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.

Application of a Gallic Acid–Based Oxygen Scavenger Label for the Preservation of L‐Ascorbic Acid in Orange Juice

ABSTRACTCitrus juices are rich sources of antioxidants, including vitamin C, but are prone to oxidation during storage. We investigated the application of gallic acid (GA), an environmentally friendly reducing agent, as active packaging to mitigate this issue. Orange juice was packaged in airtight glass containers both with and without GA‐based oxygen scavenger (GA‐OS) label and stored at 20°C and 4°C. During the storage, we monitored oxygen levels in the headspace and dissolved oxygen concentration in the orange juice, vitamin C content and browning. In the presence of GA‐OS, oxygen levels in the headspace were reduced by half in under 1 h at 21°C and within 2 h at 4°C. Dissolved oxygen concentration decreased 50% after 8 h at 21°C and after 1.2 days at 4°C. In the absence of GA‐OS, vitamin C degraded completely within 30 days at 21°C and 45 days at 4°C. In contrast, GA‐OS nearly fully preserved vitamin C for 105 days at both temperatures. Browning, quantified by delta E, escalated in GA‐OS‐absent samples to 16.79 ± 0.16 at 21°C to 12.19 ± 0.10 at 4°C, whereas GA‐OS samples exhibited no significant browning. Our results underscore GA‐OS's efficacy in preserving the quality of liquid foodstuffs, exemplified by orange juice, suggesting its broad range applicability as active packaging.

Simultaneous analysis of benzoic and sorbic acids in orange juice using thymol/ water natural deep eutectic solvent and DLLME method followed by high performance liquid chromatography

Simultaneous analysis of benzoic and sorbic acids in orange juice using thymol/ water natural deep eutectic solvent and DLLME method followed by high performance liquid chromatography

Glycidol‐modified polyethylenimine‐capped carbon dots with ultrastable fluorescence for sensitive and selective detection of folic acid in food samples

AbstractGlycidol‐modified polyethylenimine (PEI‐OH)‐capped carbon dots (PEI‐OH‐CDs) were prepared and applied for selectively and sensitively detecting folic acid in food samples. PEI‐OH‐CDs were firstly synthesized by a one‐pot hydrothermal method using PEI‐OH and citric acid as precursors, and the transmission electron microscopy characterization reveals that the PEI‐OH‐CDs were of spherical shape with diameters of 2–3 nm and well dispersed in solution. The PEI‐OH‐CDs have high fluorescence and exhibit ultrastrong stability against pH, ion strength, and UV light irradiation. In a wide pH range higher than pH 6, the fluorescence of PEI‐OH‐CDs can be effectively quenched by folic acid through static quenching process and inner filter effect but is not affected by many typical chemicals including cations, anions, amino acids, and vitamins. A good linear relationship was found between the F0/F and the concentration of folic acid in the range from 0.1 to 100 μM, and the detection limit of folic acid is 0.07 μM. The PEI‐OH‐CDs were successfully applied for sensitive determination of folic acid in orange juice, fresh pear, grape spinach, and celery samples at pH 7.2, which is helpful to the stability of folic acid and provides a new strategy for accuracy detection of folic acid in food samples.

Preparation of molecularly imprinted PDMS elastomer for selective detection of folic acid in orange juice

Herein, it is reported an effective method to prepare novel molecularly imprinted polymers (MIP) on poly(dimethylsiloxane) (PDMS) elastomer via a combination of non-covalent imprinting approach and surface initiated reversible addition fragmentation chain transfer (SI-RAFT) polymerization for sensitive and selective detection of folic acid (FA). For this purpose, 2-(2-Methoxyethoxy) ethyl methacrylate (MEOMA), ethylene glycol dimethacrylate (EGDMA), azobisisobutyronitrile (AIBN), FA and dimethylsulfoxide (DMSO) were used as functional monomer, cross-linker, initiator, template molecule, and porogen, respectively. The adsorption behavior followed the Scatchard equation between FA and PDMS-MIP with a saturation adsorption capacity of 4.51 mg/g and pseudo-second-order kinetics with 60 min equilibrium adsorption time. Furthermore, PDMS-MIP elastomer was successfully applied for selective extraction and detection of FA from orange juice with sufficient recovery (95.5–100.5%) and relative standard deviation less than 7.0%. The limit of detection (LOD) for FA was found to be 0.0031 µg/mL with a linear range between 0.01 and 100 µg/mL and a correlation coefficient of 0.9997. Results showed the proposed method could easily, efficiently and selectively extracted FA from complex media. Note that this novel proposed method will open a new way to detect any selected molecules such as pesticide, protein, drug, etc. using molecularly imprinted PDMS elastomer materials.

