Acid In Orange Juice Research Articles

Characterization and analysis of amino acids in orange juice by HPLC–MS/MS for authenticity assessment

Twenty protein α-amino acids have been used to detect adulterations in orange juices from Spanish oranges. An analytical method based on the use of normal-phase liquid chromatography coupled to mass spectrometry has been performed for detection and quantification of these compounds in this complex matrix. MS and MS/MS parameters were optimized and most abundant product ion of each amino acid were selected to be monitorized. Method performance is improved with the use of an Allure Acidix column in which mobile phase composition and flux were optimized. Good separation was achieved using water/acetonitrile (20:80) and water/methanol (10:90) at pH 3, with elution gradient. The method has been used to assess the presence of amino acids in different kinds of orange juice: packing orange juice from both frozen concentrates and recently squeezed oranges, and fresh sweet orange juice hand-squeezed in the laboratory just before the analysis. The differences in composition between the juices and the potential adulteration practices have been evaluated and discussed.

Sensitive Micellar Electrokinetic Chromatography−Laser-Induced Fluorescence Method To Analyze Chiral Amino Acids in Orange Juices

In this work a new method to detect the existence of chiral amino acids in orange juice is presented. The method employs beta-cyclodextrins and micellar electrokinetic chromatography with laser-induced fluorescence (MEKC-LIF) to separate and detect L- and D-amino acids (L-aa and D-aa) previously derivatized with fluorescein isothiocianate (FITC). A systematic optimization of the chiral-MEKC conditions is done bringing about in less than 20 min a good separation of the main amino acids found in orange juice (i.e., Pro, Asp, Ser, Asn, Glu, Ala, Arg, and the nonchiral GABA, i.e., gamma-aminobutyric acid). Using this procedure, the analysis time reproducibility for the 15 standard compounds (L-aa, D-aa, and GABA) has been determined to be better than 0.2% (n = 5) for the same day and better than 0.7% (n = 15) for three different days. Corrected peak area reproducibility is somewhat lower, providing values better than 3.3% (n = 5) for the same day and 6.9% (n = 15) for three different days. The limit of detection using this procedure was determined to be 0.86 attomoles for L-Arg. The optimized FITC derivatization method allows the easy and straightforward detection of amino acids in orange concentrates and juices (i.e., only centrifugation of diluted samples for 5 min is needed prior to their derivatization). D-Ala, D-Asp, D-Arg, and D-Glu were determined in orange juices and orange concentrates from different geographical origins using this new method. Moreover, the effect of different temperature treatments (50, 92, and 150 degrees C) on the content of D-aa in orange juice was evaluated.

Quantitative Analysis of Individual Sugars and Acids in Orange Juices by Near-Infrared Spectroscopy of Dry Extract

The combination of near-infrared spectroscopy (near-IR) and multivariate calibration for determination of glucose, fructose, sucrose, and citric and malic acids in orange juices was investigated. The concentrations of these components analyzed by enzymatic assays were considered as references relative to near-IR spectroscopy. Dry extract spectra of 218 orange juice samples were recorded in transmission mode between 1100 and 2500 nm. The original near-IR spectral data could be improved by mathematical pretreatments such as derivative transformations or multiplicative signal correction. Stepwise multiple linear regression (SMLR) and partial least-squares regression (PLSR) were used to create calibration models relating chemical reference values to spectral data. The prediction ability of calibration models is acceptable in comparison with the reference methods. The calibration and validation results provided by PLS-1 calibration models are slightly better than those obtained with SMLR calibration models. Keywords: Sugars; acids; orange juices; near-infrared spectroscopy; multivariate calibration

Insoluble inorganic salts as carbon paste electrode modifiers for preconcentration and voltammetric determination of oxalic acid

