Eine verbesserte Methode zur Bestimmung der maximalen Emulgierkapazit?t von Proteinl?sungen

Zusammenfassung Am Beispiel der Milchproteine wird die Methode zur Bestimmung der maximalen Emulgierkapazität optimiert. Die Methode beruht darauf, daß am Inversionspunkt einer Emulsion der elektrische Widerstand sprunghaft ansteigt. Experimentell überprüft wurden die Parameter Proteinkonzentration, pH-Wert, Öl-Dosierungsrate, Ultra-Turrax-Drehzahl und Versuchsdauer. Ferner wurden Forderungen an die Ermittlungdes Leerwertes begründet. Durch Festlegen der stofflich und methodisch bedingten Einflußgrößen gelingt es, den Variationskoeffizienten auf Werte um 2,0% zu minimieren. Die vorgestellte Methode ist mit gutem Erfolg auf alle löslichen Proteine übertragbar und erfüllt die Anforderungen einer Standardisierung.

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An improved method for determining the maximum value of emulsifying capacity of protein solutions

Summary A method for the examination of the maximum value of emulsifying capacity was optimized using milk proteins. This method is based on a sudden increase in the electrical resistance at the inversion point of the emulsion. The following parameters were tested: protein concentration, pH value, rate of oil dosage, speed of the Ultra-Turrax, time needed for one experiment, and the requirements for preparing the blank. By fixing these parameters it is possible to minimize the coefficient of variation of about 2.0%. This method is successfully applicable for all soluble proteins and meets all the requirements for standardisation.

     

Pyrolysis of waste using a hybrid argon–water stabilized torch

An experimental plasmachemical reactor equipped with the novel IPP-ASCR hybrid gas–water stabilized DC torch (160 kW) has recently been started at IPP Prague for the innovative and environmentally friendly plasma treatment of waste streams with a view to their sustainable energetic and chemical valorization and to a reduction of the emission of greenhouse gases. Since the process energy is provided by direct heat transfer from plasma, gases of widely varying chemical composition may be used. The use of electrical energy also reduces the gas flows and requirements for exhaust-gas treatment, and offers control over the chemistry. Pyrolysis of biomass was experimentally studied using wood chips as a model substance. Syngas with a high content of hydrogen and CO was produced. The influence of adding CO₂ for increase of oxygen content in the reactor was investigated.     

Isolierung der durch ?thylenoxyd-1,214C derivatisierten Inhaltsstoffe aus Kakao und ihre massenspektrometrisch ermittelte Struktur

Zusammenfassung Bei der Auftrennung zahlreicher Fraktionen durch Extraktion und PDC aus dem Äthylenoxyd-1,2-¹⁴C begasten Kakaopulver (Entkeimung) konnten aus dem Wasserextrakt 2 Verbindungen isoliert werden, deren Struktur aufgrund der Massenspektren und IR-Spektren alsN,N-Bis-(Di-Äthoxy-O-hydroxyäthyl)-isoleucyl-alanyl-cystein (MG = 569) undN-(Äthoxy-O-hydroxyäthyl)-Tyrosin gefunden wurde. Die Konzentrationen liegen ungefü:hr bei 20 bzw. 50 mg/kg Kakaopulver.

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Isolation of the derivatives from coca-powder fumigated by ethylene oxide 1,2-¹⁴C and their Structure Suggested on the Basis of I. R. and Mass-Spectrometry

Summary In Coca-powder fumigated with Ethylene Oxide-1,2¹⁴C, several derivatives were isolated by extraction and preparative Thin Layer Chromatography. Of the two compounds isolated from the water-extract, the structures have been suggested asN,N-Bis-(Di-Ethoxy-O-Hydroxy-ethyl)-Isoleucyl-Alanyl-Cysteine (MW = 569) andN-(Ethoxy-O-Hydroxyethyl)-Tyrosine (MW = 269), based on I. R. and Mass Spectrometry. Their approximate concentrations were found to be 20 and 50 mg/kg respectively.

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Wir danken der Deutschen Forschungsgemeinschaft für ihre finanzielle Unterstützung dieser Arbeit.

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Untersuchungen über das Verhalten von Äthylenoxyd bei der Begasung von Lebensmitteln, IX. Mitteilung.

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Zum Teil aus der Dissertation von I. R. Siddiqui, Universität Bonn.     

Behavioral auditory thresholds for sinusoidal electrical stimuli in the cat

Behavioral thresholds were measured in four cats by training them to respond behaviorally to acoustic auditory stimuli using food as a reward in an operant reinforcement paradigm. Following training, the subjects were implanted unilaterally with either a scaled-UCSF electrode containing four contacts or an electrode array containing eight intracochlear contacts and one extracochlear contact under temporalis muscle. Behavioral thresholds for electrical stimuli were obtained as a function of sinusoidal frequency, duration, and electrode configuration. Threshold functions for both electrode types and all animals had minima between 48 and 125 Hz and, in general, were relatively flat below this minima; functions increased at 3-6 dB/octave from 96 Hz to 1 kHz. Threshold varied predictably as a function of electrode configuration, with thresholds decreasing as much as 20 dB as electrode spacing was widened from a radial bipolar (200-microns separation) to a monopolar configuration (apical stimulating and temporalis return). With long-duration stimuli, increasing the electrode separation systematically increased the slope of the threshold-versus-frequency contours in all animals. Irrespective of electrode type or configuration, charge/phase thresholds for single-cycle sinusoids were relatively flat for stimulus periods up to 1-5 ms, approximating a constant charge/phase determination of threshold. At phase durations greater than 5 ms, charge thresholds increased at a rate slightly above 6 dB/octave (constant peak current), which was suggestive of neural accommodation. Thresholds for the cat share many features with those reported for implanted humans and monkeys.     

Nachweis der Behandlung von Hühnerbrust mit ionisierenden Strahlen und Abschätzung der Bestrahlungsdosis mit Hilfe der Headspace-Gaschromatographie und diskriminanzanalytischer Auswertung

Chicken breast was irradiated with doses of 3, 5, and 7 kGy. Headspace gas chromatographical analysis demonstrated the tendency that the amounts of volatile compounds (mainly pentanal, hexanal and heptanal) are higher in irradiated samples in comparison with non irradiated. Statistical evaluation of the gas chromatograms by discriminant analysis enabled the detection of irradiation. Unknown samples could be classified in the groups ?unirradiated“ or ?irradiated in most cases.