TY - JOUR
T1 - Chymosin-induced hydrolysis of caseins
T2 - Influence of degree of phosphorylation of alpha-s1-casein and genetic variants of beta-casein
AU - Bijl, Etske
AU - van Valenberg, Hein
AU - Sikkes, Sybren
AU - Jumelet, Stijn
AU - Sala, Guido
AU - Olieman, Kees
AU - van Hooijdonk, Toon
AU - Huppertz, Thom
PY - 2014/12
Y1 - 2014/12
N2 - The objective of this study was to investigate the impact of natural variations in αS1-casein and β-casein composition of milk on chymosin-induced hydrolysis of these caseins in milk gels and in sodium caseinate solutions. At 50% casein degradation, 15% more of αS1-casein with eight phosphate groups was hydrolysed compared with αS1-casein with nine phosphate groups in chymosin-induced milk gels. Furthermore, in sodium caseinate solutions, >10% more β-casein A2 was degraded compared with β-casein A1 and B at 50% casein degradation. Proteolysis by chymosin was not impacted by natural variation in the αS1-casein/β-casein ratio. Natural variation in αS1-casein/β-casein ratio did not impact upon firmness and gel strength in milk gels. Overall, comparison of sodium caseinate solutions to milk gels showed that differences in either phosphorylation of αS1-casein or amino acid composition of β-casein caused significant differences in degradation by chymosin, possibly due to changes in physical conformation of caseins.
AB - The objective of this study was to investigate the impact of natural variations in αS1-casein and β-casein composition of milk on chymosin-induced hydrolysis of these caseins in milk gels and in sodium caseinate solutions. At 50% casein degradation, 15% more of αS1-casein with eight phosphate groups was hydrolysed compared with αS1-casein with nine phosphate groups in chymosin-induced milk gels. Furthermore, in sodium caseinate solutions, >10% more β-casein A2 was degraded compared with β-casein A1 and B at 50% casein degradation. Proteolysis by chymosin was not impacted by natural variation in the αS1-casein/β-casein ratio. Natural variation in αS1-casein/β-casein ratio did not impact upon firmness and gel strength in milk gels. Overall, comparison of sodium caseinate solutions to milk gels showed that differences in either phosphorylation of αS1-casein or amino acid composition of β-casein caused significant differences in degradation by chymosin, possibly due to changes in physical conformation of caseins.
UR - https://www.scopus.com/pages/publications/84905698736
U2 - 10.1016/j.idairyj.2014.07.005
DO - 10.1016/j.idairyj.2014.07.005
M3 - Article
AN - SCOPUS:84905698736
SN - 0958-6946
VL - 39
SP - 215
EP - 221
JO - International Dairy Journal
JF - International Dairy Journal
IS - 2
ER -