Ascorbic Acid In Orange Juice Research Articles

Nonthermal Processing as a Tool to Enhance Fruit Juice Bioactive Compounds’ Bioaccessibility

Nonthermal processing can change and improve the composition of food. This study examines the impact of cold plasma technology—glow discharge, dielectric barrier discharge (DBD), and ultrasound (US)—on the bioaccessibility of ascorbic acid (vitamin C) and total phenolic compounds (TPCs) in orange and cashew apple juice after simulated digestion. The juices were treated by DBD plasma for 20 min at three different frequencies (50, 500, and 1000 Hz), glow discharge plasma at three synthetic air flow rates (10, 20, and 30 mL/min), and US at three potencies (183, 280 and 373 W/cm2) for 10 min. The nonthermal processing did not significantly reduce the levels of ascorbic acid in cashew apple juice. In contrast, the ascorbic acid levels either remained stable or increased by up to 80% for orange juice. The processing improved the bioaccessibility of total phenolic compounds (TPCs) in both juices, reaching 150% in cashew apple juice treated with US at 373 W/cm2. Despite the decrease in the bioaccessibility of ascorbic acid in orange juice, the nonthermal processing notably enhanced this bioactive compound’s bioaccessibility by 10% to 20% compared to the control sample, highlighting the potential of nonthermal technologies to improve the nutritional quality of foods.

Accuracy improvement via novel ratiometry design in distance-based microfluidic paper based analytical device: instrument-free point of care testing.

Developing accurate, precise, instrument-free, and point-of-need microfluidic paper-based devices is highly significant in clinical diagnosis and biomedical analysis. In the present work, a ratiometric distance-based microfluidic paper-based analytical device (R-DB-μPAD), along with a three-dimensional (3D) multifunctional connector (spacer), was designed to improve the accuracy and detection resolution analyses. Specifically, the novel R-DB-μPAD was used for the accurate and precise detection of ascorbic acid (AA) as a model analyte. In this design, two channels were fabricated as detection zones, with a 3D spacer located between the sampling and detection zones to improve the detection resolution by preventing the reagents mixing from overspreading between these zones. Two probes for AA were used: Fe3+ and 1,10-phenanthroline were deposited in the first channel, and oxidized 3,3',5,5'-tetramethylbenzidine (oxTMB) was added to the second channel. Accuracy improvement of this ratiometry-based design was achieved by enhancing the linearity range and reducing the volume dependency of the output signal. Moreover, the 3D connector improved the detection resolution by eliminating the systematic errors. Under the optimal conditions, the ratio of the distances of the color bands in the two channels was used to construct an analytical calibration curve in the range from 0.05 to 1.2 mM, with a limit of detection of 16 μM. The proposed R-DB-μPAD combined with the connector was successfully used for the detection of AA in orange juice and vitamin C tablets with satisfactory accuracy and precision. This work opens the door for multiplex analysis of various analytes in different matrices.

MnO2 nanosheet-assisted ratiometric fluorescent sensor for ascorbic acid based on Pyronin Y and thiamine

Ascorbic acid (AA) which can be supplemented by exogenous sources such as food and beverage, plays an important role in human health. Abnormal level of AA in human body usually leads to various diseases. A facile MnO2 nanosheet-assisted ratiometric fluorescent sensor for AA was constructed in this work. MnO2 nanosheet (MnO2NS) could not only greatly quench the fluorescence of Pyronin Y (PY) by inner filter effect (IFE) but also oxidize non-fluorescent thiamine (vitamin B1, VB1) to blue fluorescent thiochrome (oxVB1) by taking advantage of the oxidase-mimicking activity simultaneously. However, MnO2NS could be reduced to Mn2+ in the presence of AA, inhibiting the IFE and oxidase-mimicking activity. According to this principle, the fluorescence intensity of oxVB1 decreasing at 440 nm and the fluorescence of PY recovering at 560 nm. Under optimal conditions, the MnO2NS-PY-VB1 system showed a wide linear range towards AA in the range of 0.25–110 µM with a low detection limit reaching 0.1 µM. Furthermore, it was also applied for sensitive detection of AA in orange juice and human serum.