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.

Providing a traceable assigned value in a proficiency testing programme on the determination of benzoic acid in orange juice

A proficiency testing (PT) programme on the determination of benzoic acid in orange juice was organised by the Chemical Metrology Laboratory, Health Sciences Authority, Singapore, for the local food testing laboratories. The PT programme used a metrologically traceable assigned value determined by isotope dilution mass spectrometry to assess the performance of the participating laboratories. This paper discusses the reasons and approach to applying metrological principles to determine the assigned value of a PT programme. The procedure undertaken by the Laboratory to prepare a batch of PT sample, conduct homogeneity and stability testings, as well as value assignment, is presented. The discussions also include the estimation of the measurement uncertainties arising from the characterisation, testing for homogeneity and testing for stability of the PT sample. The Coordinator of the PT programme used the assigned value and its associated measurement uncertainty, together with those of the participating laboratories to assess their performances. Statistical tools applied in the performance evaluations are also presented.

Nuclear magnetic resonance using electronic referencing: method validation and evaluation of the measurement uncertainties for the quantification of benzoic acid in orange juice.

Quantitative nuclear magnetic resonance measurements have become more popular over the last decade. The introduction of new methods and experimental parameters has been of fundamental importance in the development of new applications. Amongst these new developments is the introduction of electronic referencing for quantifications. The use of electronic referencing eliminates errors in the analyses as a result of weighting of internal standards as well as undesired problems as a result of the solubility of the standards in the analyte solution and chemical interactions between the analyte and the internal standard. In this work, we have studied the quantification of a very important analyte in a food matrix, benzoic acid in orange juice, as a model to the validation and measurement uncertainty estimation of electronic referencing using (1)H NMR in food analyses. The referencing method applied was the pulse length-based concentration measurement. Method was validated and showed good results for the precision and accuracy parameters evaluated. A certified reference material and a reference material candidate were analyzed, and extremely good results were obtained. Reported relative expanded uncertainties are in the 1.07-1.39% range that can be considered an extremely good performance for the analysis of a food complex matrix. Measurement uncertainty was evaluated by two different approaches, and the pulse calibrations for the samples and for the reference have been shown to account for approximately 80% of the total uncertainty of the measurement.

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.

Interactions and Thresholds of Limonin and Nomilin in Bitterness Perception in Orange Juice and Other Matrices

AbstractLimonin and nomilin are two bitter compounds present in citrus and are thought to cause off‐flavor in Huanglongbing (HLB)‐infected fruit/juice. This study determined the best estimate thresholds of limonin, nomilin and their combination in matrices composed of sugars and acids at levels found in orange juice, and in orange juice, using the three‐alternate forced‐choice methodology. Further, the effect of sucrose or citric acid in orange juice on the bitterness perception of both compounds was investigated. In a simple matrix (sucrose and citric acid), the threshold of limonin was 4.0 mg/L, lower than the threshold of nomilin, which was 5.4 mg/L. Together in a 1:1 ratio, limonin and nomilin acted synergistically and both thresholds decreased. When adding nomilin at a fixed subthreshold concentration of 2 mg/L, limonin threshold decreased to 2.6 mg/L. Recognition thresholds in orange juice were 4.7 and 2.6 mg/L for limonin and nomilin, respectively. Added sucrose, but not citric acid, decreased the perception of bitterness induced by limonin and nomilin in orange juice.Practical ApplicationsFlorida orange juice processors are encountering increased juice bitterness resulting from elevated levels of the bitter compounds limonin and nomilin due to citrus greening or Huanglongbing disease (HLB). Increased knowledge of sensory perception of limonin and nomilin in orange juice will help processors determine the final quality of juice made with fruit from groves infected with HLB. In a model solution, nomilin decreased the perception threshold of limonin. In orange juice, recognition thresholds were 4.7 and 2.6 mg/L for limonin and nomilin, respectively, suggesting that orange juice containing such levels of these two compounds would taste bitter. As sucrose decreased bitterness perception of juice spiked with limonin and nomilin, blending with juice having higher sugar levels could be used for bitter off‐flavor management for juice made with fruit strongly affected by the disease.

