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Use of near infrared spectroscopy and chemometrics to evaluate the shelf-life of cloudy sonicated apple juice
摘要： Fresh products, such as cloudy apple juice, could be preserved from early spoilage through the application of non-thermal processes such as sonication. However, shelf-life analyses based on microbiological and sensory evaluations are expensive and time consuming. Few studies have applied near infrared spectroscopy to evaluate the quality and decay of apple juices. Here, a feasibility trial was conducted to study the spectral behaviour at 1300–2500 nm combined with chemometric approaches. The shelf-life was monitored during two experiments, a challenge test with juices inoculated with spoilage yeasts (inoculated non-sonicated (INS)) and then submitted to sonication treatments (inoculated sonicated (IS)), and a storage test to evaluate the spoilage on non-inoculated juices (non-inoculated non-sonicated (NINS)) and sonicated non-inoculated juices (non-inoculated sonicated (NIS)). These experiments were investigated at six different refrigeration times 7, 14, 21, 28 and 60 days. Two functions were modelled to describe the behaviours of the first principal component according to the storage time. In agreement with a previous chemical and sensory evaluation, this approach allowed us to highlight shelf-life end points of 7 and 14 days for non-sonicated and sonicated samples, respectively. Three different models were evaluated for classification purposes: (1) sonicated versus non-treated samples, (2) end-point shelf-life evaluation at seven days for the NINS and INS juices and (3) end-point shelf-life discrimination at 14 days for IS and NIS samples. A partial least square-discriminant analysis enabled a group classification with accuracy values ranging from 0.63 to 1.00. The application of a variable importance in projection index to interpret the wavelengths of the spectral features suggests a contribution of organic acids and lipids to the prediction of decay. A canonical discriminant analysis provided a clearer separation of samples according to the storage time, especially in relation to the two time thresholds of 7 and 14 days.
关键词： Apple juice,spoilage,near infrared spectroscopy,shelf-life,sonication
更新于2025-09-23 15:23:52
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Increased resistance of <i>Salmonella</i> Typhimurium and <i>Escherichia coli</i> O157:H7 to 222-nm krypton-chlorine excilamp treatment by acid adaptation
摘要： In this study, we examined the change in resistance of Salmonella Typhimurium and Escherichia coli O157:H7 to 222-nm krypton-chlorine (KrCl) excilamp treatment as influenced by acid adaptation, and identified a mechanism of resistance change. In addition, changes in apple juice quality indicators such as color, total phenols and DPPH free radical scavenging activity during treatment were measured. Acid adapted- and non-acid adapted pathogens were induced by growing the cells in TSB without dextrose (TSB w/o D) at pH 7.3 and TSB w/o D at pH 5.0 adjusted with HCl, respectively. For the KrCl excilamp treatment, acid-adapted pathogens exhibited significantly (P < 0.05) higher D5d values, which indicate dosages required for achieving 5-log reduction, than non-acid adapted pathogens in both commercially clarified apple juice and PBS, and the pathogens in the juice showed significantly (P < 0.05) higher D5d values than those in PBS because of the UV-absorbing characteristics of apple juice. Through mechanism identification, it was found that the generation of lipid peroxidation in cell membrane, inducing cell membrane destruction, of acid adapted cells was significantly (P < 0.05) less than that of non-acid adapted cells for the same amount of reactive oxygen species (ROS) generated at the same dose because the ratio of unsaturated to saturated fatty acids (USFA/SFA) in the cell membrane was significantly (P < 0.05) decreased as a result of acid adaptation. Treated apple juice showed no significant (P > 0.05) differences in quality indicators compared to untreated controls during the treatment of 1773 mJ/cm2.