Visual colorimetric ‘turn-off’ biosensor for ascorbic acid detection based on hypochlorite–3,3′,5,5′,-Tetramethylbenzidine system

An ‘turn–off’ approach for the detection of ascorbic acid (AA) using 3,3′,5,5′,-tetramethylbenzidine (TMB) as a colorimetric probe is developed. The proposed method is based on the fact that hypochlorite (ClO−) could oxidize TMB to oxidized TMB (oxTMB) along with a blue color and an absorption peak centered at 652 nm. However, the introduction of AA could cause the reduction of oxTMB, which results in a blue color fading and a decrease of the absorbance at 652 nm. Based on this finding, we proposed a sensitive colorimetric assay for quantitative determination of AA by UV–vis spectroscopy. Under the optimal conditions, a good linear response between the absorbance and AA concentration was achieved within the dynamic working range from 1 to 70 μM with a detection limit of 0.58 μM. More importantly, the proposed method offered advantages of simple, low-cost instruments and rapid assay without the utilization of nanomaterials and has also been successfully applied for the determination of AA in orange juice with satisfying recoveries over 97.0%. Furthermore, the obtained results were consistent with those measured by high performance liquid chromatography with the average relative error of 3.3%.

Fluorescent sensing of ascorbic acid based on iodine induced oxidative etching and aggregation of lysozyme-templated silver nanoclusters

In this work, we developed a sensitive and highly selective fluorescent approach for the detection of ascorbic acid (AA) by taking advantage of the oxidative etching effect of iodine (I2) on the lysozyme-stabilized silver nanoclusters (dLys-AgNCs) with fluorescence quenching. I2 could be produced from the redox reaction between iodate (IO3−) and AA, and thus the fluorescence intensity of dLys-AgNCs was turned off significantly in the coexistence of IO3− and AA. The fluorescence quenching of dLys-AgNCs had a good linear relationship with AA concentration, which allowed the detection of AA in the range from 0.05 to 45.0 μmol L−1 with a detection limit of 20 nmol L−1. The quenching mechanism was elucidated by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), zeta potential, and dynamic light scattering (DLS) measurements, confirming that the fluorescence quenching of the dLys-AgNCs was attributed to the oxidative etching of the in situ generated I2, inducing aggregation of the dLys-AgNCs probe by forming Ag@AgI nanocomposite. The dLys-AgNCs probe exhibited excellent selectivity for AA sensing over several common reducing agents tested. Moreover, this approach was extended to the detection of AA in orange juice and urine with recovery rates in the range of 96.0% (RSD: 4.11) to 100.9% (RSD: 3.28) and 94.5% (RSD: 6.40) to 99.2% (RSD: 5.36), respectively.

Electrochemical detection of nitrite and ascorbic acid at glassy carbon electrodes modified with carbon nano-onions bearing electroactive moieties

In this work, we evaluate two novel surfaces for the simultaneous detection of nitrite and ascorbic acid in aqueous media. Glassy carbon electrodes were first modified with small carbon nano-onions (GCE/CNO) and further functionalized either by electrografting ortho-aminophenol (oAP) groups or by physical adsorption of thionine to give electroactive surfaces that were characterized by cyclic voltammetry. The modified surfaces exhibited a fast electrochemical response and were able to detect the presence of nitrite and ascorbic acid by amperometry. The presence of both CNOs and the electroactive moiety on the electrode surface enhanced the sensitivity and lowered the limit of detection of the determinations as compared to GCE modified only with oAP or thionine. The CNO-modified electrodes showed good reproducibility and stability with time and were applied in the detection of ascorbic acid in orange juice.

Tailoring Molecular Permeability of Nanochannel-Micelle Membranes for Electrochemical Analysis of Antioxidants in Fruit Juices without Sample Treatment.

