Identification of low level gamma-irradiation of meats by high sensitivity comet assay

The detection of low levels of irradiation in meats (pork, beef, and chicken) using the new comet assay was investigated in order to assess the capability of the procedure. The new assay includes a process that improves its sensitivity to irradiation and a novel evaluation system for each slide (influence score and comet-type distribution). Samples used were purchased at retailers and were irradiated at 0.5 and 2 kGy at 0°C. The samples were processed to obtain comets. Slides were evaluated by typing comets, calculating the influence score and analyzing the comet-type distribution chart of shown on the slide. Influence scores of beef, pork, and chicken at 0 kGy were 287(SD=8.0), 305 (SD=12.9), and 320 (SD=21.0), respectively. Those at 500 Gy, were 305 (SD=5.3), 347 (SD=10.6), and 364 (12.6), respectively. Irradiation levels in food were successfully determined. Sensitivity to irradiation differed among samples (chicken>pork>beef).     

The Impact of Grape Varieties to Wine Isotopic Characterization

This paper highlights the results of a study regarding the impact of geo-climatic conditions, the influence of grape varieties, and harvest year on the isotopic characterization of a wine from a specific vineyard area, using stable isotope ratio analysis by continuous flow mass spectrometry CF-IRMS. This analytical technique has made a significant contribution on wine characterization, by proving the botanical and geographical origin of the wine raw material.

A great variability was observed to sap ¹⁸O and ²H isotopic ratios for different types of vine (Vitis vinifera plant) from the studied area, Dealu Mare-Valea Calugareasca, reflecting the significant influence of variety on isotopic features. On the other hand, the comparison of stable isotopic fingerprints for rainfall water and sap revealed a close approximation value for ¹⁸O isotopic ratio, and an insignificant variation coefficient of ¹³C isotopic ratio in wine varieties (about 2.85%).

The results of isotopic characterization for grape vine sap and original wines for different varieties existing in Dealu Mare-Valea Calugareasca vineyard indicates the relevance of meteorological and viticulture parameters like precipitation, date of vintage, and grape cultivar for wine authentication process.     

Magnetic Stirring-Assisted Dispersive Suspended Microextraction with Solidification of a Floating Organic Droplet for the Determination of Trace Fungicides in Water and Wine

For the first time, a simple method for magnetic stirring-assisted dispersive suspended microextraction has been developed for the determination of three fungicides (azoxystrobin, diethofencarb, and pyrimethanil) in water and wine samples. The method is based on the solidification of a floating organic droplet coupled with high performance liquid chromatography. In the proposed method, the low toxicity solvent 1-dodecanol was used as the extractant. Both the extraction and phase separation process were performed with magnetic stirring. No centrifugation step was involved. After separating the two phases, the extraction solvent droplet was easily collected through solidification at lower temperature. Important parameters such as the kind and volume of organic extraction solvent, extraction and restoration speed, extraction and restoration time, and salt concentration were optimized. Under the optimal conditions, the limits of detection for the analytes varied from 0.14 to 0.26 µg L^?1. The enrichment factors ranged from 125–200. The linearity ranges were 1–2000 µg L^?1, yielding correlation coefficients (r) higher than 0.9990. The relative standard deviation (n = 6) at two spiked level of 0.2 µg mL^?1 and 4 µg L^?1 varied between 2.2% and 7.8%. Finally, the developed technique was successfully applied to determine target fungicides in real water and wine samples, where the obtained recoveries ranged from 83.8–105.3%     

Identification and Quantitation of Hydroxytyrosol in Italian Wines

Hydroxytyrosol (HTy) is a potent natural antioxidant found in olive oil and in mill waste waters. Although wines are rich in polyphenols, hydroxytyrosol has not been identified in wines so far. We have analyzed ten wines from different grape varieties grown in several Italian regions, using a gas-chromatograph coupled to a mass selective detector (GC-MS). Solid-phase extraction of wine samples was performed on a C18 column, with ethyl acetate used as eluting agent. Eluates were derivatized with bis(trimethylsilyl)trifluoroacetamide (BSTFA) and analyzed by GC-MS using one target and two qualifying ions. The detection limit was 15 pg/μL, with 49% average recovery. Under these experimental conditions hydroxytyrosol was detected in all wines analyzed. Its average concentrations in red and white wines were 4.0 mg/L and 1.9 mg/L, respectively.     

ESR spectroscopy for detecting gamma-irradiated dried vegetables and estimating absorbed doses

In view of an increasing demand for food irradiation technology, the development of a reliable means of detection for the control of irradiated foods has become necessary. Various vegetable food materials (dried cabbage, carrot, chunggyungchae, garlic, onion, and green onion), which can be legally irradiated in Korea, were subjected to a detection study using ESR spectroscopy. Correlation coefficients (R²) between absorbed doses (2.5–15 kGy) and their corresponding ESR signals were identified from ESR signals. Pre-established threshold values were successfully applied to the detection of 54 coded unknown samples of dried clean vegetables (chunggyungchae, Brassica camestris var. chinensis), both non-irradiated and irradiated. The ESR signals of irradiated chunggyungchae decreased over a longer storage time, however, even after 6 months of ambient storage, these signals were still distinguishable from those of non-irradiated samples. The most successful estimates of absorbed dose (5 and 8 kGy) were obtained immediately after irradiation using a quadratic fit with average values of 4.85 and 8.65 kGy being calculated.     

