Evaluation of a casein micelle structure using neutron small-angle scattering

Abstract

　The structure of a bovine casein micelle has not yet been definitively identified. In this study, the casein micelle structure was investigated by neutron small-angle scattering (SANS) technique. Reconstructed milk obtained by adding various ratio of D₂O/H₂O mixed water into freeze-dried skim milk were used as samples. It was confirmed that experimentally obtained SANS profile was different from that obtained by X-ray small-angle scattering (SAXS). By calculating scattering length densities, the matching point between the scattering length density of casein micelle and serum was obtained to be D₂O/H₂O=40/60. SANS profiles were fitted and analyzed using the micelle model including water domains which is proposed by our research group as a new casein micelle model. It was found that SANS profile could be almost reproduced, when the channel structure having periodic length of 17.9 nm was taken into account in the micelle model with water domains.