Abstract: In order to set up a new rapid method to determine protein content in food, microwave digestion was adopted to treat wheat sample, ammonia gas-sensing electrode-direct reading concentration method was used to read determination results. The results showed that the content of protein in wheat is between 12.56% and 14.19%, the range of recovery is 97.16% to 104.7%, the relative standard deviations (RSD) is between 1.4% and 3.2% (n=5), the linear range is 1×10-5 to 1×10-2 mol/L with the correlation coefficient 0.9991, and the detection limit is 1.4682 μmol/L . There is no significant difference between determination results by this method and those by the national standard method of China. This method is easy-operated, sensitive, quick, exact and no need for distillation and titration, and the determination results are satisfying.

Key words: microwave digestion, direct reading concentration method, protein, ammonia gas-sensing electrode