Purpose of grinding with sand and tca in preparing glycogen?

Glycogen is extracted from animal tissue. This tissue is actually pretty tough and to liberate the glycogen from it, the tissue has to be ruptured, broken down nicely, so that all the glycogen is available for extraction. This grinding (homgenizing) process is aided by the presence of sand and TCA (Tri-Chloro Acetic acid). TCA is a higly corrosive agent and helps in rupturing the tissue.