意面中蛋白质检测方案(定氮仪)

智能文字提取功能测试中

APPLICATION NOTEF&F-D-005-2013/A1 N/PROTEIN DETERMINATIONIN PASTADUMAS COMBUSTION METHOD N/Protein Determination in Pastaaccording to the Dumas combustion method Reference： AOAC 992.23 Crude Protein in Cereal Grains and Oilseeds； AACC 46-30 Crude Protein Combustion Method；ICC 167 Determination of crude protein in grain and grain products for food and feed by the Dumas Combustion Principle Tested with VELP Scientifica NDA 701 Dumas Nitrogen Analyzer (Code F30800070) Introduction Dried and fresh pasta are traditional Italian products， known all over the world in a number of shapes and varieties， asshown by the 310 specific forms and by over 1300 names having been recently documented. Basic pasta dough has always been made mostly of durum wheat flour or semolina； other grains can be used， includingthose from barley， buckwheat， rye， rice and maize， as well as chestnut and chickpea flours. In order to meet thedemands of both health conscious and coeliac sufferers， the use of rice， maize and whole durum wheat has becomecommercially significant. It’s always more important to know the ingredients and amount of all the components， as proteins， for different reasons，including legal and nutritional purposes (labeling). Protein Determination in Pasta The Dumas method starts with a combustion furnace (CF) to burn thesample， obtaining elemental compounds. Water is removed by a first physical trap (WT1 -DriStepTM)， placed afterthe combustion， and a second chemical one (WT2). Between the two， theelemental substances passed through a reduction furnace (RF). The auto-regenerative CO2 adsorbers (CO2) let pass only the elementalnitrogen that is detected by the LoGas TM innovative Thermal ConductivityDetector(TCD) with no requirement for a reference gas. The NDA 701 is controlled via PC through the intuitive DUMASoftTM. NDA 701 Preliminary Operations (daily) Follow the operating manual to start the NDA 701 and check that the following parameters are set： Temperature Combustion reactor (Code A00000158)： 1030°C Temperature Reduction reactor (Code A00000226)： 650°C Flow rate MFC1 He： 195 ml/min Flow rate MFC2 He： 200 ml/min Condition the system by testing 2 EDTA standard (Code A00000149) and 3 to 5 empty tin foils (Code A00000153) asCheck up. Verify the calibration curve with one or more tests as Standard by testing the same standard used for the curve creation. Sample Preparation Collect 100 g of pasta for soup from durum wheat flour， into a beaker and mix it with a spoon by hand. Grind finely it using a grinder to suitable fineness to obtain ≤2，0 % relative standard deviation (RSD) for 10 successivenitrogen determinations. Using a spatula， put~ 100 mg of sample directly into the tin foil. Close the tin foil， obtaining a capsule. Load the capsule into the autosampler. Analysis Procedure Fill the following fields in the database： Sample name， Weight， Method， Sample type， Calibration number The PASTA method shows the following parameters： Protein factor： 6.25 O2 flow rate： 400 ml/min O2 factor： 1.5 ml/mg Press to start the analysis. Analysis time： from 3 minutes for one run. Typical Results on Dried Pasta Typical Results on Dried Pasta Sample quantity (mg) Nitrogen % Protein % 96.60 1.968 12.300 102.50 1.954 12.213 99.80 1.967 12.294 99.50 1.966 12.288 96.50 1.965 12.281 100.20 1.970 12.313 97.70 1.945 12.156 104.30 1.963 12.269 104.10 1.947 12.169 95.50 1.969 12.306 Average±SD% 1.961±0.009 12.259±0.058 RSD%* 0.473 0.469 Protein Labeled Value： 12.0% Protein Factor： 6.25** *RSD%=(Standard Deviation * 100)/ Average ** Generally 6，25 is the protein factor for nutritional table of pasta， but also 5，70 can be used. Conclusion The obtained results are reliable and in accordance with the labeled value. The combustion method， relying on the Dumas principle， for the determination of total nitrogen in cereals， has beenincluded as an official alternative to the Kjeldahl method. Results have been obtained with the following calibration curve： in a range of 0 -2.76 mg N with 5 measurements (from30 to 200 mg) of rice flour standard (%N=1，38±0，05)(Code A00000235). Benefits of Dumas combustion method are： High productivity， non-stop performance Time saving， few minutes required Moderate running costs ● Totally unsupervised， fully automated ● Omission of harsh and toxic chemicals Eco-friendly， low amount of residues and wastes Copyright C VELP Scientifica. All rights reserved.No part of this publication may be reproduced or transmitted in any form or for any purpose without the express permission of VELP.VELP Scientifica， Italy Tel：+ Fax： + www.velp.com 意大利VELP公司杜马斯定氮仪NDA702用于测定意大利面中的蛋白质含量：意面中的蛋白质含量测定