School of Physics and Astronomy, The University of Edinburgh, Edinburgh EH9 3FD, United Kingdom.
School of Physics and Astronomy, The University of Edinburgh, Edinburgh EH9 3FD, United Kingdom;
Proc Natl Acad Sci U S A. 2019 May 21;116(21):10303-10308. doi: 10.1073/pnas.1901858116. Epub 2019 May 7.
The mixing of a powder of 10- to 50-μm primary particles into a liquid to form a dispersion with the highest possible solid content is a common industrial operation. Building on recent advances in the rheology of such "granular dispersions," we study a paradigmatic example of such powder incorporation: the conching of chocolate, in which a homogeneous, flowing suspension is prepared from an inhomogeneous mixture of particulates, triglyceride oil, and dispersants. Studying the rheology of a simplified formulation, we find that the input of mechanical energy and staged addition of surfactants combine to effect a considerable shift in the jamming volume fraction of the system, thus increasing the maximum flowable solid content. We discuss the possible microscopic origins of this shift, and suggest that chocolate conching exemplifies a ubiquitous class of powder-liquid mixing.
将 10-50μm 粒径的初级颗粒粉末混入液体中形成尽可能高固含量的分散体是一种常见的工业操作。在最近对这种“粒状分散体”流变学的研究进展的基础上，我们研究了这种粉末掺入的一个典型例子：巧克力调温，在巧克力调温中，从不均匀的颗粒、甘油三酯油和分散剂混合物中制备出均匀、流动的悬浮液。通过研究简化配方的流变学，我们发现机械能量的输入和分阶段添加表面活性剂相结合，会使系统的堵塞体积分数发生相当大的变化，从而提高最大可流动的固体含量。我们讨论了这种转变的可能微观起源，并提出巧克力调温是粉末-液体混合的一个普遍范例。
