Unsteady heat transfer in a macroscopically isotropic and homogeneous particulate mixture is considered with the help of a general approach based on averaging the local heat conduction equations valid in mixture phases over a configurational ensemble of particles and on ideas of the self-consistent field theory. A closed set of equations for the mean temperatures of the phases is derived by neglecting the direct heat transport through contacts with contiguous particles. Both mean heat flux and interphase exchange are shown to be essentially frequency dependent so that the effective heat conductivity deviates considerably from its stationary value. This is representative of the relaxation processes influencing unsteady heat transfer and generates corresponding dispersion effects. Under the weak non-stationary condition the set can be reduced to either a single 'equivalent' equation belonging to the elliptic type or a system of two simplified equations whose reliability has been discussed in detail previously on the example of heating a motionless granular bed through a flat boundary.