2011年《粉末技术》上有一篇相关论文,将奶粉、豆奶、速溶咖啡等粉末的冲泡分为4个阶段:i) the wetting of the agglomerate followed by the penetration of the liquid into the pore system due to capillary forces(团聚体的润湿,随后液体因毛细力而渗入孔隙系统)
ii) the immersion of the agglomerate into the liquid(团聚体浸入液体)
iii) the dissolution of the solid bridges between the primary particles followed by the dispersion of the primary particles within the liquid volume(初级粒子之间的固体桥的溶解,随后初级粒子在液体体积内分散)
iv) the dissolution of soluble primary particles(可溶性初级粒子的溶解)
显然,奶粉由干其疏水特性,在第一步(润湿)便卡住了,于是形成外层被润湿,内部保持干燥的一个团,内部干燥的粉有约10~15%的空气。毛细现象使得液体能通过粉间的缝进入这个团,但由于粉疏水,内部有空气的因素,只能渗入2~4mm(冲水后短期,之后会越来越深)
那么,只要团内没有空气,毛细现象自然是大大的促进,所以你只要一台真空机,冲豆奶时把它放进真空机中进行磁搅拌便可得到一杯完美的豆奶

Forny L , Marabi A , Palzer S . Wetting , disintegration and dissolution of agglomerated water soluble powders [ J ]. Powder technology ,2011,206(1-2):72-78.