Lower Ascorbic Acid Content Research Articles

Effect of exogenous fludioxonil postharvest treatment on physiological response, physico-chemical, textural, phytochemical and sensory characteristics of pomegranate fruit

The study investigated the effects of fludioxonil (FLU) on the postharvest quality of pomegranate fruit (cv. Wonderful). Fruits were dipped in FLU concentrations (control, 150, 300 and 600 mg/L) and stored for 4 months at 5 °C and 90–95% relative humidity (RH) plus an additional 4 days at 20 °C and 65% RH. Effects of FLU were evaluated on physiological responses, quality and sensory attributes. Results showed that fruit weight loss and decay incidence were reduced by FLU treatment, with fruit treated with 600 mg/L concentration showing the best results. Fruit respiration rate was more influenced by storage duration than FLU concentration. The severity and occurrence of physiological disorders increased with storage duration but were more pronounced in fruits treated with FLU. Storage duration influenced fruit colour whereas aril colour was affected by FLU concentration. Untreated fruit showed better aril redness and chroma although treated fruit also had acceptable red colour. Chemical quality attributes of fruit juice were not significantly affected by FLU concentrations. Fruit treated with FLU had significantly (p < 0.05) higher total phenolic content during storage although lower ascorbic acid content was observed compared to untreated fruit. Treating fruit with FLU resulted in better sensory attributes with regards to crispness, juiciness and sweetness. Overall, this study showed that fruit treated with FLU at 600 mg/L had the best quality with respect to decay incidence, weight loss, total phenolics and sensory attributes.

Assessment of quality characteristics of new Vitis vinifera L. cultivars for temperate climate vineyards

ABSTRACTSince quality requirements for table grapes are mainly related to their physico-chemical and mechanical features, the aim of this work was to provide useful data for grape producers and consumers concerning the quality characteristics of table grapes of five new Vitis vinifera L. cultivars created in Romania and tending to spread within the temperate climate vineyards. During grape maturation, sugar content increased in a lesser extent than the reducing of total acidity, a balanced taste of grapes was given by the decrease in total acidity rather than sugar accumulation. Grapes of analysed cultivars showed lower concentrations of ascorbic acid and a higher content of organic nitrogenous compound. Berries with higher weight and volume (Transilvania cv.) incurred a higher mechanical deformation, while long berries (Gelu cv.) showed higher resistance to detachment from the pedicel, indicating higher resistance of grapes to packing, transport and storage. Antioxidant activity of mature grapes was high, but involvement of nonflavonoids in increasing the antioxidant capacity was statistically non-significant. Seeded table grapes of new Vitis vinifera L. cultivars showed superior physico-chemical and mechanical characteristics, indicating their high quality in the conditions of temperate continental climate, and promoting the studied cultivars as important grapevine germplasm resources.

Facile hierarchical assembly of gold particle decorated conductive polymer nanofibers for electrochemical sensing

In this study, we successfully applied vapor-phase polymerization towards the synthesis of PEDOT nanofibers which were subsequently functionalized with gold particles and used as electrodes for electrochemical sensing. Two methods were used to synthesize the PEDOT nanofibers including (1) electrospinning followed by vapor-phase polymerization (EVP), and (2) one-step vapor-phase polymerization (OSVP). The average diameter of EVP fibers was approximately 350 nm, and OSVP was approximately 200 nm. Gold particles (∼500 nm) were synthesized by an oxidation-reduction reaction between gold precursors and residue EDOT monomers on the surface of the PEDOT nanofibers. In order to investigate the electrochemical performance of these electrodes, ascorbic acid was chosen as an analyte model. Our results indicated that PEDOT nanofiber electrodes showed an enhanced response with respect to bare gold electrodes. Furthermore, the OSVP PEDOT nanofibers with gold particles demonstrated the highest sensitivity at low ascorbic acid concentrations. These hierarchically assembled, gold particle-decorated, conductive polymer nanofibers were further fabricated into flexible electrodes, demonstrating a potential in advanced applications such as wearable electronics.

