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  • 1975-1979  (9)
  • 1
    Electronic Resource
    Electronic Resource
    GAS-LIQUID CHROMATOGRAPHIC DETERMINATION OF LENTHIONINE IN Shiitake MUSHROOM (Lentinus edodes) WITH SPECIAL REFERENCE TO THE RELATION BETWEEN CARBON DISULFIDE AND LENTHIONINE (1978)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 43 (1978), S. 0 
    Details
    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 simple gas chromatographic procedure for the determination of lenthionine, a flavor component in shiitake mushroom, was developed. The method involves the extraction of lenthionine with n-hexane from the soaked mushrooms and soak solution and subsequent determination by flame photometric detector gas chromatography. Lenthionine was formed by soaking dried mushroom in water and warming at neutral or alkaline pH, but a little amount of lenthionine was produced at acidic pH. The relation coefficient between the formation of lenthionine and the evolution of carbon disulfide in 20 samples was 0.507. It is assumed that lenthionine is formed by immersing the dried mushroom in water and gradually decomposes to carbon disulfide.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2621.1978.tb15289.x
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  • 2
    Electronic Resource
    Electronic Resource
    GAS-LIQUID CHROMATOGRAPHIC DETERMINATION OF CARBON DISULFIDE IN SHIITAKE MUSHROOM (Lentinus edodes) (1978)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 43 (1978), S. 0 
    Details
    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 simple, rapid chromatographic procedure for the determination of carbon disulfide in shiifake mushrooms was developed. The method involves homogenization of dried mushroom, followed by distillation of the homogenate in the presence of acetone. Carbon disulfide in acetone is determined by GLC with a flame photometric detecting system. The carbon disulfide content in dried mushroom was affected considerably by the pH of homogenation and distillation; 0.02–3.4 ppm of carbon disulfide in dried mushrooms under acidic condition increased to 0.98–72.5 ppm under neutral conditions. The increased carbon disulfide under neutral conditions is purported to be derived from a mushroom component. Therefore, residual carbon disulfide in dried shiitake mushrooms must be determined under acidic conditions of homogenation and distillation. The lower delection limit was 0.025 ppm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2621.1978.tb15290.x
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  • 3
    Electronic Resource
    Electronic Resource
    Application of gas chromatography for the separate determination of free and combined sulphites in foods. I. (1979)
    Springer
    European food research and technology 168 (1979), S. 195-199 
    Details
    ISSN: 1438-2385
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Description / Table of Contents: Summary A combination of head-space technique and FPD gas chromatography was applied to the separate determination of free and combined sulphite in foods. 0.1 M-Tartaric acid was chosen as an excellent extractant for the selective extraction of free sulphite in the presence of combined sulphite, whilst (N) alkaline extractant containing potassium-sodium tartarate and ferrous sulphite (deoxidant) liberated free and combined sulphite completely. Sulphite was released from each solution in the following way. To 1 ml of filtered solution, 5 ml of 10% phosphoric acid was added, the mixture was shaken vigorously for 10 s kept for 10 min at 0 °C, then again shaken vigorously for 10 s. An aliquot of the head-space gas thus obtained was immediately injected into a FPD gas chromatograph. Recoveries of 10–20 ppm of free sulphite and 100–200 ppm of combined sulphite from dried pineapple, dried apricot, white and red wines were 92.5–104.0 and 93.5–98.0%, respectively, the detection limit being 0.5 ppm.
