Acid In Fruit Juices Research Articles

Biopolymer immobilization enhanced the survival of lactobacillus casei ATCC334 in mangosteen probiotic beverage

This study aimed to enhance the viability of Lactobacillus casei ATCC334 in highly acidic fruit juice via an immobilization process using coconut meat insoluble fibres. Immobilized probiotics were introduced to mangosteen juice, and the probiotics' viability was evaluated for 4 weeks at 4°C. The immobilized probiotics were studied for their effects on the beverage's physicochemical and rheological properties and metabolites. Mangosteen with immobilized probiotics showed increased probiotic viability, lower glucose, fructose, and sucrose reduction, lower production of lactic acid, and higher pH than the control. The cell count of the immobilized probiotics was log10 9.25 CFU mL-1 and the free cell probiotics was log10 7.89 CFU mL-1 after 4 weeks at 4°C. The results illustrated that coconut meat insoluble fibres can be used to immobilise probiotics with enhanced viability and improved metabolites that enhance consumer acceptability and product quality.

Integrated tetrahydroxyphthalocyanine-coated graphene decorated with ionic liquid-functionalized gold nanoparticles for highly sensitive and selective electrochemical determination of ascorbic acid in fruit juices.

Surface functionalization and the combined utilization of zero-dimensional and two-dimensional nanomaterials is an effective method to achieve highly sensitive detection for electrochemical analysis. Using an all-in-one strategy, phthalocyanine, gold nanoparticles, and ionic liquid were successively modified on the graphene surface as a highly integrated electrode modification material. Phthalocyanine can repair the defects of reduced graphene oxide by binding to the graphene structure surface through non-covalent functionalization. The combination of ionic liquid on the surface of gold nanoparticles can enhance their physical and chemical activity while preserving their stability. The obtained phthalocyanine-coated graphene nanosheets decorated with ionic liquid-functionalized gold nanoparticles nanocomposites had enhanced electrocatalysis and conductivity ability, and were used for highly sensitive electrochemical detection of ascorbic acid in fruit juices. Excellent results were obtained for the detection of ascorbic acid in thelinear range 0.05 to 50µmol/L with a detection limit of 6.80nmol/L (S/N = 3) and a sensitivity of 2.68μA μM-1cm-2, indicated that the proposed sensor strategy with multiple signal amplification can achieve higher detection sensitivity. Furthermore, the sensor was used to quantify ascorbic acid content in grapefruit and orange juice with good selectivity and accuracy. The highly integrated electroactive nanocomposites construction method described may also be used with other electrode modification materials and is anticipated to yield fresh perspectives on the advancement of ultrasensitive detection.

Low-Cost Electrochemical Determination of L-Ascorbic Acid Using Screen-Printed Electrodes and Development of an Electronic Tongue for Juice Analysis

Low-cost electrochemical methodologies for the determination of L-ascorbic acid (vitamin C) and the analysis of juices are developed based on its electro-oxidation on carbon screen-printed electrodes. A novel chronoamperometric methodology is developed for the quantification of L-ascorbic acid in fruit juices. The proposed method stands out for its simplicity and rapidity, demonstrating its efficacy in determining L-ascorbic acid content in various fruit juices. Notably, the results obtained with this chronoamperometric approach are compared with those yielded by chromatography, with no significant differences between the two methods being found. Additionally, an electronic tongue is developed for the differentiation of juices based on the square wave voltammetric signals.

Phenotypic Selection to Avoid Discarding Target Genotypes for Four Fruit Traits Based on Environmental Variances in a Pineapple Cross-seedling Population

Early ripening [earlier than 1 Aug during fruit harvest time (FHT)], large fruit weight (FW; >1000 g), high sugar content [>17% soluble solids content (SSC)], and low acidity in fruit juice (<0.7%) are important breeding targets of pineapple for table fresh fruit use in Japan. We investigated the efficiency of primary selection based on the four fruit traits using 129 first-fruiting F1 offspring population of ‘Yugafu’ × ‘Yonekura’ without replicates. Separately, environmental variances were estimated by an analysis of variance using evaluation data from 50 or 49 offspring in three replicates and two-year repeats. The phenotypic distribution in the 129 F1 population approached a normal distribution (P > 0.05). The genotypic distribution was obtained as a normal distribution with the population mean as the mean and genotypic variance obtained by subtracting the environmental variance from the phenotypic variance. The target genotypes were estimated at 14.4%, 58.7%, 5.0%, and 50.0% of the F1 population for FHT, FW, SSC, and acidity, respectively. Critical phenotypic values were established as the upper (FHT and acidity) and lower (FW and SSC) limits of the critical genotypic values at the 95% probability level. The phenotypic selection was made based on the critical phenotypic value, resulting in 45.0%, 88.4%, 27.1%, and 79.1% of the offspring selected for FHT, FW, SSC, and acidity, respectively, and 12.4% simultaneously for all four fruit traits. The results showed that the phenotypic primary selection reduced the population size to 12.4%, avoiding the discarding of target genotypes with a low risk. If breeders intend to further reduce the population size, then increasing the number of traits subject to primary selection would be effective.