The effect of ascorbic acid on bone cancer cells in vitro

Ascorbic acid (Vitamin C) has long been known for its anti-cancer properties and in the present study the effects of ascorbic acid (AsA) on osteogenic differentiation, apoptosis, and signaling pathways of the human G29 osteosarcoma cell line were studied. The expression of Runt-related transcription factor-2 (RUNX2) and osteocalcin genes were evaluated by real-time polymerase chain reaction (PCR). Osteoblastic maturation was assessed with alkaline phosphatase activity and mineralization with alizarin red deposition, and apoptosis with a caspase-2 apoptotic assay as well as the cell viability via the cytotoxicity assay. The possible role of the MAP kinase pathway (p44/42, p38, and p-JNK signaling pathway) was also studied. Our results showed that RUNX2 and osteocalcin gene expression, mineralization, cell viability, and metabolic activity levels were increased in cells treated with low concentrations of AsA with respect to untreated cells. At higher concentrations, AsA resulted in decreases in these parameters and induced apoptosis of the G292 osteosarcoma cells via downregulation of the MAPK pathway. The findings presented here support the ability of AsA to modulate the viability and differentiation of the G292 type of bone cancer cell with increases or decreases depending on the AsA concentration suggesting a need for further evaluation of the possible use of this vitamin in the regulation of bone cell cancer growth.

Composition of Commercial Strawberry Cultivars and Advanced Selections as Affected by Season, Harvest, and Postharvest Storage

Strawberries are one of the most important food crops grown in Florida, with a harvested area of ≈10,000 acres. The University of Florida strawberry breeding program develops cultivars adapted to this region and its particular weather conditions, with a major aim of increasing overall quality. The objective of this study was to compare the fruit of advanced breeding selections to those of commercial cultivars, for compositional attributes. Seven different strawberry genotypes were compared at harvest and after 7 days at 4 °C across multiple harvest dates during two consecutive years. Compositional attributes were highly influenced by year, harvest date within a year, genotype, and storage. Overall, compared with other genotypes, selection FL 09-127 exhibited consistently higher soluble solids and total sugar (TS) contents at harvest and after cold storage. Higher ascorbic acid (AA) and phenolic contents at harvest were observed in selection FL 07-193. However, its anthocyanin content was among the lowest. In contrast, FL 10-47 exhibited relatively low AA content at harvest but consistently high total anthocyanins (TACs) and total phenolic (TP) contents after storage. Overall, results from this study provide valuable information to the breeding process by identifying new genotypes with improved compositional attributes combined with suitable quality characteristics after cold storage.

EFFECTS OF ASCORBIC ACID AND FERUM IONS CONCENTRATION ON THE HYDROLYSIS OF GLUCOSINOLATE AND MYROSINASE ACTIVITY IN THE WATERCRESS (Nasturtium officinale sp.)

Watercress (Nasturtium officinale sp.) from the Brassicae family contains phenethyl glucosinolates (gluconasturtiin) as the main glucosinolate (GLS). The enzymatic hydrolysis products by naturally-occuring myrosinase produced phenethyl isothicyanate (PEITC) which reported to possess anti-carcinogenic activity. Depending on several factors, its counterpart, phenethyl nitrile (PEN) can also be formed as hydrolysis product. This study investigated the effects of adding ascorbic acid and Fe2+ ions at different concentration on the hydrolysis of gluconasturtiin. Hydrolysis products were extracted using dichloromethane and analyzed semi-quantitatively by using GCMS. The results showed that PEITC increased at the low concentration of ascorbic acid (up to 0.06M). Similarly, addition of up to 0.06M Fe2+ ions increased PEITC; higher than 0.06M inhibits the formation of PEITC. Interestingly, similar trend for the production of PEN was detected. This study also investigated myrosinase activity both by exogenous and endogenous methods at different concentrations of ascorbic acid and Fe2+ ions using standard sinigrin as subsrat. Overall, the myrosinase activity was more active at the low concentrations of ascorbic acid. Also, the exogenous method is more efficient than endogenous. This study proved that the presence of reducing agents such as ascorbic acid and Fe2+ ions during the preparation of watercress as food would affect the production of the health-promoting PEITC.

