Abstract
Bovine milk contains 3-4 % protein and almost 80% of the milk protein fraction consist of four caseins; αs1-casein, β-casein, αs2-casein and κ-casein. Most of the caseins in milk are assembled in casein micelles, which consist of several thousands of individual casein molecules and salts. The unique structure of casein micelles allows the delivery of large amounts of calcium and phosphate to the neonate. Considerable natural variation in casein content and composition exists between milk samples from individual cows, however the impact of these variations on casein micelle structure and technological properties of dairy products are largely unknown. This study showed that the expression of caseins and their post-translational modification as well as inclusion of calcium in casein micelles are well-balanced processes. Analysis of the genetic background of phosphorylation of αs1-casein with eight or nine phosphate groupsshowed that αs1-casein phosphorylation was regulated by a different set of genes. Also, variation in αs1-casein phosphorylation resulted in changes in the core of casein micelles and was associated with a difference in degradation efficiency by chymosin in milk gels. Another post-translational modification, glycosylation of κ-casein, resulted in changes in the surface of casein micelles. Natural variation in αs1-CN phosphorylationand glycosylation of κ-casein are both relevant factors to consider for optimization of dairy products and the design of future breeding strategies.
| Original language | English |
|---|---|
| Qualification | Doctor of Philosophy |
| Awarding Institution |
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| Supervisors/Advisors |
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| Award date | 23 May 2014 |
| Place of Publication | Wageningen |
| Publisher | |
| Print ISBNs | 9789461739445 |
| Publication status | Published - 2014 |
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Keywords
- milk
- casein
- milk composition
- variation
Cite this
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Natural variation in casein composition of milk. / Bijl, E.
Wageningen : Wageningen University, 2014. 145 p.Research output: Thesis › internal PhD, WU
TY - THES
T1 - Natural variation in casein composition of milk
AU - Bijl, E.
N1 - WU thesis 5749
PY - 2014
Y1 - 2014
N2 - Bovine milk contains 3-4 % protein and almost 80% of the milk protein fraction consist of four caseins; αs1-casein, β-casein, αs2-casein and κ-casein. Most of the caseins in milk are assembled in casein micelles, which consist of several thousands of individual casein molecules and salts. The unique structure of casein micelles allows the delivery of large amounts of calcium and phosphate to the neonate. Considerable natural variation in casein content and composition exists between milk samples from individual cows, however the impact of these variations on casein micelle structure and technological properties of dairy products are largely unknown. This study showed that the expression of caseins and their post-translational modification as well as inclusion of calcium in casein micelles are well-balanced processes. Analysis of the genetic background of phosphorylation of αs1-casein with eight or nine phosphate groupsshowed that αs1-casein phosphorylation was regulated by a different set of genes. Also, variation in αs1-casein phosphorylation resulted in changes in the core of casein micelles and was associated with a difference in degradation efficiency by chymosin in milk gels. Another post-translational modification, glycosylation of κ-casein, resulted in changes in the surface of casein micelles. Natural variation in αs1-CN phosphorylationand glycosylation of κ-casein are both relevant factors to consider for optimization of dairy products and the design of future breeding strategies.
AB - Bovine milk contains 3-4 % protein and almost 80% of the milk protein fraction consist of four caseins; αs1-casein, β-casein, αs2-casein and κ-casein. Most of the caseins in milk are assembled in casein micelles, which consist of several thousands of individual casein molecules and salts. The unique structure of casein micelles allows the delivery of large amounts of calcium and phosphate to the neonate. Considerable natural variation in casein content and composition exists between milk samples from individual cows, however the impact of these variations on casein micelle structure and technological properties of dairy products are largely unknown. This study showed that the expression of caseins and their post-translational modification as well as inclusion of calcium in casein micelles are well-balanced processes. Analysis of the genetic background of phosphorylation of αs1-casein with eight or nine phosphate groupsshowed that αs1-casein phosphorylation was regulated by a different set of genes. Also, variation in αs1-casein phosphorylation resulted in changes in the core of casein micelles and was associated with a difference in degradation efficiency by chymosin in milk gels. Another post-translational modification, glycosylation of κ-casein, resulted in changes in the surface of casein micelles. Natural variation in αs1-CN phosphorylationand glycosylation of κ-casein are both relevant factors to consider for optimization of dairy products and the design of future breeding strategies.
KW - melk
KW - caseïne
KW - melksamenstelling
KW - variatie
KW - milk
KW - casein
KW - milk composition
KW - variation
M3 - internal PhD, WU
SN - 9789461739445
PB - Wageningen University
CY - Wageningen
ER -