Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Carotenes in processed tomato after thermal treatment
    Luterotti, S. ; Bicanic, D.D. ; Markovic, K. ; Franko, M. - \ 2015
    Food Control 48 (2015). - ISSN 0956-7135 - p. 67 - 74.
    maillard reaction-products - beta-carotene - lycopene degradation - antioxidant activity - human health - food - stability - puree - storage - isomerization
    This report adds to the ongoing vivid dispute on the fate of carotenes in tomato upon thermal processing. Although many papers dealing with changes in the raw tomatoes during industrial treatment have already appeared, data on the fate of finished, processed tomato products when they are additionally heated (e.g., when used in the household) is scarce. In this study, effects of heating and storage on a commercial, double concentrated tomato purée were examined spectrophotometrically. Our results indicate that upon exposing unopened cans with double concentrated tomato purée to thermal treatments between 100 and 135 °C during specific time intervals spectral profile of lycopene remained preserved. Likewise, a slight hypsochromic shift of lycopene peak III did not occur up to 135 °C. However, significant (20%) initial loss of lycopene content was induced by thermal treatment for 20 min at 100 °C. During the more intensive treatments that followed the lycopene content was first leveling off and then slightly increased. After storage of thermally treated samples at -18 °C the content of lycopene was found to increase. All these results suggest simultaneous working of several mechanisms: possible auto-oxidation and isomerization processes of carotenes taking place, in addition to the Maillard reaction and enhanced extractability of carotenes at increased temperatures. Results acquired from hexane solutions of samples treated at temperatures of 120 and 135 °C obtained at different time points, confirmed severe isomerization in organic solvent and/or photo-oxidative degradation of lycopene.
    Comparison of spectrophotometric and HPLC methods for determination of carotenoids in foods
    Luterotti, S. ; Markovic, K. ; Franko, M. ; Bicanic, D.D. ; Madzgalj, A. - \ 2013
    Food Chemistry 140 (2013)1-2. - ISSN 0308-8146 - p. 390 - 397.
    beta-carotene - human health - tomato fruits - lycopene - maize - extraction - products
    This report is aimed at intra-laboratory and inter-laboratory comparison of the results obtained during spectrophotometric and HPLC analyses of lycopene, ß-carotene and total carotenoids in tomato products and yellow maize flours/grits. Extensive statistical analyses are performed in order to identify the main sources of uncertainties which may occur when using: (i) different techniques/methods/approaches in the same/different laboratories, in various food samples, and (ii) to indicate the facts/conditions under which the biases between results may remain unidentified after applying statistical testing. Our data points to the inertness of t-test to detect significance of differences, particularly at low R values: in general, the higher correlation coefficient, the higher is sensitivity of statistical testing, especially of the paired t-test. Therefore, simple deviation of relationship line slope from unity could be used as additional evaluation parameter. This adds to reliable and objective quality assurance of foods in regard to carotenoids.
    Separation and direct detection of long chain fatty acids and their methylesters by the non-aqueous reversed phase HPLC and Silver Ion Chromotography, combined with CO laser pumped thermal lens spectrometry
    Bicanic, D.D. ; Mocnik, G. ; Franko, M. ; Niederlander, H.A.G. ; Bovenkamp, P. van de; Cozijnsen, J.L. ; Klift, E.J.C. van der - \ 2006
    Instrumentation Science and Technology 34 (2006)1-2. - ISSN 1073-9149 - p. 129 - 150.
    performance liquid-chromatography - beta-carotene - lipids - triacylglycerols - deflection - oils
    The potential of the CO laser pumped dual beam thermal lens spectrometer (TLS) used as the detector of infrared (IR) absorbance in non-aqueous reversed-phase high pressure liquid chromatography (NARP-HPLC) and argentation chromatography (Ag-HPLC-TLS) has been investigated. The linoleic acid C18:2 (9,11) cis, cis, the conjugated linoleic acid C18:2 (9,12) cis, cis, and (9,11) cis, cis and oleic acid C18:1 (9) cis free fatty acids present in the test mixture were separated and detected by NARP-HPLC-TLS directly, i.e., without a need for their prederivatization. The limit of detection (LOD) for the present NARP-HPLC-TLS set-up was determined using either oleic acid C18:1 (9) cis or linoleic acid C18:2 (9,12) cis, cis as the only analyte. The LOD obtained at 1750 cm-1 for C18:2 (9,12) cis, cis is 0.14% (v/v) with the standard deviation being 3.8% of the measured value. This is comparable to the LOD attainable by the bulk property refractive index detector (RID). For C18:1 (9) cis the LOD is 0.04% (v/v) with a standard deviation of 2.5%. The unique feature of the NARP-HPLC-TLS is its excellent selectivity; this was demonstrated experimentally by adding alcohols (octanol and decanol) that lack the C&dbnd;O carbonyl group to the aforementioned mixture of three fatty acids. In another experiment, the Ag-HPLC-TLS in IR was used to directly detect two different mixtures of five fatty acid methyl esters (FAMEs) after separation on the column. The results were compared to those achieved by the conventional UV absorbance detector. Despite more favourable excitation cross sections of FAMEs in the IR, the concentration LOD obtained for Ag-HPLC-TLS is inferior to that of the Ag-HPLC-UV. However, the mass LOD (11 µg) achieved by Ag-HPLC-TLS in IR for C18:3 FAME is two times better than that of the Ag-HPLC-UV absorbance detector. High IR absorption of eluent restricts, at present, the sensitivity of the Ag-HPLC-TLS and NARP-HPLC-TLS. Improved LOD's are anticipated by a judicious choice of the mobile phase and after materialising several modifications of the experimental set-up.
