40 years were compared to that of fields with the same soils located nearby but never previously cultivated, i.e. Ar0 and FL0, respectively. Application of poultry manure (PM) and sewage sludge (SS) were compared to a mineral fertilizer (T100), corresponding to 100 kg/ha of nitrogen, over three lettuce (Lactuca sativa L.) crop cycles. PM and SS were applied at 50 and 150 kg/ha nitrogen equivalent fertilizer doses. Biomass production levels in the organic and mineral treatments were similar, except for the SS-50 for FL0 and the PM-150 for Ar40, FL40 and FL0. Biomass production levels of Ar40 were higher than those of Ar0 for the first cycle. In the initial state, the soil P content in Ar40 was higher than that of the Ar0 soil. With the treatment repetition, Ar0 showed the same production level as Ar40. For the fluvisols, biomass production levels of FL40 were lower than those of FL0 for the first cycle. Indeed, the initial nitrate content in FL40 was lower than in FL0. The biomass production levels of FL40 were higher than those of FL0 for the following cycles.

Mg-Fe layered double hydroxide with chloride intercalated: synthesis, characterization and application for efficient nitrate removal

Mg-Fe layered double hydroxide intercalated with chloride (Mg-Fe-Cl LDH) was synthetized, characterized, and evaluated as adsorbent to remove nitrate from aqueous solution. The pH, initial nitrate concentration, adsorbent dosage, and particle size were investigated. Kinetic data was best represented by pseudo-second order model indicating that the rate limiting step was chemisorption. Intraparticle diffusion model indicates that adsorption kinetic is limited by external and intraparticle diffusion. Sips model was selected, based on R2, ARE, and AIC, to adequately represent the adsorption isotherms, which permits to affirm that the adsorption occurs in heterogeneous surface, obtaining the maximum adsorption capacity of 18.17mg.g-1 at 30oC. Thermodynamics parameters indicate that the adsorption was spontaneous, exothermic, and with structural modification. These findings come up with Mg-Fe-Cl LDH as a suitable adsorbent for nitrate and could contribute to its removal from the water and wastewater.

Phytoremediation of nitrate contaminated water using ornamental plants

Abstract This work aims at evaluating the potential of two ornamental plant species, i.e., money plant (Epiprennum aureum) and arrowhead plant (Syngonium podophyllum), to treat nitrate containing wastewater. Statistically designed experiments were performed to ascertain the effect of initial nitrate concentration (40–120 mg/L), growth period (1–12 days) and plant density (20–80 g/L) on nitrate removal. Based on the results of analysis of variance (ANOVA), it was observed that the individual effects (F = 78.04 and P = 0.013) of process parameters influenced the nitrate removal efficiency by money plant stronger than the 2-way (F = 0.2 and P = 0.89) and 3-way interaction effects (F = 0.46 and P = 0.569). In the case of the arrowhead plant, the individual effects significantly affected the nitrate removal efficiency than the 2-way and 3-way interaction effects. Low nitrate concentrations (40 mg/L) and high plant density (80 g/L), showed ∼88% nitrate removal by arrowhead plant, during a growth period of 6 d. On the contrary, under similar conditions, the money plant showed a nitrate removal efficiency of ∼93% during a growth period of 12 d. Concerning the removal kinetics, an increase in the growth period increased the nitrate removal rate for both the plants.

Impact factors on the production of β-methylamino-L-alanine (BMAA) by cyanobacteria.

