Effect of Ultrasound and Enzymatic Mash Treatment on Bioactive Compounds and Antioxidant Capacity of Black,Red and White Currant Juices

Ultrasound treatment is recognized as a potential technique for improvement in the nutritional values of fruit juices. This study was initiated with the objective of evaluating bioactive compounds and some important quality parameters of black (BC), red (RC) and white (WC) currant juices obtained from fruit mash preliminarily treated by enzymes combined with ultrasound. Individual and total phenolic content (TPC), anthocyanins, color parameters, ascorbic acid, antioxidant capacity (TEAC), juice yield, pH, titratable acidity, and soluble solids were investigated. Significant increases in the levels of TPC and antioxidant capacity of sonicated samples were observed. However, ultrasound treatment had no effect on individual phenolic compounds of juices. Sonication of mash before juice pressing did not cause any noticeable changes in ascorbic acid content. Only in the case of WC was an increase in content of vitamin C noticed. The color of juices obtained after treatment was similar to the control sample. It was demonstrated that enzymatic combined with ultrasound treatment of mash for different colored currant fruit did not have any dismissive effect and could even improve some parameters of the juice obtained.     

Application of capillary isotachophoresis for fruit juice authentication

A method using capillary isotachophoresis (ITP) was developed and applied for the determination of the anionic profile of orange juices with the aim to obtain some useful information on the authenticity or adulteration of imported and native beverage products. An EA 100 electrophoretic analyser (Villa-LABECO, Slovak Republic) was used for capillary isotachophoretic determination of anions in tested samples. More systems of leading and terminating electrolytes were used. Detection conductivity and UV detection at 254 nm were used. Sample injection volume was 30 microl. These systems allow one to determinate inorganic anions, organic acids and some additives--adulterants in anionic forms in orange juices. By capillary isotachophoretic determination the lengths or areas of characteristic zones were established and compared to authentic orange juices of different species and origin and with RSK reference values (Code of Practice). Special emphasis was placed on D-isocitric acid ITP determination as a reliable fruit juice authentication marker. The presented multicomponent analysis of orange juice authenticity according to ITP anionic profiles obtained by capillary isotachophoresis presents an alternative information source necessary for deciding about authenticity of the products.     

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.     

Chiral separation of diastereomeric flavanone-7-O-glycosides in citrus by capillary electrophoresis

The 2S- and 2R-diastereomers of major flavanone-7-O-glycosides found in sweet orange (Citrus sinensis), mandarine (Citrus deliciosa), grapefruit (Citrus paradisi), lemon (Citrus limon), and sour or bitter orange juice (Citrus aurantium) were separated for the first time by chiral capillary electrophoresis (CE) employing various buffers with combined chiral selectors. Native cyclodextrins (CDs), neutral and charged CD derivatives were examined as chiral additives to the background electrolyte (BGE). Separation efficiency has not proved satisfactory with one single CD as chiral selector in the buffer, a full and simultaneous separation could often be achieved only by using combined buffer with two different CDs. Chiral separation of major flavanones in sweet orange, mandarine and grapefruit juices raised more difficulties than in lemon and sour orange juices as narirutin will not readily build complexes with most CDs. Diastereomeric flavanones of mature and immature grapefruits were compared and some differences were found: naringin showed different diastereomeric ratio and 2S-prunin appeared only in immature grapefruit. Marmalade was also examined by chiral CE. Its major flavanones corresponded to flavanone pattern of mixed sour and sweet oranges.     

Comparison of some additives used in the preparation of freeze-dried lemon juice candidate reference materials

The stability, storage, and distribution of certified reference materials which consist of liquid or frozen fruit juices is rather problematic. As a better alternative a stable orange juice powder has been obtained by freeze-drying to a moisture content below 0.4%. However, freeze-drying lemon juices resulted in unstable materials which collapsed into lumps after standing some weeks in brown bottles under argon. An additive was sought which can be used to obtain stable lemon juice powders without influence on important analytical parameters as amino acids, sugars, organic acids, minerals and flavanone glycosides. The additives pectin, hydroxy ethylcellulose, and hydroxypropyl methylcellulose were examined. Powders containing pectin quickly showed a loss of structure (collapse) and resulted in non-acceptable changes in amino acids, sugars or minerals compared to the original lemon juice. The addition of up to 3% hydroxypropyl methylcellulose seemed more promising, although some minor changes in the sugar and sodium concentration occurred.     

