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  • 1
    Electronic Resource
    Electronic Resource
    Microwave-assisted extraction of free amino acids from foods (1998)
    Springer
    Zeitschrift für Lebensmittel-Untersuchung und -Forschung 207 (1998), S. 26-30 
    Details
    ISSN: 1431-4630
    Keywords: Key words Food ; Free amino acids ; Microwave-assisted extraction ; Shaking extraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  A microwave-assisted solvent extraction technique was developed for the extraction of free amino acids from foods. Four different samples were subjected to microwave extraction with varying amounts of extractant at several temperature values, for varying times to determine optimum extraction conditions. The extractions were performed with or without shaking the vessels in order to investigate the effects of mixing on the extraction efficiency and reproducibility. A comparison was made between this method and the traditional 1 h shaking extraction. The experiments indicated that the microwave-assisted extraction is an effective technique for the extraction of free amino acids from samples of plant or animal origin. The extraction yields obtained by the microwave method were about 10% better than by the conventional shaking technique. The times needed for the complete sample preparations were reduced by 66% with the application of microwaves.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002170050290
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    BIOGENIC AMINE CONTENT AND MICROBIAL CONTAMINATION OF LEAFY VEGETABLES DURING STORAGE AT 5C (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food biochemistry 17 (1993), S. 0 
    Details
    ISSN: 1745-4514
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Biogenic amine content and microbial contamination of prepacked salad mixtures and the fresh leafy vegetables Chinese cabbage (Brassica pekinensis Rupr.), endive (Cichorium endivia L.), iceberg lettuce (Lactuca sativa var. capitata) and radicchio (Cichorium intybus var. foliosum) were examined during storage at 5C for 6 days. Putrescine, histamine, spermidine, spermine and tyramine were detected in concentrations ranging from 0.1 to 17 μg/g fresh weight. Only putrescine showed a progressive increase during storage, depending on the type of leafy vegetable; its level of increase ranged from 3- to 8-fold, with the most pronounced for Chinese cabbage. A relationship seems to exist between the Enterobacteriaceae population (representing up to 90% of the total microbial numbers determined by plate count methods) and the putrescine concentration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-4514.1993.tb00483.x
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  • 3
    Electronic Resource
    Electronic Resource
    Genetic manipulation of proline levels affects antioxidants in soybean subjected to simultaneous drought and heat stresses (2005)
    Oxford, UK; Malden, USA : Munksgaard International Publishers
    Physiologia plantarum 124 (2005), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: It was assumed that the genetic manipulation of the proline (Pro) level would also affect the (homo)glutathione content as both compounds have a common precursor, glutamate. To test this hypothesis, the levels of Pro, reduced and oxidized (homo)glutathione [(h)GSH and (h)GSSG] and other antioxidants were compared under simultaneous drought and heat stress conditions and in a control treatment in a time course experiment on wild-type soybean (Glycine max cv. Ibis) and on transgenic plants containing the cDNA coding for l-Δ1-pyrroline-5-carboxylate reductase (EC 1.5.1.2), the last enzyme involved in Pro synthesis, in the sense and antisense directions. At the end of the recovery period, the highest H2O2 and lipid hydroperoxide concentrations were observed in the antisense transformants, which exhibited the greatest injury, while the lowest H2O2 content was detected in the sense transformants, which exhibited the lowest injury percentage. During stress treatment, the highest Pro and ascorbate (AA) levels were detected in the sense transformants, while the highest GSH and hGSH contents, AA/dehydroascorbate (DHA) and (h)GSH/(h)GSSG ratios and ascorbate peroxidase (APX) activity were found in the antisense transformants. The greatest APX (EC 1.11.1.11) activity was observed in the first part of the stress treatment in the antisense transformants, and the greatest glutathione reductase (EC 1.6.4.2) activity was observed in the second part of the treatment in the same genotype. The present experiments indicate that the manipulation of Pro synthesis affects not only the (h)GSH concentrations, but also the levels of other antioxidants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.2005.00504.x
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  • 4
    Electronic Resource
    Electronic Resource
    Determination of biogenic amines in leafy vegetables by amino acid analyser (1994)
    Springer
    European food research and technology 198 (1994), S. 230-233 
    Details
    ISSN: 1438-2385
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Description / Table of Contents: Abstract An automated ion-exchange Chromatographic method is described for determination of biogenic amines in leafy vegetables using a cation-exchange resin column in potassium form and a three-buffer system. The following amines were separated and quantified for Chinese cabbage, endive, iceberg lettuce and radiocchio: putrescine, histamine, cadaverine, spermidine, agmatine, spermine, tyramine. Amines from vegetable samples were extracted with 10% trichloroacetic acid. The total concentration of these amines ranged from 14 to 20 μg/g fresh weight. Spermidine was the major polyamine detected, present at concentrations of 7–15 μg/g fresh weight.