    Homopteran insects from the collection of E.-F. Germar in the Zoological museum of LNU (Catalogue)
    Holovachov, O.V. - \ 2005
    Lviv : Ivan Franko National University - 80 p.
    Ultratraces of carotenes in tomato purees : HPLC-TLS study
    Luterotti, S. ; Markovic, K. ; Franko, M. ; Bicanic, D.D. ; Vahcic, N. ; Doka, O. - \ 2003
    Review of Scientific Instruments 74 (2003)1. - ISSN 0034-6748 - p. 684 - 686.
    performance liquid-chromatography - thermal lens detection - trans-beta-carotene - ultrasensitive determination - lycopene - isomers - oxygen
    The present study was designed to provide information about (i) the profile of carotene pigments and (ii) trace quantities of lycopene and -carotene left in tomato purées. The ultrasensitive method comprising HPLC and thermal lens spectrometric (TLS) detection enabled us to detect as low as 0.3 and 1.1 ng ml¿1 lycopene and -carotene in purée extracts, respectively. Total concentration of -carotene and lycopene (varying from 3 to 170 ng g¿1) in the examined tomato purées may serve as an indicator of the carotene-specific antioxidative capacity of these products. Although conventional spectrophotometry can be used to rapidly assess the quality of products derived from tomatoes, a highly sensitive and selective method such as HPLC-TLS is needed for reliable analyses of samples such as, for example, those subjected to inappropriate storage and/or handling
    Carotenoids in some mediterrenean foodstuffs : HPLC-TLS studies
    Luterotti, S. ; Franko, M. ; Bicanic, D. ; Markoviv, K. ; Vahcic, N. - \ 2002
    In: MBCAC IV : 4th Mediterrenean Basin Conference on Analytical Chemistry, Portoroz, Slovenia / Veber, M., Portoroz, Slovenia : - p. 205 - 205.
    Ultrasensitive assays of trans- and cis-beta-carotenes in vegetable oils by high-performance liquid chromatography-thermal lens detection
    Luterotti, S. ; Franko, M. ; Sikovec, M. ; Bicanic, D. - \ 2002
    Analytica Chimica Acta 460 (2002)2. - ISSN 0003-2670 - p. 193 - 200.
    Fast quality screening of vegetable oils by HPLC-thermal lens spectrometric detection
    Luterotti, S. ; Franko, M. ; Bicanic, D. - \ 2002
    Journal of the American Oil Chemists Society 79 (2002)10. - ISSN 0003-021X - p. 1027 - 1031.
    Isocratic reversed-phase HPLC with thermal lens spectrometric (TLS) detection enabled identification of linseed, olive, sesame, and wheat germ vegetable oils to control the authenticity of the oils based on characteristic carotenoid/carotene profiles. Four characteristic regions of carotenoids (i.e., lutein, xanthophyll, carotene, and lycopene) have been identified in each type of oil. The concentrations of total β-carotene (BC) and α-carotene (AC), together with trans- to cis-isomers of β-carotene (TBC/CBC) and BC/AC ratios were shown to be reliable and useful indices for fast screening of oils for nutritional quality. The oil TBC/CBC ratio and the BC concentration (in μg/mL) should meet the following numerical criteria: linseed (≥2:1, ≥1.7), olive (≥3:1, ≥0.4), sesame (≥1:1, ≥0.1), and wheat germ oil (≥1:1, ≥1.7). Based on the above criteria, unsatisfactory olive oils differed significantly from the consumable ones. Likewise, the concentration of AC in consumable wheat germ and sesame oil should not be lower than 0.6 and 0.02 μg/mL, respectively. The AC level in saf-flower oil should not be higher than 0.04 μg/mL. The BC/AC ratios exceeding 3:1, 6:1, and 8:1 should be used as an additional quality requirement for consumable wheat germ, sesame, and saf-flower oil, respectively.