Epoxycarotenoids esters analysis in intact orange juices using two‐dimensional comprehensive liquid chromatography

In this work, the native carotenoid pattern of different orange juices was studied by LC×LC‐DAD/APCI‐IT‐TOF‐MS for the first time. Special attention was given to the epoxycarotenoids components. It has been already proposed that the relative proportions and composition of these epoxycarotenoids can be used to estimate the age and freshness of an orange juice. Re‐arrangements from 5,6‐ to 5,8‐epoxides can occur with time, partially due to the natural acidity of the juices. Thus, the study of these carotenoids in their intact form, that is, esterified with fatty acids, is of great interest. Besides, other free carotenoid and carotenoids esters were identified in seven different monovarietal orange juices and a commercial orange juice. Moreover, the higher separation power of the present LC×LC approach allowed a clearer identification of the compounds contained in the sample compared to the more commonly used approach which uses C₃₀ stationary phases in conventional LC, thanks to the attainment of clearer MS spectra due to the higher resolution and separation degree obtained in LC×LC. This method could also be used to establish authenticity markers among orange varieties that could be potentially used to prevent or detect adulterations or to establish ripeness indexes.     

Isolation of Alicyclobacillus acidoterrestris from fruit juices

K agar, a novel isolation medium developed for the food industry, was compared with other acidified media for isolation of Alicyclobacillus acidoterrestris spores. Spores were inoculated into apple juice, orange juice, and a fruit juice blend and then isolated on the following media: K agar, pH 3.7; semi-synthetic medium, pH 4.0; orange serum agar, pH 3.5; and minimal salts medium, pH 4.0. Media were incubated at 24, 35, 43, and 55 degrees C. Highest recovery of spores was obtained with either K agar or semi-synthetic medium, incubated at 43 degrees C. The effect of heat shocking spores at different times was also determined; heat shocking at 80 degrees C for 10 min was considered appropriate. Peptone, previously shown to inhibit A. acidoterrestris, was not inhibitory when present in K agar. A collaborative trial with 9 laboratories was undertaken to determine the repeatability and reproducibility of counts on K agar. K agar prepared from individual components was compared with dehydrated K agar prepared by International BioProducts (Redmond, WA). There were no significant differences between log mean counts for the 2 media for each of the juices analyzed at both the high and the low inoculum levels. Repeatability and reproducibility values were not significantly different either within juices, within trials, or across all samples tested in both trials. K agar is suitable for isolation of A. acidoterrestris spores from fruit juices.     

Application of stepwise discriminant analysis to classify commercial orange juices using chiral micellar electrokinetic chromatography-laser induced fluorescence data of amino acids

The use of chiral amino acids content and stepwise discriminant analysis to classify three types of commercial orange juices (i.e., nectars, orange juices reconstituted from concentrates, and pasteurized orange juices not from concentrates) is presented. Micellar electrokinetic chromatography with laser-induced fluorescence (MEKC-LIF) and beta-cyclodextrins are used to determine L- and D-amino acids previously derivatized with fluorescein isothiocyanate (FITC). This chiral MEKC-LIF procedure is easy to implement and provides information about the main amino acids content in orange juices (i.e., L-proline; L-aspartic acid, D-Asp, L-serine, L-asparagine, L-glutamic acid, D-Glu, L-alanine, L-.arginine, D-Arg, and the non-chiral gamma-amino-n-butyric acid (GABA), i.e., gamma-aminobutyric acid). From these results, it is clearly demonstrated that some D-amino acids occur naturally in orange juices. Application of stepwise discriminant analysis to 26 standard samples showed that the amino acids L-Arg, L-Asp and GABA were the most important variables to differentiate the three groups of samples. With these three selected amino acids a 100% correct classification of the samples was obtained either by standard or by leave-one-out cross-validation procedures. These classification functions based on the content in L-Arg, L-Asp and GABA were also applied to nine test samples and provided an adequate classification and/or interesting information on these samples. It is concluded that chiral MEKC-LIF analysis of amino acids and stepwise discriminant analysis can be used as a consistent procedure to classify commercial orange juices providing useful information about their quality and processing. To our knowledge, this is the first report about the combined use of chiral capillary electrophoresis and discriminant techniques to classify foods.     

