Improved method for determination of sulfites in shrimp

A method for the determination of sulfites in shrimp developed by Kim and Kim and modified by Paíno-Campa et al. for sausages has been further modified. Total sulfites are extracted by initially adding aluminum oxide to the sample and using an extraction solution at pH 12. In the reproducibility assays, coefficients of variation (CVs) were 4.8% for free sulfite and 7.8% for total sulfite in the edible part of the shrimp. In the inedible part, CVs were 7.5% and 8.9% for free and total sulfite, respectively. Mean recovery was 87.8% for the edible part and 84.4% for the inedible part of the shrimp. The method was compared with the optimized Monier-Williams method. The results obtained with both methods for determination of total SO2 in the edible part of the shrimp did not show significant differences (P = 0.05).