Origin of Hydrogen Sulfide in Heated Chicken Muscle

SUMMARY About 90% of the hydrogen sulfide (H 2 S) produced by heated chicken muscle comes from muscle protein. To identify specific H 2 S precursors, the identity, quantity, and H 2 Sproducing capability of sulfur compounds in chicken muscle were investigated. The only sulfur compounds found in muscle nonprotein were methionine, taurine, and glutathione. Of these, only glutathione produced H 2 S. Therefore the principal H 2 S precursor in chicken muscle nonprotein is sulfur, occurring as eystine and/or cysteine in the tripeptide glutathione. Since the only sulfur compounds reported in chicken muscle protein are methionine, cystine, and/or cysteine, and since methionine does not produce H 2 S, the sulfur in the H 2 S produced by muscle protein must also come from cystine and/or cysteine. Glutathione gives off H 2 S about 180 times as fast as does chicken muscle protein, but, because there is approximately 1 to 2 thousand times as much protein as glutathione in muscle, protein is the principal H 2 S precursor. Since cystine plus cysteine, sulfur in protein and in glutathione is the only H 2 S precursor, the rate of H 2 S evolution from heated chicken muscle can be approximately predicted from its cystine content.