关键词： acid adaptation,ROS,E. coli O157:H7,apple juice,cell membrane fatty acid,ultraviolet irradiation,S. Typhimurium,222-nm KrCl excilamp
更新于2025-09-23 15:22:29
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UV-C light processing of Cantaloupe melon juice: Evaluation of the impact on microbiological, and some quality characteristics, during refrigerated storage
摘要： UV-C light is a non-thermal technology with potential application in food industries. The objective was to assess UV-C radiation effect (13.44 W/m2) on microbiological decontamination and some quality characteristics of Cantaloupe melon juice, during refrigerated storage. Juice was inoculated with Listeria innocua (non-pathogenic surrogate of L. monocytogenes) and Alicyclobacillus acidoterrestris spores (spoilage indicators) used as indicators of the UV-C treatment efficacy. Total mesophylls and yeasts and molds were also enumerated. Results demonstrated that 5 minutes of exposure allowed 3.7– 0.3 log10 cycles reduction of L. innocua, while for A. acidoterrestris, 20 minutes were required to decrease 4.7– 0.1 log10 cycles. At the end of refrigerated storage for 13 days, UV-C treated juices retained color, total phenolics content and antioxidant activity, and yeast and molds did not grow. Since UV-C process was effective on microbial inactivation and allowed juice quality maintenance, it can be considered as a promising alternative to thermal pasteurization.
关键词： UV-C radiation,L. innocua,storage,melon juice,A. acidoterrestris
更新于2025-09-23 15:22:29
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Degradation kinetics of anthocyanin and physicochemical changes in fermented turnip juice exposed to pulsed UV light
摘要： In this study, the effects of pulsed UV (PUV) light on the degradation kinetics of anthocyanins and physicochemical properties of turnip juice were investigated. PUV light was applied to turnip juice at 3 different distances (5, 8, 13 cm) from the quartz window of the xenon lamp for 5 different times (5, 15, 30, 45, 60 s). The pH, total acidity (% lactic acid), monomeric anthocyanin content, color density, hue, brightness, and percent color components (yellow, red, and blue) of turnip juice changed significantly after PUV-light treatments at each level. The maximum degradation of anthocyanin after PUV-light treatments was found to be about 63%. The anthocyanin degradation, brightness, yellow and blue color (%) increased, while red color (%) decreased with longer treatment time and shorter distance. The degradation of monomeric anthocyanins in turnip juice exposed to PUV light was described by the Weibull model (R2 0.982–0.998, RMSE 0.087–0.133) more accurately than the first-order kinetics (R2 0.906–0.992, RMSE 0.071–0.192).
关键词： Degradation kinetics of anthocyanin,Pulsed UV light,Physicochemical properties,Turnip juice,Weibull model
更新于2025-09-23 15:21:21
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Inactivation of ascospores of Talaromyces macrosporus and Neosartorya spinosa by UV-C, UHPH and their combination in clarified apple juice
摘要： This work addresses the use of a thin-film short wave ultraviolet radiation (UV-C) reactor and its combination with ultra-high pressure homogenization (UHPH) for the inactivation of Talaromyces macrosporus (CBS 130.89) and Neosartorya spinosa (CBS 586.90), fungal species that can cause food spoilage in products made of fruits. Ascospores of these microorganisms were inoculated in phosphate buffer solution (PBS) and clarified apple juice at a concentration between 5 and 6 Log10 spores/mL before treatments. Ascospores of both microorganisms were not detected in PBS after UV-C treatments even at the lowest assayed dose (1.8 J/mL), but in apple juice T. macrosporus showed to be significantly more UV-C resistant than N. spinosa. A UV-C dose of 21.5 J/mL in a single pass achieved decimal reductions of 2.15 Log10 and 5.4 Log10 respectively. Decimal reductions of both strains significantly increased in many cases when the same UV-C dose was applied in 2 or 3 passes throughout the UV-C reactor achieving T. macrosporus a maximum reduction of 3.88 Log10 after a UV-C dose of 21.5 J/mL applied in 3 passes. UHPH treatments at 100 and 200 MPa were ineffective in inactivating ascospores of both microorganisms, However, UHPH left ascospores more vulnerable to UV-C resulting in a synergistic effect achieving a maximum reduction of 3.6 Log10 on T. macrosporus after a combined treatment of UHPH at 200 MPa and a single pass of UV-C at 21.5 J/mL. The use of scanning electron microscopy revealed that only UHPH caused small changes in the cell wall structure of ascospores, but that might have left cells better exposed to UV-C.
