 Solution

The coarse texture comes from large ice crystals. Form many small crystals by rapid cooling with agitation and avoid extended storage near partial melting or repeated warming/cooling cycles. Curvature raises the chemical potential of smaller ice crystals, so material can transfer from smaller to larger crystals during recrystallization; partial melting followed by slow refreezing accelerates loss of a fine texture. A more viscous unfrozen phase and suitable stabilizing ingredients slow molecular transport and coarsening. Create small crystals quickly and suppress their subsequent growth with stable cold storage and slow transport. This applies interfacial and phase-change physics; it is not a claim that reducing droplet vapor pressure alone completely models a multicomponent frozen mixture.