FOOD SCIENCE

• Analysis & Detection • Previous Articles     Next Articles

Rapid Determination of Crude Protein in Sonchus asper by Microwave Digestion-Conductivity Titration

GAO Xiang-yang1,3, GAO Qiu-zhu2, WANG Chang-qing3, LIU Yao-wei1   

  1. 1. School of Food Science and Engineering, University for Science and Technology of Zhengzhou, Zhengzhou
    450064, China; 2. School of Food Science and Technology, Jiangnan University, Wuxi 214122, China;
    3. College of Food Science and Technology, Henan Agricultural University, Zhengzhou 450002, China
  • Online:2014-11-25 Published:2014-12-09

Abstract:

A rapid and simple method to determine crude protein content in Sonchus asper was established in this study.
Samples were digested with nitric acid-hydrogen peroxide by microwave digestion technique to convert crude protein to
NH4+. The NH4+ generated in the digestion was further converted to H+ ions by neutral formalin for conductivity titration with
standard NaOH solution. The results indicated that the average content of protein in wild Sonchus asper from Zhengzhou
was determined to be 20.16% with relative standard deviation (RSD) of 2.5% (n = 6). Compared with the classic method,
the conductivity titration method did not exhibit significant difference as analyzed by F-test and t-test at 95% confidence
level. This method has the advantages of convenient operation, high sensitivity, quick determination, accurate results and no
requirements for indicators.

Key words: Sonchus asper, microwave digestion, conductivity, crude protein

CLC Number: