Abstract
A large portion of the shrimp harvested in the Gulf of Mexico are treated with sodium bisulfite to prevent melanosis. The Food and Drug Administration recognizes the need for this additive and regards a one minute dip in a 1.25% sodium bisulfite solution as current good manufacturing practice (CGMP). Recently, sulfites have come under close scrutiny by regulatory authorities because they have been implicated as causing severe reactions in asthmatics. The objective of this study was to develop a rapid, efficient method for determining SO₂ in shrimp and to determine the stability of SO₂ in shrimp during frozen storage. Fresh shrimp, harvested in the Gulf of Mexico, were transported to the Seafood Technology laboratory, headed, sorted according to size and species, then dipped in sodium bisulfite according to CGMP. These shrimp were then either tested immediately after treatment or placed in frozen storage. Frozen shrimp, previously dipped according to CGMP contain from 60 to 93 ppm SO₂ as estimated using the Monier-Williams procedure. After 5 to 10 days of frozen storage, these values ranged from 54 to 86 ppm SO₂. The USFDA's limit of 40 ppm SO₂ on peeled shrimp was unattainable, regardless of size or species. Loss of SO₂ was independent of frozen storage time and species. Preliminary extractions of SO₂ from shrimp using distilled water, tris buffer and/or heat treatment were ineffective. Therefore alkaline extraction at pH 11.66 was used to recover SO₂ from the shrimp. Two p-rosanaline methods recovered 24% more SO₂ than the Monier-Williams procedure, and although both correlated well with this procedure, they had no correlation between themselves (r = 0.13). The Monier-Williams procedure was capable of detecting the absence of SO₂ in shrimp, but was only able to recover from 44 to 59% of SO₂ from shrimp spiked with 50 to 200 ppm SO₂, while the enzyme method recovered 64 to 91% of the available SO₂ in these shrimp. Using partial recovery techniques and alkaline extraction, the dual enzyme procedure was able to recover 48% more SO₂ than the Monier-Williams procedure, however, the two methods did not correlate well, r = 0.33. By using quantitative recovery methods and alkaline extraction, the enzyme procedure recovered 43% more SO₂ than the Monier-Williams procedure and the two methods had an excellent correlation, r = 0.933.
DeWitt, Bernard John (1987). An improved methodology for the estimation of sulfur dioxide in shrimp. Texas A&M University. Texas A&M University. Libraries. Available electronically from
https : / /hdl .handle .net /1969 .1 /DISSERTATIONS -745803.