TY - JOUR
T1 - Structural and compositional characterization of Ca- and β-casein enriched casein micelles
AU - Møller, Thea Lykkegaard
AU - Bang Nielsen, Søren
AU - Pedersen, Jan Skov
AU - Corredig, Milena
PY - 2024/6
Y1 - 2024/6
N2 - There is an increased interest in understanding the potential of modifying casein micelles composition, or even creating them de novo. In this study, soluble casein fractions were created by dissociation from native casein micelles, and their properties were studied in isolation, and after their addition to native casein micelles. The structure of these enriched casein micelles was investigated by small-angle X-ray scattering (SAXS) to evaluate if the enrichment caused changes in their internal structure. Acidification of native casein micelles from pH 6.8 to 5.6 caused colloidal calcium phosphate dissociation, and SAXS data showed a decrease in intensity at q = 0.08 Å−1, where q is the modulus of the scattering vector. Additionally, the acidification of native casein micelles (to pH 6.0) and incubation at 4 °C caused a decrease in scattering intensity at the intermediate q region (0.01–0.02 Å−1), signifying a loss of heterogeneity among the intermediate structure elements in the casein micelle. This change was caused by micellar dissolution of calcium phosphate and the release of β-casein at 4 °C. After the resuspension of casein micelles with a β-casein enriched serum, the absence of soluble β-casein suggested that most β-casein was re-associated in the colloidal fraction. These samples showed no changes in the structural features probed by SAXS. The work brings new evidence that, while a small extent of dissociation may affect the structure of the casein micelles, the enrichment with β-casein results in similar structures as those of the native micelle.
AB - There is an increased interest in understanding the potential of modifying casein micelles composition, or even creating them de novo. In this study, soluble casein fractions were created by dissociation from native casein micelles, and their properties were studied in isolation, and after their addition to native casein micelles. The structure of these enriched casein micelles was investigated by small-angle X-ray scattering (SAXS) to evaluate if the enrichment caused changes in their internal structure. Acidification of native casein micelles from pH 6.8 to 5.6 caused colloidal calcium phosphate dissociation, and SAXS data showed a decrease in intensity at q = 0.08 Å−1, where q is the modulus of the scattering vector. Additionally, the acidification of native casein micelles (to pH 6.0) and incubation at 4 °C caused a decrease in scattering intensity at the intermediate q region (0.01–0.02 Å−1), signifying a loss of heterogeneity among the intermediate structure elements in the casein micelle. This change was caused by micellar dissolution of calcium phosphate and the release of β-casein at 4 °C. After the resuspension of casein micelles with a β-casein enriched serum, the absence of soluble β-casein suggested that most β-casein was re-associated in the colloidal fraction. These samples showed no changes in the structural features probed by SAXS. The work brings new evidence that, while a small extent of dissociation may affect the structure of the casein micelles, the enrichment with β-casein results in similar structures as those of the native micelle.
KW - Casein dissociation
KW - Casein micelle structure
KW - Casein recombination
KW - SAXS
KW - β-casein enrichment
UR - http://www.scopus.com/inward/record.url?scp=85183629068&partnerID=8YFLogxK
U2 - 10.1016/j.foodhyd.2024.109811
DO - 10.1016/j.foodhyd.2024.109811
M3 - Journal article
SN - 0268-005X
VL - 151
JO - Food Hydrocolloids
JF - Food Hydrocolloids
M1 - 109811
ER -