Induced electric field pasteurization of acidic fruit juices: Engineering characteristics, simulation model, microbiological analysis

The continuous-flow pasteurization apparatus was presented, and the electric field within orange juice was produced via an oscillating magnetic field at 50 kHz, causing the volumetric heating of the juice with initial conductivity of 6.85 mS/cm and 8.76 mS/cm. The process principle, especially numerical relationships between excitation voltage, magnetic field, induced electric field (IEF), induced current density, and temperature profile were elaborated. When applying a rectangular wave of the voltage at 50–1000 V, the waveforms of the magnetic field and IEF in the juice were sine-like and sawtooth waves, respectively. Through electromagnetic simulation, the model was established, which indicated the indirect heating of orange juice via oscillating magnetic field was feasible. As the magnetic field increased, the outlet temperature and induced current density in the juice was improved. Notably, the 4–5 logs CFU/ml inactivation effects on aerobic bacteria, yeast and mold in orange juice could be achieved at 65 °C for 60 s after the treatment.

Molecular mechanism of acid stress response of Alicyclobacillus acidoterrestris DSM 3922T under sublethal pH

Alicyclobacillus acidoterrestris (A. acidoterrestris) causes the spoilage of pasteurized acidic fruit juice due to its unique thermoacidophilic properties, which caused economic losses to fruit juice industry. To reveal the molecular regulatory mechanism of how A. acidoterrestris responded to acid stress is the key to hazard control of this microbe. Herein, acid-responsive proteome expression profiles of A. acidoterrestris were analyzed using label-free quantitative mass spectrometry to investigate its acid resistance mechanism at sublethal pH. Totally, 325 differential expression proteins were identified during acid stress (pH 2.5, 15 min duration), of which the expressions of 83 proteins were up-regulated and the other 242 protein expressions were down-regulated. The identified differentially expressed proteins were mainly involved in small molecule metabolism, organic nitrogen compounds metabolism, organic acid metabolism, and signal transduction. Overall, they were mapped into 97 metabolic pathways. Combination of KEGG pathway analysis and protein functional analysis suggested that the pH homeostasis system variation and relevant changes in metabolic pathways, cell membrane permeability and DNA repair are the main acid resistance mechanisms of A. acidoterrestris. Our finding implied that A. acidoterrestris might sense and transmit pH signals from the external environment through NhaB protein which holds histidine-dependent acid resistance system, initiating a series of acid tolerance reactions. Taken together, our study demonstrated global physiological response of A. acidoterrestris to sublethal pH, which provided a better understanding of acid adaption mechanism of A. acidoterrestris.

A fluorescence “turn-on” sensor for ascorbic acid in fruit juice and beverage based on ascorbate oxidase-like activity of citric acid-derived carbon dots

Citric acid-derived carbon dots (CA-CDs) without any modifications were found to have the ascorbate oxidase (AAO)-like activity. The CA-CDs have high affinity for ascorbic acid (AA), which is similar to natural AAO. The robustness of CA-CDs is greater than that of AAO. Based on the AAO mimetic activity of CA-CDs, a sensitive turn-on mode and natural enzyme-free fluorescence detection method has been developed for AA in some fruit juice and beverage samples with satisfied recoveries. This study provides CDs-based AAO mimetic nanozymes to replace the expensive natural enzymes or heavy metal-based nanozymes, which will show great potential in biological and food assays.

