Does anyone know any tricks to keep a opened container of formula "fresh" longer? I mostly nurse, but I'm currently too lazy to pump, so I bought some formula for my mom to give Reid when she watches him (about three times a week while I run.) So, he's getting like 3 formula bottles a week, tops. I was looking at the formula container today, and it said that once it's opened it's only good for a month, which means I'm going to have to throw most of it away soon and buy a whole new one. That seems like such a waste! Is there anything I can do (I don't know, refrigerate or air tight bags or something?) that would keep it fresh longer? I know you can also buy those individual serving pre-mixed bottles but he has to have soy and I haven't seen them in soy. I bought the smallest container they had, but it's still mostly going to be wasted. Boo!