Supercritical fluid extraction of mononitrated polycyclic aromatic hydrocarbons from tea – correlation with the PAH concentration

The ability of supercritical fluid extraction (SFE) to extract nitropolycyclic aromatic hydrocarbons (nitro-PAHs) from tea matrices is described and discussed. An experimental approach was set up to determine the influences of various extraction parameters, i.?e. pressure, temperature, extraction time and addition of modifier. The evaluation of the method was carried out by analysing samples of fortified tea and then comparing the results with those obtained from conventional extraction procedures, such as Soxhlet extraction and ultrasonication. SFE proved to be far better than the conventional methods at monitoring levels of nitro-PAHs in tea. However, due to the wide range of polarity of the analytes investigated, selective extraction with supercritical carbon dioxide was not possible; hence, subsequent purification steps were necessary, prior to the final GC/MSD analyses. The nitro-PAHs and PAHs concentrations in several tea samples were determined, any correlation between nitro-PAHs and PAHs was studied and the results are presented in this article.     

5,6-Dihydro-2,4,6-trimethyl-4H-1,3,5-dithiazine – an aroma-active compound formed in course of the Likens–Nickerson extraction

 5,6-Dihydro-2,4,6-trimethyl-4H-1,3,5-dithiazine (thialdine) is an aroma-active compound that has been isolated from different species of meat. In this study we have investigated the formation of thialdine using the simultaneous distillation–extraction according to Likens–Nickerson for the extraction of aroma compounds. Three isomers of thialdine were identified in the aroma extract of cooked and dried hen meat. It was shown that these compounds are not genuine substances from the sample examined, but that they are artefacts formed during sample preparation. Received: 30 October 1996     

Detection and activity evaluation of radical scavenging compounds by using DPPH free radical and on-line HPLC-DPPH methods

The antiradical activity of crude extracts (80% methanol, 20% water) of S. officinalis, S. glutinosa, S. sclarea and S. aethiopis was determined using the 2,2-diphenyl-1-picrylhydrazyl (DPPH·) radical scavenging method. For validation of this method several well known antioxidants (ascorbic acid-6-palmitate, gallic, chlorogenic, ferulic, caffeic, uric, gentisic and vanillic acids, catechin, quercetin, epicatechin, phloridzin, rutin and naringin) were investigated additionally. In these experiments ascorbic acid-6-palmitate had highest antiradical activity. Within the group of phenolic acids gentisic acid had the highest antiradical activity comparing with the other tested phenolic acids. Uric acid, vanillic acid, phloridzin and naringin have a much lower antiradical activity. Different reaction kinetics behaviour was observed. The validated DPPH radical scavenging method was applied to the evaluation of the antiradical activity of plant extracts. The Salvia extracts showed very high antiradical activity towards the DPPH·. An on-line HPLC-DPPH method was developed using a methanolic solution of DPPH· for a rapid detection of radical scavenging components after HPLC separation. The HPLC-DPPH on-line method was also applied to a screening of several radical scavenging components in plant extracts as well as for quantitative analysis. The HPLC analysis revealed the presence of several radical scavenging components in the all Salvia extracts. This HPLC-DPPH on-line method can also be used for quantitative determination of radical scavenging compounds.     

An analysis of the manganese supply in Austria on the basis of a selected diet

 The average daily intake of manganese by Austrians has been tested with a selected diet at 12 different locations all over Austria. A diet was made up of foodstuffs produced within a radius of 10 km from each location and calculated for a person with a body weight of 70 kg (10 700 kJ). The size of the locations was chosen in such a way that all the foodstuffs could be bought within this area. The average daily intake was 4.69 mg Mn (range: 4.39–5.66 mg Mn). The Deutsche Gesellschaft für Ern?hrung (DGE) recommends a daily intake of 2–5 mg Mn. The intake with this diet was therefore optimal according to the DGE recommendation. Received: 2 June 1998     