    Investigation of Carotenoid Patterns in Tomato and Orange Juices by Hyphenated HPLC-Thermal Lens Spectrometry
    Sikovec, M. ; Franko, M. ; Bicanic, D. ; Veber, M. - \ 2001
    In: Book of Abstracts : 12th International DAC/FECS Symposium: Spectroscopy in Theory and Practice, Bled (Slovenie), 2001. - Bled : [s.n.], 2001 - p. 47 - 47.
    Thermal lens spectrometry in food analysis and environmental research
    Franko, M. ; Sikovec, M. ; Kozar-Logar, J. ; Bicanic, D. - \ 2001
    Analytical Sciences 17 (2001). - ISSN 0910-6340 - p. S515 - S518.
    Assessing the Extent of Oxidation in Thermally Stressed Vegetable Oils. Part l: Optical Characterization by Photothermal and Some Conventional Physical Methods
    Bicanic, D. ; Doka, O. ; Luterotti, S. ; Bohren, A. ; Sikovec, M. ; Veldhuizen, B. van; Berkessy, O. ; Chirtoc, M. ; Franko, M. ; Szabo, G. ; Sigrist, M. - \ 2001
    Analytical Sciences 17 (2001). - ISSN 0910-6340 - p. 547 - 549.
    Evaluating Thermo-Oxidative Stability of Safflower Oil by Conventional and Photothermal Methods
    Bicanic, D. ; Doka, O. ; Kantor, Z. ; Bohren, A. ; Dadarlat, D. ; Berkessy, O. ; Franko, M. - \ 2000
    In: Book of Abstracts, 11th Topical International Meeting on PA and PT Phenomena, Kyoto, Japan, June 25-29, 2000. - Kyoto, Japan : Kyoto University Press, 2000 - p. 1 - 1.
    Ultrasensitive Determination of Trans-beta Carotene in Fish Oil Based Supplementary Drugs by HPLC/TLS
    Luterotti, S. ; Franko, M. ; Bicanic, D. - \ 1999
    Journal of Pharmaceutical and Biomedical Analysis 21 (1999). - ISSN 0731-7085 - p. 901 - 999.
    Infrared Photothermal Spectroscopy in the Science of Human Nutrition
    Bicanic, D. ; Fink, T. ; Franko, M. ; Mocnik, G. ; Bovenkamp, P. van de; Veldhuizen, A. van; Gerkema, E. - \ 1999
    In: Photoacoustic and Photothermal Phenomena / Scudieri, F., Bertolotti, M., Woodburry, New York : American Institute of Physics (American Institute of Physics (AIP) Conference Proceedings 463) - ISBN 9781563968051 - p. 637 - 639.
    Some Laser Based Photothermal Methods and Their Applications for Optical and Thermal Characterisation of Lipids
    Bicanic, D. ; Franko, M. ; Mocnik, G. ; Dadarlat, D. ; Sikovec, M. ; Niederlander, H. ; Bovenkamp, P. van der; Lutteroti, S. ; Gibkes, J. ; Klift, E. van der; Bogoni, P. ; Cerni, L. ; Procedda, G. - \ 1999
    In: Proceedings of 23rd World Congress of the International Society for Fat Research (ISF), October 3-7, 1999, Brighton, England. - Champaign, Illinois, USA : American Oil Chemical Society (AOCS) Press, 1999. - ISBN 1-893997-08-1 - p. 77 - 78.
    Determination of trans-beta carotene and other carotenoids in blood plasma using HPLC and thermal lens detection.
    Franko, M. ; Bovenkamp, P. van de; Bicanic, D. - \ 1998
    Journal of chromatography. B, Biomedical sciences and applications 718 (1998). - ISSN 1387-2273 - p. 47 - 54.
    Determination of carotenoids by HPLC-TLS.
    Franko, M. ; Luterotti, S. ; Bovenkamp, P. van de; Bicanic, D. - \ 1998
    In: 5th International Conference Chromatography and Hyphenated Techniques, Bled - p. 133 - 133.
    Photoacoustic study of in-depth distribution of compounds on TLC plates affected by secondary chromatography.
    Vovk, I. ; Franko, M. ; Gibkes, J. ; Prosek, M. ; Bicanic, D. - \ 1998
    In: Proceedings of OJI International Seminar on Photothermal Phenomena and Their Applications, Sapporo, Japan - p. 255 - 258.
    Photoacoustic study of the in-depth distribution of compounds on TLC plates affected by drying conditions.
    Vovk, I. ; Franko, M. ; Gibkes, J. ; Prosek, M. ; Bicanic, D. - \ 1998
    In: 10th International Conference on Photoacoustic and Photothermal Phenomena, Rome, Italy - p. 549 - 549.
    Application of infrared photothermal spectroscopy in human nutrition.
    Bicanic, D. ; Fink, T. ; Franko, M. ; Bovenkamp, P. van de; Veldhuizen, B. van; Gerkema, E. - \ 1998
    In: 10th International Conference on Photoacoustic and Photothermal Phenomena, Rome, The Netherlands - p. 513 - 514.
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