Werner Pfannhauser

Urinary excretion of cyanidin glycosides

Anthocyanins, which are natural plant pigments from the flavonoid family, represent substantial constituents of the human diet. Several fruits (blackcurrant, blue berries, red grape and elderberry) are rich sources of these efficient antioxidant compounds. The present study was designed to determine the potential bioavailability in humans of the anthocyanins of elderberry, mainly cyanidin-3-glucoside and cyanidin-3-sambubioside, and the influence of the simultaneous ingestion of sucrose on the absorption of anthocyanins. Urinary samples from 16 healthy volunteers--8 women and 8 men--were collected before and over a period of 6 h with intervals of 1 h after the ingestion of 11 g elderberry concentrate (containing 1.9 g of anthocyanins equivalent to 235 ml of fresh juice) 1 day diluted with water, the other day with 30 g sucrose. Using high-performance liquid chromatography, it was possible to quantify the two main anthocyanins of elderberry excreted unchanged in the urine (0.003-0.012% of the oral dose). The ingestion of sucrose led to a reduced excretion of anthocyanins.

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.

Variability of fatty acid content in pumpkin seeds (Cucurbita pepo L.)

Pumpkin (Cucurbita pepo L.) seed oil is a common salad oil which is produced in Slovenia, Hungary and the southern parts of Austria. It is dark green and has a high content of free fatty acids. The seed itself can be eaten. Due to its colour and the foam formation, the oil cannot be used for cooking. The content of vitamin E, especiallyγ-tocopherol, is very high. The oil content of the pumpkin seed is about 50%. The variability in the oil content is very high resulting from a broad genetic diversity. Thus a breeding programme for increasing the oil productivity is very promising. The four dominant fatty acids are palmitic, stearic, oleic and linoleic acids. These four fatty acids make up 98±0.13% of the total amount of fatty acids, others being found at levels well below 0.5%.

Variability of vitamin E content in pumpkin seeds (Cucurbita pepo L.).

Pumpkin (Cucurbita pepo L.) seed oil is a common salad oil which is produced in the southern parts of Austria, Slovenia and Hungary. It is dark green and has a high content of free fatty acids. Due to its colour, the oil cannot be used for cooking. The content of vitamin E, especiallyγ-tocopherol, is very high. The oil content of the pumpkin seed is about 50%. The seed itself can be eaten. Therefore a pumpkin variety with high vitamin E content is desirable. The aim of this work was to find a variety ofCucurbita pepo which has a high oil yield and a high vitamin E content. A total of 100 breeding lines were tested for their tocopherol content. The tocopherols and tocotrienols are extracted with hexane and analysed by NP-HPLC/FLD with hexane/dioxan (96/4) as eluent, with fluorescence detection at 292/335 nm. The/gg-tocopherol content, which is about 5–10 times as much as that of α-tocopherol varies over a broad range (41–620 mg/kg dry pumpkin seeds).β- andδ-tocopherol are found at low levels.

Formation of the food associated carcinogen 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) in model systems

Abstract Food-related mutagens play a major role in human carcinogenesis. Heterocyclic aromatic amines which are formed in meat or fish during cooking contribute to food-related carcinogenesis, at least in rodents. The mechanism of formation of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) was clarified by using 13 C-labelled phenylalanine as a reaction partner in a model system containing additionally creatinine. Isolation of the labelled reaction product (PhIP) and 13 C-NMR experiments showed that the carbon atoms of phenylalanine form a part of the pyridine moiety. Carbon atoms C-5, C-6 and C-7 in PhIP originated quantitatively from phenylalanine, leading to the conclusion that PhIP is formed by a defined mechanism and that two phenylalanine molecules are needed to form PhIP in this model system. In the proposed mechanism phenylacetaldehyde plays a key role which undergoes an aldol condensation with creatinine. The six-membered pyridine ring is completed by formation of a Schiff’s base and cyclisation.

Stability of pumpkin seed oil

In Austria pumpkins are grown primarily for the production of pumpkin seeds that can be used for eating or the production of salad oil. Pumpkin seed oil is dark green and its fatty acid composition consists typically of linoleic acid and oleic acid as the dominant fatty acids. The saturated fatty acids palmitic and stearic acid occur at lower levels. The samples for this study were taken from a breeding program that intends to increase the seed and oil productivity. 15 samples with different contents of linoleic acid (40—57%) and vitamin E (100—600 μg/g) were selected. The stability of the oil was measured in a Rancimat that oxidizes the oil at 120 ?C and measures the induction time that is needed for the oxidation. The correlation analysis showed that only the ratio of linoleic acid to oleic acid had a significant influence on the oxidative stability of the oil. Vitamin E did not show any correlation. When α-tocopherol was added to the oil a strong pro-oxidative effect was observed.

