6 0.33% gum guaiac, ' 0.08% hydrogen peroxide. d Peroxidase in distilled water.• Peroxidase in pH 6.5 phosphate buffer.and their statistical significance are presented in Table I for unbuffered peroxidase solutions and for peroxidase dilutions prepared in 0.1 M phosphate buffer at pH 6.5; corresponding values for gum guaiac covering the range from 1.0 X 10-4 to 1.0 X 10~6 weight % peroxidase are also given (Table I).Regression lines were calculated using the least mean square method (3).
Use of C3 carbon dioxide (CO2) fixation cycle by the sugar maple (Acer saccharum Marsh.), a dicotyledenous plant, and C4 carbon fixation cycle by 2 monocotyledenous plants, corn and cane, results in a physiological discrimination between 13C and 12C isotopes. Therefore, determination of 13C/12C ratio of maple syrup by mass spectrometry can be used to detect adulteration with cane and corn sugars. Four samples of pure maple syrup and 3 adulterated maple syrup samples were analyzed in a collaborative study. Results indicate that stable carbon isotope analysis can determine authenticity of maple products. Samples with δ13C values less negative than – 23.49%c (parts per thousand) can, with a high degree of confidence (95%), be classified as adulterated. The method has been adopted official first action.
To enhance the shelf life of a late variety of Moroccan Citrus clementina (Nour), ionizing treatments were applied at 0.3 kGy, as well as washing (cold water) and waxing treatments. It has been found that, despite the irradiation treatment, the washing and waxing treatment do not improve the quality of C. clementina, but rather result in yellower peels, peel injury, and reductions of vitamin C content, acidity, and soluble solids. However, gamma-irradiation alone enhanced significantly (p
Natural isotopic labelling of animal metabolic processes presents great advantages over the use of artificially enriched compounds. These advantages include the use of natural diets, low cost and easiness of handling, sampling and disposal. Changes in the 13C/12C ratio of expired CO2 after ingestion of a test meal containing a variable proportion of C3 and/or C4 plant-derived products permits measurements of the immediate oxidation of dietary carbohydrates. A breathing device for collection of expired CO2 and purification techniques are described. The breath-sampling device is composed of a polypropylene enclosure and a rubber bag. The rubber bag is blown up by the animal and a sample of the expired gas is transferred to a sampling glass holder in which a vacuum had been previously achieved. Sample purification of expired CO2 is done by differential freezing. Key words: Breath device, carbon 13, calf
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