    Notes: Zusammenfassung Schweflige Säure in Lebensmitteln — sowohl freie als auch gebundene läßt sich gaschromatographisch bestimmen. Dazu wird die freie schweflige Säure mit 0,1 m-Weinsäure, die gesamte schweflige Säure mit einem alkalischen Extraktionsmittel, das Seignettesalz und Eisen(II)-sulfat enthält, extrahiert und das SO2 aus dem Extrakt mittels Phosphorsäure freigesetzt. Das Dampfraum-Gas wird in einem Gaschromatographen mit flammenphotometrischem Detektor analysiert. Die Wiederfindungsrate von Sulfit, das getrockneter Ananas, getrockneten Aprikosen, Weiß- und Rotwein zugesetzt wurde, betrug beim freien SO2 zwischen 92,5 und 104,0%, beim gebundenen SO2 zwischen 93,5 und 98% bei einer unteren Nachweisgrenze von 0,5 ppm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01123172
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  • 4
    Electronic Resource
    Electronic Resource
    On the combination of sulphite with food ingredients (aldehydes, ketones and sugars). II. (1979)
    Springer
    European food research and technology 168 (1979), S. 200-205 
    Details
    ISSN: 1438-2385
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Description / Table of Contents: Summary Three kinds of combined sulphites (bisulphite adducts of acetaldehyde, pyruvic acid and D-mannose), different in combination strength, were prepared to provide a model system for comparative studies on the accuracy of several determination methods for combined sulphites. The purity of the combined sulphites, obtained either as crystals or amorphous powder, was shown to be not less than 99%. Five methods, formerly applied on the determination of residual sulphites in foods, were subjected to the determination of these combined sulphites. A modified Monier-Williams method, iodimetry and distillation-colorimetry were effective for the determination of combined sulphite, whilst a microdiffusion method and direct colorimetry (by use of mercuric chloride) were shown to be inadequate for the determination of combined sulphite. Three combined sulphites were shown to be produced by the reaction between free sulphite and acetaldehyde, pyruvic acid or D-mannose at room temperature within a short time in the weak acid to slightly alkaline pH range. About 50% of combined sulphite were produced by the reaction of equimolar amounts of sodium bisulphite and acetaldehyde or pyruvic acid.
    Notes: Zusammenfassung Es wird die Darstellung der Bisulfit-Anlagerungsverbindungen von Acetaldehyd, Brenztraubensäure undd-Mannose beschrieben. Die Reinheit der gen. Verbindungen beträgt 99%.fünf An Hand dieser Verbindungen wird überprüft, welche von fünf Standardmethoden zur Sulfitbestimmung in Lebensmitteln für die Bestimmung des gebundenen Sulfits geeignet ist. Hierbei ergeben die abgeänderte Monier-Williams-Methode, die Jodometrie und die Wasserdampfdestillation/Colorimetrie befriedigende Ergebnisse, während die Mikrodiffusion und die direkte Colorimetrie ungeeignet erscheinen. Die gen. Anlagerungsverbindungen bilden sich bei Zimmertemperatur im schwach sauren bis schwach alkalischen Milieu innerhalb kurzer Zeit. In einer äquimolaren Lösung aus Acetaldehyd bzw. Brenztraubensäure und Natriumhydrogensulfit liegt nach kurzer Zeit 50% des Sulfits als Anlagerungsverbindung vor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01123173
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  • 5
    Electronic Resource
    Electronic Resource
    Establishment of a modified rankine method for the separate determination of free and combined sulphites in foods. III (1979)
    Springer
    European food research and technology 168 (1979), S. 206-211 
    Details
    ISSN: 1438-2385
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Description / Table of Contents: Summary Considerable improvements were made to the original Rankine method. Replacement of aspiration with an injection system contributed a great deal to the simplification of procedure, being accompanied with an increase in reproducibility. Air (flow rate 1.01/min) was used for injection because the use of inert gas gave little increase in recovery rate. Sodium bisulphite (free sulphite) and three kinds of combined sulphite compound (bisulphite adducts of acetaldehyde, pyruvic acid and D-mannose) were used to find the most suitable conditions for the separate determination of free and combine sulphites. Free sulphite was expelled from the sample by bubbling at 0 °C for 30 min. It was confirmed that no combined sulphite was dissociated under these conditions. The phosphoric acid concentration had an important role in the liberation of sulphite. When 25% phosphoric acid was used, more than 99% of free sulphite was expelled by cold bubbling and more than 99% of combined sulphite was recovered by heating afterwards for 10 min. The scope of the modified Rankine method was also extended to the determination of sulphite in concentrated orange juice.