关键词： Talaromyces macrosporus,Apple juice,Heat-resistant ascospores,Neosartorya spinosa,UHPH,UV-C
更新于2025-09-23 15:21:01
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Fluorescent-Nitrogen-Doped Carbon Quantum Dots Derived from Citrus Lemon Juice: Green Synthesis, Mercury(II) Ion Sensing, and Live Cell Imaging
摘要： In this study, we report a green and economical hydrothermal synthesis of fluorescent-nitrogen-doped carbon quantum dots (NCQDs) using citrus lemon as a carbon source. The prepared NCQDs possess high water solubility, high ionic stability, resistance to photobleaching, and bright blue color under ultraviolet radiation with a high quantum yield (～31%). High-resolution transmission electron microscopy (HRTEM) results show that the prepared NCQDs have a narrow size distribution (1?6 nm) with an average particle size of 3 nm. The mercury ion (Hg2+) sensing efficiency of the NCQDs was studied, and the result indicated that the material has high sensitivity, high precision, and good selectivity for Hg2+. The limit of detection (LOD) is 5.3 nM and the limit of quantification (LOQ) is 18.3 nM at a 99% confidence level. The cytotoxicity was evaluated using MCF7 cells, and the cell viabilities were determined to be greater than 88% upon the addition of NCQDs over a wide concentration range from 0 to 2 mg/mL. Based on the low cytotoxicity, good biocompatibility, and other revealed interesting merits, we also applied the prepared NCQDs as an effective fluorescent probe for multicolor live cell imaging.
关键词： mercury(II) ion sensing,citrus lemon juice,green synthesis,live cell imaging,fluorescent-nitrogen-doped carbon quantum dots
更新于2025-09-23 15:19:57
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Cost effective synthesis of p-type Zn-doped MgAgSb by planetary ball-milling with enhanced thermoelectric properties
摘要： A melamine-based porous organic polymer (mPMF) was synthesized as solid phase extraction (SPE) adsorbent for inline SPE-high performance liquid chromatography (HPLC)-ultraviolet detector (UV) analysis of five phytohormones. Melamine contributed to the rich π-electron and N-containing triazine structure for mPMF, which could form π-π interaction and intermolecular hydrogen bond with -COOH containing phytohormones. The synthesized mPMF adsorbent shows extremely high extraction efficiency for five target analytes (>80%) including salicylic acid, indole-3-acetic acid, abscisic acid, 2,4-dichlorophenoxyacetic acid and 1-naphthalene acetic acid. The factors affecting extraction of the target phytohormones were investigated and the optimized experimental conditions were established. The linear range was 0.2–100 μg/L for five target phytohormones. The developed method of mPMF-inline-SPE-HPLC-UV was applied for the analysis of trace target phytohormones in tomato and grape juice samples, and the recovery in the range of 83.1–116% and 87.2–121% was obtained for the spiked tomato and grape juice, respectively. This method has the advantages of high sensitivity and good reproducibility, and it has good application potential for the analysis of phytohormones in fruit samples. Moreover, inline analysis avoided the problems of sample pollution and sample loss, and provided a sample throughput of 5/h.
关键词： Phytohormones,Porous organic polymer,Fruit juice,Inline solid phase extraction,High performance liquid chromatography
更新于2025-09-19 17:15:36
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[IEEE 2019 European Space Power Conference (ESPC) - Juan-les-Pins, France (2019.9.30-2019.10.4)] 2019 European Space Power Conference (ESPC) - The JUICE Photovoltaic Assembly - from prequalification coupons to full-scale qualification model
摘要： In the frame of the JUICE (JUpiter ICy moon Explorer) mission, Leonardo Spa has been selected as PVA supplier of the Solar Array module. Due to the demanding environmental and general requirements, it was necessary to develop specific technological solutions to fulfill the low temperature, low sun intensity and very high radiation levels linked to the Jovian specific environment. The paper illustrates this development process, verified with engineering coupons and then applied to full-scale qualification model, which test campaign is currently ongoing.