Cyanobacteria produce a series of secondary metabolites, one of which is beta-N-methylamino-l-alanine (BMAA). BMAA is considered to be the cause of human neurodegeneration. Compared with other cyanotoxins, the role of BMAA in cyanobacteria remains unclear. To investigate this question, six strains of cyanobacteria were cultured and tested in this experiment with an optimized and validated BMAA determination method. The results show that four strains can produce BMAA. The effects of nutrient levels on the production of BMAA by Anabaena sp. FACHB-418 were studied by changing the initial concentrations of nitrate (NaNO3) and phosphate (K2HPO4) in mediums. Bound BMAA was detected in all samples and the concentrations were within 50-100 ng/g. Free BMAA was presence when the concentration of nitrogen was lower than 1.7 mg/L (121.43 μM). Free BMAA was released from the dead and ruptured cells during the cell decline period, so dissolved BMAA cannot be detectable in the adaptation and logarithmic periods, but could be abundant in the decline periods. Statistical analyses show that free BMAA concentrations were negatively correlated with nitrogen strongly (p = 2.334 × 10-10 and r = -0.842), but positively correlated with phosphorus weakly (p = 0.016 and r = 0.405). Moreover, the results of culture experiments indicated that exogenous BMAA could inhibit the growth of cyanobacteria that cannot produce BMAA, and the effect was enhanced as the concentration of exogenous BMAA increased. This phenomenon implies that the production of BMAA may be the stress response by some cyanobacteria to low nitrogen conditions to kill other cyanobacteria, i.e., their competitors.

Statistical optimization of lipid production by the diatom Gyrosigma sp. grown in industrial wastewater

The marine diatom Gyrosigma sp. was cultured in a medium comprised of inorganic nutrients dissolved in palm oil mill effluent (POME) wastewater. The production of lipids in the biomass was optimized using a statistical design of experiments in combination with the response surface method. The experimental factors were incident light level and initial concentrations of nitrate, phosphate, and silicate in the medium in batch culture. At 25 ± 2 °C, the maximum lipid content in the biomass harvested at the end of a 12-day batch culture was 70.7 ± 6.0% by dry weight for the following values of the experimental factors: an incident light level of 131 μmol photons m−2 s−1, a nitrate concentration of 1.8 mg L−1 (29.0 μM), a phosphate concentration of 6.8 mg L−1 (71.6 μM), and a silicate concentration of 10.1 mg L−1 (132.7 μM). Under the optimized conditions, the maximum dry mass concentration of the diatom was 560 mg L−1 on day 8 of a batch culture, declining to ~409 mg L−1 on day 12. For the 12-day batch operation, the final average productivities of the biomass and the lipids were 34.1 ± 5.5 mg L−1 day−1 and 24.1 ± 0.2 mg L−1 day−1, respectively. The fatty acids in the algal lipids were found to be as follows (%, w/w of total lipids): palmitic acid (48.6%), eicosapentaenoic acid (10.6%), myristic acid (8.1%), stearic acid (8.0%), linoleic acid (7.5%), oleic acid (6.4%), and linolenic acid (5.8%). The response surface model predicted the lipid content in the biomass with a high degree of confidence.

Examination of indigenous microalgal species for maximal protein synthesis

The expanding aquaculture industry increases the prices of fishmeal, the main protein source in fish diet. A promising alternative is microalgal protein. Therefore, we investigated the protein production capacities of green microalgae Chlorella sorokiniana CY1 and Chlorella vulgaris ESP-31. After optimization, the maximum biomass and protein productivities of Chlorella sorokiniana CY1 reached high values of 4.35 ± 0.09 and 0.856 ± 0.025 g/L/d, while that of Chlorella vulgaris ESP-31 also reached high values of 4.636 ± 0.10 and 0.946 ± 0.065 g/L/d. The cultivation time for both species was only 2 days, wherein Chlorella sorokiniana CY1 and Chlorella vulgaris ESP-31 amassed moderate protein contents of 25.9 ± 1.3% and 26.8 ± 1.3%. The optimum conditions for both species were 50% initial nitrate concentration of Basal medium, 5% CO2 aeration, and 750 μmol/m2/s light intensity. The high biomass and protein productivities of both species indicated their capability as potential protein sources.

