Yes, it is fine to split the boiling of peanuts over two days as long as you store them safely overnight. The FDA recommends storing hot foods at 140° F or hotter, and cold foods at 40° F or colder.
It is not safe to keep a pot of peanuts simmering overnight on the stove, therefore I suggest you put the peanuts in the refrigerator overnight. You can store the partially boiled peanuts in the salt water, or drain them before refrigeration.
Jan 01, 2014
Ice by: Dan
I don't know how many you're cooking, but I use ice in my pots. I cook about 100 pounds at a time and I have drains, just drain the water and put ice in the pot.
Jan 01, 2014
Ice by: Bret
Dan, thank you for posting about using ice to cool hot boiled peanuts. It is best to cool the peanuts quickly in order to minimize the time that the boiled peanuts are within the temperature danger zone, which is between 40° F and 140° F.
On further reading I realize that it is not recommended to put a large amount of hot boiled peanuts directly into the refrigerator, or freezer. The hot peanuts do not cool quickly enough to ensure minimum time in the temperature danger zone. Further, the heat from the boiled peanuts will raise the temperature inside the refrigerator, which may cause spoilage of other foods in the refrigerator.
Putting clean ice directly in the pot of fresh boiled peanuts will cool the contents quickly. Reboiling the iced boiled peanuts should take care of any possible contaminants that were in or on the ice. Of course, the ice should be made from drinking water, and handled with clean utensils to prevent cross contamination.
Another approach to rapidly cooling hot foods is to use an ice bath, where the peanuts do not come in direct contact with the ice. Place the pot of boiled peanuts and brine in a sink filled with ice. As the ice melts, drain the water, and replenish the ice until the contents of the pot reach 40 F. Then they can safely put in the refrigerator for overnight storage.
For further reading on safely cooling foods see this pdf.