Antioxidants are widely found or used in food, pharmaceutical, and cosmetics industries; thus, rapid and sensitive detection of antioxidants is of great interest. The present work reports a simple and fast electrochemical method for direct analysis of antioxidants in fruit juices by modulating the permeability of mesochannels on the electrode surface. This goal was achieved by growing vertical silica mesochannel array (SMA) with a channel diameter of 2-3 nm on the indium tin oxide (ITO) electrode surface using the cylindrical micelles (CMs) as the template. As-prepared electrodes, designed as CM@SMA/ITO, are only permeable to lipophilic antioxidants, e.g., retinol, with the hydrophobic hydrocarbon cores of CMs. After excluding CMs from silica mesochannels, the ITO electrode modified with bare SMA, namely SMA/ITO, possesses a high density of silanol groups on the channel wall and thus is only permeable to hydrophilic antioxidants, such as ascorbic acid (AA). Two types of sensors allowed the selective analyses of retinol and AA in buffer solutions and demonstrated a wide linear range for retinol (1-60 μM) and AA (10-2000 μM), respectively, and a low detection limit (0.65 μM for retinol and 0.52 μM for AA). Moreover, the SMA/ITO electrode can selectively determine the concentration of AA in orange juice. The CM@SMA/ITO electrode can measure the sum activity of lipophilic antioxidants, such as retinol, α-tocopherol, and others possibly coexisting, in carrot juice. In addition, the ultrasmall mesochannels and CMs could effectively exclude the access of large substances, rendering an excellent antifouling and anti-interference ability for direct analysis of antioxidants in fruit juices without sample pretreatment.

Graphene ceramic composite as a new kind of surface-renewable electrode: application to the electroanalysis of ascorbic acid

This study introduces a new surface-renewable electrode based on a sol–gel derived graphene ceramic composite. The electrode was prepared by dispersing graphene nanosheets into a solution of the sol–gel precursors containing methyl triethoxysilane in methanol and hydrochloric acid. During hydrolysis of methyl triethoxysilane, the graphene nanosheets are trapped in the gel. After moulding and drying the composite, it can be used as a surface-renewable electrode to which we refer as a graphene ceramic composite electrode (GCCE). Cyclic voltammograms of the hexacyanoferrate(II/III) model redox system at the GCCE were compared to those obtained with a conventional carbon ceramic electrode and showed a highly improved electron transfer rate at the GCCE. The electrocatalytic oxidation of ascorbic acid as a model analyte was then studied at working potential of 50 mV and over the 3–84 μM concentration range. It revealed a sensitivity of 6.06 μA μM−1 cm−2 and a detection limit of 0.82 μM. The GCCE was successfully applied to the determination of ascorbic acid in orange juice and urine samples. Advantages such as good mechanical and chemical stability, ease of fabrication, and reproducible preparation make the GCCE a potentially useful and widely applicable renewable electrode for use in routine analysis.

Self-powered biosensor for ascorbic acid with a Prussian blue electrochromic display

We report on the development of a nanocarbon based anode for sensing of ascorbic acid (AA). The oxidation of AA on this anode occurs at a quite low overpotential which enables the anode to be connected to a biocathode to form an ascorbic acid/O2 biofuel cell that functions as a self-powered biosensor. In conjunction with a Prussian blue electrochromic display the anode can also work as a truly self-powered sensor. The oxidation of ascorbic acid at the anode leads to a reduction of the Prussian blue in the display. The reduced form of Prussian blue, called Prussian white, is transparent. The rate of change from blue to colourless is dependent on the concentration of ascorbic acid. The display can easily be regenerated by connecting it to the biocathode which returns the Prussian blue to its oxidized form. In this way we have created the first self-powered electrochromic sensor that gives quantitative information about the analyte concentration. This is demonstrated by measuring the concentration of ascorbic acid in orange juice. The reported quantitative read-out electrochromic display can serve as a template for the creation of cheap, miniturizable sensors for other relevant analytes.

Construction of an Optical Sensor for the Determination of Ascorbic Acid Using Ionic Liquids as Modifier

An optode was designed for an indirect determination of ascorbic acid by using neocuproine, which has been coated on transparent triacetylcellulose film as a membrane. The proposed method is based on the oxidation of ascorbic acid to dehydroascorbic acid with the Cu(II) and neocuproine reagent. The increase in the absorbance value of the optode at the maximum wavelength of 455 nm was related to the ascorbic acid concentration in aqueous samples. The sensitivity of the method was improved by using room-temperature ionic liquid, [C(8)MIM][PF(6)]. The linear dynamic range for the determination of ascorbic acid was 7.4 × 10(-5) - 3.5 × 10(-3) mol L(-1) with a limit of detection of 2.2 × 10(-5) mol L(-1) (n = 10) and a response time range of 6.0 - 8.0 min. The optode was successfully applied for the determination of ascorbic acid in orange juice.