Simultaneous analysis of ascorbic and dehydroascorbic acid in fruit juice using HILIC chromatography coupled with mass spectrometry

A HILIC-MS/MS method was developed for the simultaneous analysis of ascorbic acid (AA) and dehydroascorbic acid (DHA). Ammonium acetate buffer and acetonitrile were used as mobile phases under gradient elution mode at a flow rate of 0.3 mL/min. A SCIEX Triple QUAD 5500+ system was operated under MRM mode to acquire data with 175 → 115 and 173→113 as the quantifier ions for AA and DHA, respectively. Samples were prepared with a simple dilute and shoot method. A calibration and accuracy study was performed as part of method validation in fruit juices. The accuracy profiles were estimated from the measurement uncertainty determined from the validation data according to the ISO/DTS 21748. The recoveries of the analytes were between 92 – 130 %. The LOQs achieved in the current study for AA and DHA were 4.5 µg/L and 18 µg/L, respectively. These LOQs were substantially lower than what has been previously reported in the literature. The study concludes with a straightforward analytical method for the determination of total vitamin C content that does not involve timing consuming steps i.e., reduction or derivatization reaction. The method can be implemented in quality control labs for routine analysis of food samples.

Evaluation of the Physicochemical Characteristics of a Blend Fruit Juice Powder Mixed with Lactiplantibacillus plantarum: A Comparison of Spray Drying and Freeze Drying

The physicochemical properties and the survival of Lactiplantibacillus plantarum mixed with blend of fruit juice powders dried by spray and freeze drying methods were investigated. A formula containing maltodextrin 14% and malt extract 6% as a carrier and juices of red grape 20.4%, mulberry 75.6%, and strawberry 4.0% along with the bacterium (Lpb. plantarum) with 3 × 10 9 CFU/mL were dried by spray drying and freeze drying methods, separately. The physicochemical properties including color attribute, nutritional properties of the powders such as antioxidant, and phenolic content were measured. Drying efficiency of freeze-dried was 80.48%, which was higher than the spray-dried powders (50.84%). The higher antioxidant (87.95) and total phenolic content (3032.6 mg GAE/L) was achieved by freeze drying technique; however, lower moisture content and flowability as well as higher solubility and bulk density were obtained for spray-dried powders. The survival of probiotics in freeze-dried powders was higher than the spray-dried powders which can be related to mild conditions. The study indicated that the juice powders are suitable carriers for Lpb. plantarum and constitute good alternatives to highly acidic fruit juices.

One-step pre-column derivatization method for HPLC-UV determination of organic acids in fruit juices

A simple and effective one-step pre-column derivatization method for reversed-phase HPLC-UV determination of the major organic acids (citric, malic, tartaric, and succinic acids) in fruit juices has been developed. The method is based on the coupling reaction of organic acids with 1-naphthylamine in the presence of N,N′-diisopropylcarbodiimide. The resulting organic acid amide derivatives were successfully separated on an AQ-C18 column and detected by a UV detector at 222 nm. Isocratic elution was performed using an acetonitrile-methanol-tetrahydrofuran-water (37:4:1:58; v/v) mixture as a mobile phase at a flow rate of 2.0 mL/min. Validation studies showed good recoveries ranging from 88.97 to 92.52% with RSD % between 2.95 and 4.56%. The detection limits obtained were 0.18, 0.48, 0.14, and 0.69 µg/mL for tartaric acid, malic acid, succinic acid, and citric acid, respectively. The method was successfully applied to three different commercial fruit juice and nectar samples with little or no clean-up procedures.

Electrochemical sensing of caffeic acid antioxidant in wine samples using carbon paste electrode amplified with CdO/SWCNTs

An electrochemical sensor was introduced as an analytical tool for monitoring caffeic acid in food samples. This analytical tool was amplified by cadmium oxide decorated on single wall carbon nanotubes as a new catalyst and showed a powerful ability to sensing of caffeic acid in food products. The presence of cadmium oxide decorated on single wall carbon nanotubes catalyst improved the oxidation signal of caffeic acid about 2.4 times at optimum conditions. The pH investigation confirmed that the redox reaction of caffeic acid was pH dependent and showed maximum sensitivity at pH 7.0. The paste electrode amplified with cadmium oxide decorated on single wall carbon nanotubes was successfully monitored caffeic acid in the concentration range 0.02–200 µM with a detection limit of 9.0 nM, respectively. The standard addition strategy showed a recovery range of 97.96 – 102.59 % to the measurement of caffeic acid in fruit juice, white and red wine that was acceptable for the fabrication of a new analytical tool in food monitoring.

