香肠中蛋白质检测方案(定氮仪)

APPLICATION NOTEF&F-D-001-2016/A1 N/Protein Determination in Sausageaccording to the Dumas method (He as Carrier) Reference： AOAC 992.15 Crude protein in meat and meat products， combustion method Tested with VELP Scientifica NDA 702 Dual Carrier Gas Dumas Nitrogen Analyzer (Code F30800080) VELP Scientifica， Italy Tel： +39 039 628 811 Fax： +39 0396288120 www.velp.com APPLICATION NOTEF&F-D-001-2016/A1 Introduction Mortadella is a large Italian sausage or cold cut (salume ) made of finely hashed or ground， heat-cured pork， whichincorporates at least 15% small cubes of pork fat (principally the hard fat from the neck of the pig). Mortadella is atypical product of the area of Bologna； this territory， which in ancient times was first settled by the Etruscans (Felsina)then by the Gauls (Bononia) and finally by the Romans ， has always thrived thanks to the presence of pigs (Sus scrofadomesticus) and wild boar (Sus scrofa majori or similar). Mortadella was born in this area， whose noun is difficult totrace； plausible hypotheses are two， according to which the term would come respectively from murtatum (mortar， toolused in the meat mince) or myrtatum (myrtle， originally used in aromatization). Quality control of Mortadella encloses thecheck of chemical parameters， among these， the protein content. The mortadella proteins are of high biological value. Protein Determination in Mortadella Sausage 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 702 is controlled via PC through the intuitive DUMASoftTM. NDA 702 Preliminary Operations (daily) Follow the operating manual to start the NDA 702 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)： 190 ml/min Flow rate MFC2 (He)： 220 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 Mortadella Sausage Expected Protein range： 15-18% Samples have been homogenized by using a grinder， up to creamy consistency. Using a spatula， put ~ 100 mg of homogeneous sample directly into the tin foil. Close the tin foil， obtaining a capsule and load the capsule into the autosampler. Analysis Procedure Fill the following fields in the database： Sample name，Weight， Method， Sample type， Calibration number The MEAT AND DERIVED PRODUCTS method shows the following parameters：Protein factor： 6.2502 flow rate： 400 ml/minO2 factor： 1.4 ml/mgPress to start the analysis. Analysis time： from 3 minutes for one run. Typical Results on Mortadella Sausage Results have been obtained with the following calibration curve： in a range of 0 - 9 mg N with 5 measurements of EDTAstandard (N%=9.57) (Code A00000149). The data obtained are included in the tolerance admitted by the EDTA certificate. The table below shows the accuracy and repeatability of the data obtained for 30 trials/day of mortadella analysis for 4weeks. The obtained results are in accordance with the expected value. HELIUM as Carrier Gas Analysis Period Protein Average ± SD (%) RSD% Week 1 16.311±0.191 1.172 Week 2 16.329±0.140 0.855 Week 3 16.766±0.131 0.782 Week 4 16.747±0.210 1.255 Protein Expected range： 15-18 % *RSD%=(Standard Deviation * 100) / Average Conclusion The determination of protein in mortadella product with Velp NDA 702 Dumas Analyzer using helium as the carrier gasprovides extremely reliable and reproducible results as demonstrated by the RSD， since the goal is to obtain < 2.0 %relative standard deviation， as requested by official methods. The data obtained demonstrates also the stability of thesystem. Copyright @ 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. 香肠中的蛋白质测定。