Effects of industrially produced flavours with pro- and antioxidative properties on the formation of the heterocyclic amine PhIP in a model system.

PhIP (2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine) is a heterocyclic aromatic amine belonging to a class of mutagens found in food. This project studied the effects of commercially available flavours of spices on the formation of PhIP, one of the most common heterocyclic aromatic amines in heated meat and fish products. The model reactions were carried out in diethylene glycol. Highest amounts of PhIP were obtained at 200 degrees C, a heating time of 60 min and an equivalent molar ratio of phenylalanine and creatinine. With this model system, the influence of Monascus red and flavours extracted from thyme, marjoram and rosemary on the formation of PhIP was tested. The flavours were added to the model system in different amounts. The oxidative properties were determined with the rancimat method. It was shown that all tested products, independent of their pro- or antioxidative properties, increased PhIP in the model system.

Untersuchung über den Gehalt biogener Amine in vier Gruppen von Lebensmitteln des österreichischen Marktes

SummaryThis article summarizes the results of an investigation into the content of seven biogenic amines in wine, cheese, fish and dry fermented sausages. 160 samples were investigated. Highest content of amines was recovered in fermented sausages, but some samples of cheese e.g. “Emmentaler type” also showed high content of histamine. Frozen, as well as pickled fish were low in biogenic amines, but high contents of amines were found in some smoked mackerel samples. Austrian red wine did not contain an appreciable content of amines.ZusammenfassungDie vorliegende Arbeit berichtet über den Gehalt von sieben biogenen Aminen in insgesamt 160 Proben von Wein, Käse, Fisch and Rohwürsten. Danach stellen Rohwürste die aminreichste Lebensmittelgruppe dar, während Käse nur in Einzelfällen (z. B. Emmentaler) durch ihren Histamingehalt auffielen. Tiefgekühlte Fische sowie marinierte Fische erwiesen sich als aminarm, während in geräucherten Makrelen vereinzelt hohe Amingehalte auftraten. Österreichischer Rotwein enthielt keine beachtenswerten Amingehalte.

Key odourants of pressure-cooked hen meat

Abstract The volatile aroma compounds of pressure-cooked hen meat isolated by simultaneous distillation-extraction and extraction-high vacuum distillation were investigated by GC/MS and GC-olfactometry. We found out that 2-furfuryl thiol, 3-(methylthio)propanal, 4-hydroxy-2,5-dimethyl-3(2H)-furanone, (E,E)-2, 4-decadienal, 2-methyl-3-furanthiol and 2-ethyl-3,5-dimethyl pyrazine are the most potent odourants of the pressure-cooked hen meat. We assume that aroma-active compounds such as 2,4,6-trimethyltetrahydro-1,3,5-thiadiazine, 3,5-dime-thyl-1, 2,4-trithiolane, 5,6-dihydro-2,4,6-trimethyl-4H-1,3,5-dithiazine and some unknown compounds, which could only be found in extracts obtained by simultaneous distillation-extraction, are artefacts formed during this isolation process.

Qualitative und Quantitative Analyse der Anthocyane in Schwarzen Apfelbeeren (Aronia melanocarpa Michx. Ell.) mittels TLC, HPLC und UV/VIS-Spektrometrie

Total anthocyanin content and qualitative and quantitative anthocyanin composition in black chokeberries [Aronia melanocarpa (Michx.) Elliott] were determined by TLC, HPLC and UV/VIS methods. After ethanol extraction and cleaning operations we found, in different varieties of black chokeberries (Nero, Rubina and Viking), between 650 mg and 850 mg total anthocyanins per 100 g dry weight. The anthocyanin composition was analysed; (cyanidin was the only aglycon (anthocyanidin) found and the monosaccharides galactose (68.9%), arabinose (27.5%), xylose (2.3%) and glucose (1.3%) were identified. The quantitative distribution is given in parentheses. In comparison with other berries and fruits, which are rich in anthocyanins, black chokeberries have a simple anthocyanin spectrum, but a many times higher anthocyanin content. For that reason chokeberries are of special interest as a source for a natural colourant.