I'm glad you decided to post the recipe and method, as it allowed me to analyse the recipe. What I think is happening is, as you are freezing the kebab meat the unbound water contracts causing micro fissures, then as the log is heated and some unbound water expands it is forcing these micro fissures open.
The cure is to bind all the water. The easiest way of doing this is to add some tri-phosphate to your mix, this should bind any unbound water solving the problem.