    Notes: Zusammenfassung Die Rankine-Methode wurde bedeutend verbessert. Ein Umtausch der Aspiration mit Blasensystem trug beträchtlich zur Vereinfachung des Bestimmungsverfahrens bei, und die Reproduzierbarkeit wurde verbessert. Luft (Fließrate 1,01/min) wurde als Blasengas benutzt, da der Gebrauch von Inertgas für die Wiederfindungsrate unbedeutend ist. Natriumhydrogensulfit (freies Sulfit) und drei Arten gebundener Sulfite (Acetaldehydhydrogensulfit, Pyruvathydrogensulfit undd-Mannosehydrogensulfit) dienten dazu, die geeignetsten Bedingungen für die getrennte Bestimmung der freien und gebundenen Sulfite zu ermitteln. Freies Sulfit wurde bei 0 °C durch 30 min Durchblasen vertrieben. Hierbei ging kein gebundenes Sulîit verloren. Die Phosphorsäurekonzentration war wichtig für die Freisetzung des Sulfites. Wenn man 25%ige Phosphorsäure verwendet, werden 〉 99% freien Sulfites beim Durchblasen in der Kälte vertrieben, während 〉 99% gebundenen Sulfites durch nachheriges 10 min langes Erhitzen wiedergewonnen werden. Die modifizierte Rankine-Methode wurde weiterhin für konzentrierte Säfte verwendet.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01123174
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  • 6
    Electronic Resource
    Electronic Resource
    Colorimetric microdetermination of sulphites in foods by use of the modified rankine apparatus. IV. (1979)
    Springer
    European food research and technology 168 (1979), S. 293-298 
    Details
    ISSN: 1438-2385
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Description / Table of Contents: Summary Detection and determination of traces of sulphites in foods was attempted by use of the modified Rankine apparatus and pararosaniline colorimetry. Replacement of alkaline titration reported previously by pararosaniline colorimetry lowered the absolute detection limit from 30 μg (titration method) to 2 μg. In view of clean analysis, in the color developing system, 0.1 N-sodium hydroxide was used in place of mercuric chloride solution commonly used as an absorbant of sulphites. In order to prevent oxidative decomposition of sulphites during operation, nitrogen gas was used as carrier instead of air. Dimedone and sodium azide were used for the elimination of aldehydes and nitrites, respecitvely, in the sample, which will disturb the color development of sulphites with pararosaniline-formaldehyde reagents. With this improved method, it was possible to determine the residual sulphites in frozen peeled shrimps, sugared beans and other foods with low sulphite contents accurately.
    Notes: Zusammenfassung Geringe Sulfitmengen in Lebensmitteln (geschälte Garnelen, gezuckerte Bohnen) können colorimetrisch bestimmt werden. Die neuentwickelte Methode beruht auf einer Kombination von colorimetrischer Bestimmung mittels p-Rosanilin und der Bestimmungsmethode nach Rankine. Auf diese Weise lassen sich Gehalte von 2 μg noch genau bestimmen. Bei der Farbentwicklung wurde das giftige Quecksilbertetrachlorid durch 0.1 n-NaOH ersetzt, anstelle von Luft Stickstoff als Trägergas verwendet und somit eine Oxydation des Sulfits während der Bestimmung vermieden. Da Nitrit und Aldehyde die Farbentwicklung stören, wurde ihr Einfluß durch Dimedon und Natriumazid ausgeschaltet.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01353068
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  • 7
    Electronic Resource
    Electronic Resource
    Comparative determination of free and combined sulphites in foods by the modified rankine method and flame photometric detection gas chromatography. V. (1979)
    Springer
    European food research and technology 168 (1979), S. 299-304 
    Details
    ISSN: 1438-2385
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Description / Table of Contents: Summary Application of the modified Rankine (MR), GLC and present official Monier-Williams methods to the determination of sulphites in a variety of foods was attempted. Generally, sulphite contents determined by these three methods were in good agreement although the values obtained by the modified Monier-Wiliams method were slightly higher than by the other two. A marked interfering effect of other sulphur compounds was observed in the case of determinations by the Monier-Williams method. On the other hand, the determined sulphite values by the MR and GLC methods were independent of the coexisting sulphur compounds. The ratios of free or combined sulphites to total sulphites were compared among the two methods, and in most foods tested the rations of combined to total sulphites were not less than 65%. We conclude that both the MR and GLC methods are valid for the separate determination of free and combined sulphites in most foods, and these two methods will be preferred for routine analysis because of their simplicity and speed.