Evaluation of denitrification performance and bacterial community of a sequencing batch reactor under intermittent aeration

Effects of operational parameters (initial nitrite concentration, initial nitrate concentration, carbon source, and COD/N ratio) on denitrification performance was evaluated using a sequencing batch reactor (SBR) under intermittent aeration. Complete denitrification was observed without N2O accumulation when the initial nitrite concentration was 100–500 mg-N·L−1. When the initial nitrate concentration was 75–300 mg-N·L−1, 95–96% of NO3−-N was completely reduced to N2 gas. Acetate was the most effective sole carbon source for the complete denitrification of the SBR under intermittent aeration, and 99% of NO3−-N was reduced to N2 gas. The optimum COD/N ratio was 8–12 for the complete denitrification, while NO2− accumulation was observed at low COD/N ratios of 1 and 2. In this study, N2O accumulation was not observed during the denitrification process regardless of operational condition. Paracoccus (15–68%), a representative aerobic denitrifying bacterium, was dominant in the SBR during the denitrification process, and the intermittent aeration condition could affect the abundance of Paracoccus in this study.

Comparative studies on revival of nitrate and phosphate ions using quaternized corn husk and jackfruit peel

Adsorbent using quaternary amino anion exchanger from agro waste such as corn husk (CHQ) and jackfruit peel (JPQ) were synthesized. The surface positive charges on the adsorbents are used for the removal of nitrate and phosphate ions from aqueous solutions. Batch adsorption parameters such as contact time, initial concentration of nitrate and phosphate solutions, dosage, solution pH, co-existing anions and temperature studies were carried out. Adsorbents were characterized using FT-IR, SEM with EDX, CHNS analyses, etc. In the adsorption isotherms study, Langmuir isotherm was found to be best for both the adsorbates and Q° of nitrate and phosphate ions were 79.09 and 100.01 mg g−1 for CHQ and 62.91 and 72.39 mg g−1 for JPQ resin at 30 °C. Studies on thermodynamic parameters revealed exothermic and spontaneous nature. It is suggested that quaternary amino anion exchanger of JPQ and CHQ are promising cost-effective adsorbents with good removal efficiency.

Experimental evaluation of nitrate reduction from water using synthesis nanoscale zero-valent iron (NZVI) under aerobic conditions

The aim of this research was to study the potential of synthesized nanoscale zero-valent iron for nitrate reduction in aqueous solution. Batch technique was used to determine the kinetics and effective parameters. The effects of initial pH level, initial nitrate concentration and nanoscale Fe° concentration on nitrate reduction were studied. Nanoscale zero-valent iron was synthesized by chemical reduction method. The TEM image showed that synthesized nano Fe° has a size in the range of 40-120 nm. Experimental results exhibited that reduction efficiency of nitrate decreases with increasing initial pH and increases significantly due to increasing the concentration of zero-valent iron nanoparticles. Also, it was illustrates that initial concentration of nitrate has little effect on the nitrate reduction efficiency. Under acidic and neutral conditions, pH level of the reaction solution increased considerably after 60 min. However, under alkaline conditions, pH level of the reaction solution decreased. The reduction rate of nitrate reached 80% in 60 min with nanoscale Fe° dosage of 1.0 gl -1 and pH in4. The observed reaction rate constant was determined to be 0.0255 in min -1 for nanoscale concentration 1.0 gl -1. The experimental results indicated that the nitrate reduction with zero-valent iron nanoparticles do not comply the first-order reaction model with respect to nitrate concentration.

Synthesis and Characterization of Waterglass-Based Silica Aerogel Under Heat Treatment for Adsorption of Nitrate from Water: Batch and Column Studies

In this work, hydrophobic silica aerogels were synthesized using sol-gel method and drying at ambient pressure. The surface morphology, pore size, and the presence of functional groups on the surface of the nanoparticles were analyzed using FE-SEM, TGA, FT-IR, and EDX, respectively. After calcination at 500 °C, the hydrophilic property of the adsorbents was evaluated by water contact angle measurements. The calcinated silica aerogels were used for adsorption of nitrate from aqueous solution in both batch and continuous processes. In the batch process, the effect of initial nitrate concentration, contact time, pH level, and adsorbent dosage were investigated. Results showed that the nitrate removal percentage increased with the decrement of the pH level and the initial nitrate concentration. On the other hand, increasing the contact time and the adsorbent dosage resulted in higher removal percentage. Accordingly, process optimization resulted in a nitrate removal of 92.2 %. Furthermore, it was found that the equilibrium results were in agreement with the Langmuir isotherm model better than with the Freundlich model and also the adsorption kinetics followed the pseudo-second-order model. In the continuous process, the effects of the input flow rate, the bed height, and the initial nitrate concentration were investigated.

Synthesis ratios of Mg-Al and Zn-Al layered double hydroxides efficiency and selectivity in nitrate removal from solution

Four diverse chlorides layered double hydroxides with diverse ratios, i.e. Mg-Al (3:1), Mg-Al (4:1), Zn-Al (4:1), and Zn-Al (3:1) LDHs, were prepared to evaluate their efficiency and selectivity towards nitrate removal from aquatic solutions. A batch experiment was done at the initial nitrate concentration of 5-1000 mg/L, pH 5 to 12, and contact time of 5-180 min. Isotherms of nitrate adsorption on LDHs, soil and soil-LDH mixtures were studied. Kinetics of adsorption, temperature effect, nitrate adsorption in nitrate adsorption, simulated soil solution and desorption on Mg-Al-LDH (4:1) were measured. At an optimum speed of 250 rpm, pH value of 7 and adsorbent dosage of 2 g/L, the amounts of nitrate adsorption on Mg-Al- LDH (3:1) and Mg-Zn-LDH (3:1) and also on Mg-Al- LDH (4:1) and Mg-Zn-LDH (4:1) were obtained after 30 and 60 min, respectively. Isotherm studies indicated that nitrate adsorption on soil, soil-LDH mixture, and LDH fitted Langmuir linear isotherm. The highest nitrate adsorption on Mg-Al-LDH (4:1) and a mixture of soil-Mg-Al-LDH (4:1) were 188.67 and 107.52 mg/g, respectively. Among the studied kinetic equations for nitrate adsorption on Mg-Al-LDH (4:1), the pseudo-second-order with R2=0.998 had the best fitness. Negative values of ∆H in different nitrate concentrations indicated the exothermic process of nitrate adsorption on Mg-Al-LDH (4:1). In the presence of other anions, Mg-Al-LDH (4:1) removed nitrate preferentially. Moreover, Mg-Al-LDH (4:1) could exchange nitrate 20 times in different concentrations with no reduction in its adsorption capacity.

Suitability of Borago officinalis for Minimal Processing as Fresh-Cut Produce

Borage (Borago officinalis L.) is a wild vegetable appreciated as a folk medicine and for culinary preparations. The introduction of borage as a specialized cultivation would allow for the diversification of vegetable crops and would widen the offerings of raw and minimally processed leafy vegetables. Thus, the aim of the research was to evaluate the quality and shelf-life of fresh-cut borage stored at different temperatures. Borage plants were grown during the autumn–winter season and immediately minimally processed after harvest. Fresh-cut borage leaves packed in sealed bags were stored at 2 or 6 °C for 21 d. Weight loss, total soluble solids (TSS), titratable acidity (TA), ascorbic acid, nitrates, leaf color characteristics and overall quality were determined through the storage period. Borage plants were deemed suitable for minimal processing. Storage temperature significantly influenced the rate of quality loss. Borage leaves had an initial nitrate content of 329.3 mg kg−1 FW that was not affected by temperature or storage. TSS and TA were higher in leaves stored at 6 °C. TSS, TA and ascorbic acid content increased during storage. Minimally processed borage leaves stored at 2 °C had lower weight loss and leaf color modifications during storage and a longer shelf life than those stored at 6 °C, so were still marketable after 21 d of storage.