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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 57 (1992), S. 0 
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new approach, alternative to currently available methods, for studying cholesterol oxidation in egg powder is reported. The quantitative analysis of cholesterol oxides was carried out by high-resolution proton nuclear magnetic resonance (1H-NMR). The following oxides were isolated from spray-dried egg powder by rapid chromatographic procedures and detected by selecting “marker”1H-NMR signals: 7-ke-tocholesterol, 7α-hydroxy-cholesterol, 7β-hydroxy-cholesterol, cholesterol-α-epoxide and cholesterol-β-epoxide. The quantified cholesterol derivatives ranged from 4.9 to 9.1 ppm with a detection limit of 0.3 ppm (5 μ.g from 16g of matrix). The main usefulness of the method should be in investigating intermediates and products due to chemical transformation of cholesterol during storage and heating of foodstuffs.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical ecology 17 (1991), S. 625-636 
    ISSN: 1573-1561
    Keywords: Opisthobranch ; nudibranch ; Hypselodoris webbi ; Hypselodoris ; villafranca ; sponge ; Dysidea fragilis ; chemical defense ; longifolin ; nakafuran-9 ; isotavacfuran
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Hypselodoris nudibranchs from different geographic areas (Spain and Italy) have been studied in order to investigate their general defensive strategy. Longifolin (1) and nakafuran-9 (2) are the main ichthyodeterrent allomones used by the mollusks to avoid predation. Evidence of their dietary origin is presented and the very effective strategy against predators, which includes secretion of allomones into the mucus and their storage into specific mantle dermal formations (MDFs), is also discussed.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2048
    Keywords: Calorimetry ; Cell culture (temperature responses) ; Lysopersicon (temperature responses) ; Temperature response and stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Precise time and temperature dependences of the decrease of metabolism of cultured cells of tomato (Lysopersicon esculentum (L.) Mill. L. peruvianum (L.) Mill.) resulting from exposures to high and low temperatures were determined. Equations of the form Ln (activity)= C +1 [A+(T-Tm)N+B] describe thermal inactivation and allow prediction of activity loss following any thermal excursion beyond limits of temperature stability. The experimental parameters A, B, C and N derived from these equations allow precise comparison of temperature sensitivities of cells. Analysis of metabolic heat rates, O2-consumption rates and CO2-evolution rates demonstrated simultaneous shifts in metabolic pathways and metabolic activities towards more anaerobic metabolism below about 12° C and at high temperatures that stress growth of tomato cells.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1573-6776
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary At high flow rates, the continuous alcoholic fermentation of sucrose in a laboratory fermenter with internal cell recycle, using a strongly flocculating yeast can be limited by the substrate hydrolysis. This system is sensitive to glucose catabolic repression and to mineral deficiency. The release of invertase activity in the medium is negligible. From theoretical and experimental considerations, the hydrolysis rate is imposed by diffusionnal limitations in the biomass particles. Nevertheless, ethanol productivities as high as 68 g/L.h can be reached, without biomass retention problems. A better understanding of the basic phenomena involved in floc formation and evolution is required to control reactor performances.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Biotechnology techniques 5 (1991), S. 133-138 
    ISSN: 1573-6784
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The diffusion of small molecules (sugars and alcohols) through a dense layer of flocculating yeast has been studied and compared to the theorical value calculated from parameters such as porosity and yeast density. Lactose, ethanol and methanol were chosen as model molecules. In comparison with water, the diffusion rate of lactose is divided by three. Alcohols which cross the cell envelope diffuse relatively faster than lactose which was assumed not to penetrate the cells. An increase of the lactose diffusion rate is observed when the yeast are heat killed.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0749-1581
    Keywords: Saraines ; 2D COSY NMR ; 2D 1H-13C COSY NMR ; Alkaloids ; Sponge ; Reniera sarai ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An extensive application of two-dimensional proton-proton and proton-carbon shift correlated spectroscopy allowed the structural elucidation of isosaraine-2, a minor component of an unique family of alkaloids from the sponge Reniera sarai.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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