I order extracts from NB and most of them come with a disposable mesh bag with specialty grains, the instructions specifying to take the grains out after the temperature reaches 170*F.
After pulling the mesh bag out, I have always squeezed it relentlessly to get every drip out of the mesh bag (often hurting myself from the heat in the process -- but I figured it was worth it).
Just 2 minutes ago, however, I was squeezing the mesh bag as normal when I noticed that the liquid seeping out of the mesh bag was altering the color of the (pre-)wort, and it struck me that this might not be a good idea. Thinking back on it, I've seen this before but it never bothered me.
Primary question: is it ok to squeeze the bag to remove every particle of liquid?
Secondary question: what accounts for the difference in color that I noted while squeezing the bag?