New Ultralow-Cost Telemetric System for a Rapid Electrochemical Detection of Vitamin C in Fresh Orange Juice

Ascorbic acid (AA), one of the principal micronutrients in horticultural crops, plays a key role in the human metabolism, and its determination in food products has a great significance. Citrus fruits are rich in AA, but its content is highly susceptible to change during postharvest processing and storage. We present a new ultralow-cost system, constituted of an amperometric microsensor composed of three rod carbon electrodes connected to a telemetric device, for online detection of AA in orange juice, as an alternative to conventional analytical methods. The in vitro calibration, ranged from 0 to 5 mM, and AA juice content was calculated by adding low volumes of sample into an acetate buffer solution at a constant potential of +120 mV vs carbon pseudoreference. This new approach, which is simple, expandable, and inexpensive, seems appropriate for large scale commercial use.

Ascorbic acid in orange juice–milk beverage treated by high intensity pulsed electric fields and its stability during storage

The degradation of ascorbic acid was determined in a ready-to-drink orange juice–milk beverage treated by high intensity pulsed electric fields (PEF). The effects of PEF treatment were compared to those of heat pasteurization (90 ºC, 20 s). Four electric field strengths (15, 25, 35, 40 kV/cm) and six treatment times for each field (from 40 µs to 700 µs) were studied. Ascorbic acid degradation was adjusted to an exponential model. The obtained ascorbic acid degradation rate constants (kE) were − 0.11·10− 3 ± 0.03·10− 3 μs− 1, − 0.23·10− 3 ± 0.07·10− 3 μs− 1, − 0.42·10− 3 ± 0.09·10− 3 μs− 1 and − 0.60·10− 3 ± 0.06·10− 3 μs− 1 for field strengths of 15, 25, 35 and 40 kV/cm, respectively. For the shelf-life study a 25 kV/cm at 280 µs treatment was applied and the beverages were stored at 4 and 10 ºC. The ascorbic acid degradation rate during storage was adjusted to zero-order kinetics showing that beverages stored at 4 ºC had better ascorbic acid retention than beverages stored at 10 °C. No significant differences were found between heat pasteurization and PEF treatments during storage. Food beverages are mainly preserved and made available to the consumer by different thermal treatments which involve a destruction of desirable food constituents such as nutrients, bioactive compounds, colour, flavour and texture. The present work demonstrates that the ascorbic acid degradation in an orange juice–milk beverage treated by pulsed electric fields was adjusted to zero-order kinetics and degradation rate during storage was adjusted to first-order kinetics. The shelf life of the orange juice–milk beverages is similar so much for the pasteurized beverages as for the treated by PEF.

Ascorbic acid degradation kinetics of sonicated orange juice during storage and comparison with thermally pasteurised juice

Abstract Ascorbic acid degradation kinetics of sonicated orange juice during storage were determined and compared to thermally pasteurised samples. Acoustic energy densities (AED) ranging from 0.30 to 0.81 W/mL and treatment times of 2–10 min were investigated. The degradation kinetics of sonicated samples followed first-order kinetics ( R 2 ≥ 0.91) during processing. During storage ascorbic acid degradation of sonicated samples followed the Weibull model ( R 2 ≥ 0.97) with β values ranging from 0.662 to 0.697. Comparatively, first-order degradation kinetics were observed during storage for thermally pasteurised ( R 2 = 0.98) and control samples ( R 2 = 0.96). Increased shelf life based on ascorbic acid retention was found for sonicated samples compared to thermally pasteurised samples. Predicted shelf life for sonicated orange juice ranged from 27 to 33 days compared to 19 days for thermally pasteurised juice during storage at 10 °C. These results indicate that sonication results in enhanced retention of ascorbic acid in orange juice during storage compared to thermal processing.

Triiodide PVC Membrane Electrode Based on a Charge‐Transfer Complex of Iodine with Ditertbutyl‐Dicyclohexyl‐18‐Crown‐6

AbstractA new triiodide ion‐selective electrode based on a charge‐transfer complex of iodine with ditertbutyl‐dicyclohexyl‐18‐crown‐6 (t‐Bu)2DC18C6 as membrane carrier was prepared. The electrode has a linear dynamic range from 6.3 × 10−3‐5 × 10−6 with a Nernstian response of 58.6 ± 1 mV decade−1 and a detection limit of 1.3 × 10−6 M. The response time of the sensor was 25 s. The membrane could be used for two months without any divergence in potentials. The electrode exhibits an anti‐Hofmeistetr selectivity sequence with a preference for triiodide at pH 2.0‐10.0. The response mechanism of the electrode was investigated by Uv‐Vis spectroscopic technique. The electrode can be used for the determination of ascorbic acid in orange juice.