Exposure to ozone reduces postharvest quality loss in red and green chilli peppers

The effect of continuous exposure to ozone at 0.45, 0.9 and 2μmolmol−1 on quality changes during the storage of red and green chilli peppers at 10°C was investigated. Ozone at 0.45 and 0.9μmolmol−1 reduced disease incidence in red peppers, with no further benefits at 2μmolmol−1. Ozone at 0.9μmolmol−1 reduced weight loss during storage and improved firmness maintenance. Skin colour was bleached in red peppers exposed to ozone at 2μmolmol−1, and in green ones at all tested doses. Total phenolic content was not affected by ozone but antioxidant activity was reduced in green chilli peppers exposed to ozone at 2μmolmol−1, due to lower ascorbic acid content in those samples. Ozone at 0.9μmolmol−1 extended the shelf-life of chilli peppers.

A comparative assessment of long-term storage stability and quality attributes of orange juice in response to pulsed electric fields and heat treatments

Processing of orange juice by pulsed electric fields (PEF) and heat treatments was carried out to determine the quality variables during storage of 180 days at 4°C. Depending on the magnitude of applied electric field strength (13.82–25.26kVcm−1), energy (10.89–51.32J), in comparison with heat treatment (90°C for 10 and 20s); significant changes in pH, titration acidity, total dry matter, and browning index were found during the storage period. With no significant change in shelf-life period, the PEF processing better preserved orange juice quality than did the heat processing. Ascorbic acid content peaked with PEF-treated orange juice under the electric field strength of 17kVcm−1, the treatment time of 1034μs, and the energy of 17.37J through which no significant degradation occurred during the storage with the longest half-life (1112 days). Although ascorbic acid retention of the most of the PEF processed samples was higher than that of the heat processed ones; samples processed by 10.89, 12.70 and 29.57J energies resulted in lower ascorbic acid content than did the heat processing (90°C for 20s). Except for the samples treated by 43.99 and 51.32J energies on 180th day, the PEF processing led to no hydroxyl methyl furfural formation during and at the end of the storage, unlike the heat treatment.

Comparisons and correlations of phenolic profiles and anti-oxidant activities of seventeen varieties of pineapple.

Major phenolic, β-carotene, and ascorbic acid (AA) contents in 17 pineapple varieties were quantified and compared. Anti-oxidant activities were evaluated using 2,2-Diphenyl-l-picrylhydrazyl (DPPH), 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), ferric reducing anti-oxidant power (FRAP), and metal chelating capacity (MCC) assays. MD-2 exhibited the highest AA and total phenolic (TP) contents and DPPH and ABTS assay results, but was lower in β-carotene contents. Ripley had the highest total flavonoid (TF) content with a low AA content. Comte de Pairs exhibited the highest MCC and the lowest FRAP values. TP contents and both DPPH and ABTS activities, FRAP values and both AA contents and DPPH activities, and TF contents and ABTS activities were positively correlated. MD-2 exhibited the greatest diversity of phenolics and highest anti-oxidant activities in all assays. Information included herein can be useful for development of pineapple-based food products containing high levels of health promoting anti-oxidants.

Ascorbate Oxidase Minimizes Interference by High-Concentration Ascorbic Acid in Total Cholesterol Assays