UV-C treatments extend the postharvest quality of ‘0900 Ziraat’ sweet cherries by protecting the physical and biochemical features of the fruits during the storage

Sustainable practices to extend the postharvest quality of horticultural products lead to cost-effective marketing during the prolonged season. Sweet cherries are among the most commonly consumed and traded fruits worldwide although they necessarily deteriorate after harvest. In the present study, the effects of UV-C irradiation in different application durations along with modified atmosphere packaging (MAP) on quality maintenance of the ‘0900 Ziraat’ sweet cherries were investigated for two years (2018 and 2019). The fruits were divided into six application groups; (1) storage in plastic cups control, (2) using MAP (Xtend®) packages, (3) 5 min UV-C exposure, (4) 10 min UV-C, (5) 20 min UV-C, and (6) 30 min UV-C irradiation. Treatment of UV-C was performed at a 15 cm distance using a metal cabinet equipped with 8 UV-C lamps of 15 watts, 230V/50Hz at 254 nm wavelength. The sweet cherries were stored at 1 °C and 90% RH for 35 days. At the end of the storage, the greatest weight loss occurred in the control fruits, while the lowest loss was obtained from the fruits subjected to 10 min of UV-C for both years. Also, 10 min of UV-C provided the highest firmness value for both years. This treatment also has better effects on maintaining several quality features such as pedicel chlorophyll content, titratable acidity in fruit juice, and total phenolic contents compared to the control fruits. General findings indicated that 10 min UV-C irradiation would be a beneficial practice for extending the general quality features of ‘0900 Ziraat’ sweet cherry during cold storage up to 35 d.

Disposable three-dimensional graphene oxide electrode with sandwich-like architecture for the determination of ascorbic acid in fruit juices

This work reports the development of a three-dimensional graphene oxide structure on the screen-printed electrode surface for the detection of ascorbic acid. This electrode was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, RAMAN spectroscopy, cyclic voltammetry and electrochemical impedance spectroscopy. The present work also investigated the electrochemical behavior of ascorbic acid and its electrooxidation mechanism on the three-dimensional graphene oxide surface. The detection of ascorbic acid was conducted by linear scanning voltammetry in the concentration range from 1.0 × 10−5 to 1.0 × 10−2 mol L−1, and the limits of detection and quantification obtained for the proposed electrode were 3.4 × 10−6 and 1.1 × 10−5 mol L−1 (n = 3), respectively. The device also exhibited excellent selectivity, repeatability, reproducibility and stability. The methodology developed was applied for the determination of ascorbic acid in grape and orange juice samples with an accuracy rate ranging from 99% to 105%. These results show that the proposed electrode can be safely and reliably applied for the monitoring of ascorbic acid in fruit juices.

Enhancement of the fruit quality and postharvest life expectancy of mango fruit (Mangifera indica L.) applying ecofriendly bio-coatings

The higher losses of fruits and vegetables during post-harvest handling are a serious matter for any country whose economy is based on agriculture. The products of this plant are a significant source of horticultural produce storage used for the control of different post-harvest losses, which include diseases as well as microorganisms. Bio-coatings may be used as a better alternative to the synthetic chemicals. The impact of edible coating on the quality and storage life of mango (cv. ‘Anwar Rataul’) fruit was investigated by harvesting the fruits at a firm green stage of physiological maturity and coating them with corn oil, peanut oil, sunflower oil, soya bean oil, and animal fat. The uncoated and coated fruits were stored at 25 °C and the relative humidity (RH) was 75%. The fruits were analyzed for physicochemical quality attributes during storage at 0 (harvest time), 5, 10, 15, 20, and 25 days. The data showed that most of the parameters were affected significantly by the materials of coating and storage intervals (P ≤ 0.05). The fruits coated with animal fat had significantly superior fruit color, taste, aroma, firmness, total sugar content, and acidity of fruit juice, total soluble solids, and ascorbic acid content, as well as delayed ripening. Animal fat-coated fruits retained titratable acidity, ascorbic acid content (mg.100g-1) and fruit firmness (kg.cm-2) with minimal disease incidence, and weight loss (%), whereas uncoated fruits did not retain all quality attributes and deteriorated after 20 days of storage. In conclusion, mango fruits could be coated with animal fat and stored for up to 25 days without deterioration in quality.

