Freezing creates a "salting out" precipitate of the tissue; tissues recombined on a salt chemistry level. It will not go back into solution.

Thank you Richard..

Is there any solution for this.

Can we prevent this?

Did you freeze the supernatant or the whole lysate and what was the concentration.

I worked with brain lysates in urea (7M), which were fine after centrifugation at concentrations around 2mg/ml.

Thank you for your reply Markus.

I freeze only the supernatent. The concentration was 100 mg/ml

This is far too concentrated to freeze it, you will get some kind of jelly then. i would not

recommend more then 10-20mg/ml, which is still critical.