True density, apparent density, and pore size distribution were measured for a vacuum cooled cooked beef product using helium pycnometry and mercury porosimetry. Vacuum cooled samples resulted in the development of high porosity and lower density in comparison to more conventional cooling methods. Pore size distribution for vacuum cooled samples revealed the presence of random pore sizes with no distinct pore size but rather a pore size range of 10 μm to 0.02 μm. It was determined that the vast majority of porosity in vacuum cooled samples was composed of void space volume as distinct to regular pores. Analysis of estimated diffusion coefficients revealed that the efficiency of vacuum cooling is dependent on the development of porosity within the samples during cooling which leads to more efficient cooling times and higher diffusion rates in samples with higher porosity and larger pore size distributions.