AbstractA novel approach for chemical modification of carbon paste electrodes (CPEs) has been investigated. Selected water‐insoluble inorganic salts as modifiers were found to exhibit preconcentration capability for oxalic acid under open‐circuit conditions in a pH 4.3 buffered solution. After medium exchange to a pure electrolyte (Britton–Robinson buffer, pH 8), the accumulated oxalate was measured by square‐wave anodic stripping voltammetry with a peak current response at 1.2 V (vs. Ag/AgCl). The water‐insoluble inorganic salts as modifiers were active through the interfacial accumulation of insoluble oxalate by the exchange of anions. The candidate inorganic salts should be, therefore, less insoluble than the corresponding oxalates, whereas, the differences in solubility between the modifiers and the corresponding oxalates are of minor importance. Among the investigated inorganic salts, lead sulfate produced the highest response under the employed conditions and was therefore exploited as accumulating material for oxalic acid. With suitable preconcentration times, a linear calibration graph from 0.7 mg/L to 42.8 mg/L of oxalic acid in the analyte solution was obtained, and a detection limit of 0.3 mg/L at a preconcentration time of 5min was achieved. The lead sulfate‐modified CPE was used to determine oxalic acid in orange juice without pre‐separation.

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).

Liquid Chromatographic Determination of Benzoic Acid in Orange Juice: Interlaboratory Study

An interlaboratory study was carried out for the determination of benzoic acid in orange juice by liquid chromatography. The orange juice was fortified with 0.5-10 ppm benzoic acid. Statistical analysis of the results showed that relative reproducibility (RSDR) between laboratories ranged from 6.92 to 15.97% for juice fortified with 1-10 ppm benzoic acid; RSDR was 27.90% for juice fortified with 0.5 ppm benzoic acid. Mean recoveries ranged from 94.5% for 4 ppm benzoic acid to 114% for 0.5 ppm benzoic acid. Total variability increased with increasing fortification level as measured by standard deviation for reproducibility (SR).

HPLC method for separation and determination of nonvolatile organic acids in orange juice

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTHPLC method for separation and determination of nonvolatile organic acids in orange juiceHyoung S. LeeCite this: J. Agric. Food Chem. 1993, 41, 11, 1991–1993Publication Date (Print):November 1, 1993Publication History Published online1 May 2002Published inissue 1 November 1993https://doi.org/10.1021/jf00035a033RIGHTS & PERMISSIONSArticle Views1461Altmetric-Citations30LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (426 KB) Get e-Alerts Get e-Alerts

Improved HPLC determination of hydroxycinnamic acids in orange juice using solvents containing THF

Solvent optimization techniques were used to maximize chromatographic resolution between sinapic, coumaric, ferulic, and caffeic acids and components in orange juice. Various reversed-phase solvent systems consisting of binary, ternary, and quaternary combinations of methanol, acetonitrile, and THF with water were evaluated. Greatest chromatographic resolution was realized from binary mobile phases consisting of THF and water and ternary solvents containing THF, methanol, and water

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.

H.p.l.c. Determination of trace levels of succinic acid in orange juice from Freeze‐damaged and undamaged fruit

AbstractSuccinic acid was determined by high‐performance liquid chromatography (h.p.l.c.) in juice from oranges subjected to freeze damage on the tree and by storage at below freezing temperatures. Succinic acid levels did not change in fruit subjected to freezing temperatures while on the tree or in storage. In order to measure succinic acid at these low levels (5–180 mg litre−1 juice) an earlier h.p.l.c. procedure was modified.

Determination of benzoic and sorbic acids in orange juice by high-performance liquid chromatography.

The first page of this article is displayed as the abstract.

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.

Stability of ascorbic acid in orange juice exposed to light and air during storage

Single-strength orange juice prepared from three nationally available brands of frozen orange juice concentrate was analyzed for ascorbic acid after exposure to light and air for varying periods up to eighteen days. For two of the brands, brown, foil-covered bottles offered no greater protection against ascorbic acid loss than clear glass bottles. Storage time appeared to be a greater contributor to ascorbic acid loss than type of container in two brands. One brand showed both the effect of storage time and type of container, since the juice stored in the brown bottle lost significantly less ascorbic acid after the same period than juice stored in the clear bottle.

Ascorbic Acid in Orange Juice

To the Editor.— The article Bioavailability of Ascorbic Acid in Orange Juice by Horowitz et al (235:2624, 1976) gives some useful information on the amount active and inactive ascorbic acid in fresh, frozen concentrate, and pasteurized orange juice. However, the authors should have indicated that the recommended dietary allowance (RDA) of ascorbic acid for adult men and for nonpregnant and nonlactating women is 45 mg. 1 Therefore, the 39 mg/100 ml of active ascorbic acid in the pasteurized orange juice, though substantially less than the values found for the fresh and frozen concentrate forms, provides almost the recommended intake of ascorbic acid per day if 100 ml is consumed. A diet that would include other fruits, tomatoes, potatoes, and leafy vegetables, together with the pasteurized orange juice, would certainly provide the recommended intake of ascorbic acid. Furthermore, a recent market research survey indicated that orange juice remains the most popular

Letter: Ascorbic acid in orange juice

Letter: Ascorbic acid in orange juice

Determination of benzoic and sorbic acids in orange juice.

A procedure has been devised for the separate determination of benzoic and sorbic acids in orange juice. It is based on the steam distillation of these preservatives from an acidified juice into an alkaline trap. The distillate is divided into two portions, each of which is treated with potassium dichromate and sulphuric acid, but under different conditions. Drastic oxidation leads to the destruction of sorbic acid and, after re-distillation, allows the determination of benzoic acid at 225 nm (with no interference from sorbic acid). Milder oxidation selectively converts sorbic acid into malonaldehyde, and the latter is subsequently converted into a coloured compound and determined at 532 nm (with no interference from benzoic acid).

Detection of Adulterations in Citrus Juices. XIII. Identification of Amino Acids in Orange Juices And in Commercial Citric Acids and Sucroses

Detection of Adulterations in Citrus Juices. XIII. Identification of Amino Acids in Orange Juices And in Commercial Citric Acids and Sucroses

Rapid Determination of Sorbic Acid in Orange Juice

Abstract This article presents a review of the most important methods of analysis which have been published during the last decade for the common preservatives sulfur dioxide, sorbic acid, nitrate and nitrite, and benzoic acid

Effect of Vitamin K5 on Ascorbic Acid Stability in Orange Juice

SUMMARYVitamin K5 was found to accelerate the loss of ascorbic acid in orange juice stored at refrigerator temperatures in waxed fiberboard cartons. It is suggested that vitamin K5 functions as an oxygen carrier. Its activity was not inhibited by antioxidants. Of a number of antioxidants suitable for food use, only gentisic acid or its sodium salt did not produce a very objectionable off‐flavor. Vitamin KG was not an effective antimicrobial agent.

ANALYSIS OF THE ORGANIC ACIDS OF ORANGE JUICE

The total acidity of orange juice is ordinarily determined by titrating a known volume of juice with a standard solution of NaOH, with phenolphthalein as indicator, the result being expressed as citric acid. This value includes all the substances of an acidic nature in the juice that react with NaOH. It so happens, however, that in most fruits the chief substances reacting with NaOH are the organic acids; for this reason, the titratable acidity represents fairly well the organic acid content of a given juice. The predominating organic acid in orange juice is citric acid ; but other organic acids, namely, tartaric, malic, benzoic, and succinic, have been reported present (2). According to Scurti and De Plato (11), the acidity of the orange is due to citric and malic acids. Menchikovsky and Popper (?) have reported that in the grapefruit of Palestine, 98.72 per cent, of the total acid is citric, 0.05 per cent, tartaric, 1.0 per cent, malic, and 0.23 per cent, oxalic. Nelson (7) found that the nonvolatile fruit acids of California lemons were chiefly citric, with a trace of 1-malic acid. For Florida orange juice, Hartmann and Hillig (5) reported a citric acid concentration of 0.92 per cent, and a malic acid concentration of 0.18 per cent., fresh weight. Hall and Wilson (3) identified formic acid in the volatile fraction of orange juice. All of these acids, if present in the juice, would have an additive influence on the titratable acidity. It was therefore decided to determine the amounts of citric and malic acids in orange juice and correlate these with the free-acid content as determined by titration with standard NaOH. Undoubtedly, other organic acids are present in the juice in minute amounts, but in the present work it has been assumed that they are negligible in comparison with the concentrations of citric and malic acids. Furthermore, the concentrations of combined and free acids have been determined on various juice samples, and the relation between the combined acid and the inorganic cations in the ash of orange juice has. been ascertained.