How does the gycogen isolation process work?

The supernatant fraction of the homogenized liver was added with acetic acid, and was boiled for 10 minutes. It was centrifuged and the precipitate was discarded. The filtrate was cooled to room temperature and was cooled in the refrigerator. Then ethanol was added and appearance of white flocculent precipitate was observed. The solution was then left in the refrigerator for one hour and was centrifuged.





What happened here? What was the role of Acetic acid and ethanol in the process?How does the gycogen isolation process work?
(1) Acetic acid produced the first glycogen precipitate, which constituted approximately 85% of the total glycogen of the liver.





(2) The white flocculent precipitate, produced by placing the supernatant in a cold room with 95% ethanol for more than an hour, is the remaining glycogen fraction of the liver, as well as some RNA.