Growth and inactivation of Listeria monocytogenes in sterile extracts of fruits and vegetables: Impact of the intrinsic factors pH, sugar and organic acid content

Intrinsic characteristics of fresh produce, such as pH, water activity, acid content and nutrient availability are critical factors in determining the survival and growth of Listeria monocytogenes (Lm). In this study, sterile fresh produce juice was used to analyze Lm growth potential among 14 different commodities and to identify physicochemical characteristics in those juices that affect Lm growth. Significant growth of Lm was observed in juices with pH ≥5.6 and low acidity (0.04–0.07 % titratable acidity (TA)) (cantaloupe, carrot, celery, green pepper, parsley, and romaine lettuce), slight reduction of Lm was observed in juices with pH 4.1 (tomato) and pH 3.9 (mango), and no Lm counts were recovered from juices with pH ≤3.8 and high acidity (0.28–1.17 % TA) (apple, blueberry, grape, peach, and pineapple). Although these acidic fruit juices possessed a high sugar content, the pH and acidity of produce juice seemed to be the primary determinants for Lm growth. The neutralization of acidic juices (i.e., Fuji and Gala apple, blueberry, grape, mango, pineapple, peach, and tomato) enabled Lm growth at 37 °C in all juices except for Gala apple and peach. Strong decline in Lm populations in Gala apple, grape and peach juices might be linked to sensitivity to organic acids, such as malic acid. Furthermore, Lm populations significantly decreased in pH-neutral (7.6) cauliflower juice, suggesting that potential antilisterial substances may play a role in Lm decline in cauliflower juice.

Colorimetric detection of acid-base in organic solvents, water, and food products using polydiacetylene/Zn2+/ZnO nanocomposites with tunable sensitivity

Colorimetric sensors based on polydiacetylene (PDA) materials have been developed for detecting acid-base. Since PDAs often change color upon exposure to organic solvents, most of previous studies used water as a medium. This presents a problem for detecting organic acids and bases with limited solubility in water. In this contribution, we explore the applications of PDA/Zn2+/ZnO nanocomposites as colorimetric sensors for detecting organic acid-base in various organic solvents and food products. Owning to its high color stability, this class of PDA materials can be dispersed in tetrahydrofuran, dimethyl sulfoxide, and ethanol while the blue phase remains. We have found that the sensitivity of PDA/Zn2+/ZnO nanocomposites to acid-base varies with the solvent properties. The sensors prepared by dispersing in different solvents can detect acid-base at different concentrations. Raman spectroscopy carried out directly in the liquid suspensions reveals the mechanisms of color transition in each system. Fine-tuning of the sensitivity can also be achieved by varying the ZnO ratios within nanocomposites. The ability to control the sensitivity allows the utilization of PDA/Zn2+/ZnO nanocomposites for semi-quantitative analysis of acid-base in food products. Solid-state sensors fabricated by embedding in nylon filters can determine the concentration of sorbic acid in fruit juices. The freshness of milk can be indicated via naked-eye detection as well. Our study expands the applications of PDA materials as colorimetric sensors for food industries.

Acid adaptive response of Alicyclobacillus acidoterrestris: A strategy to survive lethal heat and acid stresses

Alicyclobacillus acidoterrestris causes the spoilage of pasteurized acidic fruit juice, seriouslydecreasing quality and posing a significant safety concern. We previously discovered that acid adaptation could induce stress adaptive responses of A. acidoterrestris, however, the underlying mechanisms of this induction have not been fully elucidated. In this work, the effects of acid adaptation (pH = 3.0, 1 h) on intracellular pH (pHi) and the morphophysiological properties of A. acidoterrestris under lethal heat and acid stresses were investigated, and gene expression profiles after acid adaptation were measured by transcriptomic analysis. The results showed that acid adaptation increased the pHi of A. acidoterrestris cells in response to lethal stresses, enhanced membrane integrity, decreased surface shrinkage and roughness, and altered the Fourier transform infrared spectra profiles. After acid adaptation of A. acidoterrestris, 517 differentially expressed genes (DEGs) were detected. Consistent with resistance phenotypes, DEGs included genes related to cell surface modification and pHi homeostasis. Specifically, the barrier function of cell membrane was strengthened during acid adaptation by increasing fatty acid (FA) chain length, promoting unsaturated FA biosynthesis, and maintaining balanced synthesis of zwitterionic and acidic phospholipids. To reduce excessive intracellular protons, cells upregulated glutamate decarboxylation, urease system, and branched-chain amino acid synthesis. Additionally, the nucleotide salvage pathway was activated, and homologous recombination, UvrD-mediated transcription-coupled, and ribonucleotide excision repair pathways were applied to repair DNA lesions. Sporulation metabolism was also induced. The findings of this study provide insight into the multiple layers of acid adaptive response strategies of A. acidoterrestris, with implications for the formulation of improved control measures in the fruit juice industry.

A Novel Endo-Polygalacturonase from Penicillium oxalicum: Gene Cloning, Heterologous Expression and Its Use in Acidic Fruit Juice Extraction.