Dear Editor, Ascorbic acid interferes with certain clinical chemistry assays based on peroxidase and redox indicators [1]. Ascorbic acid is reported to interfere with the measurement of glucose, total cholesterol, triglycerides, and uric acid [2,3,4,5]. We recently encountered several cases of interference from ascorbic acid in serum total cholesterol assays based on colorimetric enzymatic reactions. A 48-yr-old-female with recurrent ovarian cancer underwent palliative segmental resection surgery of the small intestine. The patient showed progressive renal impairment following surgery, and total cholesterol level was <3 mg/dL, as measured using the OSR6516 total cholesterol assay (Beckman Coulter, Brea, CA, USA) on an AU5800 analyzer (Beckman Coulter). We repeated the test with the same sample, using the Pureauto S CHO-N total cholesterol assay (Sekisui Medical Co., Tokyo, Japan) on a Hitachi7600 analyzer (Hitachi Co., Tokyo, Japan) and observed a concentration of 121 mg/dL. We did not repeat the OSR6516 assay after a certain period. The specimen was checked for lipemic, hemolytic, and icteric indices to rule out other possible interferents. The patient was administered 30 g of ascorbic acid intravenously daily for 22 days prior to total cholesterol measurements. Dipstick analysis of the patient's urine was performed by using an URiSCAN SUPER analyzer (YD Diagnostics, Seoul, Korea), which showed a value of 2+ (equivalent to 25 mg/dL) for ascorbic acid. Three additional cases characterized by spuriously low total cholesterol values owing to ascorbic acid interference are summarized in Table 1. Although we could not determine serum ascorbic acid levels, we detected its presence by using a urine dipstick assay in three of the four cases. Table 1 Summary of the four cases with inappropriately low total cholesterol level Several studies recommend the addition of ascorbate oxidase to minimize ascorbic acid interference in assays to assess uric acid, triglyceride, oxalate, and cholesterol [5,6,7,8]. Most cholesterol assays in clinical laboratories use an enzymatic colorimetric method with the Trinder end-point reaction, in which hydrogen peroxide reacts with a chromogen via peroxidase to form a colored product; absorbance of this product is proportional to the concentration of total cholesterol in the sample [1]. Ascorbic acid interferes with peroxidase-based oxidation of the chromogen [6]. Since dehydroascorbic acid is already oxidized and has lost its reducing power, interference via ascorbic acid can be successfully prevented. Commercially available total cholesterol assays are summarized in Table 2. Ascorbate oxidase included in the Sekisui total cholesterol assay effectively converts serum ascorbic acid (up to concentrations of 50 mg/dL) to dehydroascorbic acid. Table 2 Summary of commercially available total cholesterol assays with respect to the presence of ascorbate oxidase Since ascorbic acid rapidly auto-oxidizes over time, it is difficult to detect its interference in cholesterol measurements [3,9]. Reviewing medical records can also be problematic; some ascorbic acid supplements are not physician-prescribed but are readily available over-the-counter. Furthermore, it is difficult to predict serum ascorbic acid concentrations based on ingested doses of ascorbic acid in patients with impaired renal function. Artiss et al. [9] suggested that we can exclude ascorbate oxidase in wet-chemistry reagent systems for cholesterol determination because solvated ascorbic acid is subject to air oxidation. Thus, the interfering substance is oxidized prior to analysis by laboratory instruments. This is partly true for most samples from patients whose renal function is intact and for those consuming typical ascorbic acid doses. It might be particularly problematic for patients with impaired renal function or for those taking high ascorbic acid doses. In the second case (Table 1), we presumed that this low cholesterol level was likely due to ascorbic acid accumulation in the blood owing to impaired renal function, even though the prescribed dose of ascorbic acid was not high. As all of our cases showed extremely low total cholesterol levels, the laboratory technician easily noticed analytical errors and tried to troubleshoot them before reporting the results. These problems occurred in approximately one case bimonthly and were reported to managers and documented. However, interference from low concentrations of ascorbic acid causes a small negative bias in total cholesterol levels, which may go unnoticed. Ascorbic acid is one of the most widely consumed nutritional supplements, and some physicians prescribe megadoses for cancer therapy [10]. Consequently, managers of clinical laboratories should consider the use of cholesterol assays that include ascorbate oxidase. In conclusion, when colorimetric enzymatic assays detect inappropriately low levels of total cholesterol, we should suspect ascorbic acid interference. Addition of ascorbate oxidase to cholesterol reagents can minimize the inference of ascorbic acid in total cholesterol assays.

SYNERGIC CARCINOSTATIC EFFECTS OF ASCORBIC ACID AND HYPERTHERMIA ON EHRLICH ASCITES TUMOR CELL

In this study, we evaluated the carcinostatic effects of combined ascorbic acid (AsA) and a capacitive-resistive electric transfer (CRet) hyperthermic apparatus-induced hyperthermic treatment on Ehrlich ascites tumor (EAT) cells. EAT cells were exposed to various AsA (0-10 mM) concentrations for 1 h; they subsequently underwent CRet treatment for 15 min at 42 °C. Cell viability was assessed by the WST-8 assay 24 h after the combined treatment. Reactive oxygen species involvement was evaluated using catalase and tempol; caspase-3/7 activation was determined by their fluorescent substrates; cell proliferation were estimated by time-lapse observation. The effect on the cell cycle was analyzed by flow cytometry. Combined AsA and CRet treatment synergistically suppressed cell viability compared with either treatment alone, and these synergistically carcinostatic effects were evident even at noncytotoxic concentrations of AsA alone (≤ 2 mM). The carcinostatic effects of combined AsA and CRet treatment were attenuated in a dose-dependent manner by catalase addition, but not by the superoxide anion radical scavenger tempol. Time-lapse observation revealed that combined AsA and CRet treatment activated caspase-3/7 at 10-24 h after treatment, accompanied by significant cell growth suppression. Cell cycle analysis revealed that the rate of sub-G1-phase (apoptotic) cells was drastically increased at 12 h and 24 h, and that the G2/M-phase cells gradually increased at 6-24 h after treatment. These results indicate that combined AsA and CRet treatment synergistically inhibits EAT cell growth through G2/M arrest and apoptosis induction via H2O2 generation at lower AsA concentrations; this carcinostatic effect cannot be exerted by AsA alone.

U937 cell apoptosis induced by arsenite is prevented by low concentrations of mitochondrial ascorbic acid with hardly any effect mediated by the cytosolic fraction of the vitamin.

Arsenite directly triggers cytochrome c and Smac/DIABLO release in mitochondria isolated from U937 cells. These effects were not observed in mitochondria pre-exposed for 15 min to 10 µM L-ascorbic acid (AA). In other experiments, intact cells treated for 24-72 h with arsenite were found to die by apoptosis through a mechanism involving mitochondrial permeability transition. Pre-exposure (15 min) to low micromolar concentrations of AA and dehydroascorbic acid (DHA), resulting in identical cytosolic levels of the vitamin, had a diverse impact on cell survival, as cytoprotection was only observed after treatment with AA. Also the mitochondrial accumulation of the vitamin was restricted to AA exposure. An additional indication linking cytoprotection to the mitochondrial fraction of the vitamin was obtained in experiments measuring susceptibility to arsenite in parallel with loss of mitochondrial and cytosolic AA at different times after vitamin exposure. Finally, we took advantage of our recent findings that DHA potently inhibits AA transport to demonstrate that DHA abolishes all the protective effects of AA, under the same conditions in which the mitochondrial accumulation of the vitamin is prevented without affecting the overall cellular accumulation of the vitamin.

Facile Precipitation Method for Morphological Tuning of Cu2O Crystals

We have developed a simple method for tuning the morphologies of <TEX>$Cu_2O$</TEX> microcrystals. <TEX>$Cu_2O$</TEX> microcrystals were prepared by precipitation at room temperature from a mixture of <TEX>$Cu(CH_3COO)_2{\cdot}H_2O$</TEX>, N,N,N',N'-tetramethyl ethylenediamine (TMEDA), ascorbic acid, and polyethylene glycol (PEG). TMEDA was used to promote the formation of copper-TMEDA complexes. A variety of <TEX>$Cu_2O$</TEX> microcrystal morphologies were obtained simply by varying the concentrations of TMEDA and ascorbic acid. Aggregated <TEX>$Cu_2O$</TEX> microspheres are formed at higher concentrations of ascorbic acid in the absence of TMEDA. Aggregated <TEX>$Cu_2O$</TEX> microcubes are formed at lower concentrations of ascorbic acid and higher concentrations of TMEDA. The crystal growth mechanism of these <TEX>$Cu_2O$</TEX> morphologies is explained.

