Sulfhydryl and Disulfide Groups in Meats

Abstract

This chapter discusses the methods for determination of sulfhydryl (SH) and disulfide (SS) groups in meats and their advantages and disadvantages. The choice of determination method depends on the type of investigation in question. Protein SH groups may react quickly, slowly or not at all depending on the type of reagent, on the protein's state, and on the conditions of reaction. Meat contains both protein SH and nonprotein SH groups. Results found in the literature do not always show clearly whether it is the total SH or the SH content only in a soluble fraction that was determined. This differentiation is important because most SH groups are bound to the water insoluble myofibrillar proteins. One of the most convenient and accurate techniques for the determination of SH groups in meat is a “double–indirect” amperometric titration method. The sum of SH and SS represents the total cystine content. In general, the total SH as well as the nonprotein SH contents of the same organs of different species are less variable than the SH contents of different organs of the same species. The texture of meat is influenced by the formation of SS groups during heating. As the nonprotein N content increases, the SH/N ratio decreases simultaneously. Several SH compounds are able to potentiate the microbial inhibition effect of known food preservatives.