Analysis of Sulfites in Shrimp Using Rapid Distillation Followed by Redox Titration .

The use of rapid steam distillation followed by redox iodine titration provides a rapid and accurate determination of total sufite residual in shrimp. Values obtained for sulfite-treated shrimp using the rapid distillation method gave comparable results to those of the officially recognized Monier-Williams method. Values for the rapid distillation method ranged from 6 to 212 ppm while those of the Monier-Williams procedure ranged from 6 to 241 ppm for untreated and treated shrimps, respectively. Statistical analysis using two-sample Student's t-test indicated that there were no significant differences (p>0.05) for residual levels below 100 ppm but the values obtained by the rapid distillation method and the Monier-Williams procedure were significantly different (p<0.05) at concentrations near and above 100 ppm.