An endo-polygalacturonase (endo-PGase) exhibiting excellent performance during acidic fruit juice production would be highly attractive to the fruit juice industry. However, candidate endo-PGases for this purpose have rarely been reported. In this study, we expressed a gene from Penicillium oxalicum in Pichia pastoris. The recombinant enzyme PoxaEnPG28C had an optimal enzyme activity at pH 4.5 and 45°C and was stable at pH 3.0-6.5 and < 45°C. The enzyme had a specific activity of 4,377.65 ± 55.37 U/mg towards polygalacturonic acid, and the Km and Vmax values of PoxaEnPG28C were calculated as 1.64 g/l and 6127.45 U/mg, respectively. PoxaEnPG28C increased the light transmittance of orange, lemon, strawberry and hawthorn juice by 13.9 ± 0.3%, 29.4 ± 3.8%, 95.7 ± 10.2% and 79.8 ± 1.7%, respectively; it reduced the viscosity of the same juices by 25.7 ± 1.6%, 52.0 ± 4.5%, 48.2 ± 0.7% and 80.5 ± 2.3%, respectively, and it increased the yield of the juices by 24.5 ± 0.7%, 12.7 ± 2.2%, 48.5 ± 4.2% and 104.5 ± 6.4%, respectively. Thus, PoxaEnPG28C could be considered an excellent candidate enzyme for acidic fruit juice production. Remarkably, fruit juice production using hawthorn as an material was reported for the first time.

Transcriptome-Based Selection and Validation of Reference Genes for Gene Expression Analysis of Alicyclobacillus acidoterrestris Under Acid Stress.

Alicyclobacillus acidoterrestris is a major concern in fruit juice industry due to its spoilage potential of acidic fruit juice. Quantifying the expression levels of functional genes by real-time quantitative polymerase chain reaction (RT-qPCR) is necessary to elucidate the response mechanisms of A. acidoterrestris to acid stress. However, appropriate reference genes (RGs) for data normalization are required to obtain reliable RT-qPCR results. In this study, eight novel candidate RGs were screened based on transcriptome datasets of A. acidoterrestris under acid stress. The expression stability of eight new RGs and commonly used RG 16s rRNA was assessed using geNorm, NormFinder, and BestKeeper algorithms. Moreover, the comprehensive analysis using the RefFinder program and the validation using target gene ctsR showed that dnaG and dnaN were the optimal multiple RGs for normalization at pH 4.0; ytvI, dnaG, and 16s rRNA at pH 3.5; icd and dnaG at pH 3.0; and ytvI, dnaG, and spoVE at pH 2.5. This study revealed for the first time that A. acidoterrestris had different suitable RGs under different acid conditions, with implications for further deciphering the acid response mechanisms of this spoilage-causing bacterium.

Gas chromatography-mass spectrometric determination of organic acids in fruit juices by multiwalled carbon nanotube-based ion-pair dispersive solid-phase extraction and in situ butylation.

Fruit juices are naturally acidic, and the acidity is due to the formation of various organic acids formed in several metabolic processes. The content of acids varies due to various processing parameters during the preparation of fruit juices and their packaging for commercialization. Quantitative determination of organic acids provides the necessary information leading to changes occurred during processing. The organic acids were extracted by ion-pair dispersive solid-phase extraction by multiwalled carbon nanotubes and analyzed using gas chromatography-mass spectrometry (GC-MS) and in situ butylation. The developed analytical method was validated, and the obtained results showed a linearity in the range of 0.5-5000 μg/L levels of the analytes with limit of detection and quantification values of 2-10 and 5-20 μg/L, respectively. The inter- and intra-day reproducibilities are less than 15% with 80%-98% recoveries and less than 20% matrix effect. The developed method was used for the quantitative determination of organic acids present in fresh and packaged apple, grape, orange, and pomegranate juice samples. The content of organic acids was observed in the range of 0.26-3793 μg/L. Pimelic acid was not detected in any of the analyzed fruit juices. Fumaric acid (FA) was observed to be a major organic diacid present in the natural fruit juices. The results indicated that the processing of fruit juices for packaging decreases the content of organic acids in fruits. The developed GC-MS-based analytical method for the analysis of organic acids has good sensitivity and reproducibility for the quantitative determination of various organic acids in fruit juices. FA was observed to be the major carboxylic acid present in fruits. The processed juice samples possess the lowest concentration of organic acids, suggesting that processing has a significant effect on the concentration of organic acids in fruits.