Degradation and conversion of thiamin and thiamin phosphate esters in fresh stored pork and in raw sausages

Abstract

Pork samples were extracted with trichloroacetic acid (4%) and analyzed for thiamin (T) and thiamin phosphate esters with high performance liquid chromatography (HPLC). The following concentrations (on protein basis) were found in samples analyzed 0.5 h after slaughter: non-phosphorylated T, 1.0 nmol/g; thiamin monophosphate (TP), 1.3 nmol/g; thiamin diphosphate (TP 2), 9.1 nmol/g; and thiamin triphosphate (TP 3), 65.7 nmol/g. A fifth substance was also detected, which has not yet been identified in pork and may be related to thiamin tetraphosphate (TP 4) or adenosine thiamin triphosphate (ATP 3); when calculated as thiamin tetraphosphate the content (on protein basis) of the fifth substance was 15.0 nmol/g. After 216 h storage, the contents (on protein basis) of T and TP had changed as follows: 46.3 nmol/g T; 3.2 nmol/g TP, 5.0 nmol/g TP 2, and 12.5 nmol/g TP 3, The fifth substance completely degraded within 6 h. These changes are probably due to the instability of highly phosphorylated thiamin phosphate esters, which undergo dephosphorylation during storage. In addition, there was a decrease in total thiamin concentrations (on protein basis) during the first 24 h of storage from 92.1 nmol/g to 24.0 nmol/g, followed by an increase to 67.0 nmol/g over a 216 h storage period. One possible explanation for the decrease observed during the first 24 h might be that thiamin is converted into a reversible, binding form that cannot be extracted by trichloroacetic acid.