Selective fortification of lysinoalanine, fructoselysine and N epsilon-carboxymethyllysine in casein model systems.
In the present study, a promising strategy to study nutritional effects of selected chemical reaction products formed in heat treated protein containing foods is addressed. In due course, a selective fortification of different marker compounds for lysine damage in casein-sugar mixtures was performed to provide model systems being applicable to investigate biological effects of the cross-link lysinoalanine (LAL), the MRPs fructoselysine (FL) and N epsilon-carboxymethyllysine (CML) in a casein-linked preparation. The three different model proteins, casein-LAL, casein-FL and casein-CML were prepared by heating casein either in strong alkaline conditions at 105 degrees C for 1 h, in the presence of glucose at 65 degrees C for 68 h, or in the presence of glyoxylic acid at 37 degrees C for 19 h. Finally, the degree of lysine modification achieved was 39%, 75% and 55% for the casein-LAL, casein-FL and casein-CML, respectively. The calculation of lysine recovery and the respective analysis of each single modified casein (LAL-, FL- and CML-MP) for the selected fortified compound and each other compound vice versa proved that the individual procedure provides a specific fortification for LAL, FL and CML, respectively. The modified proteins are suitable as reference model proteins to be investigated for specific biological and toxicological effects of casein-linked LAL, FL and CML.
Faist
V
V
University of Kiel, Institute for Human Nutrition and Food Science, Duesternbrooker Weg 17, D-24105 Kiel, Germany. vfaist@nutrfoods.uni-kiel.de
Müller
C
C
Drusch
S
S
Erbersdobler
H F
HF
D002364:Caseins / Q000737:chemistry*; D005511:Food Handling; D006863:Hydrogen-Ion Concentration; D008239:Lysine / Q000031:analogs & derivatives* / Q000737:chemistry*; D008241:Lysinoalanine / Q000737:chemistry*; D015416:Maillard Reaction; D008956:Models, Chemical; D013696:Temperature
D002364:Caseins; C005205:epsilon-N-methyllysine; D008241:Lysinoalanine; C033186:fructosyl-lysine; D008239:Lysine