Detection of irradiation treatment of foods using DNA ‘comet assay’

Microgel electrophoresis of single cells (DNA comet assay) has been investigated to detect irradiation treatment of some food samples. These samples of fresh and frozen rainbow trout, red lentil, gram and sliced almonds were irradiated to 1 or 2 kGy using 10 MeV electron beam from a linear accelerator. Rainbow trout samples yielded good results with samples irradiated to 1 or 2 kGy showing fragmentation of DNA and, therefore, longer comets with no intact cells. Unirradiated samples showed shorter comets with a significant number of intact cells. For rainbow trout stored in a freezer for 11 days the irradiated samples can still be discerned by electrophoresis from unirradiated samples, however, the unirradiated trouts also showed some longer comets besides some intact cells. Radiation treatment of red lentils can also be detected by this method, i.e. no intact cells in 1 or 2 kGy irradiated samples and shorter comets and some intact cells in unirradiated samples. However, the results for gram and sliced almond samples were not satisfactory since some intact DNA cells were observed in irradiated samples as well. Probably, incomplete lysis has led to these deviating results.     

Optimization and validation of a method for the direct determination of catechin and epicatechin in red wines by HPLC/fluorescence

The present paper describes a direct procedure for the determination of catechin and epicatechin concentrations in red wines employing reverse-phase high performance liquid chromatography (RP HPLC) and detection by fluorescence. The method was performed using a sample volume of 10 µL without dilution. The separation process employed a Chromolith performance RP-18e (100 mm × 4.6 mm) column, and the mobile phase was composed of solvent A: methanol-acetic acid-water (90:8:2) and solvent B: water-acetic acid-methanol (10:2:88) at a flow rate of 1.0 mL min^− 1. Linearity was observed in the range of 1 to 30 mg L^− 1, with limits of detection and quantification of 0.27 and 0.89 mg L^− 1, respectively, for catechin and 0.33 and 1.01 mg L^− 1, respectively, for epicatechin. The precisions estimated by the relative standard deviation were 3.34 and 1.09% for catechin concentrations of 0.5 and 20 mg L^− 1 respectively and 2.82 and 0.49% for epicatechin concentrations of 0.5 and 20 mg L^− 1, respectively. The evaluation of the accuracy was done using an addition/recovery assay. Four wine samples were used, and the recoveries varied from 105 to 108% for catechin and from 97 to 119% for epicatechin. The method was applied to the analysis of red wine samples collected from the São Francisco region, Bahia State, Brazil. Nine samples were analyzed, and the catechin and epicatechin concentrations varied from 7.51 to 73.20 and from 5.08 to 43.32 mg L^− 1, respectively. The concentrations found agree with data reported in the literature.     

Ultrasound-assisted dispersive liquid–liquid microextraction combined with high-performance liquid chromatography-fluorescence detection for sensitive determination of biogenic amines in rice wine samples

Ultrasound-assisted dispersive liquid–liquid microextraction coupled with high-performance liquid chromatography-fluorescence detection was used for the extraction and determination of three biogenic amines including octopamine, tyramine and phenethylamine in rice wine samples. Fluorescence probe 2,6-dimethyl-4-quinolinecarboxylic acid N-hydroxysuccinimide ester was applied for derivatization of biogenic amines. Acetonitrile and 1-octanol were used as disperser solvent and extraction solvent, respectively. Extraction conditions including the type of extraction solvent, the volume of extraction solvent, ultrasonication time and centrifuging time were optimized. After extraction and centrifuging, analyte was injected rapidly into high-performance liquid chromatography and then detected with fluorescence. The calibration graph of the proposed method was linear in the range of 5–500 μg mL⁻¹ (octopamine and tyramine) and 0.025–2.5 μg mL⁻¹ (phenethylamine). The relative standard deviations were 2.4–3.2% (n = 6) and the limits of detection were in the range of 0.02–5 ng mL⁻¹. The method was applied to analyze the rice wine samples and spiked recoveries in the range of 95.42–104.56% were obtained. The results showed that ultrasound-assisted dispersive liquid–liquid microextraction was a very simple, rapid, sensitive and efficient analytical method for the determination of trace amount of biogenic amines.     

Characterization and Potential Applications of Immobilized Glucose Oxidase and Polyphenol Oxidase

Pyrrole functionalized polystyrene (PStPy) was copolymerized with pyrrole to obtain a conducting copolymer, P(PStPy‐co‐Py) which is used as the immobilization matrix. Glucose oxidase and polyphenol oxidase enzymes were immobilized via the entrapment method by electrochemical polymerization. Enzyme electrodes were prepared by electrolysis at a constant potential using sodium dodecyl sulfate (SDS) as the supporting electrolyte during the copolymerization of PStPy with pyrrole. Maximum reaction rates (V_max) and enzyme affinities (Michaelis‐Menten constants, K_m) were determined for the enzyme entrapped both in polypyrrole (PPy) and P(PStPy‐co‐Py) matrices. Optimizations of enzyme electrodes were done by examining the effects of temperature and pH on enzymes' activities along with the shelf life and operational stability investigations. Glucose oxidase enzyme electrodes were used for human serum analysis and glucose determination in two brands of orange juices. Polyphenol oxidase enzyme electrodes were used for the determination of phenolics in red wines of Turkey.     

酒中甲醇的离子排斥色谱-脉冲安培法测定

建立了离子排斥色谱-脉冲安培法测定酒中甲醇的检测方法。方法使用IonPac ICE-AS6离子排斥柱,以45 mmol/L HClO4为淋洗液,脉冲安培法检测（工作电极为Pt电极）。甲醇的检出限为0.03 mg/L（50μL进样,3倍基线噪音）;在7.9～158 mg/L范围内方法具有良好的线性（r=0.9990）。79 mg/L甲醇标准连续进样9次,峰面积相对标准偏差（RSD）为2.82%。用该方法检测了多种酒样中的甲醇含量,其加标回收率为91%～104%。