Antioxidant spices reduce the formation of heterocyclic amines in fried meat

 Heterocyclic aromatic amines (HAs) are mutagenic compounds that are formed during heating of meat and fish. These substances are reaction products of creatine with amino acids and carbohydrates. It is recommended that exposure to these probable human carcinogens should be minimised. Five heterocyclic aromatic amines which occur in beef were investigated: 2-amino-3-methyl-imidazo[4,5-f]quinoline (IQ), 2-amino-3,4-dimethyl-imidazo[4,5-f]quinoline (MeIQ), 2-amino-3,8-dimethyl-imidazo[4,5-f]quinoxaline (MeIQx), 2-amino-3,4,8-trimethyl-imidazo[4,5-f]quinoxaline (4,8-DiMeIQx), and 2-amino-1-methyl-6-phenyl-imidazo[4,5-b]pyridine (PhIP). Clean-up was done by acid-base partition followed by SPE using blue cotton. HPLC analysis was carried out by using electrochemical detection for IQ- and IQx-type compounds and fluorescence detection for PhIP. The concentrations of the aromatic amines were as follows: IQ, 10.2 μg/kg; MeIQ, 2.46 μg/kg; MeIQx, 13.2 μg/kg; 4,8-DiMeIQx, 2.26 μg/kg; and PhIP, 5.48 μg/kg. The application of spices (rosemary, thyme sage, garlic, brine) reduced the content of the HAs below 60% of the amount found in the control. Received: 23 April 1998     

Dünnschichtchromatographische Trennung und quantitative Direktauswertung einiger zinnorganischer Verbindungen

Rückstände zinnorganischer Verbindungen auf Futtermitteln und Lebensmitteln werden nach Isopropanol-Extraktion und Extraktreinigung über Sephadex LH-20 dünnschichtchromatographisch mit dem Laufmittel Methylisobutylketon/Pyridin/Essigsäure (97,5+1,5+1) getrennt. Die quantitative Direktauswertung auf der Platte für Fungicide vom Typ der Triphenyl- und Tricyclohexylzinnverbindungen mit Hilfe eines Chromatogrammspektralphotometers wird beschrieben.     

Versorgungszustand der ?sterreicher mit dem Spurenelement Chrom

A duplicate diet study to determine the daily chromium intake of Austrians was made. Ten probands (five women and five men) collected the same as they ate seven days running. The mean chromium intake of these probands was 34,5 g per day with a range of 28,5 g up to 44,7 g, the mean intake of the women was 31,4 g and of the men was 37,6 g. This value indicates a suboptimal supply status and shows a good agreement with an Austrian estimation of the daily dietary intake from 200 single foods.

     

Solid-phase extraction (SPE)—a comparison of 16 materials for the purification of anthocyanins from aronia melanocarpa var Nero

There is an increasing interest in anthocyanins, not only as natural food colourants but also for pharmaceutical products due to their antioxidative potential. Common extraction procedures of anthocyanins from plant material are non-selective and yield pigment solutions with large amounts of by-products such as sugars, sugar alcohols, organic acids, amino acids and proteins. Some of these impurities may accelerate anthocyanin degradation or cause problems in further processing steps such as spray drying. In order to obtain a highly concentrated and purified anthocyanin pigment from black chokeberry (Aronia melanocarpa var Nero), juices and skin extracts were purified by solid-phase extraction (SPE). Sixteen solid-phase materials were tested on a laboratory scale, whereby the anthocyanin and sugar content of collected fractions were determined to represent elution profiles. Among these, reversed-phase silica gels and macroreticular non-ionic acrylic polymer adsorbents such as Serdolit PAD IV or Amberlite XAD-7 turned out to be most suitable. SPE was investigated with these materials in an enlarged scale, improving elution gradient and column purification. Amberlite XAD-7 was successfully applied in a 36-litre-scale separation. © 1998 Society of Chemical Industry.