Degradation and conversion of thiamin and thiamin phosphate esters in fresh stored pork and in raw sausages.
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 0.5h after slaughter: non-phosphorylated T, 1.0nmol/g; thiamin monophosphate (TP), 1.3nmol/g; thiamin diphosphate (TP(2)), 9.1nmol/g; and thiamin triphosphate (TP(3)), 65.7nmol/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 15.0nmol/g. After 216h storage, the contents (on protein basis) of T and TP had changed as follows: 46.3nmol/g T; 3.2nmol/g TP, 5.0nmol/g TP(2), and 12.5nmol/g TP(3), The fifth substance completely degraded within 6h. 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 24h of storage from 92.1nmol/g to 24.0nmol/g, followed by an increase to 67.0nmol/g over a 216h storage period. One possible explanation for the decrease observed during the first 24h might be that thiamin is converted into a reversible, binding form that cannot be extracted by trichloroacetic acid.
Poel
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Institute of Food Toxicology and Analytical Chemistry, Department of Analytical Chemistry - Center for Food Science, University of Veterinary Medicine Hannover, Foundation, D-30173 Hannover, Germany.
Bäckermann
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Ternes
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