Determination of antioxidant activities in fruit juices based on rapid colorimetric measurement and characterisation of gold nanoparticles

A simple and green synthesis of gold nanoparticles (AuNPs) was achieved in tea solution and fruit juices with auric tetrachloride (HAuCl₄) without the addition of any other chemicals. Natural antioxidants present in tea leaves and fruit juices were able to reduce Au³⁺ ions to form AuNPs spheres with an average diameter of 22.9 ± 2.7 nm in the tea solution and 12.8 ± 2.4 nm in the orange juice. A colorimetric determination of antioxidant activities based on the formation of citrate-capped AuNPs has been developed. It was found that the colorimetric response of AuNPs was dependent on the concentration of antioxidants tested. As compared with the standard reference assay, i.e., the Folin–Ciocalteu method, the colorimetric method reported in this study showed a very good correlation (R² = 0.9996). The results indicate that the AuNPs-based colorimetric method provides a simple, effective and reliable measurement of the antioxidant capacity in the tested fruit juices.     

Detection of orange juice dilution by canonical correlation analysis

Canonical correlation analysis is used to detect orange juice dilutions masked by addition of citric acid and sugars. The values of 28 analytical characteristics (experimental variables) were determined in 105 pure orange juices, and canonical correlation analysis was applied to two groups of experimental variables (citric acid, sucrose, glucose, and fructose versus the other variables). The first pair of canonical correlation variables (one from each group) showed a correlation coefficient of 0.966. By dividing the whole set of 105 juices into reference sets (to compute predictive equations) and test sets (to check the efficiency of the equations), dilutions of 10, 20, and 30% were detected in, respectively, 28, 62, and 91% of the juices from the test sets.     

Evaluation of a polymerase chain reaction-based heteroduplex assay for detecting the adulteration of processed orange juice with mandarin juice

A polymerase chain reaction (PCR)-based heteroduplex assay was evaluated for the detection of mandarin juice in processed orange juice. PCR amplification of a fragment of the chloroplast trnT-trnL intergenic spacer derived from mixtures of DNA extracted from orange and mandarin juice resulted in heteroduplex formation. The heteroduplex resulted from the co-amplification of a fragment containing an 8 base-pair indel that distinguished mixtures of orange and mandarin juice from orange juice and mandarin juice alone. The heteroduplex assay was evaluated against authentic juices obtained from different citrus species and confirmed that the marker was homogeneous within Citrus. The data obtained demonstrated maternal inheritance of chloroplast type in Citrus sp. and allowed the identification and confirmation of the maternal parentage of unknown and known citrus hybrids. Analysis of the quantitative potential of the PCR and polyacrylamide gel electrophoresis (PAGE) analysis demonstrated good repeatability with a coefficient of variation of 7.5%. Greatest sources of variance in experimental results were attributable to species and varietal differences in the levels of the PCR target. Mandarin juice contained approximately 18% (w/v) less PCR target sequence than did orange juice. The assay was tested in a blind trial using processed juices and correctly identified 20/22 samples with no false-positive results.     

Development and validation of a capillary electrophoresis method for direct measurement of isocitric, citric, tartaric and malic acids as adulteration markers in orange juice

Fruit juices each have very distinct organic acids profiles that can be used as fingerprints for establishing authenticity. A method has been developed, optimised and validated for measuring by capillary electrophoresis citric, isocitric, malic and tartaric acids as authenticity markers in orange juices, without any sample treatment other than dilution and filtration. Final conditions were phosphate buffer 200 mM, pH 7.50, -14 kV as applied potential, and 57 cm length neutral capillary. Detection was direct UV at 200 nm. Different kinds and marks of orange juice, chosen from the great variety existent in the market, were analysed and clear differences could be found between them and just pressed orange juice.     