关键词： Solar cell,Solar panel,qualification,Solar Array,JUICE
更新于2025-09-16 10:30:52
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Feasibility study for rapid near-infrared spectroscopic identification of different gallbladder diseases by direct analysis of bile juice
摘要： A whole-sample-covering near-infrared (NIR) spectroscopy scheme has been adopted for the simple drop-and-dry measurement of raw bile juice for the identification of gallbladder (GB) diseases of stone, polyp, and cancer. For reproducible measurement, a non-NIR absorbing polytetrafluoroethylene (PTFE) providing a hydrophobic surface was chosen as a substrate to form bile juice droplets of a consistent shape. To ensure representative spectroscopic sampling, NIR radiation illuminated the whole area of the dried sample for spectral acquisition. The NIR band shapes and relative band intensities of GB cancer differed moderately from those of GB stone and GB polyp. The composition of GB cancer samples was presumed to be dissimilar from other sample compositions. Differentiation between GB polyp and GB stone, however, was less facile; nevertheless, in the case of GB polyp samples, the obtained NIR features were informative in the identification of various pathological conditions such as adenomyomatosis (abnormal growth of epidermal tissue) and hepatitis B. To elucidate the NIR features of bile juice samples, separate NIR spectra of major bile constituents such as conjugated bile salts, lecithin, cholesterol, and albumin were analyzed. The demonstrated NIR spectroscopy scheme requiring no sample pretreatment or separation of bile juice could be useful for fast bile juice-based screening of GB diseases, especially the identification of early GB cancer.
关键词： gallbladder diseases,bile juice,drop-and-dry measurement,PTFE substrate,near-infrared spectroscopy
更新于2025-09-12 10:27:22
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The Ganymede laser altimeter (GALA): key objectives, instrument design, and performance
摘要： The Ganymede Laser Altimeter (GALA) is one of the ten scientific instruments selected for the Jupiter Icy Moons Explorer (JUICE) mission currently implemented under responsibility of the European Space Agency (ESA). JUICE is scheduled for launch in mid 2022; arrival at Jupiter will be by end of 2029 with the nominal science mission—including close flybys at Ganymede, Europa, and Callisto and a Ganymede orbit phase—ending by mid 2033. GALA’s main objective is to obtain topographic data of the icy satellites of Jupiter: Europa, Ganymede, and Callisto. By measuring the diurnal tidal deformation of Ganymede, which crucially depends on the decoupling of the surface ice layer from the deep interior by a liquid water ocean, GALA will obtain evidence for (or against) a subsurface ocean in a 500 km orbit around the satellite and will provide constraints on Ganymede’s ice shell thickness. In combination with other instruments, it will characterize the morphology of surface units on Ganymede, Europa, and Callisto providing not only topography but also surface roughness and albedo (at 1064 nm) measurements. GALA is a single-beam laser altimeter operating with up to 50 Hz (nominal 30 Hz) shot frequency at a wavelength of 1064 nm and pulse lengths of 5.5 ± 2.5 ns using a Nd:YAG laser. The return pulse is detected by an Avalanche Photo Diode (APD) with 100 MHz bandwidth and is digitized at a sampling rate of 200 MHz providing range measurements with a subsample resolution of 0.1 m and surface roughness measurements from pulse-shape analysis on the scale of the footprint size of about 50 m at 500 km altitude. The instrument is developed in collaboration of institutes and industry from Germany, Japan, Switzerland, and Spain.
关键词： Satellites of Jupiter,JUICE mission,Solar System,GALA,Ganymede,Laser Altimetry
更新于2025-09-11 14:15:04