IMPROVEMENT OF ALKALINE-HYDROLYSIS TREATM ENT FOR THE DETERMINATION OF RESIDUAL SULFITE IN LIQUID FOODS BY A MICROBIAL SENSOR METHOD

For the determination of residual sulfite in liquid foods by a microbi al sensor method, the conditions for decomposition of combined sulfite into free form by sodium hydroxide and antioxidant were examined. The microbial sensor method was applicable to the determination of sulfit e in beer by being made flat. The optimum antioxidant and the concentr ation was determined to be L-cysteine monohydrochloride and 4(w/v)%, r espectively. Under the optimum conditions, the recovery of added sulfi te from 7 kinds of liquid foods was 90.0 to 99.4%. For the determinati on of total sulfite, the reproducibility of this method was better tha n that of the modified Rankine's titration method. These results indic ated that the microbial sensor method by alkaline hydrolysis treatment was applicable to the determination of residual sulfite in liquid foo ds.