The stress factor, exogenous ascorbic acid, affects plant growth and the antioxidant system in Arabidopsis thaliana

Ascorbic acid (AsA) is one of the most important soluble antioxidant molecules in plants, but excess AsA is a type of stress factor that inhibits plant growth. The exposure of Arabidopsis thaliana seedlings to 2 and 8 mM AsA decreased fresh weight to 78.6 and 64.3% of the control, respectively, after 5 days of treatment. A more than fivefold increase in the MDA content following the exposure to AsA suggests that the plant cellular structure is severely damaged by an increase in the ROS content. We also found that the transcripts of several antioxidant genes were down-regulated, which resulted in decreased activities of several antioxidant enzymes. These events caused an imbalance between oxidants and the antioxidant system. Real-time PCR demonstrated that the exogenous AsA reduced the transcript abundance of several aquaporins, whereas 2 mM exogenous AsA increased the transcripts of four aquaporins after 5 days of exposure. A high concentration of AsA significantly down-regulated aquaporins compared to a low concentration of AsA, especially PIP 2;1 and PIP 2;2, which were only 6 and 10% of the control, respectively. These results demonstrated that exogenous AsA was a stress factor that caused ROS overproduction, inhibited antioxidant ability, regulated aquaporin gene expression, and inhibited plant growth.

Synthesis of convex hexoctahedral palladium@gold core-shell nanocrystals with {431} high-index facets with remarkable electrochemiluminescence activities.

Convex hexoctahedral nanocrystals have been synthesized through fast growth kinetics and the use of cetylpyridinium chloride as a capping agent. Monodisperse convex hexoctahedral Pd@Au core-shell nanocrystals with {431} high-index facets are obtained at high reaction rates by using high concentrations of ascorbic acid in the presence of cetylpyridinium chloride. In contrast, octahedral nanocrystals with {111} low-index facets and their {100}-truncated counterparts are formed at low ascorbic acid concentrations. The substitute of cetylpyridinium chloride with cetyltrimethylammonium chloride leads to the generation of concave trisoctahedral Pd@Au core-shell nanocrystals with {331} high-index facets, indicating that cetylpyridinium plays an important role in the formation of convex hexoctahedral nanocrystals. The as-prepared convex hexoctahedral Pd@Au core-shell nanocrystals exhibit remarkable catalytic performances toward electrochemiluminescence compared with truncated octahedral and concave trisoctahedral Pd@Au core-shell nanocrystals.

A novel biological role of dehydroascorbic acid: Inhibition of Na+-dependent transport of ascorbic acid

A U937 cell clone, in which low micromolar concentrations of ascorbic acid (AA) and dehydroascorbic acid (DHA) are taken up at identical rates, was used to investigate possible interactions between transport systems mediating cellular uptake of the two forms of the vitamin. Results obtained with different experimental approaches showed that DHA potently and reversibly inhibits AA uptake through Na+-AA cotransporters. Hence, a progressive increase in extracellular DHA concentrations in the presence of a fixed amount of AA caused an initial decrease in the net amount of vitamin C accumulated, and eventually, at higher levels, it caused an accumulation of the vitamin solely based on DHA uptake through hexose transporters. DHA-dependent inhibition of AA uptake was also detected in various other cell types. Taken together, our results provide evidence of a novel biological effect mediated by concentrations of DHA compatible with those produced at inflammatory sites.

Diameter-controlled synthesis of polyaniline microtubes and their electrocatalytic oxidation of ascorbic acid.

An easy and convenient method for the synthesis of polyaniline (PANI) microtubes was developed using polystyrene (PS) electrospun microfibers as a template. The diameter range of these microtubes was from 0.63 to 2.93 μm. This accuracy was achieved by tuning the template microfiber's diameter. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to study the effect of these microtubes' diameters on their electroactivity. When the diameter is 1.43 μm, the PANI microtube exhibited the maximum electroactivity and a distinguished electrocatalytic oxidation of ascorbic acid (AA). Herein, the PANI microtube was fabricated into an amperometric AA sensor. At the working potential of 0.4 V (vs. SCE), the oxidation current was significantly enhanced by the addition of a low concentration of AA but no such current was observed with other selected small molecules. The AA detection limit was 0.28 μM at the signal-to-noise ratio of 3. A linear relationship was demonstrated between the oxidation current enhancement and the AA concentration ranging from 5.0 μM to 4.7 mM. The detection limit was better than a reported PANI nanotube (1.0 μM), nanofiber (1.7 μM) and nanoparticle (8.3 μM). The high sensitivity could be attributed to the PANI microtube's high conductivity, high electroactivity for the AA electrocatalytic oxidation, as well as its high surface-to-volume ratio resulting in an efficient interaction between the microtube and the AA molecule. A promising application of the PANI microtube-based sensor was offered.

