Gelation of casein micelles with different origins observed by spin-echo small-angle neutron scattering

Dairy production has a large impact on the environment. Cheese has one of the highest amounts of greenhouse gas emission and land use among protein rich food products [1]. We are proposing a novel way to produce dairy products, namely, we will use yeasts to express the different types of milk caseins and assemble them into micelles. To verify the possibility of assembling the individual components into micelles, we would like to compare the structural properties of skim milk with reconstituted casein micelles. Small-angle X-ray and neutron scattering has been shown to be a suitable method to describe the internal structure of casein micelles [2][3]. However, upon acidification the primer casein micelles form networks. The resulted particles are too big to investigate with classical small-angle scattering. Spin-echo small-angle neutron scattering (SESANS) has been shown to be a powerful method to investigate the structure of milk upon acidification [4]. We would like to set up a set of experiment of skim milk, reconstituted casein micelles and micelles assembled from its components and investigate the evolution of structure by decreasing the pH by the means of SESANS. References [1] Poore, J. et. al. (2018) 360(6392), 987-992. [2] Ingham, B. et. al. (2016) 12(33), 6937-6953. [3] Holt, C. et al. (2003) 213(2-3), 275-284 [4] Tromp, R. H. et. al (2007) 21(2), 154-158.乳制品生产对环境具有显著影响。在高蛋白食品品类中，奶酪的温室气体排放量与土地占用量均位列前茅[1]。 本研究提出一种新型乳制品制备路径：通过酵母表达不同类型的乳源酪蛋白，并将其组装为胶束（micelles）。为验证单一组分组装为胶束的可行性，本研究拟对比脱脂乳与重组酪蛋白胶束的结构特性。 小角X射线与中子散射（Small-angle X-ray and neutron scattering）已被证实可用于表征酪蛋白胶束的内部结构[2][3]。然而，经酸化处理后，原生酪蛋白胶束会形成网状结构，由此产生的颗粒尺寸过大，无法通过经典小角散射技术开展表征。 自旋回波小角中子散射（Spin-echo small-angle neutron scattering，SESANS）已被证实是研究酸化乳体系结构的有效手段[4]。本研究拟搭建针对脱脂乳、重组酪蛋白胶束及由其组分组装而成的胶束的实验体系，并通过自旋回波小角中子散射技术，探究pH降低过程中的结构演化规律。 参考文献 [1] Poore, J. et. al. (2018) 360(6392), 987-992. [2] Ingham, B. et. al. (2016) 12(33), 6937-6953. [3] Holt, C. et al. (2003) 213(2-3), 275-284 [4] Tromp, R. H. et. al (2007) 21(2), 154-158.