    Notes: Zusammenfassung Es wurde eine vergleichende Sulfitbestimmung in verschiedenen Lebensmitteln mit Hilfe der modifizierten Rankinemethode (MR), der Gaschromatographie und der Monier-Williams-Methode durchgeführt. Die Ergebnisse stimmen gut überein, wobei die Monier-Williams-Methode geringfügig höhere Werte erbrachte. Diese Methode wird durch schwefelhaltige Lebensmittelinhaltsstoffe empfindlich gestört. Des weiteren wurde in verschiedenen Lebensmitteln die Relation von freiem zu gebundenem Sulfit ermittelt. Dabei stellte sich heraus, daß in den meisten Lebensmitteln 65% des Sulfits in gebundener Form vorliegen. Sowohl MR-Methode als auch Gaschromatographie erlauben eine getrennte Bestimmung von freiem und gebundenem Sulfit. Da beide Methoden einfach und schnell durchzuführen sind, eignen sie sich für die Routinebestimmung.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01353069
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  • 8
    Electronic Resource
    Electronic Resource
    Non-Newtonian behavior in steady flow over the range from the lower to the upper Newtonian region for polystyrene solution (1975)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 35-41 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Graessley's entanglement theory of viscosity modified by a frictional viscosity parameter ηfric is applied to data on solutions of polystyrene in diethyl phthalate at various concentrations and different temperatures. All the data modified give a single master curve over the entire rates of shear, as obtained previously with polydimethyl-siloxanes of various molecular weights and their solutions of various concentrations. The zero-shear viscosity η0, the upper Newtonian viscosity η∞, and ηfric are compared. Three activation energies for flow are estimated from η0, η∞ and ηfric, and are compared. The result suggests that the flow behavior in the upper Newtonian region is much more dependent on ηfric than on the entanglement viscosity term ηent. The ratio of zero-shear entanglement viscosity ηent,0 to ηfric can be used as a measure of the non-Newtonian behavior of the present solutions. Non-Newtonian behavior of the investigated polymer solution becomes appreciable at about ηent,0/ηfric = 2.5. These results are in agreement with previous conclusions based on comparison between η0, η∞ and ηfric for polydimethyl-siloxanes and their solutions.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1975.180130104
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  • 9
    Electronic Resource
    Electronic Resource
    Non-Newtonian flow curves including lower and upper Newtonian regions for dilute and moderately concentrated polystyrene solutions (1978)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 16 (1978), S. 725-734 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The non-Newtonian viscosity in steady flow was measured for solutions of polystyrene (M̄w/M̄n = 1.1) in diethyl phthalate at 30.0°C. In the moderately concentrated solutions, from 6.03 × 10-2 to 5.62 × 10-1g/cm3, the viscosity data modified by frictional parameters fit the Graessley theoretical curve for a narrow distribution polymer. The dilute solutions, from 3.26 × 10-3 to 1.57 × 10-2 g/cm3, were nonentangled systems whose non-Newtonian properties could be explained by the excluded volume effect as proposed by Fixman. On the basis of the non-Newtonian data, it was concluded that the solution of 3.30 × 10-2 g/cm3 was a lower critical entanglement concentration, which was distinguished from the usual higher critical concentration for entanglement. This lower critical concentration was also found in the concentration dependence of the activation energy of flow and the absorbance at 310 nm.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1978.180160414
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