Oxidative stress and antioxidant indices of the marine red alga Porphyra vietnamensis

Abstract -Oxidative stress and antioxidant defence systems were assessed in a marine red alga Porphyra vietnamensis Tanaka et Pham-Hoang Ho, from India. Lipid peroxidation (LPX) and hydrogen peroxide (H2O2) were measured as oxidative stress markers. Antioxidant defences were measured as catalase (CAT), glutathione S-transferase (GST) and ascorbic acid (AsA), in order to understand their dissimilarity with respect to environmental conditions (pollution levels) from selective locations along the central west coast of India. Levels of LPX, H2O2, CAT and GST were significantly higher in samples collected from Dona Paula than in samples from Malvan and Kunkeshwar, while a lower concentration of AsA was found in samples from Dona Paula. Heavy metals such as Cd, Pb and Hg in higher concentrations in these areas than in other sites were also observed. Variation of oxidative stress indices in response to the accumulation of heavy metals within P. vietnamensis could be used as molecular biomarkers for the assessment and monitoring of environmental quality in ecologically sensitive marine habitats.

Comparison postharvest quality of conventionally and organically grown ‘Washington Navel’ oranges

This study aimed to compare postharvest quality of conventionally and organically grown ‘Washington Navel’ oranges. Oranges from the conventional and certified organic citrus orchards were harvested at commercial maturity and kept at 4°C for 5 months. Changes in weight loss, juice percentage, titratable acidity (TA), total soluble solid (TSS), sugars (fructose, glucose and sucrose), organic acids (citric, malic and ascorbic acid) content and incidence of fungal decay and chilling injury were determined at a month interval during storage. Conventionally grown oranges had lower weight loss and higher juice percentage than organically grown oranges during storage. Rind color (L*, C*, ho), TSS, sugar (fructose, glucose and sucrose) and malic acid content were not affected by the production systems at harvest and during storage. In both conventionally and organically grown oranges, rind color become darker (lower L*), more intense (higher C*) and deeper orange color (lower ho) while malic acid content remained constant during 5 months of storage. As storage time extended, a significant increase in TSS and sugar content and a decrease TA and citric acid content occurred in fruits from both production system. Compared to conventionally grown oranges, organically grown oranges had lower TA and citric acid, but better taste scores since they attained higher TSS/TA ratio at harvest and during storage. The taste of conventionally and organically grown oranges was rated as an acceptable throughout the storage period. Although there was no significant difference in ascorbic acid content of fruits between two production systems at harvest, lower ascorbic acid content was found in organically grown oranges, compared to conventionally grown oranges during storage. Incidence of fungal decay was low in conventionally and organically grown oranges after 5 months of storage and the production system did not affect the sensitivity to fungal decay. Chilling injury was not observed any of fruits from both production systems throughout storage period.

A self-seeding synthesis of Ag microrods of tuned aspect ratio: ascorbic acid plays a key role

Control of the shape and size of nanoparticles is crucial for using them as labels or as building blocks in nanotechnology. In fact, silver has so far been considered as having the widest variety of different morphologies at the nano-scale and micro-scale levels. To make progress in these criteria, in our paper we have synthesized highly reproducible silver (Ag) microrods of controlled aspect ratios through a rapid self-seeding method. The Ag nano seeds are formed via the reduction of Ag ions in hot ethylene glycol by ascorbic acid, and the subsequent growth of microrods is controlled by further deposition of Ag atoms in the presence of poly(vinylpyrrolidone). Moreover, ascorbic acid is exclusively responsible for the rod morphology, as we describe here in detail. A very low concentration of ascorbic acid forms very few Ag microrods along with a majority of Ag colloidal particles, while random overgrowth on the surfaces is observed for higher concentrations. The critical reaction condition has been found in that the aspect ratio of the Ag microrods can be systematically tuned between 4 and 90. Also, the method in which ascorbic acid is added to the reaction medium plays a key role in controlling the aspect ratio of the Ag microrods. The non-monotonic dependence of the length and the diameter of the Ag microrods has been described by an empirical equation. The function can be interpreted by means of concentration-dependent competition between the adsorption of ligands and metal deposition.