International comparison APMP.QM-P23：determination of benzoic acid in orange juice

A method was developed for the separation and determination of benzoic acid in orange juice by high performance liquid chromatography-ultraviolet detection (HPLC-UV) and liquid chromatography-isotope dilution mass spectrometry (LC-IDMS). National Institute of Metrology (NIM) of China participated the international comparison activity organized by Asia Pacific Metrology Programme (APMP) and got good results using this method. The effects of several important factors, such as the chromatographic conditions and sample preparation conditions, were investigated to acquire optimum conditions. A method of uncertainty determination was also developed which can be used in similar measurements of uncertainty. The limit of detection (LOD, S/N > 3) of HPLC-UV method was 0.75 mg/kg, and the recovery of benzoic acid in orange juice at the spiked level 100 mg/kg was 99.4%. The LOD of LC-IDMS method was 0.05 mg/kg, and the recovery of benzoic acid at the same spiked level was 99.6%. The final determination result of benzoic acid in the orange juice sample by both methods was (102.0 +/- 2.1) mg/kg (coverage factor kappa = 2). The two methods are both simple, accurate, reliable and reproducible. The LC-IDMS method is more suitable for the determination of benzoic acid at low concentrations due to its high sensitivity.

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.

Analysis of Organic Acids in Fruit Juices by Liquid Chromatography−Mass Spectrometry: An Enhanced Tool for Authenticity Testing

Organic acid analysis plays a fundamental role in the testing of authenticity of fruit juices. Analytical methods used routinely for organic acids suffer from poor reproducibility, often give false positives/negatives for tartaric acid, and do not offer the possibility of analyte confirmation. There are conflicting reports in the literature on the presence/absence of tartaric acid in pomegranate juice, a potential indicator of adulteration with grape juice. In this work, a method based on stable isotope dilution liquid chromatography-tandem mass spectrometry is described for citric, malic, quinic, and tartaric acid in fruit juices. Validation data including precision and recovery in six types of juice are presented. Tartaric and quinic acids were confirmed in pomegranate juice at concentrations of 1-5 and ∼1 mg/L, respectively. These concentrations are much lower than those resulting from adulteration with grape juice and apple juice, respectively, at the 5% level. A separate method for isocitric acid in orange juice based on the single standard addition method is also described.

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.

Visible and near infrared spectroscopy for rapid detection of citric and tartaric acids in orange juice

The use of visible and near infrared spectroscopy (Vis/NIRS) was explored as a tool to detect the citric acid and tartaric acid in orange juice. Calibration models were developed from high performance liquid chromatography (HPLC) as a reference method and Vis/NIRS data using partial least squares (PLS) regression with cross-validation. “Fingerprint” was investigated based on PLS loadings and regression coefficients, offering theories for feature recognition and also providing possibilities to develop a simple and rapid device. The correlation coefficients ( r) and root mean squares error of prediction (RMSEP) in the best model for citric acid was 0.944 and 0.596, and 0.930 and 0.013 for tartaric acid. The results indicate that it is very feasible to detect the quality of orange juice using Vis/NIRS technique. Comparing the parameters with those derived from HPLC determination of the extract obtained from the same samples, the results of Vis/NIRS analysis were not better than those of HPLC analysis with low coefficient of variation below 0.18% and high correlation coefficient over 0.9999. Nevertheless, due to the short consuming time, low cost of monitoring and a guaranteed high sample throughout, Vis/NIRS technique has its potential for the rapid, reliable and nondestructive detection of organic acids 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.