基于代谢组学技术的快速蒸发电离质谱与智能手术刀联用实时鉴别果汁掺伪方法研究

近年来,果汁掺伪问题日益突出。作为一种新型的实时鉴别方法,智能手术刀(IKnife)与快速蒸发电离质谱(REIMS)联用技术无需样品前处理即可解决这一问题。该文采用代谢组学指纹识别技术建立橙汁、苹果汁和葡萄汁的实时鉴别方法,并对其掺假水平进行预测。主成分分析-线性判别分析联用法建立的判别模型能够区分不同类型的果汁,排除20%交叉验证法的正确率为97.28%,未知样品实时鉴别正确率高达100%。筛选出不同果汁中的标志物,并对部分化合物进行鉴定。结果表明,此方法能够成功区分掺有10%-50%苹果汁和葡萄汁的橙汁。通过对比分析REIMS单极质谱和串联质谱(REIMS/MS)的检测结果,两种方法建立的偏最小二乘分析模型均能准确预测掺假水平(所有模型的R 2和Q 2均大于0.82)。与传统的REIMS方法相比,REIMS/MS的预测值更加精确。     

Determination of thiabendazole in fruit juices by a new monoclonal enzyme immunoassay

A competitive, indirect enzyme-linked immunosorbent assay (ELISA) for thiabendazole has been developed and applied to the analysis of fruit juices spiked with this fungicide. The immunoassay is based on a new monoclonal antibody derived from a hapten functionalized at the nitrogen atom in the 1-position of the thiabendazole structure. To our knowledge, such a structure has not been previously used to obtain antibodies to thiabendazole. The I50 value and the detection limit of the ELISA for standards were 0.2 and 0.05 ng/mL, respectively. Fruit juices were analyzed by diluting samples in assay buffer, without extraction or cleanup. Samples were not even centrifuged or filtered to remove fruit pulp. Under these conditions, the immunoassay was able to accurately determine thiabendazole down to 1 ng/mL in orange and grapefruit juices, down to 5 ng/mL in banana juice, and down to 20 ng/mL in apple and pear juices. Sensitivity differences of the ELISA were caused by the minimum dilution required by each juice to minimize matrix effects: 1/10 for orange and grapefruit juices, 1/50 for banana juice, and 1/100 for apple and pear juices. In an attempt to further increase the sensitivity of the immunoassay for matrixes showing the strongest interferences, apple and pear juices spiked with thiabendazole at low levels (1-20 ng/mL) were extracted with ethyl acetate before analysis. This simple procedure entailed a significant reduction of matrix effects, which in fact allowed us to determine accurately as low as 5 ng/mL thiabendazole in apple and pear juices. Irrespective of whether samples were analyzed by the direct dilution method or after extraction, the simplicity, sensitivity, and sample throughput of this monoclonal immunoassay makes it a very convenient method for the routine monitoring of thiabendazole residues in fruit juices.     

Comparative Evaluation of Juices from Red-Fleshed Apples after Production with Different Dejuicing Systems and Subsequent Storage

In this work, two vintages (2019 and 2020) of red-fleshed ‘Weirouge’ apples were processed with the innovative spiral filter press technology to investigate juice production in an oxygen-reduced atmosphere. After pressing, a more brilliant red color and appreciably higher amounts of oxidation-sensitive constituents (ascorbic acid, anthocyanins, and colorless (poly)phenols) were seen in spiral filter pressed juices compared to those produced with conventional systems (horizontal filter press and decanter). In a subsequent stability study (24 weeks storage at 4, 20, and 37 °C), the color and phenolic compounds were monitored and differences in the juices produced with the different pressing-systems were widely maintained during the storage period. The analyses of the anthocyanins and colorless (poly)phenols were conducted by UHPLC-DAD-ESI-QTOF-HR-MS/MS and UHPLC-DAD. The spiral filter press emerged as a promising technology for the production of juices with a more attractive color and a better retention of oxidation-sensitive constituents during processing and storage compared to conventional juices.     