    Notes: Zusammenfassung Es wird eine Methode zur Bestimmung biogener Amine in Blattgemüse mittels automatisierter Ionenaustausch-Chromatographie beschrieben. Die Trennung erfolgte auf einer K+-Kationenaustauschersäule mit Hilfe eines Drei-Puffer-Systems. In Chinakohl, Endivie, Eisbergsalat und Radicchio sind folgende Amine bestimmt worden: Putrescin, Histamin, Cadaverin, Spermidin, Agmatin, Spermin und Tyramin. Die Extraktion erfolgte mit 10% Trichloressigsäure. Die Gesamtkonzentration biogener Amine betrug 14–20 μg/ g Frischsubstanz. Von den nachgewiesenen Polyaminen war Spermidin mit einer Konzentration von 7–15 μg Frischsubstanz am stärksten vertreten.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01192600
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  • 5
    Electronic Resource
    Electronic Resource
    Biogenic amines and microbial quality of sprouts (1995)
    Springer
    European food research and technology 200 (1995), S. 261-265 
    Details
    ISSN: 1438-2385
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Description / Table of Contents: Abstract Changes in the biogenic amine content relative to microbial activities in mung bean, lentil and radish sprouts were investigated in prepacked and “homegrown” products. Biogenic amines were determined by ion-exchange chromatography. The major groups of micro-organisms were enumerated by aerobic plate count procedures, using universal and selective media. Putrescine, cadaverine, spermidine, agmatine and spermine were detected in different concentrations, depending on the type of sprouts. In prepacked retail products the total biogenic amine content was higher than in home-grown samples (mung bean 106 ⧎g/g compared to 87 ⧎g/g; lentil 316 ⧎g/g compared to 181 ⧎g/g; radish 1486 ⧎g/g compared to 252 ⧎g/g). It is concluded that sprouting time and storage conditions play a major part in the hygienic quality of legume sprouts.
    Notes: Zusammenfassung Der Gehalt an biogenen Aminen in Mungbohnen-, Linsen- und Rettichkeimlingen in Abhängigkeit von der mikrobiellen Belastung wurde an vorverpackten Produkten des Einzelhandels und hausgezogenen Keimlingen untersucht. Die biogenen Amine wurden mit Hilfe der Ionenaustauschchromatographie, die Mikroorganismen auf universellen und selektiven Medien bestimmt. Die Konzentrationen von Putrescin, Cadaverin, Spermidin, Agmatin und Spermin waren je nach Art der Keimlinge unterschiedlich hoch. In vorverpackten Produkten aus dem Einzelhandel war der Gesamtgehalt an biogenen Aminen höher als in hausgezogenen Keimlingen (Mungbohnen: 106 bzw. 87 ⧎g/g; Linsen: 316 bzw. 181 ⧎g/g; Rettich: 1486 bzw. 252 ⧎g/g). Keimdauer und Lagerungsbedingungen beeinflussen die hygienische Qualität von Keimlingen deutlich.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01187516
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    Paper (German National Licenses)
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