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  • 1
    Electronic Resource
    Electronic Resource
    Non-starch polysaccharides of tomatoes I. Characterizing pectins and hemicelluloses (1999)
    Springer
    European food research and technology 209 (1999), S. 43-46 
    Details
    ISSN: 1438-2385
    Keywords: Key words Tomatoes ; Methanolysis ; Polysaccharides ; Pectins ; Hemicelluloses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  For analysing the non-starch polysaccharides (NSP) of tomatoes, the alcohol-insoluble solids were fractionated using water, EDTA solution and sodium hydroxide solution, and the sugar and uronic acid components were determined by capillary gas chromatography. Highest yields of monosaccharides were obtained when the pectin and cellulose fractions were treated with methanesulfonic acid prior to methanolysis by diluting with methanol and heating to 100  °C for 2 h. However, treatment with concentrated formic acid followed by methanolic hydrochloric acid was best suited for the hemicellulose fractions. In this way, 81% of total tomato NSP (5.1 g/kg fresh weight) were characterized for their monosaccharide pattern. Free and associated pectins amounted to 28%, xyloglucans and other hemicelluloses to 30% and cellulose to 23%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002170050454
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Non-starch polysaccharides of tomatoes II. Influence of thermal processing (1999)
    Springer
    European food research and technology 209 (1999), S. 47-51 
    Details
    ISSN: 1438-2385
    Keywords: Key words Tomatoes ; Tomato processing ; Polysaccharides ; Pectins ; Hemicelluloses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  A series of samples was taken from different stages of an industrial production process for tomato purée and was analysed for the contents and composition of the non-starch polysaccharides (NSP). The NSP were fractionated into the pectins, hemicelluloses and cellulose groups. All fractions were methanolysed to give their sugar and uronic acid percentages and were characterized for the maxima of their molar mass distributions. During the hot-break of tomatoes, the pectins and cellulose were reduced considerably by enzymatic degradation, owing to the action of tomato polygalacturonases and cellulases. Anion exchange chromatography of the pectins showed a simultaneous demethylation by pectinmethylesterases. Keeping the tomato pulp for 10 min at 100  °C caused additional NSP losses by hydrolysis and/or ß-elimination. The hemicelluloses were affected only to a minor extent and showed no essential alterations. Some of the pectins were removed by squeezing off some liquid serum from the pulp, but a tomato purée with the desired high-molecular pectins was left behind. However, a substantially improved texture quality is expected when the loss of NSP is avoided by a more effective deactivation of the enzymes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002170050455
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    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Solid-phase extraction for replacing dichloromethane partitioning in pesticide multiresidue analysis (1999)
    Springer
    Zeitschrift für Lebensmittel-Untersuchung und -Forschung 208 (1999), S. 259-263 
    Details
    ISSN: 1431-4630
    Keywords: Key words Residue analysis ; Pesticides ; Fruits and vegetables ; Plant material ; Solid-phase extraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  The Deutsche Forschungsgemeinschaft S 19 method is widely used for pesticide multiresidue analysis in crops. It includes a liquid-liquid partition step with dichloromethane, which is undesirable for toxicological and ecological reasons. Therefore, this step was replaced by a solid-phase extraction (SPE) of the diluted acetone extract with a mixture of RP-18-PolarPlus and cyano material, which was afterwards eluted with ethyl acetate. Using this novel approach for extraction, concentration and clean-up, the recovery rates from fruits and vegetables fortified with 0.12–0.48 mg/kg of 31 pesticides with different chemical structures and polarities averaged 80% in most cases, except for some extremely polar compounds. The variation coefficients observed were near 5%. Compared to the partitioning step used hitherto, even higher recoveries were obtained by SPE for non-polar and medium-polar pesticides. In addition, the gas chromatograms often showed fewer interfering peaks from plant coextractives.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002170050413
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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