Conductometric transducing in electrocatalytical sensors: Detection of ascorbic acid

Conductometric transducing is suggested for electrocatalytic chemical sensors based on conductive polymers. Lateral conductivity of the polymer layers was measured by two- and four-point techniques. The approach was applied for electroanalytical detection of ascorbic acid on the electrocatalytically active polyaniline and poly- ortho-methoxyaniline electrodes. Both polymers displayed a monotonous concentration dependence of their conductance in the analytically important sub-millimolar concentration range of ascorbic acid. The approach was tested in model solutions of ascorbic acid in buffer and applied for detection of ascorbic acid in orange juice.

Charge-Transfer Triiodide Ion-Selective Electrode Based on 7,16-Dibenzyl-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane

A new PVC membrane electrode for the triiodide ion based on a charge-transfer complex of iodine with 7,16-dibenzyl-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane as a membrane carrier was prepared. The electrode exhibits a Nernstian response for triiodide ions over a wide concentration range (1.0 x 10(-1)-1.0 x 10(-5) M) with a slope of 59.3 +/- 0.9 mV decade(-1) and a detection limit of 6.3 x 10(-6) M. It has a response time of 30 s and can be used for at least 3 months without any divergence in the potential. The potentiometric response is independent of the pH, in the pH range 1.6 - 10.0. The proposed electrode has shown very high selectivity for the triiodide ion over a wide variety of other anions. This electrode was successfully applied as an indicator electrode in the potentiometric titration of ascorbic acid and hydroquinone from pharmaceutical preparations as well as ascorbic acid in orange juice and dissolved O2 in tap water.

Quality changes in orange juice packed in materials based on polylactate

The present study demonstrates that a rigid packaging material based on polylactate (PLA) was at least as effective as conventional high density polyethylene (HDPE) and polystyrene (PS) packaging materials in protecting fresh, unpasteurised orange juice against quality changes. Fresh, unpasteurised orange juice was stored in PLA, HDPE, and PS at 4 °C for 14 days. Quality changes were evaluated by determination of colour stability, ascorbic acid (AA) degradation, and sorption of limonene by the polymers (scalping). Results showed a significantly greater loss of AA in orange juice stored in HDPE and PS compared to PLA, significantly less colour changes of orange juice stored in PLA and PS than in HDPE, and no detectable limonene scalping into PLA and PS, as opposed to a high degree of scalping into HDPE.

Ascorbic Acid Determination in Natural Orange Juice: As a Teaching Tool of Coulometry and Polarography

Procedure for determining the concentration of ascorbic acid in orange juice using electroanalytical techniques (coulometry and polarography).

Kinetic-spectrophotometric method for the determination of ascorbic acid in orange juice, parsley and potatoes.

A kinetic-spectrophotometric method using stopped-flow techniques is described for the determination of ascorbic acid based on its reaction with 2,6-dichlorophenolindophenol (DCPl). The initial rate was measured with a specially designed system, which consists of an operational amplifier, a window comparator and a scaler which counts the pulses from a 1 MHz square-signal generator in order to measure the time interval, Δt, between two pre-set levels, E1 and E2, of the electrical signal. The regression curve for the results is (Δt)–1=(0.4 ± 0.1)±(162240 ± 541)[ascorbic acid] with a correlation coefficient r=0.99988. It was found that 4 × 10–5M DCPl gives the best stability, reproducibility and linearity of the calibration graph. The optimum oxalic acid concentration is 0.2 M. Ascorbic acid can be quickly determined in samples of orange juice, parsley and potato in the range 2 × 10–5–5 × 10–4M. Recoveries of 98.0, 95.0 and 90.0% were obtained for orange juice, parsley and potato, respectively. The standard additions method gave recoveries of 101.7, 100.1 and 100.2% for orange juices, parsley and potato, respectively. The results obtained have been compared with the official method. The accuracy and reproducibility of the method are better than 2%. The concentrations of ascorbic acid in orange juices from four different areas of Greece are also presented.

A stopped-flow method for the determination of ascorbic acid in orange juice containing triose reductone.

A stopped-flow method for the determination of ascorbic acid in orange juice containing triose reductone.