Effect of storage temperature on degradation of methidathion in fortified orange and peach juices

The effect of storage temperature on methidathion degradation in orange and peach juices was studied. The insecticide was aseptically added to packed orange and peach juices, which were stored at 40, 15, and 0 degrees C. Samples were taken at regular intervals and examined for residues of methidathion. Residues were determined with a simple gas chromatographic method; recoveries of methidathion from orange and peach juices ranged from 88.1 to 110% for both juices, and the limits of determination were 0.004 and 0.003 mg/kg, respectively. The experimental data were used to evaluate rate constants, half-lives, and times required to reach legal maximum residue limits, and activation energies for the decomposition of methidathion in orange and peach juices. Storage of fruit juices in refrigerated rooms greatly extended the half-life of methidathion beyond that of methidathion in samples stored at higher temperatures. Half-life values for methidathion in orange and peach juices, respectively, were 4.1 and 3.8 days for storage at 40 degrees C, 115 and 113 days for storage at 15 degrees C, and 330 and 385 days for storage at 0 degrees C. Activation energies for methidathion degradation in orange and peach juices were 22.6 and 21.7 kcal/mol, respectively.     

Evaluation of a low-cost,automated pyrolysis-mass spectrometer

A low-cost, automated pyrolysis-mass spectrometer based on a quadrupole mass analyser (Prutec PYMS system) was evaluated by analysing three sample sets (orange juices, pectins and micro-organisms) and by comparison with results obtained on a manual pyrolysis-mass spectrometer based on a magnetic mass analyser (VG Gas Analysis, Pyromass 8–80). Reproducibility of replicate analyses was better on the PYMS system for orange juices and pectins and was comparable with the Pyromass for micro-organisms. Discrimination of samples was always achieved by the PYMS system and, if the data analysis was restricted to m/z 51–140, the PYMS discrimination was superior to that obtained on the Pyromass for orange juices and pectins but was inferior for micro-organisms. The use of a wider mass range in the data analysis on the Pyromass 8–80 improved the discrimination of orange juices and pectins but impaired the discrimination of micro-organisms.     

Color measurement of rosemary honey in the solid state by reflectance spectroscopy with black background

A colorimetric method was developed to measure the color of rosemary honeys in the solid state, without liquefaction. The color of 20 solid samples of rosemary honeys was measured by reflectance spectroscopy with white and black background in cells of 1 cm pathlength. The Kulbelka-Munk theory of turbid media was applied to calculate the spectral distribution of reflectivity, internal transmittance, and coefficients of absorbance and scattering of light. From these spectral distributions, 2 different types of honey were found. The honey colors measured from reflectivity and internal transmittance are well grouped. The colors obtained from reflectivity and those obtained from reflectance with black background show high linear correlation (r2 > 0.99). As a practical application, measurements of reflectance with black background in cells of 1 cm pathlength can be used to determine the color of these honeys in the solid state.     

Electrode and electrodeless impedance measurement for determination of orange juices parameters

Electrical impedance spectroscopy (EIS) is a non-destructive, rapid and real-time measurement method which does not require special high-tech measurement devices and can be applied to food quality assessment. This method is rapid, effective and affords low-cost investigation of the product. The conventional EIS method requires a set of metal electrodes in direct contact with the medium to be measured. The complicated electrochemical processes on the electrodes-electrolyte interface could substantially affect the value of the impedance measured. The present study sought to explore the possibilities of using the impedance method for quality control in orange juices, to introduce the electrodeless method of electrolyte impedance measurement and to compare this with the conventional impedance methods. The electrical properties of the orange juices were described with the help of an equivalent circuit. An equivalent circuit was designed with constant phase element approximation. The values of the equivalent circuit components were fitted using a non-standard algorithm inspired by the behaviour of actual ant colonies. Implementing the electrodeless method obviated the electrodes phenomena effects and the behaviour of the electrolyte is similar to inductance. The proposed electrodeless method is generally applicable to measuring the electrochemical properties of electrolytes.